## Sandy solution for renewable energy storage; Thermal Energy Storage System

##### 11 November 2015

by Andrew Spence

Sand is emerging as a key ingredient in the race to develop a viable electricity storage system for renewable energies. Australia-based Latent Heat Storage has developed a low cost thermal energy storage system based on the latent heat properties of silicon derived from sand.

The device—known as TESS (thermal energy storage system)—is being developed in South Australia with the help of an AUD $400,000 government grant to take it from prototype to commercial reality. The TESS device stores electricity as thermal energy by heating and melting containers full of silicon. The high latent heat capacity and melting temperature of silicon makes it ideal for the storage of large amounts of energy. Latent Heat Storage Chief Executive Officer Jonathan Whalley said storage was the next big challenge for energy generation worldwide. Renewable energy sources generally spill energy due to supply and demand mismatches, so we’ve designed the TESS device to capture this ‘spilt’ energy for later use or release to the grid. Our system also means that energy consumers will be able to purchase stored electricity off-peak at low tariffs, which ultimately means cheaper energy. —Jonathan Whalley A key benefit of the TESS device is its capability to handle an increasing workload from 500kW applications through to an industrial scale of up to several hundred megawatt hours—enough to power about 7000 homes for a day. The patented device is small enough to fit inside a 20-foot shipping container but is readily scalable as demand requires. TESS is suitable for grid and off-grid applications and has been designed to overcome the intermittent nature of renewable energies such as wind and solar by providing a stable energy output suitable for base load power. It can be integrated anywhere within an electricity network and is suitable for commercial and industrial businesses where heat and electricity are required such as hotels, schools and hospitals. After three years of research and development, our key objective now is to complete building a commercial prototype of the TESS device and start showcasing its potential to global markets. —Jonathan Whalley A commercial prototype will be ready in early 2016 to be used as a selling tool to potential clients and Whalley said devices would initially be built to meet the needs of individual sites rather than mass produced. The Australian Government grant, through its Entrepreneur’s Program, has been matched by Latent Heat Storage shareholders to generate$800,000 of total project funding.

The device has been developed in partnership with Adelaide-based engineering consultancy ammjohn, and final year engineering students at the University of Adelaide.

Whalley said the commercial introduction of energy storage systems would encourage more renewable energy generation such as wind farms and solar arrays.

Energy prices are increasing around the world while storage technology costs are reducing, so we’re approaching the tipping point where energy storage systems are finally becoming commercially viable. We are developing an energy storage system to meet market demand … we anticipate that this will result in exponential growth of the energy storage market worldwide.

—Jonathan Whalley

Are ultra high efficiency Heat Pumps a possibility to transfer more or multiply excess e-energy into the thermal heat storage unit?

Silicon melts at 1410°C, so this is not going to be done with cheap metal containers.  SiC works thermally but it would probably be corroded by elemental Si.

1410°C is on the order of the peak turbine inlet temperature of high-performance gas turbines, so heat storage for later conversion to electricity is a possible use.

Harvey, this seems like a good application of solar energy from a power tower. Avoid the conversion to electricity until needed late in the day. Then use the gas turbine.

Siemens wind power is now in the early stages of developing a new idea based on storing heat up to 600 degrees Celsius in large reservoirs of sand or stone that is buried underground and insulated to prevent heat losses. Just one facility 3 to 4 square kilometers large and 10 meters deep can store enough heat to power steam turbines that could make all the electricity that Denmark typically consumes in 10 days. That would solve the intermittency problem completely for a country like Denmark that strive to go 100% fossil free using wind power. Heat is transferred into the heat sink using heat pumps (compressors) compressing ambient air at 1 bar and 20 degrees Celsius to 30 bars and 600 Celsius and blown through standard steel tubes within the heat sink. After delivering some of the heat to the heat sink the air is decompressed through a gas turbine that helps turn the compressor. That process also produces freezing cold air at minus 100 degrees as the exhaust of the gas turbine to be used for cooling (say industrial food storage).

Siemens early estimates is that they can store electricity at about 10 cents per kwh using such a facility which is lower than all the alternative methods including compressed air, hydrogen or pumped hydro storage. These alternative methods also require suited geographic locations like a depleted gas field for storing compressed air or hydrogen or a steep mountain for hydro storage. The heat sinks can be build anywhere and at any size. Potentially even a house owner with solar panels on the roof and heat sinks buried in the garden could do this but the cost would go up in such a small scale facility. Mass production could of cause bring it down for such micro facilities.

Danish source for Siemens project
http://ing.dk/artikel/siemens-vil-lagre-stroem-i-kaempe-sandbunker-172557

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Thanks for the link Henrik, I'm sold on the Danish idea. Cheap=good when it comes to season scale storage.

Clett it is still an early estimate. I think the future of massive seasonal renewable energy storage is either hydrogen in old gas fields or liquid hydrogen in buried and insulated cryogenic tanks or thermal storage in sand. It may be a combination of all three.

Just one facility 3 to 4 square kilometers large and 10 meters deep can store enough heat to power steam turbines that could make all the electricity that Denmark typically consumes in 10 days.

FINALLY a serious suggestion for dealing with the intermittency issue!  I said that this requires a storage medium costing pennies, not dollars per kWh, roughly cheap as dirt... and someone came up with a way to use dirt.

Siemens early estimates is that they can store electricity at about 10 cents per kwh

That's a major problem.  Denmark already has sky-high electric rates, and adding another 10¢/kWh is only going to produce more energy poverty and do things like making EVs cost more to run than ICEVs.  Also, the 50% round-trip efficiency is poor; to get 1 kWh of electricity out, you have to put 2 kWh of (very expensive "renewable") electricity in.

This is going to become a textbook study in "how to bankrupt an industrial economy".

EP I would hardly imaging that 10 cents for long-term storage (over 2 days) of a kwh is an issue when you only need to use such stored energy from thermal heat sinks for probably 10% of your total annual consumption of electricity. Probably 55% of solar and wind power need not be stored at all but can be used directly. And the remaining 35% of the annual electricity consumption can use short-term storage (less than 2 days) using lower cost high cycle life batteries costing about 130 USD per kwh at the pack level in 2030. With 5000 cycles that is 2.6 cents for battery storage per kwh (=130/5000).

The average cost of solar and wind power is going below 3 cents per kwh by 2030. That is lower that any fossil fuel or nuclear. Add 3 more cents for grid services and storage services and 6 cents per kwh will be what the average electricity consumer will pay for 100% pollution free electricity by 2030. We can't use nuclear and fossils for electricity production as they both pollute and we are going towards a zero pollution society. Pollution will be an issue only for primitive and poor civilizations. It will not be accepted in future western societies.

EP I would hardly imaging that 10 cents for long-term storage (over 2 days) of a kwh is an issue when you only need to use such stored energy from thermal heat sinks for probably 10% of your total annual consumption of electricity.

Peter Lang's graph of British wind power scaled up to 50% of demand over a month shows that you'll have a lot more than 10% going in and out of storage even over that short example period.  For Britain, the FITs required to get off-shore wind built are higher than the projected cost of new nuclear builds... WITHOUT storage.  Now double that and add 10¢/kWh.  You will need weeks of storage, because over many areas of the world (like the Bonneville Power Administration service area) wind generation can go to zero or near-zero and stay there literally for weeks.  Evening out seasonal supply/demand variations requires much more.  Very large amounts of energy will be going through storage.

UK wind receives both grid payments for power delivered (with CFD) and ROCs.  To quote db.com, "Currently offshore wind receives 2 ROCs/MWh. So with a wholesale price of ~£50, this gives ~£130/MW which is generally competitive for offshore wind development currently".  At the current exchange rate of £1=USD1.521, that's a whopping 19.8¢/kWh... wholesale.

And that is for raw energy delivered whenever Nature feels like it, not the dispatchable power that the grid cannot do without.  Dispatchability costs quite a bit more.

The average cost of solar and wind power is going below 3 cents per kwh by 2030.

Given the shenanigans in today's "cheap" wind and PV costs, I frankly don't believe such claims.

EP forget about off-shore wind power. It is niche and is about 2 to 3 times as expensive as onshore wind power and is primarily promoted by the oil and gas industry that wants to tap into green funds by building expensive offshore platforms with wind turbines on top of it. Offshore wind power is BS and a pipedream IMO. Less than 2GW of offshore wind power is build per year compared to about 50Gw of onshore wind power. Wind power cost onshore in the USA for new turbines is about 5 cent per kwh without subsidies. By 2030 it will be about 3 cents per kwh for new turbines onshore. Utility scale solar PV is about 10 cents today in southern California. I think 3 cents per kwh is possible for solar there by 2030 or maybe 2040.

Tesla's 50Gwh battery factory will sell backup batteries for renewable for about 200 USD per kwh and build 20 more 50Gwh factories and the price for battery backup will drop to 130 USD at the pack level. Same price for electric cars. I think that by 2030 there will be about 20 50GWh factories in operation worldwide.

This link shows the monthly wind power production for USA. You can click the other sources, coal, gas etc to remove them and get only wind power for best view.

http://www.eia.gov/electricity/data/browser/

The graph shows there is very little non-seasonal intermittency in US wind power. Can be managed by power lines and battery backup. However, there is a large 40% drop in wind power during the summer months for wind power. The solution is to add solar power that produces a lot more power during summer than during all other months. We will not need a lot of long-term power back up (over 2 days). At most 10% for total electricity consumption. In order to go 100% hydro, wind and solar we will need a more powerful grid and a lot of backup batteries from Tesla like 50Gwh factories. Conventional power plants should all be powered by renewable hydrogen or renewable heat sinks in large reservoirs of sand or rock.

EP forget about off-shore wind power. It is niche and is about 2 to 3 times as expensive as onshore wind power

The UK doesn't have nearly enough on-shore resources, even if they were willing to pollute their viewscapes and mince their raptors.  Throwing in 50% losses just adds insult to injury.

about 50Gw of onshore wind power.

Compared to almost 1 TW of thermal and hydro in the USA alone.

Wind power cost onshore in the USA for new turbines is about 5 cent per kwh without subsidies.

That is not dispatchable power.  That is the intermittent input from which you hope Siemens' thermal-storage scheme can power a real grid.  After 50% losses in storage you have 10¢/kWh, plus O&M and amortization of the storage system.

Tesla's 50Gwh battery factory will sell backup batteries for renewable for about 200 USD per kwh

Average US grid load:  ~450 GW.
Typical US electric power consumption:  1.08e10 kWh/day.
Cost of 2 days' storage at $200/kWh:$2.16 TRILLION.

Amount of nuclear generation $2.16 trillion will buy at$6000/kW:  360 GW.  In other words, for the price of 2 days worth of PowerWalls, you could nuclearize most of the remaining generation of the USA and not have to worry about unreliable sources like wind at all.

I think that by 2030 there will be about 20 50GWh factories in operation worldwide.

It would take 9 of them running for a year to produce a 1-hour backup for the USA.  I'd much rather have them in cars, displacing petroleum, than sitting on walls ready for the sun to go down (which happens every day).

EP for two days or 48 hours of battery backup we only need 12 hours max at full average load. There will never be a day in the US where solar, wind and hydro produces 0%. You will also have variable prices that automatically go up when the batteries are needed and more so the more they are needed. You can shot down a lot of energy intensive production like iron and aluminium, cement when electricity prices are expected to rise above a certain threshold. In periods of excesssive electric production you make heat and hydrogen for traditional power plants for seasonal variability and extreme weather. Moreover, 200 USD per kwh at the pack level is what Tesla can do profitable with their 50Gwh factory. It will be 130 USD when 20 of those factories are up and better chemistry is used.

Also when all cars and trucks are long range BEVs you have a lot of intermittency leverage right there. There are approximately 300 million vehicles and people in the US. If the average vehicle has 100kwh. (busses and heavy duty will have 300 to 600 kwh batteries small cars probably only 70kwh). That is about 100kwh per person in the US in vehicles. Average electric consumption per person also for industrial and commercial applications in the US is 10,000kwh per year or 27 kwh per day. So your numbers must be wrong. There will be plenty of electric backup in that fleet alone for 4 days full average load or 16 days if conservatively used and also accounting for minimal production in solar, hydro and wind.

There will never be a day in the US where solar, wind and hydro produces 0%.

I'm impressed that you were able to get FIVE falsehoods, misleading factoids and critical omissions into one sentence.  It's a feat worthy of a professional propagandist.

1. Solar goes to zero at night, every night.  Even units with thermal storage are not designed to run overnight.  There are also seasonal deficits in e.g. winter.
2. Wind can go to zero or near-zero not just for hours but for weeks.  All the wind farms in the BPA area, spanning nearly 1000 km, had zero or minimal output for 13 days in 2014.  We can be certain that winds near that zone were also sub-par for the same period.
3. Hydro produces less than 7% of US electric power, and a far smaller fraction of total energy.  As a way of evening out major fluctuations in other generation on the scale of seasons, it is hopelessly inadequate.
4. The problem doesn't begin at 0%, it begins whenever generation falls short of need and storage begins depleting.  That is going to include every calm evening.
5. Having power elsewhere in the USA is useless unless "elsewhere" has
• a surplus to share,
• enough transmission capacity in between to get it there.
The transmission part alone is a massive infrastructure project with huge legal obstacles.
In summary:  not going to happen.
for two days or 48 hours of battery backup we only need 12 hours max at full average load.

And when the wind takes 2 weeks of vacation in January, when the sun is also working a very light schedule, what do you need then?

Do you wonder why I think "renewables" advocates are nuts?  It's because digging even slightly into their claims shows that they are delusional, if not full-blown insane.  If you're not getting paid to write this, you're crazy; if you are, you're despicable.

It will be 130 USD when 20 of those factories are up and better chemistry is used.

So you'd only be able to build 234 GW of new nukes for the same price.  Oh, include the fact that such a large nuclear effort would create economies of scale as the Nth repetition becomes faster and cheaper than the 1st.  Upshot:  you wouldn't need the storage, the "ruinables" to fill it up or the continent-spanning transmission network to patch the holes.  You could do it all with a few sites occupying perhaps 50 square miles for the entire USA.

Also when all cars and trucks are long range BEVs you have a lot of intermittency leverage right there.

Only on the scale of a day or so.  Any deficit has to be followed very quickly by a surplus or you have dead vehicles on the road, and significant use of vehicles as backup also leaves dead vehicles waiting for juice after a very short time.  EPRI's V2G concept used EVs for regulation, with cycles lasting not days but minutes.

There are approximately 300 million vehicles and people in the US. If the average vehicle has 100kwh....

100 kWh * 300 million = 30 TWh.  30 TWh / 50 GWh/yr/plant = 600 plant-years.  3e10 kWh * $130/kWh =$3.9e12.

You have NO concept of the size of the effort you're proposing, Henrik.  You can't even calculate the numbers.

Germany is planning to store up to 200 TWh of excess wind and solar energy, via power-to-gas, in their existing natural gas network as part of the energiewende. That's enough to cover 3 weeks worth of total national primary energy requirements (transport, heating and electricity).

Wow, battle of the strawmen.

Simple cycle natural gas costs $0.25 per watt when you convert an old coal plant,$0.60 new. A blended 50/50 cost of $0.43 per watt. So 234 gigawatts costs$100 billion vs. $1400 billion for nuclear.* Fuel cost would be in the big picture negligible (say 5 cents per kilowatt-hour in the UK fuel price at$7 per mmBTU), as you're running these 4% of the year ($150 million in fuel costs). Run it on biotmethane or just methane with a$100 per tonne carbon price if you wish - won't make much of a dent in the total price difference.

So let's repurpose some Engineer-Poet vitriol:

You have a clear concept of the size of the effort you're proposing, Engineer-Poet. You can even calculate the numbers - but you don't.

Do you wonder why I think some "nuclear" advocates are despicable? It's because digging even slightly into their claims shows that they are are advocating something they *know* is financially deluded. If you're not getting paid to write this, you're despicable; if you are, you're even more despicable.

@Engineer-Poet Henrik can't do math - that's his excuse. What's yours? How does it feel to be more despicable than what you contempt for?

*There's also a time cost of money. At 7%, saving $1300 billion up front over 60 years is a real savings of *64 times that number*. EP you are creating a problem that does not exist. It is entirely possible to deal with the intermittency of renewable wind, solar and hydro and not spend more than running on either nuclear or fossils that have huge external expenses because of their not paid for pollution. No nuclear power plant could be build if it had to be fully self-insured also being liable for worst case accidents that could make large parts of an entire nation inhabitable for hundreds of years. And then you have the problem of nuclear companies producing loads of nuclear waste that need to be safely stored for 1000s of years. This will be an annual expense for thousands of years after they have stopped generating any power and revenue to pay for that. No thanks putting that burden on future generations. It is simply immoral. The externalities of fossils are even more obvious with 7 million people that dies prematurely every year because of air pollution from fossil fuel burning. So fission nuclear and fossils are not an option for the future energy supply. Fusion nuclear and renewable are the only way forward. You overlook the fact that solar and wind power is a constant energy resource for all of the planet as 50% of the planet is always energised by the fusion reactor at the centre of our solar system. Global power lines (using superconductors) could do the trick. The batteries that are used for vehicles are already paid for so there is no extra expense here. You could have been a little clever and said that 300 million vehicles with 100kwh battery packs on average are not needed in the future because all these vehicles will be fully autonomous and therefore only about 75 million are needed to do the same transportation as 300 million non-autonomous vehicles. 75 million with 100kwh each will still give use 25kwh per person in America or about one full day of electric use or 4 days when power lines and variable electricity prices are considered. Stationary grid storage could add another 25kwh per person so we get 2 days of full load and 8 days of managed storage from batteries, grid transport and variable prices. That is still 50kwh per person or 6500 USD per person (=50*130) or 325 USD per year for 20 years for part of an infrastructure that can make fossils or nuclear fission redundant. It is certainly not impossible in a wealthy society. So we need 300 years of 50Gwh plant years to make 50kwh per person in the USA. That is the steady state production of 15 of those 50GWh plants assuming 20 years average life before recycling of those batteries. So what? What is the problem? Just build it. Sweden is already closing their nuclear power plants because they are uneconomical not because they have been ordered to do so. The Swedish nuclear power plants are all written off so what makes them uneconomical is maintenance, fuel and waste handling. The Scandinavian grid is getting more renewable capacity every year and the average inflation adjusted prices in the grid is going down. That is killing nuclear in Sweden. When the USA also get a lot of renewable capacity it will also make the US nuclear uneconomical. Germany is planning to store up to 200 TWh of excess wind and solar energy, via power-to-gas, in their existing natural gas network as part of the energiewende. Questions yet unanswered: 1. How far has Germany gotten with these "plans"? Are they actually plans, with schedules and budgets, or just hot air? 2. How much has it cost so far? 3. What would it cost to complete the plan? 4. How much can Germany afford to spend on this? So far, ignored. My bet is that costs will continue to be hidden and budgets never mentioned, while consumer "environmental fees" continue to escalate and energy poverty deepens. That's enough to cover 3 weeks worth of total national primary energy requirements (transport, heating and electricity). Unanswered: 1. Is 3 weeks enough to deal with seasonal and short-and-long cyclical variations in the availability of the "ruinable" energy supplies? 2. Will any "unanticipated" deficits still be made up by burning lignite? Inquiring minds want to know! EP you are creating a problem that does not exist. It is entirely possible to deal with the intermittency of renewable wind, solar and hydro and not spend more than running on either nuclear or fossils You keep using the label "renewable" to describe impoundment-fed hydro (dispatchable), wind and PV (both highly unreliable) which have nothing in common except the label. Further, you provide no evidence. I keep asking people to show me ANYWHERE that a fossil-dominated grid has been decarbonized (say, to 100 gCO2/kWh) by substituting wind and solar, and maintains the ability to supply wind and solar hardware to expand the system. ANYWHERE. Where is this being done? NOWHERE. Most of the "renewable" PV panels are coming from China, which is choking on coal emissions. It isn't being done anywhere because it ISN'T possible. You have a few villages in India and Nepal and Pacific islands where PV and batteries have mostly replaced diesel generators. These places can scarcely support domestic refrigerators, and don't have the industry to so much as build a sewing machine. Meanwhile, France soldiers along with its 78%-nuclear, 40 gCO2/kWh grid with some of the cheapest electric rates in Europe while Germany spews 460 grams and prides itself on its virtue because it intends to shut down all its non-emitting base load plants. You overlook the fact that solar and wind power is a constant energy resource for all of the planet as 50% of the planet is always energised by the fusion reactor at the centre of our solar system. Global power lines (using superconductors) could do the trick. In other words, use the prospect of technology we don't have and couldn't afford anyway to tell Germans that someday solar farms bobbing in the South Pacific will keep their houses bright and warm on frigid January nights, while switching the existing grid away from non-emitting sources to lignite. Insane or evil, pick one. And back in his role as "Mr. Apples Equal Oranges" is NewtonPulsifer! Simple cycle natural gas costs$0.25 per watt when you convert an old coal plant, $0.60 new. Comparing incommensurables. A converted coal plant is not simple-cycle. Neither option is emission-free. You put forth two "options" that cannot do what they're supposed to be an alternative to. Fuel cost would be in the big picture negligible (say 5 cents per kilowatt-hour in the UK fuel price at$7 per mmBTU), as you're running these 4% of the year ($150 million in fuel costs). Numbers just pulled out of your butt. Run it on biotmethane Do you have any idea how scarce biomethane is? I looked up the numbers on a major landfill gas project once (I believe it was in King county, WA). The methane coming from all of the MSW of the county wasn't even enough to fuel the jetliners coming in and out of SEATAC, let alone the many-times-larger demand of LDVs. The market potential is just 1-2.5 quads per year, compared to roughly 100 quads total US energy consumption. Last year, nuclear generated 797 billion kWh, 2.87 EJ. If this was instead generated from methane at 45% efficiency, you'd need 6 quads out of your 1-2.5 quads market potential to do it. So much for "renewable methane". let's repurpose some Engineer-Poet vitriol Stupid people do that a lot. They can't figure out that lying doesn't help their case, but if they could figure out how dumb they look they wouldn't have made an argument dumb enough to get fisked in the first place. That's a "moving of the goalpost" attempt there. There isn't going to be some non-fossil non-nuclear example before it exists, especially if that grid has already built nuclear and fossil plants (very likely). That's like insisting on "evidence" in 1955 on a grid that is mostly nuclear before any such thing existed yet. It's unreasonable. Its been established gas turbines can back any capacity issues for an extremely cheap capital cost (1/14th of nuclear in the USA/Europe). Next question - does wind and/or solar provide power at a cheaper cost in$/MWh than nuclear? Plenty of markets yes, and where it doesn't, it certainly will in as little as 5 years.

Next question. What about the eventual night time issue?

Is there enough already built plants (fossil+nuclear+hydro) to cover nighttime? If the answer is yes, you either slowly ratchet up your carbon prices or wait until old coal plants cost to much to fix.

Years later when the cost/benefit warrants it....

You start buying/building intraday storage to store cheap wind and solar. Not a day before. Probably 10 years later.

And you go past intraday to perhaps 2 days (to store spare cheap power from the weekend nadir) assuming the cost warrants it et. cetera. Maybe not - it well could be just overbuilding wind and solar by multiple times and sticking with intraday storage is the cheaper result. It all depends on what the price ends up 10 years later.

Really no big deal at all, because if you're using 15% gas for elecricity by TWh to back bad solar+wind days, it just doesn't matter. Plant some trees to compensate or use biomethane. Or don't. You've still reduced your emissions by 85% or so, which is plenty.

Since it looks like my last comment isn't getting out of moderation jail any time soon, I'm going to re-write and re-post.

Back in his role as "Mr. Apples Equal Oranges" is NewtonPulsifer!

Simple cycle natural gas costs $0.25 per watt when you convert an old coal plant,$0.60 new.

Comparing incommensurables.  A converted coal plant is not simple-cycle.  Neither option is emission-free.  You put forth two "options" that cannot do what they're supposed to be an alternative to.

Fuel cost would be in the big picture negligible (say 5 cents per kilowatt-hour in the UK fuel price at $7 per mmBTU), as you're running these 4% of the year ($150 million in fuel costs).

Numbers just pulled out of your b***.

Run it on biotmethane [sic]

Do you have any idea how scarce biomethane is?  I looked up the numbers on a major landfill gas project once (I believe it was in King county, WA).  The methane coming from all of the MSW of the county wasn't even enough to fuel the jetliners coming in and out of SEATAC, let alone the many-times-larger demand of LDVs.  The market potential is just 1-2.5 quads per year, compared to roughly 100 quads total US energy consumption.

Since it looks like my last comment isn't getting out of moderation jail any time soon, I'm going to re-write and re-post.

Back in his role as "Mr. Apples Equal Oranges" is NewtonPulsifer!

Simple cycle natural gas costs $0.25 per watt when you convert an old coal plant,$0.60 new.

Comparing incommensurables.  A converted coal plant is not simple-cycle.  Neither option is emission-free.  You put forth two "options" that cannot do what they're supposed to be an alternative to.

Fuel cost would be in the big picture negligible (say 5 cents per kilowatt-hour in the UK fuel price at $7 per mmBTU), as you're running these 4% of the year ($150 million in fuel costs).

Numbers just pulled out of your b***.

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