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University of Nottingham Developing New Large-Scale Energy Storage Device Combining Properties of Supercapacitors and Batteries
21 June 2008
Researchers at the University of Nottingham (UK), supported by €1.4m (US$2.2 million) from E.ON, one of Europe’s leading power and gas companies, are developing new energy storage systems for use with renewable energy generation including a device that combines the properties of supercapacitors and batteries (“supercapattery”) and undersea compressed air storage bags.
The effective and efficient storage of energy produced from renewable sources such as wind, solar, wave and tidal power is a challenge facing the energy industry. As these types of renewables only produce energy under certain conditions, storage capacity will help ensure supply can be matched to demand.
Supercapattery storage system. Dr. George Chen in the University’s School of Chemical and Environmental Engineering and Dr. Christian Klumpner in the School of Electrical and Electronic Engineering are developing a new electrical energy storage system consisting of supercapatteries and power electronics. The core materials are chemically modified carbon nanotubes, and the power electronics ensure that the current flow is integrated in a stable and high-quality manner.
Electricity generated from renewable sources can be transported instantly through cables over long distances but storage is a problem—if you don’t use it, you lose it. Our aim is to develop something which will bring together the best of both worlds—the high electrical energy storage capacity of a battery and the fast charge/discharge rates of a supercapacitor.
—George Chen
The supercapatteries, which are constructed from carbon nanotubes chemically engineered with traditional battery materials, can be designed with different specifications depending on the user need, according to Chen. Two papers he and his colleagues recently published describe the use of manganese oxide-coated carbon nanotubes and conducting polymer-coated carbon nanotubes.
The specific capacitance (Farads per gram) of the manganese oxide-carbon nanotubes composite is normal (140~150 F/g), but the electrode specific capacitance (Farads per square centimeter) is very high. The value reported, 4~5 Farads per square centimetre, is actually the world record amongst all published results. The charge/discharge chemistry of this composite is mainly that of manganese oxide with some contribution from carbon nanotubes.
—George Chen
On its own a supercapattery would be ideal for powering a portable electrical device, but the researchers are investigating the potential of using stacks of supercapatteries which would offer energy storage on a large scale for a grid stabilization application.
Currently about five per cent of the power of the national grid is standing by in reserve (often thermal) in case of a power surge—for example when everyone puts their kettle on after the football match has finished. To have generators on standby costs a great deal of money, whereas these devices could be called into action at very short notice and provide extra power within a very short timeframe.
—George Chen
Undersea airbags. Professor Seamus Garvey in the University’s School of Mechanical, Materials and Manufacturing Engineering is looking at using a combination of wind, wave, tidal and solar power to compress and pump air into underwater bags anchored to the seabed. During periods of high demand, the air would be released through a turbine, converting it to electricity.
ICARES (Integrated Compressed Air Renewable Energy Systems) could help support the development of vast offshore energy farms off the coastline around the UK.
Resources
Xianbo Jin, Wuzong Zhou, Shengwen Zhang and George Z. Chen (2007) Nanoscale Microelectrochemical Cells on Carbon Nanotubes, Small, doi: 10.1002/smll.200700139
Chuang Penga, Jun Jina and George Z. Chen (2007) A comparative study on electrochemical co-deposition and capacitance of composite films of conducting polymers and carbon nanotubes, Electrochimica Acta, doi: 10.1016/j.electacta.2007.07.004
June 21, 2008 in Batteries | Permalink | Comments (107) | TrackBack (0)
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these kinds of developments are essential if we are really serious about increasing renewable energy to 15% of total generating capacity by 2020 (the current target). great work, and nice to see the UK leading rather lagging for once in cutting-edge tech.
Posted by: eric | Jun 21, 2008 8:03:37 AM
Smaller supercapacitor-battery combo may also be a very good solution as Hybrid-PHEV-BEV ESSUs, specially to capture the maximum decelleration-breaking energy and to supply the large short energy burst required for quick accellerations.
It makes you wonder why it's not on the market allready. Didn't an Australian Co. do it combined with a standard sealed Lead Battery? It should work with different battery technologies?
Any recent news on the ESStor ESSU?
Posted by: HarveyD | Jun 21, 2008 8:30:03 AM
This reminds me of altairnano's deal with AES to use their batteries in a way that reduces the need for spare capacity on the grid. What ever became of that deal?
Posted by: jimb | Jun 21, 2008 9:48:33 AM
if devices could be cheap enough and have a long enough life span, small businesses could install batteries at communities to make them "off peak". Specific power and energy be damned. Such a business would buy off peak power in bulk at say .05c/kW/hr and sell it to residents at $.10c/kW/h.
Posted by: GreenPlease | Jun 21, 2008 9:58:57 AM
Blah blah blah with the supercapatteries - I'm tired of this kind of hype. What is really interesting is UNDERSEA AIRBAGS. It sounds simple enough, but there are a lot of variables that need to be explored - ie. how deep? what kind of material for the bag? What is the energy input to fill the bag vs. energy output upon release at the sea floor as it floats to the surface? What are the potential implications on sea life?
Posted by: ejj | Jun 21, 2008 10:46:52 AM
The best way to store renewable energy is to use it to compress natural gas into vehicles during the night...the vehicles then run during the day. Perfect solution, 25% lower CO2 than petrol vehicles, no waste of energy.
Posted by: John Baldwin | Jun 21, 2008 12:16:13 PM
Reference:
http://www.cnn.com/2008/TECH/science/03/31/windpower/index.html?section=cnn_latest
Excerpt:
At a depth of around 600 meters, Professor Garvey calculates that the bags would be able to store 25 megajoules of energy for every meter cubed. The deep water is essential. "Only in deep water, where the pressure is greatest, are the bags a good economic proposition," Garvey explained.
At 15/lbs sq in for every 10 meters of water depth that is
(600/10)(15) = 900 lbs/sq in air pressure
Professor Garvey wants to put the air compressor in the blades of the wind mill. I can’t see how that can create the 900 lbs pressure needed. I see a high pressure compressor in the central housing connected to the central hub to do that.
I could be wrong here. If falling weights in the wind mill blades solution can be made to work, it is an elegant solution.
Also the undersea storage bags should be piped to an on shore power generator that converts the compressed air to electric power.
This is a peak energy producer. These floating wind mills can meet peak demand and their air storage should be reserved for that purpose.
There is no limit to the size of the air storage that can be implemented.
Another advantage here is that water pressure can reduce the strength and quality of the material needed (plastic) to contain the air pressure both in the bag and the undersea pipeline (until it emerges from the sea to shallow depth).
However, it will take some engineering to keep the air bags secured at the proper depth.
Another advantage is the elimination of the use of copper in the mill and undersea cables. At $4/lb that is a lot of money. Use only concrete, steel, and plastic in the construction.
The compressed air mill is simpler and more reliable than standard wind mill construction. This is very important in the offshore environment because of the difficulty of repair out at sea.
anther off shore wind mill story
http://www.bbc.co.uk/nottingham/content/articles/2007/10/12/wind_turbine_invention_feature.shtml
Posted by: Axil | Jun 21, 2008 12:16:42 PM
While the under sea air bags are an interesting alternative towards the very real need of a dispatchable storage device the batteries could hold a double reward. With all the various battery types out there Altairnano’s seem to hold the most promise with the ultra fast charge and discharge rates combined with a long lifespan if only the price was something that was affordable. Once again as with all the other promising hopefuls they are in a chicken or the egg situation. If only someone with deep pockets would buy a few million cells the rest of us could hop on for the ride. For all those types out there who like to legislate change, a simple requirement for the Wind Turbine folks “whose pockets are extremely deep” to store the energy up and provide it at a controlled rate could go along way towards providing power system stability and open the door for even more wind energy than is currently planned due to the limitations of the power system to regulate. And if they happened to use a proven technology as was demonstrated by AES and Altair then the rest of us just might be able to afford a few for our transportation needs. As far as the need to regulate wind farms it can’t be understated as I recently watched a 70 million watt wind farm oscillate between 40mw and 70mw as the wind gusted with an 8 second period and could see the frequency bouncing along with it. Nothing in the power system moves that fast not even hydro.
Posted by: Powerpro | Jun 21, 2008 12:19:40 PM
Powerpro:
Reference:
If it can be upscaled, A storage ring may be a better solution to the wind farm problem you saw.
Posted by: Axil | Jun 21, 2008 12:48:23 PM
Olde world domestic and small workshop battery chargers were constant current, constant voltage. Add a resistor and the voltage rises with state of charge, a simple improvement. More advanced versions allowed the option of fast charge.
Serious chargers started to become available with more voltage and current control, but it was up to the serviceman to manually match the output for the purpose in mind.
Trickle charge or in a stationary battery a 10* C thrash charge for a while to stir the electrolyte and discourage sulphation, and bridging, a good shake etc . This enabled the recovery of ailing batteries and improved the lifespan of others.
Meanwhile the consumer market had to wait for second generation Nicads , Alkaline alkaline, NiMh and laptop computers with auto sensing ,a"interrogative" smart chargers to have this in common everyday appliances.
There was no user adjustment possible, everything is performed by the "smarts"
The smarts could increasingly monitor or interrogate the type of battery, state of charge, heat, condition and set in place appropriate charging strategy.
In a laptop, similar strategies apply to the discharge side.
When the battery technology changes within the same family this system becomes challenged as there are now effectively as many strategies as manufactures and products.
Along came the idea that building some of the smarts into the battery ie capacitor will be a great help to battery manufacturer optimise their product on both charge and discharge cycles.
Windmill manufacturers are on the ball with smarts built in to some degree.
With this technology it should be possible to maximise the performance and reliability of battery technology.
Apparently the reported benefits(without knowing the extent of conditioning ) are meeting expectation.
Posted by: arnold | Jun 21, 2008 2:37:57 PM
The undersea airbag technology is actually closer than we think. Firefighters already use high pressure lifting bags capable of exerting (withstanding) tons of force. There could be banks and banks of these high pressure bags placed in deep-sea locations anchored to the sea floor with massive concrete blocks. There wouldn't need to be very many high-pressure lines leading to the bag assemblies. The pumps & specialized linkages could be located in the mill towers somewhere and be pretty much completely automated.
http://www.savatrade.com/hpliftbags.htm
http://www.google.com/search?hl=en&q=%22rescue%22%22lifting+bags%22
Posted by: ejj | Jun 21, 2008 2:44:37 PM
The energy losses will be to the usual friction losses as include the internal friction of the expansion, within wall of the piping. As the pipe expands the stretching will generate heat. At the pressures envisioned, heating of he conducting fluid(air?) will occur. Heat (pumping) losses and friction losses at these pressures need looking at.
Posted by: arnold | Jun 21, 2008 3:18:07 PM
John,very good point.
Its also cooler at night so elecrical resistances are lower, cooling requirements lower, and the gas is denser so volumetric efficiency is improved - the compressor looks bigger at night.
Diurnal now thats a nice word.
But while the larger expansion conraction frequency may be dayly, a microimpulse will occour at the frequency of the compressor.
Please read The WORKING fluid, to previous comment.
Posted by: arnold | Jun 21, 2008 3:43:32 PM
John,very good point.
Its also cooler at night so elecrical resistances are lower, cooling requirements lower, and the gas is denser so volumetric efficiency is improved - the compressor looks bigger at night.
Diurnal now thats a nice word.
But while the larger expansion conraction frequency may be dayly, a microimpulse will occour at the frequency of the compressor.
Please read The WORKING fluid, to previous comment.
Posted by: arnold | Jun 21, 2008 3:44:07 PM
the undersea bag idea is brilliant, one air line going down to the bags would be enough for storing power and releasing it. The compressed air would lose energy as it cools, and it is cold downthere.. ambient air, compressed to 900psi and then cooled to whatever temperature you have downthere. Can anyone calculate the energy losses?.. then again it is cheap storage, essentially free.. kind of the reverse of pumping water up to a reservoir and then releasing it to generate electricity when needed.
Posted by: Herm | Jun 21, 2008 4:49:33 PM
Herm, the short answer has to be no.
A feel for the reality may come from the proposed studies. The bag itself, as alluded to in the article and correct observation, is fairly well understood. Pump friction losses with current technologies are quite modelable, and well enough understood by laypersons to sink this idea (at least the extreme proposals) as horribly ineficcient. @200 psi we can pump lead. New ways of doing buisness and new materials not included, either reducing the working pressure or the flow either of wich reduces capacity of the system will be usefull - to workable.
But if efficiency is seen as relative.
Efficiency relative to 0 ( or X ? for the current battery storage methods) can be described as improved over say where a real world efficient system like pumpwater storage 90% +, is unavailable.
Not a magic bullet, possibly a good idea, but again depends on what can be cobbled together with the resources available.
There are similar concepts in wave power generation wich power the compressor directly with movement provided by rocking motion of waves and tidal rise and fall .
The same floating barge could presumably be a patform for wind turbine reducing infrastructure footprint smoothing in still times, carrying shipping hazard lights.
Heck why not go the whole hogg and desalinate then electrolyse a few barrels of H to be picked up by H powered tankers or cargo ships en route?
Posted by: arnold | Jun 21, 2008 6:26:02 PM
OOPS! 2,000 psi we can pump lead.
Posted by: | Jun 21, 2008 6:29:06 PM
Undersea airbag sounds cheap but may not be that cheap! That is due to the long 600-meter high-pressure corrosion-resistant pipe needed to reach the airbag at that depth, requiring considerable amount of material. The pipe must have large diameter in order to reduce the friction of airflow over such an extended distance. Heat loss from the tubing at that distance of travel and the coldness of the sea depth and the high thermal conductivity of sea water would reduce the efficiency of the CAS (Compressed-Air Storage). Making the airbag thicker for protection agains the Crustaceans snd stingrays (sharp shell and teeth) and more insulation would increase the cost.
Furthermore, anchoring and servicing anything at that depth requires much more than just SCUBA diving gears, adding to the cost, all for merely 900 psi of pressure.
By contrast, a large 900-psi steel tank on the surface serving as the floating base for each off-shore wind turbine, with minimum length of air tubing required, won't be that much more expensive, but much more serviceable. The wind turbine at 100-200 meters above will power an electrical generator, which supplies excess electricity down below to an electric motor powering an air compressor right next to the compressed air tank, which is insulated from heat loss to improve efficiency. This setup is more efficient.
For much higher-capacity of energy storage, the tank can be used to store hydrogen instead, that can store 20 times the energy as when compressed air is used. This would be what required for seasonal energy storage, from a season of high wind but low demand for used in a season with little wind but higher demand.
Posted by: Roger Pham | Jun 21, 2008 7:10:25 PM
Reference:
Fellow GCC contributors let dream big, and go all the way. Instead of batteries and smart grids let’s build the super grid. This grid can store electrical power with zero resistance if the superconductive cables are looped around the continent in a racetrack pattern. Electricity can be fed into this grid in the mid west by wind mills and extracted on the east or west coast without electrical loss. All generation that feeds this grid can stop and the grid will act as a big battery until all the circling electrons are used. The grid can absorb power spikes intermittent power generation and generation failures like a lake can absorb a thunderstorm.
Unlike in the smart grid, no expensive microprocessor controls are needed. Every thing is done by the laws of physics like water in a pipeline and a tank.
This grid uses liquid hydrogen filled pipes to carry massive currents in new iron superconductors at 20k.
Another related dream is super conductive energy storage in cars. A few megawatts can be stored in a coil of 100 miles of iron superconductive wire. Recharge can be done in seconds and liquid hydrogen is used only to cool the superconductor.
When someone discovers a room temperature superconductor the super grid cost will drop from a trillion dollars to a few billon dollars. Then, no hydrogen cooling is required.
Such a discovery will be the equivalent of cold fusion: a game changer.
Posted by: Axil | Jun 21, 2008 7:35:24 PM
@ Roger Pham
long 600-meter high-pressure corrosion-resistant pipe needed to reach the airbag at that depth, requiring considerable amount of material
Commercial off the shelf high pressure plastic large diameter pipe is now available.
Making the airbag thicker for protection agains the Crustaceans snd stingrays (sharp shell and teeth) and more insulation would increase the cost.
Commercial fishing net will protect the bags from fish.
Furthermore, anchoring and servicing anything at that depth requires much more than just SCUBA diving gears, adding to the cost, all for merely 900 psi of pressure.
Raise the mostly empty bags to the surface for repair by wench, then after repair, lower it back down.
By contrast, a large 900-psi steel tank on the surface serving as the floating base…..
IF there is no difference in pressure between the air and the water a very thin plastic can be used for the bag.
Only the large pressure difference on the surface requires steel.
The stress points are at the fastening points for the restraining bands keeping the bag under the water because of the large floatation force. This will require some engineering to minimize the structure and the material used.
The simplicity of the Seamus Garvey's design is what makes it elegant. It is really only a large high pressure bicycle pump in each wind mill rotor blade. There is only one moving part: The falling weight that forces air down through a one way valve.
KISS is the governing design principal.
Posted by: Axil | Jun 21, 2008 10:08:18 PM
>>"The stress points are at the fastening points for the restraining bands keeping the bag under the water because of the large floatation force. This will require some engineering to minimize the structure and the material used."
Care to elucidate the magnitude of the flotation force, Axil? Water weighs one tonne per cubic meter! Forget about using a thin bag, since for a bag the size of a medium-size room 3m x 5m x 5m would cause flotation force of ~70 tonnes (148,000 lbs). This the weight of a Boeing 737 at takeoff. You will need a heck of a bag to hold that kind of force, and a heck of an anchor at the sea floor to keep it down. I'd choose a steel tank for CAS, doubled as a flotation platform for the wind turbine, over those super sea bag anytime.
>>"Commercial off the shelf high pressure plastic large diameter pipe is now available."
Large-diameter plastic pipe that can withstand 900 psi for 600 meter long? Must be a heck of a pipe, awfully thick plastic...(read: expensive) or carbon-fiber reinforced (read: more expensive). Steel tank is dirt-cheap, even after having a corrosion-proof coating.
It would not be practical to couple the wind turbine directly to the air pump, since the wind varied greatly in speed, hence the available torque on the turbine shaft. At higher wind speed, it would be difficult to harness the higher torque available from the wind turbine shaft without using a mechanical transmission placed between the compressor and the turbine shaft. Otherwise, wind energy will be wasted. By contrast, an electrical generator can directly absorb the higher torque of the wind turbine at higher wind speed, up to a point, of course, hence can get more energy out of a wind turbine without requiring a mechanical transmission requiring more frequent servicing...Just what you don't need in an off-shore device.
The superconducting powerline sounds good, though, as was once featured in Scientific American. Transporting electricity and H2 all in the same line is tough to beat.
Posted by: Roger Pham | Jun 21, 2008 11:40:27 PM
LOL.
From basic thermodynamics of ideal gases, for example from this article:
http://www.efcf.com/reports/E14.pdf
it is obvious that overall efficiency of undersea compressed air energy storage/release cycle is less than 40% theoretical limit, and on practice will be less than 30%.
Posted by: Andrey Levin | Jun 21, 2008 11:42:02 PM
Currently pumps of energy storage lakes are powered by coal and nuclear power plants, in the future they will be powered by renewable energy.
http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
An energy storage lake can store way more energy than a flywheel or a battery and reaches efficiencies of 80%.
There are single pump-turbine-generators with a power rating of 1000 MW. Enough power for over 300 Windturbines during storm conditions.
Transmitting electricity over thousands of miles with little losses is easy and available now:
http://www.abb.com/hvdc
Why wait for fancy solutions, why not just do it?
Posted by: Realist | Jun 22, 2008 1:38:28 AM
Realist:
Hydro pumping energy storage is severely limited. Moreover, it is freakishly expensive, and makes economical sense only for daily leveling of peak electricity demand.
Any intermittent electricity generating source, like wind or solar, robs the system from highly valuable maneuverable reserves.
To put it simple, you can have 20% renewable electricity mix in the grid for overall 20 cents per KWh, or you can have coal/nuclear baseload with hydro and hydro pumping leveling for overall 7 cents per Kwh.
This is reality of contemporary electricity grid. Make your choice.
Posted by: Andrey Levin | Jun 22, 2008 2:59:52 AM
And by the way HVDC has a loss of 3% per 1000 km.
In other words:
South Dakota - Chigaco 3% loss.
South Dakota - San Francisco 5% loss.
http://www.abb.com/hvdc
No need for fancy superconductors, just do it with HVDC available now.
Posted by: Realist | Jun 22, 2008 3:09:52 AM
Andrey,
Actually hydro electricity can also be distributed over large distances and is cheap.
http://www.abb.com/cawp/gad02181/f5933693d1a92404c1256d8800401782.aspx
Switzerland is the size of Massachusetts with a population of 7.5 Million and has almost 10 GW extremely flexible hydro power installed producing 38 billion kWh per year.
If it was expensive it wouldn't make huge profits buying coal and nuclear power from France and Germany and selling it expensively every single day.
Needless to say: These hydro power plants were built without subsidies as opposed to the French nuclear and the German coal power plants.
The power consumption during daytime is actually way higher than at night. Having more solar power installed does reduce the load on the grid, because solar power plant do never produce power at night when demand is low.
In addition, when power is produced locally there's less need to distribute power to the air conditioners on a sunny day.
By the way, with the money needed for one new nuclear power plant one can purchase 15 turnkey high tech and highly automated thinfilm solar module factories with a yearly output of 160 MW per factory from Oerlikon.
So, with these 15 Oerlikon solar module factories one can produce solar modules with a total peak power of 24'000 MW in 10 years.
The substrates needed for this process is inexpensive window glass.
www.oerlikon.com/solar
Posted by: Realist | Jun 22, 2008 3:39:32 AM
Supplying Baseload Power and Reducing Transmission Requirements by Interconnecting Wind Farms:
http://www.stanford.edu/group/efmh/winds/aj07_jam.pdf
Oh well, ignorance is bliss.
Posted by: Realist | Jun 22, 2008 3:48:36 AM
Also, the capacitiy of the storage lakes mentioned above is 20'000 GWh.
At 10 GW of wind power you need 83 days of no wind to run into any energy storage problems.
Posted by: Realist | Jun 22, 2008 4:04:01 AM
Why can't we go with stationary sodium sulfur batteries?
Posted by: Ben | Jun 22, 2008 5:57:19 AM
Whatever happened to the Vanadium Bromide Redox battery?
Last I heard was it was being used on windfarms in Australia (King Island) for storage and smoothing power.
Also re compressed air, there is a beautiful engine from Engineair that holds much promise (rotary with few moving parts)
Posted by: JohnE | Jun 22, 2008 7:41:03 AM
<shakes head>
I wonder about some of the people who post here. They don't seem to have any concept of consequences and vulnerabilities. Take the idea of running a superconducting loop around the country. If it failed at any point (say, a cooling system went out or an earthquake or flood broke a section) the entire system would go down. Could you have a bigger national security nightmare than 8000+ linear miles of target?
How much of a realist can you be if you can't even consult Google Maps to find that it's 2,710 km between SFO and Minot, SD and your 5%/1000 km is going to cost you around 14%?
Deep-water air bags are an interesting concept, and ballasting them is going to present some engineering challenges. But I don't think that a system which operates at less overpressure than a bicycle tire is going to present much in the way of difficulties.
Posted by: Engineer-Poet | Jun 22, 2008 7:53:18 AM
Make that 3%/1000 km and 8%.
Posted by: Engineer-Poet | Jun 22, 2008 7:55:36 AM
Am I missing something.
Are we to take these people seriously? Advocating batteries for large scale (city) storage ? Or is this simply aimed at improving the battery state of the art?
As far as underwater CAS (compressed air storage) of energy, Andrey Levin's source
http://www.efcf.com/reports/E14.pdf
makes "it obvious that overall efficiency of undersea compressed air energy storage/release cycle is less than 40% theoretical limit, and on practice will be less than 30%." Even less because the air will be cooled to ocean bottom temperatures before it's used.
Maybe put electric air compressors at the bottom to approximate COLD, isothermal compression and put the air turbines at the surface where it's warm. Then use the same machinery for compression and expansion - oops, can't combine those 2 ideas.
Air compressors in the blades using sliding weights? I guess that answers the question about "taking them seriously".
Posted by: ToppaTom | Jun 22, 2008 8:09:05 AM
Thinking of this some more, I envision a deep sea air bag system that could be engineered & contained within mill towers extending deep into the sea. Instead of bags being permanently moored to the sea floor and relying on air pressure going in and out, the bags themselves could be filled at the base of tower (on the inside hollow part), be released and rise to the surface while pulling on a cable going around a pulley at the base of the tower that leads back up to a generator - kind of like one incredibly long piston. The mill towers would have to be vented along the way with small enough ports to keep sea life out but large enough to allow the relatively free flow of water in and out.
HERE'S A BETTER IDEA.. alternatively, the bags could be arranged on the outside of the mill towers in a doughnut-like formation that rose to the surface when inflated. The generator could be housed within the "traveling doughnut" - the generator flywheel would be interlocked with, and travel up, a toothed-track built into the mill tower; it actually could generate power going in both directions!!! Air-powered going up, gravity-powered going down! This probably has already been thought of though....
Posted by: ejj | Jun 22, 2008 8:30:41 AM
Andrey:
The most recent 2000 MW private wind farms are getting about 9.5 cents/Kwh. Grid connections cost another 1.5 cents/Kwh for a total of 11 cents/Kwh.
The Hydro power grid is setup to use all wind power available by automatically reducing production from the water turbines. More wind power = less water used. Water is never pumped back into the resevoirs. The reservoirs are like huge energy batteries to be used as required and overflow during rainy seasons.
Posted by: HarveyD | Jun 22, 2008 8:33:49 AM
@Engineer-Poet
Re:
consequences and vulnerabilities
The super grid is configured to include sufficient load balanced alternate circuits to assure 100% uptime as a central part of its design. All transmission lines are placed underground to exclude access.
Zero resistance allows the super grid designer to ignore circuit length when alternate routs are designed. For example, a power source in the mid west can be connected to a user on the west coast through the east coast with no decrease in voltage or current.
Also, a super grid design would provide for sufficient overdesign capacity to allow for any foreseeable failure contingency.
The super grid is similar to the internet in the assurance of robustness through alternate circuit routing.
Posted by: Axil | Jun 22, 2008 8:57:36 AM
@Realist
Transmitting electricity over thousands of miles with little losses is easy and available now:
http://www.abb.com/hvdc
Why wait for fancy solutions, why not just do it?
From the referenced SA article as follows:
If we have an opportunity to move away from our dependence on fossil fuels, clearly we should take it. But fully exploiting nonfossil energy sources, including wind, solar, agricultural biomass and in particular advanced nuclear power, will require a new grid for this new era. To distribute trillions of kilowatt-hours of extra electricity every year, the U.S. grid will have to handle roughly 400 gigawatts more power than it does today.
The current infrastructure can be enhanced only so far. New carbon-core aluminum wires can be stretched more tautly than conventional copper wires and so can carry perhaps three times as much current before sagging below safe heights. And U.S. utilities will take advantage of provisions in the 2005 Energy Act that make it easier to open new transmission corridors.
But high-voltage lines are already approaching the million-volt limit on insulators and the operating limits of semiconductor devices that control DC lines. AC lines become inefficient at distances around 1,200 kilometers, because they begin to radiate the 60-hertz power they carry like a giant antenna. Engineers will thus need to augment the transmission system with new technologies to transport hundreds more gigawatts from remote generators to major cities.
Posted by: Axil | Jun 22, 2008 9:16:22 AM
I still like air-bags-and-generator-on-mill-tower idea. The bags could be arranged on the outside of the mill towers in a doughnut-like formation that rose to the surface when inflated. The generator could be housed within the "traveling doughnut" - the generator flywheel would be interlocked with, and travel up, a toothed-track built into the mill tower; it actually could generate power going in both directions!!! Ballast air-powered going up, gravity-powered going down!!
Posted by: ejj | Jun 22, 2008 9:22:40 AM
Suggestion/Comment -- why not use off peak power (or renewable power -- wind. solar. ect.) to pump water from just below Hoover Dam back up above the dam for a second shot at re-using the water for power generation. Sort of two birds with one stone. No need for TVA to build a whole new dam (no environmental concerns with new dams ect) -- just thinking out loud....
Posted by: JJ | Jun 22, 2008 9:23:16 AM
Engineer Poet,
Hello, anybody home?
HVDC has nothing to do with superconducting grids. HVDC is High Voltage Direct Current and has been available for decades.
http://www.abb.com/hvdc
http://en.wikipedia.org/wiki/HVDC
And HVDC is 3% per loss per 1000 km.
And you don't need to build your Windfarm in the city center of Minot, but even if you do you end up with 8% loss and not 14% loss. 8% loss - So where's your problem?
While Americans are busy buying houses from each other with foreign money and are incapable of winning wars against a bunch of barefooted fanatics with the most expensive military in the world, China has already been busy building HVDC transmission lines transmitting electricity NOW:
http://www.abb.com/cawp/gad02181/f5933693d1a92404c1256d8800401782.aspx
Posted by: Realist | Jun 22, 2008 9:35:41 AM
Eng-Poet commented "I wonder about some of the people who post here. They don't seem to have any concept of consequences and vulnerabilities. Take the idea of running a superconducting loop around the country. If it failed at any point (say, a cooling system went out or an earthquake or flood broke a section) the entire system would go down. Could you have a bigger national security nightmare than 8000+ linear miles of target?"
As engineer, u ought to think a little deeper. It's called redundancy, same as in the space program. Have two lines geographically apart, running at under 50% capacity, or cheaper til, have 4 lines running at under 75%. The failure of any single line will cause other line(s) to run at below 100% to assume the load.
Posted by: Roger Pham | Jun 22, 2008 9:39:10 AM
HVDC with 3% loss per 1000 km in China NOW
As I said, ignorance is bliss.
Posted by: Realist | Jun 22, 2008 9:42:36 AM
Axil,
I agree that there is way more potential in efficiency and making efficient almost energy independent buildings than having to build new renewable power plants and new transmission lines to keep on powering inefficient buildings.
However, even if more renewable power plants are built to power an inefficient economy, energy storage of renewable power is not the problem with an efficient HVDC grid in place.
Posted by: Realist | Jun 22, 2008 9:51:53 AM
why not use off peak power (or renewable power -- wind. solar. ect.) to pump water from just below Hoover Dam back up above the dam for a second shot at re-using the water for power generation.
This is already being done with coal and nuclear power: http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
Posted by: Realist | Jun 22, 2008 9:55:49 AM
"Engineers will thus need to augment the transmission system with new technologies to transport hundreds more gigawatts from remote generators to major cities."
But do we need to envision the energy as electrons? Conversion to H2 for transport is another option. And why not modularize a super grid? Build much smaller perimeter connected rings across the continent. Reduce redundancy requirements, eliminate single target, lower MTBF.
Posted by: gr | Jun 22, 2008 11:10:24 AM
Andrey,
30-40% overall efficiency for CAS involving polytropic processes is too low, and probably a worst-case-secenario. A better-designed system should be around 60%.
A system with good thermal management and closer to isentropic processes involving insulation of the tank and the tubings would only incur mainly friction loss at assuming 10% at compression and 10% at expansion, for overall efficiency of 80%. This can be done more practically using surface steel tank, since the plastic tubing and bag for undersea system cannot withstand the high heat of compression. Furthermore, heat loss from the tubing going down 600 meters would be too much to insulate. Plus, the high thermal conductivity of sea water makes insulation of the airbag less effective in comparison to a surface tank exposed only to air.
Posted by: Roger Pham | Jun 22, 2008 11:20:43 AM
You could allow the bags to rise to the surface while they "vent". This would allow the bags to reclaim some heat, though it would ruin the KISS aspect of this system.
BTW let's keep our eye on the ball. The most important metric is $/kW delivered. Factors that impact that metric are initial capital investment, fuel cost, and capacity factor.
Posted by: GreenPlease | Jun 22, 2008 11:28:43 AM
You can also produce hydrogen with wind, combine it with CO2 produced in a biogas reactor to produce Methane (sabatier reaction) and thus double the output of the biogas reactor.
Posted by: Realist | Jun 22, 2008 2:12:59 PM
Can we take the comments within these pages seriously?
As far as one can take the arguments for or against any Idea or claim as to be accurate or proven fact, I wouldn't think most people posting here claim infallibility.
Indeed the ideas and experience, The supportive ,if at times cutting criticism is proof of that.
The opportunity to think out loud and bounce ideas, present "out there" suggestions to an interested audience and stay abreast of developments via the excellent reports is what interests me.
I have certainly learned as much from the more fanciful claims about how the media, and sprukers do business and much about the issues surrounding transportation, and the energy sector.
A lot of new and innovative ideas, old ideas and many bottom drawer concepts come to light.
This is the Internet and one needs to be aware that as in any media , buyer beware.
Hopefully we are all able to learn and contribute something here.
Posted by: arnold | Jun 22, 2008 2:16:41 PM
Are you looking for facts? Here's one:
HVDC with 3% loss per 1000 km in China NOW
It is transmitting electricity now - 3000 MW per transmission line.
Posted by: Realist | Jun 22, 2008 2:31:47 PM
To answer an early question by jimB about Altairnano's AES collaboration -
It has been reported to be on track. They have finished testing the prototype and according to Altairnano sources it performed completely up to expectations. The actual third party report has not yet been released however so a few grains of salt are justified - especially since ALTI just took an inexplicable 22% hit before close on Friday. If it indeed really did perform that well then AES and ALTI would be expected to develop the line further and probably implement some in fairly short order. These megabatteries are not however designed for shifting power from off-peak to peak but only for dealing with very brief demand spikes during the day.
How well does CO2 compress and store energy? Seems like these bags could store some of that too! :)
I don't understand the problems here. Pipes that can stand 900 psi don't seem to be so unusual to me. Anchoring large bags to the sea bed seems to be a very simple engineering problem. Winds are strongest at night when demand is at the lowest; winds are strongest farther off-shore than on land or near shore; the bag storage makes the most sense in deeper water and compared to mega-batteries are likely to store more energy for same long term investment for use during peak demand; some of the extra cost of windmills in deeper waters is the need to secure them - the work of anchoring the bags and anchoring the mill could be done at the same time. Hell, it may even be cost effective to build in a way to capture to flotation force as energy to generate electricity as well.
Or alternatively do it all by flotation forces: use excess peak production to winch it down and let it rise up when extra electricity generation is needed, the winch cables then in parallel driving the windmill's turbines.
Clever idea that helps offset some of the
Posted by: Don | Jun 22, 2008 4:11:59 PM
Absolutely no one with any kind of serious engineering background would even consider the kind of energy storage in the article. You don't need super high density energy storage for this application, Chen is only fishing for funding when mentioning that. If can't store the energy at a reasonable cost with todays technology, you certainly will not be better of with a super expensive nano-capattery. The airbag idea doesn't have to fail for thermodynamical reasons, cause the water would re-heat the air as it expands. But it fails for practical reasons, the cost and complexity of building such a storage facility would be far greater than building another power-plant.
Posted by: Chase | Jun 22, 2008 4:58:18 PM
Additional details about the air storage bag construction here: http://www.cnn.com/2008/TECH/science/03/31/windpower/index.html?section=cnn_latest
Posted by: | Jun 22, 2008 5:14:19 PM
@ Realist
In response to your posts regarding HVDC, here is how it looks.
Terms:
HVDC – High Voltage Direct Current electric power transmission lines.
HVAC – High Voltage Alternating Current electric power transmission lines.
HVDC has a number of advantages over HVAC.
- Unlike HVAC, HVDC can be put underground which decreases NIMBY. It is almost impossible to get approval for new HVAC transmission lines; between aesthetics and EMF, nobody wants them in their backyard.
- An important feature of HVDC is that it can never becomes overloaded!
- Interconnection of HVAC local grids with HVDC provides “firewall” functionality.
- HVDC don’t propagate voltage, frequency or phase faults that take down grids.
- HVDC carries more power then HVAC per circuit.
- HVDC don’t radiate EMF that may affect people that live under HVAC lines.
- The power loss on HVDC is less then HVAC.
- HVDC lines can run longer distances compared to HVAC.
- HVDC costs less for power line construction litigation with runs about 15% of construction cost.
Superconductive DC (SDC) lines have all the advantages of HVDC plus the following:
- SDC has 5 times the capacity per circuit.
- SDC can run very long distances with no electric power loss.
- SDC can carry hydrogen as well as electric power.
- SDC can be configured to store current like a battery without power loss.
Conclusions:
- HVDC should be used for long haul grid circuits vs. HVAC.
- If the USA is serious about a hydrogen economy with renewable energy then SDC is the way to go.
Ideas I like that SDC high capacity lines makes possible are as follows:
- Generation IV nuke units will produce some radioactive waste. So it will be least expensive and easiest politically to build them in "nuclear clusters," far from urban areas; Say near Area 51 or Yucca Mountain. Each cluster could produce on the order of 10 gigawatts plus hydrogen.
- Massive geothermal generation can be placed on the west coast say near the outskirts of Yellowstone Park.
- Massive wind farms can be sited in the mid west.
- Large solar generation in the desert.
Posted by: Axil | Jun 22, 2008 5:31:25 PM
umm, should have said "lengthen" MTBF.
Posted by: gr | Jun 22, 2008 5:49:58 PM
I'm not that starry eyed about HVDC in the light of experiences of an underwater cable http://en.wikipedia.org/wiki/Basslink
The costs blew out and the direction of flows were not as anticipated. The seafloor cable had to include a secure earth in case it was snagged by oil drilling rigs. The idea was that peak hydro would be sent to boost coalfired generation but it has worked out kind of the opposite. For undersea cable and I guess underground you are looking at a million dollars per kilometre plus power electronics at the nodes. I'm inclined to think that with a storage breakthrough local generation could be cheaper and more secure.
Posted by: Aussie | Jun 22, 2008 6:31:57 PM
Details of the air pumping system with a working model:
http://www.youtube.com/watch?v=KUhlsV32iHk&feature=related
Posted by: | Jun 22, 2008 6:33:39 PM
The real problem to be dealt with is grid fluctuations. We have peaking loads, and a large day night power use differences. Incorporating renewable energy sources into the grid to more than 20% and adding Cars to the grid load requires rethinking of the grid. However, with grid losses at 60% of total produced power, rethinking is a necessity just from the point of conservation because we are running short of the fuel used now.
Lets look at some of the solutions proposed.
Water to hydrogen to electricity
This Electric storage system is one of the first envisioned. It is scalable, but involves losses in storage, transport, and use. Cars being converted to hydrogen suffer a severe penalty in efficiency. If wind power generation becomes greater than the grid night load, hydrogen might be useful for storage of night wind power to burn as daytime “peaking power” in old previously coal oil or gas power plants
Batteries.
From Lead acid to Lithium these are all proven capable of running our car fleet. Obviously, the lighter weight and higher capacity chemistries are better, but price is also a consideration. Economies of scale should make the price come down. Using batteries for grid load shifting is possible, but so far, not cost effective.
Supercapattery storage system.
This is essentially a battery with somewhat better charge discharge capabilities. It may be an ideal Electric storage system if the technology is workable, cost effective, and scalable.
Undersea airbags.
These store power that has never been made into electricity in deep water beyond the continental shelf. The idea is to have the same sort of bladder tanks that store air/water pressure on the surface weighted and sank to depth. Anchoring a lot of bladder tanks to the sea floor is not hard as it just involves weights. The tanks are never raised to the surface except when a repair is indicated. Seawater would be let into and out of the tank through a very fine filter that would keep bacteria out. Undersea constant pressure lets the bladders expand to maximum or contract to zero with no increase or loss of pressure. Pressure will be between 1000 to 1500 psi (300 atmospheres) depending on the depth of the area chosen.
There are a variety of ways wind machines can pump air to high pressure, many are quite efficient, especially multi stage compressors. Some valving control system would need to work co-operatively with all units in the system to ensure the bladders did not get overfilled, and to detect leaks.
The resulting combined high pressure air could be piped to shore and used as an energy source for making electricity or for powering France's “air-car” design. The loss of heat to the sea could be later made up for by reheating the air onshore, preferably by waste heat such as building air conditioning, it would then regain it's previous volume. We need expect only a single day of stored power as sea wind is quite reliable. Despite losses in the system, because the power source is free wind, we can see a good rate of return per investment dollar.
In all, a very workable idea.
Energy storage lakes
Here all one needs is a cliff or other substantial elevation difference. Water is pumped up using excess power when available, then used to provide power when needed. There is no theoretical limit to the system capacity. Most hydroelectric power plants use a more passive version of this and just shut off unnecessary generation capacity while letting water sit in storage above the dam. Most dams are far from the cities they supply, so long distance power transmission is necessary.
Superconducting
Here we have a transmission/storage system that needs very cold temperatures to work, and is vulnerable to catastrophic failure. As higher temperature superconductors are discovered, the system may become more cost effective. So far construction costs are far too large to make these a consideration for general power distribution. Superconducting rings are useful to compensate for “spiking” because these can deliver high instantaneous power for startup loads on very large motors.
HVDC Load sharing
HVDC has a loss of 3% per 1000 km. Los Angeles and New York are about 4,000 km apart. 3% x 4 = 12%. Compare this to normal grid losses of 60%.
We see that interconnecting the world with HVDC could easily share power loads and power sources with a much reduced need for peaking power as each city peaks at a different time. High voltage Direct Current transmission is going to be used because it is one of the best and cheapest solutions to both peaking loads and generating facilities that are far away from user areas.
Posted by: John Taylor | Jun 22, 2008 6:36:55 PM
Self-styled Realist: I noted that error immediately afterward my long post. Perhaps you need glasses.
Quoth Roger Pham, one of the people I was wondering about:
As engineer, u ought to think a little deeper. It's called redundancy, same as in the space program.Redundancy is feasible with an HVDC system, but not with a continent-scale SMES as proposed by Axil (another one I was wondering about) here:
This grid can store electrical power with zero resistance if the superconductive cables are looped around the continent in a racetrack pattern. Electricity can be fed into this grid in the mid west by wind mills and extracted on the east or west coast without electrical loss.Even if you had redundant paths, current would only flow through the outermost loop (least-energy configuration) and any break would cause enormous voltage transients.
Posted by: Engineer-Poet | Jun 22, 2008 7:38:15 PM
I don't know who has really tried this or even costed it out, but (like some other posters here) I think there may be lots of economical energy storage potential simply by using buoyancy:
Use wind or photovoltaic power to slowly drag some buoyant mass the size of the Titanic down about a mile.
If done slowly and if the buoyant mass was fairly streamlined, then fluid-motion energy losses could be kept relatively small.
Then when the stored energy is needed, just slowly re-float the mass connected by links to crank a generator.
Posted by: Jaydee | Jun 22, 2008 7:56:44 PM
@Jaydee, that sounds like a more robust solution than the air bag for large scale. You could use some kind of foam or other "air-captive" flotation device that wouldn't fail catastrophically as an air bag would. You could also limit the max/min depths so that it wouldn't interfere with surface navigation. You could use either an electric motor (90+% efficiency round trip), or a pneumatic motor (eff%?).
Posted by: | Jun 22, 2008 8:24:59 PM
@ Jaydee
Your flotation idea is fun but not practical.
The energy of a flotation device going up is equal to the energy of the volume of displaced water going down.
Even a titanic sized volume of water is not going to add much to the grid. Have a look at Niagara. The idea is impractical and not scalable at any reasonable cost.
Posted by: J T | Jun 22, 2008 8:49:24 PM
@Engineer-Poet
Redundancy is feasible with an HVDC system, but not with a continent-scale SMES as proposed by Axil (another one I was wondering about) here:
………..
Even if you had redundant paths, current would only flow through the outermost loop (least-energy configuration) and any break would cause enormous voltage transients.
HVDC grids can be controlled either under amperage control or voltage control. At present, all major HVDC power lines operate under amperage control, which requires a nearly instantaneous synchronization of power injection and power removal between all the AC/DC converters connected to the grid. This becomes an unmanageable control problem above about 5 AC/DC converters connected to a single line.
In order to build the sort of continental HVDC energy grid that would be required to share power across North America, it will be essential to operate the grid under voltage control (similar to the way a computer power supply works).
Energy storage devices connected to the grid are an essential feature of such a control scheme. These storage devices either inject or remove power nearly instantaneously to maintain stable operating conditions (local voltage) for the grid. A byproduct of such a control scheme is added reliability due to the presence of the storage capacity. There is a need for further research in this area before an HVDC grid can be built, but this is a soluble problem.
A feature shared by all electric pipeline designs is that to insure reliability, it must be possible to gain rapid access to the line anywhere along its course to perform repairs (for example, to repair a coolant leak or to replace a shorted out section of the line). This essentially requires that the electric pipeline
(whether it is based on conventional conductors or superconductors) be installed in a service corridor, rather than being directly buried, so that it can be rapidly repaired. Such a high capacity, cross continental (or even global) power link would become so important economically that it would be intolerable to have the link out of service for a sustained time for repairs.
The service corridor per se is a major portion of the total projected cost of a long distance high capacity power line (electric pipeline) project.
Electric pipelines are far more compatible with multiple uses of the transmission corridor than are overhead transmission lines. The service corridor could in principle be beneath a road; however, the possibility of attack by a truck bomb may mean that it would not be desirable to allow heavy traffic to use the corridor of an electric pipeline. Route planning for electric pipelines could allow for simultaneous uses for the right of way that would not be practical or desirable for overhead transmission lines, such as bike trails or future high speed rail lines.
The greatly reduced EMF from underground DC power lines also implies that electronic telecommunications wires and occupied buildings can be in close proximity to the transmission line without electromagnetic interference or health concerns based on alternating magnetic fields.
Posted by: Axil | Jun 22, 2008 9:05:20 PM
Axil, again you are confusing HVDC with your SMES of national circumference. If you don't understand the difference, or the physics, just give it a rest.
Posted by: Engineer-Poet | Jun 22, 2008 9:26:24 PM
Engineer-Poet:
SMES is a HVDC network; its capacity per circuit is just higher and operational characteristics are a little different.
As per my last post, a HVDC network requires superconductive storage for control and fault tolerance so in the national electric pipeline network there is an abundance of superconductive storage available.
Redundancy is the reason for a multi electric pipeline loop between the east and west coasts.
Because there will be more power stored in the national grid then is used, a circulation or current load balancing will occur between the major continental loop and the various sub loops in the network.
When standard metal lines are used, the excess current will dissipate rapidly through line heating. In a SMES system no dissipation will occur and the network will act as a battery.
If I am wrong here, be patient and bring me to right thinking.
Posted by: Axil | Jun 22, 2008 10:06:28 PM
FYI - Engineer-Poet
"The American Superconductor D-SMES system provides us with a technically and economically superior solution for improving the voltage stability of the Northern Loop," said Larry Weyers, WPS' CEO. "This system will allow us to provide improved reliability to our customers immediately and create a better base for load growth and new transmission facilities in the future."
American Superconductor has deployed similar, power quality SMES systems over the past several years at industrial facilities and data centers, but this D-SMES installation is the first commercial application of superconductor technology as an integral, ongoing part of an electric power grid.
GE Industrial Systems, a business of General Electric Company, will serve as American Superconductor's channel to the U.S. utility market for D-SMES. The D-SMES product line for U.S. utilities is co-branded by GE and American Superconductor.
SMES components are housed in a semi-tractor trailer and attached to transformers at utility substations at strategic locations within a power grid (D-SMES configuration) or installed as an interface between a utility power supply and an industrial user to improve power quality (PQ-SMES configuration). When a voltage drop is detected by the unit's power electronics, SMES instantaneously injects precise amounts of both real and reactive power into the system it is protecting, thereby keeping voltage levels stable.
Posted by: Axil | Jun 22, 2008 10:31:40 PM
Sorry, Don and Jaydee,
but your flotation idea just won't swim nor float!
Using airbags, and due to the crushing pressure of water at depth, the bags must be very highly pressurized to hold volume. But when you float this bag upward, the lower pressures above will cause the bag to expand and explode...unless you will vent the bag, but then it means more complicated venting pressure line that will get loose in the way...
The crushing pressure of ~900 psi at depth will crush any styrofoam material or any tin can to nothing, so, nothing will work there unless you have highly pressurized air inside, or a very thick air container to avoid being crushed , but then, it will be expensive due to the heavy use of material, which will reduce boyancy.
Not much energy can be stored this way, either.
Posted by: Roger Pham | Jun 22, 2008 11:29:19 PM
Roger Pham:
Undersea bag compressed air energy storage inherently loss all heat produced during compression of air. Hence very low efficiency.
BTW, guys, why engineer extremely expensive continental grid when it is possible to do with distributed local power, like co-generation, or PV single home air conditioning/heating (heat energy of hot water or cooled house already provides energy fluctuation buffering).
Posted by: Andrey Levin | Jun 23, 2008 3:07:03 AM
Roger,
Valid enough points. Admittedly, it was just an idea that popped into my head as I was typing. Would there be a way to capture the strain of the buoyancy pull on the moorings as energy? Again, I see nothing too problematic with building sufficient anchoring systems for the air bladder energy storage device and the windmill at the same time and see the siting of off-shore windmill farms for best wind resource and the siting of the air bladder energy storage device as both benefiting from the same relatively deeper water location. And wind needs a cheap energy shifting method to be useful. If there are cost effective means of getting as much energy out of these things as possible all the better. None of the naysaying here has been all that convincing: this seems a clever enough idea for that particular purpose anyway.
Posted by: Don | Jun 23, 2008 5:06:30 AM
Axil,
Efficiency, Photovoltaics, Solar hot water, Solar thermal, HVDC, Hydro and Wind already exists.
GenIV nuclear reactors do not exist and GenIII nuclear reactors are significantly more expensive than wind. SDC does not exist either.
Instead of waiting for solutions, it's faster to just do what already works.
BTW, guys, why engineer extremely expensive continental grid when it is possible to do with distributed local power, like co-generation, or PV single home air conditioning/heating (heat energy of hot water or cooled house already provides energy fluctuation buffering).
True, but that would be too easy.
Posted by: Realist | Jun 23, 2008 6:28:11 AM
@ Don ... come on how many times do you guys need told?
The energy of a flotation device going up is equal to the energy of the volume of displaced water going down.
Flotation has lots of power, but simply not enough energy to be useful considering the problems involved.
Posted by: J T | Jun 23, 2008 8:14:12 AM
@Realist, Andrey Levin
One thing holding back development of wind and solar energy in America is the lack of capability to send electric power around the country. The best wind and solar sites are often far from major electrical energy markets.
Although the present power grid allows electric utilities to send power hundreds of miles, it is not capable of transporting power efficiently from coast to coast.
Overhead power lines are simply not able to transmit significant electric power coast-to-coast in the USA. Underground power lines (“electric pipelines”) would however be capable of transporting power all around the USA.
A grid based on these electric pipelines would improve the security and stability of our electric power system (against both accidents and terrorism), and would facilitate wind and solar power becoming a much larger part of our energy mix.
The present electric power grid is vulnerable to being crashed by very low tech methods. Our grid can be brought down by the simultaneous failure of two major power lines during a period of high power demand, as occurred in both the 1964 and 2003 East Coast regional blackouts (sabotage was not involved in either of these events).
It would be simple for saboteurs to duplicate the events that caused the August 14, 2003 blackout given our present electric grid design.
A network of electric pipelines would make our power system far more resistant to being brought down by sabotage, and the electric pipelines themselves could be far more resistant to sabotage than overhead power lines.
The degree to which distant regions can share power has a direct effect on the need for new power plant construction. Electric pipelines, by increasing the distance over which power can be shared in North America, would reduce the need for new power plant construction dramatically, saving more than $100 billion in new power plant construction costs (enough to pay for the electric pipeline grid).
Posted by: Axil | Jun 23, 2008 8:21:06 AM
I really like the idea of large bags of air at the bottom of the sea.
However, there is a much cleaner and easier to handle method of achieving this. How about large bags of air stored at the bottom of a drilled well, or in a salt mine filled with water. For that matter, use any mine which has been abandoned due to the vein of whatever running out.
At 600 M you get 5-10 KWH per cubic meter of displaced water, A space which is say 100M x 20M x 100M could store 1TWH.
-Michael
Posted by: Michael McMillan | Jun 23, 2008 8:51:55 AM
Efficiency, solar hot water and photovoltaics on roofs does work well in Germany and does reduce load on the grid:
http://www.solarserver.de/solarmagazin/anlage-e.html
If it works in Germany it works even better in the US.
Posted by: Realist | Jun 23, 2008 9:06:34 AM
Don,
For cheap and transient energy storage for wind turbines, just use thermally insulated steel tank to store compressed air as a base and put a wind turbine on top of it as one integral unit. This will work for both a land-based and off-shore wind turbines. To reduce visual impact on the ground, the steel tank could be partially buried from the surface. Sea-based unit will use the steel tank as a flotation device. With good thermal insulation and proper thermal management, efficiency of this CAS can be as high as 70-80%.
Posted by: Roger Pham | Jun 23, 2008 9:41:01 AM
@Realist
Be a realist; are you willing to leave your Volt parked in the garage on a cloudy day? Most will want abundent grid electric power. What about the city people who don’t have a roof to themselves? Why do the rich suburbanites have to prop up the shaky grid? Individual action taken on the local level won’t keep the country on top. It is bold action taken on a national level that will advance the American dream.
Posted by: Axil | Jun 23, 2008 11:30:11 AM
Actually, solar hot water and photovoltaics works on cloudy days as well. Especially thinfilm PV. And schools have roofs, libraries have roofs, government buildings have roofs, hospitals have roofs, train stations have roofs, garages have roofs, appartment buildings have roofs, airports have roofs, shopping centers have roofs, bridges have roofs etc.
Besides solar heat needed for heating and cooling can easily be stored over several days - much easier and cheaper than storing electricity.
Manhattan has an area of 87.5 km2. Solar hot water has an efficiency of over 80%. If 20% of that area is roof area, you are already at 14 GW of solar hot water capacity.
But forget solar hot water and photovoltaics:
Average living standard in the US is not higher than in Germany and yet:
Electricity consumption Germany: 6742.00 kWh/capita
Electricity consumption USA: 13228.00 kWh/capita
http://iaea.org/inisnkm/nkm/aws/eedrb/data/US-elcc.html
It's still cheaper to save electricity than to build new power plants.
Posted by: Realist | Jun 23, 2008 12:14:12 PM
JT, I am sorry if my post was not clear - the last question was not one of letting it float back up and capturing that energy. It waas instead one of presuming that a bag that primarily functioned as means of storing the energy as pressure would have to be anchored to the sea bed. It would pull against the anchor attachments (with a force equal to the weight of the displaced water less the weight of the gas contained). That force would produce a strain on the moorings. Could THAT force be cost-effectively harvested rather than letting it go to waste?
I hope that is clearer.
Roger, I defer to those with greater knowledge than I regarding the relative efficiencies and costs involved. I suppose even large flywheels would be a potentially efficient storage of mechanical to mechanical energy pending later conversion into electrical. Am I correct in assuming that losses from the kinetic energy of the mills rotor blades could be used to store kinetic energy in a flywheel with good efficiency? Thank you.
Posted by: Don | Jun 23, 2008 12:25:30 PM
And while Americans are busy buying houses from each other with foreign money and keep on dreaming around, Germany and Denmark produce 70% of the world's wind turbines.
Posted by: Realist | Jun 23, 2008 12:28:18 PM
Axil note,
Roger reads correctly and the mentions Transients.
Transients in the SMES has application in smoothing or rejecting transient voltage fluctuations in the order of a few seconds. The 'energy storage aspect refers to the Hydrogen surrounding the superconducting cable.
The air bags as originally proposed are anchored to te sea bed in trenches adjacent to a shelf which supports a fixed tower. This suggests steel pipes be fixed to solid structures and seabed.
As compressing air is a very lossy process compared to electrical generation too is best used for transient storage granted may have hours of supply, or assistance. As the wind fluctuates we don't need to see it as the only input.
Then we are looking at a hybrid system. Full time electrical generation from the windmill straight to land. A compressor possibly located on the platform should be electrically powered with a regeneration side to send electrical energy back to support the troughs. As there are observed fairly high frequency fluctuations of the first order, it is here that savings and efficiencies start to make sense.
The surplus to fluctuation requirements could be stored in larger volumes, but I feel the point of diminishing returns would be quite limiting.
To sum up the transients are better described as fluctuations. The fluctuations of interests are in the form of gusting and associated slip from the mills loose air coupling.
Posted by: arnold | Jun 23, 2008 2:00:00 PM
It would pull against the anchor attachments (with a force equal to the weight of the displaced water less the weight of the gas contained). That force would produce a strain on the moorings. Could THAT force be cost-effectively harvested rather than letting it go to waste?Your impression is due to misunderstanding physics. Energy (work) is force times distance; just pulling on something expends no energy unless it moves.
You also have to restore that energy somehow to return the system to its starting state. Do you think a mechanism which handles multi-thousand ton forces at the bottom of the ocean is going to be cheap, reliable and easy to construct and install? The beauty of air flowing through pipes is that it is pretty much all of that, and all the mechanical stuff can be up at the surface where it's easy to work on.
Posted by: | Jun 23, 2008 3:54:31 PM
@ Don . The above was written by someone who understands why you can't have your cake and also eat it. Sure it takes lots of energy to hold a beach ball under water all afternoon, but you can still only get out the energy stored by the displaced water when the ball rises.
@ Axil . sure the American system cannot send power across the country, but they can and do have a working system in China (HVDC). It's time to catch up to the previously impoverished third world countries.
Posted by: J T | Jun 23, 2008 5:51:34 PM
"And while Americans are busy buying houses from each other with foreign money and keep on dreaming around, Germany and Denmark produce 70% of the world's wind turbines."
"GE was the largest supplier of wind turbines in 2007, with a 45% market share." Bloomberg
http://www.bloggingstocks.com/2008/03/12/ge-siemen-ag-vestas-benefiting-from-growth-in-wind-turbine-use/
But what are facts when you can spin your own bs?
Posted by: sulleny | Jun 23, 2008 6:15:57 PM
@J T
sure the American system cannot send power across the country, but they can and do have a working system in China (HVDC). It's time to catch up to the previously impoverished third world countries.
It’s a heady time in China for their young engineers and scientists. Big Chinese construction projects inspire the minds of their youth and lift their souls. There, the lawyers are few and the scientists and engineers are many. Their youth are inspired and enthusiastic and can taste a future that can be, and that they can make.
Today, what America needs is some big ideas, plans and dreams to bring the young back to the physical and engineering sciences. In his wisdom, JFK realized this need back in the day. Like him, we need leaders today with like vision to see, to inspire and to build the bright American tomorrow.
Like so many fools in the past, our leaders started the oil war so that they would be remembered in glory down through the centuries. But we don’t revere the war makers, the wasters and the destroyers; we remember the planners, builders and the dreamers who truly leave their mark on the future.
Posted by: Axil | Jun 23, 2008 7:07:42 PM
Perhaps I am ignorant but I have never been afraid to ask about that which I do not know. Can strain be used to produce electric current? If so can it be effectively captured?
BTW, some here would appreciate this week's Economist Magazine. The feature is "The Future of Energy" and a discussion of the DC grid especially in relation to making wind power effective and even taking into account pumped storage is included.
I am sure that many of the posters don't need to read it as they already know everything, but some us still can find some new information there of interest.
http://www.economist.com/printedition/
Posted by: Don | Jun 23, 2008 7:24:18 PM
You don't give up do you Don.
Posted by: J T | Jun 23, 2008 8:00:35 PM
Ah. http://en.wikipedia.org/wiki/Piezoelectric
Yes. Strain can be used to produce electric current. Now it may be that it is an impractical method for this circumstance (I barely and only vaguely remembered that strain can indeed be used to produce electricity with the right material, far be it from me to appreciate the cost or scale involved enough to evaluate that) but given that any buoyant object anchored to the seabed would produce that strain and lots of it, it seems like that is a lot of force to just go to waste without at least asking if it can be used effectively.
As already noted in the post above, I am admittedly ignorant. But I'd rather be ignorant with knowledge of my ignorance and enough curiosity to ask the questions designed to reduce my ignorance incrementally, then thinking I know the answers when I really do not know squat.
Posted by: Don | Jun 23, 2008 8:08:30 PM
Don: Force times distance. And strain to the mechanical engineer is the change in dimension; stress is the force. Just how much do you think a piezoelectric crystal can change shape before it breaks? I'd guess it's a fraction of a percent. This is why you see them in lighters, and not in generators.
Quoth Axil:
SMES components are housed in a semi-tractor trailer and attached to transformers at utility substations at strategic locations within a power grid (D-SMES configuration) or installed as an interface between a utility power supply and an industrial user to improve power quality (PQ-SMES configuration).Note something about this SMES: it is trailer-size, not continent-size. It's not based upon a loop of wire with a current going in one direction around a circuit some thousands of miles ln length. (It is also paired with a synchronous inverter system which can generate both real and reactive power, which is highly useful for connecting to AC systems but not really important for the energy storage end of things.)
That one-directional current is the problem. If you break it anywhere, the whole system goes down. You can only tap into it at the edges (which will be hundreds of miles away from wind farms in e.g. Kansas). It introduces too many problems. Far better to have independent storage systems of whatever kind (CAES, SMES, stockpiles of seed for the gerbils in the wheels) in many places. Connect storage to sources and loads via lines which have no conflicting storage requirements of their own.
Posted by: Engineer-Poet | Jun 23, 2008 9:37:21 PM
Don, a note to you.
Ignorance is not a sin
But we aren't paid to teach.
Want education?
Head on to the library
Ask no more of us.
Posted by: Engineer-Poet | Jun 23, 2008 9:40:15 PM
I think we may be underestimating the contribution that personal PV panels will have when they're cheap. People will plaster every surface they own with them, and long-range transmission will be reduced.
Posted by: Mark_BC | Jun 23, 2008 9:43:54 PM
go ahead and ask Don, that's what the internet and Wikipedia are for. Just take everything with a grain of salt and analyze who is saying something and what their motivations and background is. That's the only way to learn
Posted by: Mark_BC | Jun 23, 2008 9:52:20 PM
Don,
Please note If you want better mark , next time n.b. "when I really Do Not Know (diddly) squat is using a double negative, when I'm sure you mean "when I know (diddly) squat"
Posted by: Bunkum. | Jun 23, 2008 10:42:52 PM
Don .. I think you are trying to learn but not quite getting the concept.
Try an experiment to see how this works ...
A flotation device held down by a rope is quite equal to a large weight (equal to the water displaced) suspended by a rope. Both exert the same force on the rope.
You can suspend a weight but only retrieve the stored energy by letting it descend.
Placing a piezo electric device will create an instantaneous charge while it gets initially squeezed, but no further power. This is why we cannot power our houses by placing a layer of piezo-electric crystals in the foundations. To capture energy, we need to also capture the motion.
Hope this helps. The study of basic physics may often not be quite as obvious, that is why the people who first figured it out are still looked up to.
Posted by: John Taylor | Jun 24, 2008 12:46:11 AM
sulleny,
The American Market is not the same as the World Market.
http://www.bloggingstocks.com/2008/03/12/ge-siemen-ag-vestas-benefiting-from-growth-in-wind-turbine-use/
Denmark and Germany still produce 70% of the world's wind turbines. Keep in mind: The world is actually bigger than America. Regardless of what your American geography teacher might have told you.
Oh well, ignorance is bliss.
Posted by: Realist | Jun 24, 2008 1:53:07 AM
Sullenly wrote:
"GE was the largest supplier of wind turbines in 2007, with a 45% market share." Bloomberg
http://www.bloggingstocks.com/2008/03/12/ge-siemen-ag-vestas-benefiting-from-growth-in-wind-turbine-use/
But what are facts when you can spin your own bs?
That's 45% of the American market! Yes GE is strong on the home market, but Danish and German suppliers recoup some of that on the global market. Vestas is still number 1, globally.
5244 MW (nameplate) was installed in the US in 2007 and 8554 in the EU. USA has a total installed capacity of 16,818 MW and EU is at 56,535 MW by the end of 2007.
That being said, Danish and German suppliers most likely don't have 70 market share anymore. Competition is strong from India and China, especially in the sub-1MW market, which the big suppliers have retracted from. China loves their domestially built small turbines.
All the big companies see a slowly declining market share in a rapidly expanding market. No-one likes to see their market share decline, but it's almost inevitable with the current market situation.
Posted by: Thomas | Jun 24, 2008 4:14:19 AM
Thank you John Taylor for the straightforward explanation to my question.
Posted by: Don | Jun 24, 2008 4:31:47 AM
btw, while I realize that as a practical matter this is not reasonable, theoretically it still makes sense. Each time the bag is filled and emptied a pressure against the anchors is placed and released which then would cause conformational change in the material that anchors the bag. Again, unlikely to be harvested as energy in a cost-effective manner ...
Posted by: Don | Jun 24, 2008 7:46:43 AM
Has anybody mentioned V2G? The right number of BEV-s and PHEV-s integrated into UK’s future smart electric grid system could make new energy storage systems for use with renewable energy generation, including a device that combines the properties of supercapacitors and batteries (“supercapattery”) and undersea compressed air storage bags etc., redundant.
Posted by: Laszlo | Jun 24, 2008 8:56:23 AM
Yeah, US is using *your* money to build wind capacity. What are facts when you can spin your own BS? And ignorance is bliss.
"The United States is currently the best market for wind power, featuring 5.2 GW of new wind energy capacity installed in 2007, followed by Spain and China with 3.5 GW and 3.4 GW, respectively."
Global Wind Energy Council, February 2008
Posted by: sulleny | Jun 24, 2008 9:48:46 AM
Sulleny,
well at least you partially buy from us with our money.
What BS and ignorance? You are the one, who doesn't even know the difference between the World and America.
ROFL
Posted by: Realist | Jun 24, 2008 11:06:04 AM
The EU is still ahead of the US as far as wind power installations are concerned:
The total capacity of new wind turbines brought on line across the European Union last year was 8,554 MW
http://www.ewea.org/index.php?id=60&no_cache=1&tx_ttnews%5Btt_news%5D=1270&tx_ttnews%5BbackPid%5D=25...
Posted by: Realist | Jun 24, 2008 11:20:19 AM
@Engineer-Poet
That one-directional current is the problem.
Reference:
http://www.patentstorm.us/patents/5374914/description.html
http://www.patentstorm.us/patents/5682304/fulltext.html
Engineer-Poet, thank you for taking the time to correct me on superconductive energy storage. Since I am not an expert in the physics of superconductivity, I thought that energy storage using superconductivity was easier then it ready is. I looked at some patent descriptions of superconductive auto energy storage systems above, and the complexity is apparent.
With some of the technology that I have recently seen here at GCC and other sites, such auto storage systems may now be possible to build at a reasonable cost.
These technologies are as follows:
- Light weight high efficiency hydrogen storage tanks.
- Iron superconductor
http://www.eurekalert.org/pub_releases/2008-05/fsu-mlr052808.php
If iron oxyarsenide can be easily formed into wire, its magnetic properties and relatively high critical temperatures will make it ideal for small hydrogen based storage devices.
Charging such storage will take no longer then the time it takes to fill up with gas.
The amount of wire needed is reckoned as follows:
1 mile of wire per megawatt
36650 watt-hours per gallon of gas
For 18 gallons of gas (18) (36650) = 659700 watt-hours
1000000/659700 = .66 miles of wire = 3500’ of wire
This says the size and weight of the storage unit is relatively small.
The estimates here don’t reflect the 100% superconductive electric efficiency vs. 30% efficiency of gas.
The cost of hydrogen needed is a function of the tank leakage rate.
http://www.greencarcongress.com/2008/06/sierra-lobo-to.html
Let's see, 600 W * 24 hr/day = 14.4 kWh/day
Price of power = $.1/ kWh
(14.4 kWh/day) ($.1/ kWh) = $1.44 day
The advantages of this system over batteries are as follows:
- No degrading of storage unit over the lifetime of the unit.
- Fast refill times
- High efficiency capture of braking energy over 90%
- High efficiency refill
- No loss of charge over time
As always your criticism and advice is always welcome.
Posted by: Axil | Jun 24, 2008 11:21:18 AM
@J T
This goes back to what you said about China.
Reference:
http://nextbigfuture.com/2008/05/iron-and-arsenic-superconductors-could.html
excerpt:
BACK TO THE NEW IRON BASED SUPERCONDUCTORS
The biggest spurt in work on the new superconductors has come from China. Among other things, it has the laboratory labor force that can systematically look at ingredients with properties similar to those in the original recipe and try them out. China and Japan both place high priority on such work because they realize that new materials tend to translate into new technologies, says George Crabtree, a researcher at the Argonne National Laboratory outside Chicago.
While the US invests in war, China invests their money in the future.
Posted by: Axil | Jun 24, 2008 11:56:48 AM
"And while Americans are busy buying houses from each other with foreign money and keep on dreaming around..."
Read your own xenophbic words young man and get real.
Posted by: sulleny | Jun 24, 2008 1:00:57 PM
Sulleny
Learn about trade deficits facts, geography facts, housing and credit crisis facts, energy facts, efficiency facts and who is leading where and winning what wars with what expenses xenophobic young man.
But better you don't - then after all, ignorance is bliss. Keep in mind: America will always be number one in any regard as long as you just believe it. And this is what counts doesn't it?
Posted by: Realist | Jun 24, 2008 1:24:51 PM
"While the US invests in war, China invests their money in the future."
This correct. And amy protesting is being taken care of like pollution for clean and glorious Olympic game!! And China now is ready for end of free world aggression!
http://www.telegraph.co.uk/news/worldnews/1547296/China-is-accused-of-fuelling-Pacific-arms-race.html
http://www.dailymail.co.uk/news/article-528694/Olympics-clean-Chinese-style-Inside-Beijings-shocking-death-camp-cats.html
Long live Hu Jintau!!
Posted by: ccp4evr | Jun 25, 2008 8:01:34 AM
Perhaps what many countries now fear is an increasing decline in the power of the USA to protect their interests into the future.
Remember the Roman Empire: history has taught that any country can suffer greatly from mismanagement, even the USA.
Posted by: TheLastWord | Jun 25, 2008 9:25:23 AM
