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

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.

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.

Why can't we go with stationary sodium sulfur batteries?

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)

<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.

Make that 3%/1000 km and 8%.

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".

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....

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.

@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.

@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.

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!!

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....

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

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.

HVDC with 3% loss per 1000 km in China NOW

As I said, ignorance is bliss.

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.

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

"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.

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.

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.

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.

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.

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.