But it is now more expensive to build new transmission lines and other grid hardware, making battery storage potentially more attractive. "Cost is given as the reason that energy storage is not widely used on the grid," the researchers wrote, and cost reductions in lithium ion batteries—thanks to potential wide-scale deployment in electric vehicles—may change that equation. Big lithium ion batteries may soon be made very inexpensively and in large volumes, making them finally cheap enough for widespread grid storage applications, along with other possibilities. "Electric vehicles themselves can act as storage," Kamath notes. "Of course, the owner of the vehicle would have to agree to that."
Already, power company AES has opened the nation's largest battery installation in Elkins, W. Va. More than 30 megawatts-worth of lithium ion batteries from A123 Systems have been hooked up to the company's 98 megawatts-worth of GE wind turbines to ensure a steadier power output.
There is already a technological leader in the cheap storage area, however: pumped hydro, which accounts for 99 percent of the 127,000 megawatts–worth of electricity storage in use today worldwide. Its spread is limited only by geography, geology and concrete. And, ultimately, more advanced storage options—whether batteries or flywheels—may be undone by another competitor: combined-cycle turbines that employ natural gas and can be started up in seconds. "We need new technologies and techniques to make batteries lower cost, longer-lived and more efficient," Kamath says, especially to compete with fossil fuel–fired alternatives.
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Add CommentVehicle-to-Grid (V2G) holds a lot of promise. The revenue stream that electric vehicle owners can harvest from this arrangement will make EVs a no-brainer. By allowing the utility to take a few percent of their stored energy a few times a day, but still having a full battery when they want to drive away, the EV owner wins, the utility wins, and even non-EV drivers win since the utility doesn't have to upgrade their electrical grid as often. The fact that millions of EV batteries can pretty much make the concept of baseload supply obsolete is just one more reason to keep improving battery technology!
Reply | Report Abuse | Link to thisStorage and forecasting are the two technologies that are required to permit wind and solar contributions to the grid without introducing instabilities that could result in brownouts and even collapse of the distribution system. Without them the penetration variable sources, wind and solar, is limited to about 15 to 25 percent (depending on which stability model you choose) of the total energy input. On line reserves are costly and the more rapid response systems are more expensive than those with longer start up times.
Reply | Report Abuse | Link to thisMegawatt is wrongly used several times as a unit for energy.
Reply | Report Abuse | Link to thisI love flywheels for their elegant simplicity, response times, and reliability. Unfortunatley, nothing competes with a natgas CCT for heft (real MWh) and speed. Consider this take high energy density, free gas (absorbed cost of well & transmission), getting heat through oxidization (absorbed cost of turbine), and emitting the waste (no absorbed cost). Gas turbines response in 10 seconds once in standby mode, giving value added output in the mean time. Compare this with a flywheel or battery, where source and sink are burdened with absorbed cost. The only avenue forward for this technology is to either attain further big cost reductions (best), charge for emissions for conventional methods (hard), or both (unlikely).
Reply | Report Abuse | Link to thisAll home owners should have a battery. Consumption from the grid should be managed intelligently.
Reply | Report Abuse | Link to thisThe British have built energy storage systems in mountainous districts on a very large scale. The logic is simple : link a high level and low level dam through a station which can act as a power station when the water is flowing downhill, but by reversing its action becomes a pumping station which stores energy again in the high dam. The first was built at Tanygrisiau, near Blaenau Ffestiniog in the 1950s, a much large and more recent one has been built at Llanberis at the foot of mount Snowdon.The latter has a capacity of 1,800 mW; see its 'Electric Mountain' website. The original idea was to enable nuclear power stations to run continuously at their optimum power output. More recently the idea of linking such installations to a large tidal barrage in the Severn Estuary between England and Wales (which has an exceptionally high tidal range of around fifty feet) has been mooted. This could generate huge quantities of electricity, but only for 16 hours out of every 24.
Reply | Report Abuse | Link to thisAnother Big Oil infomercial from Sciam and Biello.
Reply | Report Abuse | Link to thisCCGT plant can't be used in its high efficiency mode using its steam Rankine cycle unit to load balance wind and solar as it like coal takes an hour or so each way to cycle a head of steam. Its low efficiency gas turbine section has to be run inefficiently cycling rapidly up and down as the wind gusts and the sun goes in and out of clouds instead of purring along at a steady pace. That's why utilities use dirt cheap OCGT plant for wind/solar load balance - not expensive CCGT.
Big Oil loves the current wind/solar/gas backup scam and pays shills like Biello to push it because it sells more gas that way than if the utility skipped the wind/solar and just ran on CCGT plant.
EV batteries are only good for so many charge discharge cycles. Letting the power company do it daily, in addition to your own cycling will destroy the battery much faster, quickly reduce its capacity and greatly increase the possibility that the battery is flat when an unexpected need arises.
Nobody would buy into that scam.
For truly green wind/solar the cheapest storage available at $200/kwh is pumped hydro which gets environmentalists in a dither whenever it is proposed outside of existing hydro facilities. Allowing for a month of green storage to cover rare large area climate events adds a buck a kwh to the green power consumers bill. This brings the cost of an all green solar and wind powered USA into the buck and half a kwh area, or $60K per annum for the average US household.
With the Indian and Chinese economies booming on zero environmental footprint 3 cent a kwh nukes, the prognosis for an all wind/solar/green storage US economy is grim indeed.
Just one nit: A 1,000kg flywheel spinning at 16,000 rpm does NOT "flip direction" no matter what's happening on the grid!
Reply | Report Abuse | Link to thisNow this is a useful article. I think your idea on the EV batteries is a good idea. The more places to store energy the better and the power can be immediately used. My biggest problem at my house is I have massive generating capacity in my solar panels and my NG generator does 30 KW/hr with far less fuel than a commercial Coal or NG plant can send me over the grid. The problem is 2 fold. One, the Federal Government has mandated panels can only be connected to the grid. It is illegal for my panel company to connect my panels to a battery.
Reply | Report Abuse | Link to thisIf I had a battery I would also get more efficiency out of my NG Generator. I could run it always at most efficient speed on the engine, dumping the power into a battery, reducing the waste production entirely.
BUT there is no battery available yet.
Personally, I think the grid needs to go. It is extremely inefficient because of the wasted energy lost when stepping up and down the amps and volts to get the power onto the grid. The best storage of all is a fuel. It takes minimal effort for the gas company to pipe the NG to me. I can use on demand and no fuel is wasted when I am not operating the motor.
The grid is useful for Nuke power, hydro, wind, geothermal and solar. This is because even if there is wasted energy, it is not wasted on fuel burning. Plus those forms of energy are better operated in terms of scale and the limits of geography also have an effect. Except nukes but there is some new ways of doing these plants much smaller.
I like the idea of creating fuel, hydrogen from water. Dump the power into water to separate the hydrogen and now you have a fuel, which can be stored and transported, lasts a long time and only goes back to water when used. I especially like this if we put turbines in ocean currents or something.
Still a battery would be the best option for maximizing any power production source to ensure no loss of produced power from either the fuel or alternative source of that energy. I like the idea of EV cars, the biggest issue with those and all batteries is the charging time. There needs to be a solution for cars that is an instant fill, or at least no worse than filling a tank of gasoline. It could be just you dont own the battery, they get changed out for the "fill" up. Much like a propane gas grill is.
I think the cheapest and most space efficient way to store energy is by compressed air. Air is abundant everywhere. Compress it to 690 bars and it turns into liquid nitrogen (air is 78% nitrogen). All you need is a powerful air pump and a large pressure tank.
Reply | Report Abuse | Link to thisTo release the energy, you need a gas turbine connected to an electric generator. The compressed air drives the turbine to generate electricity.
I'm still waiting for you to post even 1 bit of proof backing up your assertions. I can say the moon is made of cheese all day but I wouldn't expect you to believe me unless I have some hard evidence to back it up.
Reply | Report Abuse | Link to thisI mean, nuclear power COULD be a viable option for part of our generting capacity, but I've never been able to cut through the "enthusiasm" the nuke boosters put forward to get real, hard numbers to base my decision on either way. I HAVE seen real, hard numbers from numerous sources saying that nuclear power is way too expensive to build based on historical reactor construction and current reactor cost / schedule overruns. Give me hard numbers and cut it with the conspiracy theory stuff and maybe we can have an honest discussion.
Do you have a natural gas-powered Bloom Box or something? Having a nat gas generator is kinda cool, but I didn't think they made home units yet. The grid is a good backup for on-site renewable generation for now, but you are correct that the centralized power plant model is getting a little outdated. I just wish the utilities will someday allow people with solar PV to keep their systems running during power outages instead of remotely shutting them down. With solar getting cheaper by the day almost, vahing backup power during the day would provide even more value to solar PV owners.
Reply | Report Abuse | Link to thisMost V2G arrangements take a percent or two off the top of your EVs battery, so if you have a V2G-enable LEAF, it'll take a mile or two of range out several times a day and then put it back in. Even current battery technology can handle this tens of thousands of times as shallow discharges are mostly harmless to EV batteries. To tell you the truth, I don't even want to try and count how many times my Prius' battery has bee shallowly cycled and I only have 100K miles on it! The lithium batteries for EVs like the LEAF are even more robust and can handle higher discharge rates as well.
Distributed generation is great for renewable energy since wind turbines and solar arrays are modular and don't gain from economies of scale as much as as the mega-sized central power plants. However, your small natural gas generator has got to be inefficient because combustion technology DOES benefit moderately from economies of scale. Now, if you're using its exhaust to heat water or something, then that's different. Eventually, the grid will become more like the Internet, distributed and functioning only to balance power flow instead of mandating that it flows only one way.
Get someone to explain to you what the energy losses are with such a system. If you used 100KW/h worth of energy to compress your air you would be lucky to recover 25KW/h back. I can not be bothered to do the calculations but here are some of the problems. Your compressor does not operate at anything like 100% efficiency due to the fact that the electric motor driving it does not operate at 100%. Then there are the friction losses. When you compress a gas it heats up. It is not generating heat it is simply that the heat energy in the gas is concentrated into a smaller area & that raises the temperature. That is what provides the combustion temperature in a diesel engine & the heat from a heat pump type air conditioner. Left to stand, your compressed air quickly cools down to the ambient temperature, losing much of its pressure in the process. When it expands again in a turbine, it cools & loses pressure even more. Then you have the friction losses again plus the losses because no generator operates at 100% efficiency.
Reply | Report Abuse | Link to thisThe tragedy is that people conning the governments, taxpayers & investors must know these things yet they continue to promote them.
Similar energy loses occur with water storage though not so severe if the distance pumped is not great, also if it is already a hydro scheme, most of the infrastructure is already in place. A stand alone system not also damming a river is a different matter.
If the problem of energy storage was simple, we would have been doing it long ago. Again, what disgusts me is that all these ideas can be tested to a high degree of accuracy mathematically without wasting millions. It is criminal. As for gyros, a huge amount of research was done back in the '60s that proved that the mathematical calculations were correct when they showed that it was not a goer. It was tried in heavy vehicles for instance, recovering energy from braking. The gyroscopic effects did not do a lot for road handling either, yet here we have a company that has just wasted millions of your dollars.
Next we will have butterfly power I suppose. Probably more practical. Your suggestion though is not unique. I remember a university professor in the 1980s suggesting that the Chinese fit solar panels to their pushbikes with batteries that would charge while the peasants worked in the paddy fields. Feeding the stored energy into the grid when they got home. See if you can spot the flaws. His suggestions were peer reviewed & passed, winning him a research grant.
Reply | Report Abuse | Link to thisI too have extreme reservations about trying to supplement the grid with storage. The only reason we are trying to do this is so that we can make renewable energy sources more useable. But what if we did not have to go to any of this trouble to for carbon-free energy? There is in fact a solution here, and it is nuclear.
Reply | Report Abuse | Link to thisThe only feasible way that I've seen to replace fossil fuels is to develop a new generation of nuclear reactors, and one approach using a liquid-fuel system was prototyped in the 60s and subsequently abandoned in favor of fast breeders. Where are those plutonium-based fast breeders today? They're too expensive!
Molten salt reactors promise to be very cheap and efficient compared to conventional technology, and they make a lot more sense than trying to beef up the grid with storage to make renewables work.
If we are going to have a future, then we are in all likelihood going to use this:
http://energyfromthorium.com/2011/10/04/flibe-uk-4/
[A video overview] http://www.youtube.com/watch?v=Vbx_gFT0v7k
Let's get the Green Nuclear revolution going and usher in the Thorium Era as soon as possible.
First of all, the unit of energy is not kW/h (kilowatt per hour). It's kWh (kilowatt-hour). Second, of course there's no machine that operates at 100% efficiency. But the losses are not as high as you imagine. Pumps, turbines, generators, motors can have 80% efficiency. Third, gas heat is not a problem since the higher the temperature the more energy is stored in the gas. Some of the energy is converted into pressure, some into heat. There is no loss in energy. Not yet. Fourth, you need to insulate the tank to minimize heat loss. That's where energy is lost.
Reply | Report Abuse | Link to thisI calculated the energy storage capacity. It's 3.0 MJ/kg. That's 3x higher than lithium ion batteries (0.9 MJ/kg).
As I stated I did not calculate the exact figures & you are correct if it was a perfect world. Even so with your 80% efficiency one hundred units of input is reduced to 64 units of output allowing nothing for temperature or pressure leaks. Now suppose you are using hugely expensive solar or wind generated power. Without any cost allowance for the construction or maintenance of this infrastructure or any heat loss you are still going to lose 36% of your precious energy. In fact actual energy loss through heat loss, regardless of insulation, will significantly raise these losses. Especially if you are looking at storage over a period of hours, much less days.
Reply | Report Abuse | Link to thisThe efficiency you ascribe to compressors & turbines is also pressure related. The higher the pressure of your compressor output, the higher your losses yet conversely the lower your turbine feed pressure, the lower your output efficiency.
Regardless of the final value for the losses, it is certainly more than one third of the input. It is things like this that are overlooked in the mad enthuiasm for all things green.
By the way, I think you will find that your compressed air will not turn to liquid at 690 bars unless you do cool the gas. I do not have the tables in front of me but I understand this hugely raises the energy losses.
Reply | Report Abuse | Link to this"I can not be bothered to do the calculations..."
Reply | Report Abuse | Link to thisThat's because you NEVER do calculations and just go with what the man on the radio or the TeeVee tells you. I guess you can't be bothered with ACTUALLY LOOKING UP existing compressed air storage, so I'll do it for you:
http://en.wikipedia.org/wiki/Compressed_air_energy_storage
http://my.epri.com/portal/server.pt?space=CommunityPage&cached=true&parentname=ObjMgr&parentid=2&control=SetCommunity&CommunityID=404&RaiseDocID=TR-101751-V2&RaiseDocType=Abstract_id
But isn't that the norm for you, blindly attacking something that you know nothing about!
Great, now link to the paper and I might believe you...
Reply | Report Abuse | Link to thisSo, 66% of the energy in coal or nuclear fuel goes up the cooling towers of the plant unused! I don't hear you crying about all that lost energy in that instance...
Reply | Report Abuse | Link to this80% of the energy in gasoline never even drives the wheels of a vehicle (on a good day!), going out the tailpipe as head and unburned hydrocarbons. Where's the bellyaching about all that lost energy?
Renewables hugely expensive? Baloney:
http://bnef.com/PressReleases/view/172
http://thinkprogress.org/romm/2011/11/01/358628/group-purchasing-solar-grid-parity-los-angeles/
As usual, get your facts straight and maybe we can have a good discussion.
Actually India has a 500MW plutonium fast breeder going on the grid next year at $1.5B/Gw first of 5 for 2010 service.
Reply | Report Abuse | Link to thisThe IFR is already designed and ready to build as are several SMR's based on the Soviet Alfa sub power plants.
The MSR is great idea though an Flibe thinks it may have one on line in 5 years.
Me I like to use real costs of real projects not biased Big Oil sponsored junk science sites that all low information climate deniers like Sault prefer.
Reply | Report Abuse | Link to thisNukes are 3 cents a kwh. The cost of solar power is over 70 cents a kwh when taxpayer provided 6 times sized transmission and gas backup is included. When green storage replaces the filthy gas cost increases by a buck a kwh.
AECL has completed 8 new Candu reactor installations over the last twenty years all on time in 4 years and on budget at $2B/Gw or less than 3 cents a kwh when the 1.5 cent a kwh fuel and O&M cost is included.The last one was completed in 2007 in Europe.
Here is Bloomberg on the actual cost $1.2B/Gw ($2007) of the recent AP-1000 builds.
http://noir.bloomberg.com/apps/news?pid=newsarchive&sid=a5.20kg0SOY0
Experience in China is showing nuclear costs dropping rapidly to under 2 cents a kwh as factory module production begins.
http://nextbigfuture.com/2010/08/china-leverages-learning-curve-cost.html
Here is a real solar project just completed by expert engineers at Duke Energy.
Google "biofuelswatch.com/solar-farm-starts-operation"
$43 a watt average, 18% capacity factor, 50 cents a kwh at Dukes discount rate.
Now that's getting facts straight for low information denier types like Sault.
Since Sault has shown himself incapable of simple arithmetic, lets look at the storage requirements of a 20% wind grid. At times when the wind is blowing hard 100% of the the power supply in that grid is coming the form of wind so for at least during that storm the grid must either shut down all other power sources like nuclear which generates for free or paid for CCNG or coal which take an hour to cycle up and down, or it must store the surplus. 80% of the grids energy for an hour is not ever going to be saved by running up whatever EV batteries are available 1 or 2% - only a fraction of storage requirements can be met with EV. On the power downside lets say the wind/solar shuts down for an hour. Once again replacing that 20% with EV batteries alone would quickly destroy the battery of the foolish EV owner that left himself connected.
I'll leave it as an exercise for Sault and his arithmetic teacher to calculate how much a month required for large area climate events of the cheapest green storage would add to the cost of wind/solar.
So you contend your links do not support my point of view? ‘Early tests have demonstrated the limited storage capacity of the tanks; the only published test of a vehicle running on compressed air alone was limited to a range of 7.22 km’
Reply | Report Abuse | Link to thisJust one of many problems pointed out in your links.
Sethdayal and All,
Reply | Report Abuse | Link to thisSualt is correct and you as usual are not. But you are not going to let facts get into the way are you?
Since we are in the US lets talk here. Progress energy is charging ratepayers $.05/kwhr for nuke power they won't even get!! So much for cheap. Just repairing the reactor because of Progress bungling costs $2.5B. The reactors suppose to go up near Crystal River, Fl are going for $9k/kw and the over runs are still yrs away and billions more. Yes nukes are the sollution alright.
Next new NG cogen plants take at least 15 minutes to start and then the steam part won't for another 10 minutes or so according to utility mags I get. But if running now they can throttle 50% power fairly eff, over 50% at lower levels and now breaking 60% eff at full power. So now they can follow load.
Next battery storage isn't ever going to be utility long term but under 15 minutes it takes to turn on other sources.
Nor are batteries needed for RE as RE varies far less than demand and the utility is already set up to handle that 10-1 use range. It like most anti- RE propaganda put out by big energy.
They'll be far better off turning on, off customers AC, heat, EV charging, hot water, etc to balance the grid than battery storage. Basic physics, econo 101.
So how much will you get charged for nuke power? Do you think you'll pay $.02/kwhr? Far more likely $.10-.15kwhr. And at that rate now both PV and wind in home sizes costs less. If the full cost was in FF's RE would be less than 50% of the price.
So sethdayal, keep pumping that money into your power master instead of investing 5 yrs worth of electric bills and get 25-50 yrs of energy almost free. A fool and his money are soon parted.
The energy loss you are citing is true for all storage systems that use pumps and turbines. To be realistic, you have to compare the efficiency of different storage systems.
Reply | Report Abuse | Link to thisYou think pumping water is an efficient way to store energy. To attain the storage efficiency of lithiun ion battery of 0.9 MJ/kg, to have to pump water to a height of 92,000 m. That's already in space! And the pressure in your pump will reach 9,000 bars.
Obviously some storage systems are less efficient than others, but all storage systems are not very efficient theoretically.
BTW you don't have to cool nitrogen to turn it into liquid. The high pressure will increase its boiling point. When it reached its boiling point, it will condense. So there is no energy loss from cooling.
Jerry how are you. Always good to hear.
Reply | Report Abuse | Link to thisHow are your talks going with Vesta and Samsung on your amazing rooftop wind and run of river DIY units. Two years now since your first told us about them and still no patents on your double industry standard hyper efficient units.
I was bringing up the amazing success on the learning curve reducing costs of building 20th to 30th or so Candu nuke at only $2B/GW with all plants built to the far higher Canadian standard by far more competent engineers than the USA has available.
With Florida being the most corrupt state in the union with the least demonstrated ability to do basic arithmetic we'll let your figures stand. However it appears that the VC Summer units now under construction in South Carolina are still on time on budget at $4B/GW. Cost overruns are unlikely as 4 sister AP-1000 units are already 75% finished on time and on budget in China build by American engineers under constant NRC supervision.
Once again Jerry you come up with more amazing numbers. Yup you can load follow with CCGT plant by venting steam but the efficiency drops to zilch. These plants are just to costly to load balance wind and such low efficiencies.
I was amazed to learn that very predictable utility loads vary more than RE. I guess a cloud passing over a solar solar farm in 30 secs is so much more predictable when compared to an entire city turning all its lights on all at the same time then off again 30 seconds later to observe Florida UFO activity?
I gave you Dukes cost to build a commercial solar plant in NCarolina 50 cents a kwh + 20 cents a kwh for gas backup and transmission.
Current US nuke cost is 2 cents a kwh and yes will rise to 3 to 4 cents for public power companies like TVA. I'm sure they will sell it for a lot more with all the foolish greenies dumping superexpensive not so RE on the grid.
Seth - Have you read this article?
Reply | Report Abuse | Link to thishttp://www.epaw.org/media.php?lang=en&article=pr3
Seth- this one is interesting too:
Reply | Report Abuse | Link to thishttp://www.globalwarming.org/2011/11/23/climategate-2-0-another-nail-in-kyotos-coffin/
I only suggested water as a medium for energy storage where the infrastructure is virtually all in place already for a hydroelectric facility.
Reply | Report Abuse | Link to thisWith regard to compressed air, the link provided by Sault, contrary to his intention, demonstrates my argument. There are various processes but essentially when gas is compressed, the heat generated is surrendered to the atmosphere. When the liquefied gas is released to power a turbine there is a cooling effect that can lower the temperature at the discharge point to minus 20 degrees Celsius. To regain the lost heat energy, large heat exchangers are used to recover the lost heat from the atmosphere. While theoretical values are valuable, in practice considerable additional parasitical losses occur. You might care to have a look at : http://en.wikipedia.org/wiki/Compressed_air_energy_storage#Isothermal_storage_physics
Cold exhaust gas is not a problem because gas cools as it expands and converts thermal energy into kinetic energy. On the contrary, hot exhaust gas would be a problem as it indicates heat is not efficiently converted into motion (energy loss).
Reply | Report Abuse | Link to thisI'm refering to adiabatic storage. You need heat insulator not heat exchanger. You may not be impressed with the 70% practical efficiency quoted in your source. But note the efficiency of gasoline engines is only 25%. The best and largest diesel engines is 35% to 40%. The most efficient combined cycle gas turbine is 60%. I would say 70% is not bad.
Except that nobody has achieved 70% in actual practice, the costs are enormous, and the energy lost was electricity not low value heat awaiting conversion.
Reply | Report Abuse | Link to thisThe theoretical efficiency of adiabatic storage is close to 100%. The 70% is practical efficiency. It is attainable. The electric motor of Tesla Roadster has 97% efficiency.
Reply | Report Abuse | Link to thisWhere's the enormous cost estimate? The components are pretty basic: pump, tank, turbine, insulator. Magnetically levitated flywheels are more sophisticated.
BTW electricity and "low value heat" (gasoline) both cost about 3 cents per megajoule.
On the figures you give compressed air would indeed be an attractive proposition. The problem is converting the theory into practice. As the article states, no industrial scale unit has ever been built.
Reply | Report Abuse | Link to this(Adiabatic storage retains the heat produced by compression and returns it to the air when the air is expanded to generate power. This is a subject of ongoing study, with no utility scale plants as of 2010. Its theoretical efficiency approaches 100% for large and/or rapidly cycled devices and/or perfect thermal insulation, but in practice round trip efficiency is expected to be 70%.[3] Heat can be stored in a solid such as concrete or stone, or more likely in a fluid such as hot oil (up to 300 °C) or molten salt solutions (600 °C).)
Actually being able to rapidly recover the stored heat from these mediums is problamatic. Also the physical size of the pressure tank including the heat storage medium & exterior insulation for the scale required by a utility would be enormous due to the energy density. Large scale insulation is not cheap when you are seeking to practically eliminate heat loss.
I conceed that in theory it looks promising but converting theory into practice is a different matter. There is nothing wrong with 70% storage & recovery or even 50% if the figures really do stack up but things like molten salt are incredibly corosive & many such problems can not simply be glossed over. When I have time I will investigate the subject further. I see energy density & thus sheer scale as being a major problem.
It is rather refreshing to be ale to have a discussion on this forum & not a shouting match for which I thank you.
In the early 1980s I was involved in solar research. One of the projects that I had some involvement with was 'Salt Gradient Solar Ponds'. An Australian company is trying to revive interest in this technology. A number of things lead to its failure though power was generated at a facility near Alice Springs using hot brine & a Rankin cycle engine. The two main problems were the effect of wind over a large surface area causing mixing & the much larger problem of heat loss through the bottom of the pond, being conducted away by ground moisture beneath the waterproof membrane even though moisture could not be seen visually in this desert area. The water temperature was around 80 C. Black body radiation & phase change losses via evaporation in this area were the two other major sources of heat loss. It was a very interesting project however. See: solar pond heat storage, http://www.solarponds.com/
Reply | Report Abuse | Link to thisYou are correct. Regards Dr.Kamlander.aon.at
Reply | Report Abuse | Link to thisNo one has mentioned that there are large losses in storage and retrieval. Wind Power is already almost useless, storing the energy behind a dam just makes it even more useless.
Reply | Report Abuse | Link to thisSeems to me the free resource of the rise and fall of the tide is being overlooked. The fifty foot tides in the UK acting on a floating body of vast proportions suitably geared to generators would provide significant power. Alternatively, compressed air means could be generated to drive turbines. Then again just a fifty foot drop of water from a high tide raised contained body of water, at low tide can be scaled to effective proportions, to drive water turbines. Batteries could store the power.
Reply | Report Abuse | Link to thisThe low efficiency of such devices is not a deterrent, since the input is free, regular and basically unlimited.
Dear Sir !I am interested in your article.Compressed air is in many ways used to feed drilling tools etc. Including air locomotives. They run the few miles to the escalater, dump their load, get another fresh charge of compressed air and continue on and on and on......
Reply | Report Abuse | Link to thisBut now are the equations of theoretical physics.
( P times V equals R times T ) and there is no way around them.
When you compress air ( or any other gas ) it gets hot.When you lower the pressure like in a drill then the air gets cold. The mineros enjoy this effect.
Keep those laws of thermodynamics in your mind. Best of luck. Dr.Kamlander.aon.at
Yes but the cost of capture is not free. In fact it is prohibitive. Apart from the initial costs, maintaining the infrastructure in such a harsh environment on the scale necessary to capture worthwhile energy makes it impractical as numerous programmes have confirmed. Fifty feet of water only gives you 22 PSI & even that is only available on the high tide.
Reply | Report Abuse | Link to thisAny grid needs short-term energy storage provided by spinning reserve (partly loaded generating sets) flywheels, batteries and hydro pumped storage. These technologies will store and deliver energy over a period ranging from a few minutes to about 10 hours. In the past, one of the reasons for building pumped storage schemes was to absorb surplus nuclear power in the early hours of the morning. Because the power was essentially free, the economics were good.
Reply | Report Abuse | Link to thisBut with renewable energy we have a serious problem that nobody wants to address. We cannot rely on renewable energy to be available when we need it and, quite often, it generates lots of power when we do not need it. In many countries there can be prolonged calm periods when electricity demand peaks and, quite often, the peak demand is in winter while solar cells produce the maximum in summertime when it is not needed.
In order for new renewable energy technologies to get anywhere, we need a technology that does not yet exist. A technology that will store large amounts of electricity for periods of days, weeks or months at low cost and with high efficiency. Until such a technology is discovered–if ever–new renewable energy technologies can only play a bit part.
The only low cost and efficient methods of storing large amounts of energy for long periods are nuclear fuel, gas storage and coal stockpiles.
Compressed air energy storage is quite inefficient because of losses during compression and expansion. The two plants that are in operation use conventional gas turbines with the store of compressed air replacing the compressor.
There is no doubt that some efficient method of energy storage is the holy grail of efficient energy delivery & just with conventional generation would have a greater effect than all the alternative energy generation schemes. Unfortunately to date, no one has been able to come up with a system. Some things in nature just do not cooperate with human wishes, like faster than light travel for example. Sometimes there is no satisfactory solution.
Reply | Report Abuse | Link to thisRe post 16. You are correct but unfortunately the only solution to a non carbon based energy supply would not force humanity back into the caves as many in the environmental movement really crave, for others that is. Otherwise why is it they will have nothing to do with nuclear? Do not give me illogical answers. how many died as the result of the accident in Japan? Not one. How many in the worst accident in history at Chernobyl? Less than one hundred. How many in coal mine accidents each year in China alone? Thousands. How many from coal pollutants? Who knows. By the way more radioactivity goes up the stack in a coal fired power station than from a nuke plant. Madness reigns.
Reply | Report Abuse | Link to thisFirstly, I think that storage and grid are two different options and combination may not always be appropriate. The grid is required to distribute energy geographically preferably starting from a few centers of production. The storage is required to redistribute consumption over a time due to mismatch between production and consumption. It is very useful in remote locations not economic to join by a grid. Wind or solar energy can be stored when available and consumed when required.
Reply | Report Abuse | Link to thisThe wind energy can be stored as compressed air using mechanical pumps without any electrical intermediate. It can be converted to wind if and when required. Compressed air itself can be used in some cases.
The solar energy, on the other hand is best stored as heat in molten salt. It can be converted to electricity if and when required.
I think compressed air energy storage will work. The technology is simple and well understood. The MDI car's compressed air engine has 90% efficiency. I think of underground tanks with ceramic insulator encased in concrete. It can be done. If we think it will fail, it becomes self-fulfilling.
Reply | Report Abuse | Link to thisWe have a partnership with the world leader in solar cell technology. But energy storage system is not their line of business so we will not be building this underground tank anytime soon.
I wish you well. My main objection to most research in the industry is that it tends to repeat work done by others without any new dimensions being added & to ignore engineering or mathematically provable deficiencies before committing millions of dollars. I did a lot of research in solar many years ago, having my own factory, mostly manufacturing parabolic trough tracking collectors for industrial hot water. Gravity heat pipes, tracking photovoltaics in concentrators & absorption cycle refrigeration running on solar heat alone with no electrical input, including for the tracking mechanism. Part of my business was supplying components for research institutions, including tracking parabolic dishes powering both Stirling & steam engines.
Reply | Report Abuse | Link to thisI became disillusioned with the industry & quit. Even back then, solar was being hyped to obtain public funding. Unsustainable claims were being made. I was being asked to build so called proof of concept installations that I knew had been previously built elsewhere. If they had a wow factor that would impress journalists & politicians that was enough. The result was & is to only build something someone else has already shown at least a modicum of success with so as to attract even more capital. At least back in the eighties the projects were mostly in the tens of thousands range. Today they tend to be in the tens of millions. I would like to tell you more, especially on the heat pipe & refrigeration work but I wish to preserve my anonymity.
With regard to your storage tank, check my post 37. We were amazed by the heat losses to ground water, in a desert & only trying to contain 80 C. I was not in charge of this project & no longer have access to the actual figures but you would need to do some small scale testing first obviously. A sphere being the ideal shape of course for surface area to volume as well as pressure containment. Next is a cylinder with equal height to diameter, can’t think what it’s called, domed ends for pressure. (More for those on the sidelines, sure you know this).
Reply | Report Abuse | Link to thisAll the " Green Energy " conundrums suffer from technical enthusiasm untrammelled by inconvenient engineering facts or fundamental physics. Ultimately it is $/KWHr and 24/7 scaled availability that matters. Unfortunately the green energy crowd is not noteable for its understanding of reality. All the electrical power we will ever need can be easily supplied by modern nuclear facilities at zero CO2 footprint. Unfortunately the politics of ignorance and special interest groups have made any such consideration untenable. In the meantime we should come to our senses and reduce CO2 emissions significantly by transitioning to natural gas fuel cycles. As for transport - petroleum will rule for a very long time due to its brute force energy density, not achievable by any current alternative. Unless these facts are recognized any hope of significantly reducing CO2 emissions will be lost in the babble of "alternative" day dreams. Consider that so far the impact of "green" has been <1% in spite of the propaganda and $$ allocated.
Reply | Report Abuse | Link to thisAbsolutely. What is more it costs virtually the same to run a nuclear plant at full capacity as throttled back. Having off peak tariffs for things like hot water lowers the consumer’s costs even further. Coal plants should be sensibly phased out at the end of their operating lives as nuclear is phased in. I am not concerned by CO2 but think it is criminal to waste such a valuable resource that has so many other uses. The green misinformation machine is costing future generations a terrible price.
Reply | Report Abuse | Link to thisYou can compress it but it will not liquefy without cooling.
Reply | Report Abuse | Link to thisCritical point N2
Critical temperature : -147 °C
Critical pressure : 33.999 bar
Critical density : 314.03 kg/m3
That density figure is interesting too. Less than a third of water at 1000 kg/m3. I am afraid the idea will not go anywhere. The plus side is that those who go into the details of such schemes should end up with a better understanding of physics, though I have known those who have persisted against the laws of physics to the point of losing their house & marriage.
Reply | Report Abuse | Link to thisYour solar pond is nothing like my proposed compressed air storage system. It is easy to see why the solar pond is energy inefficient. Heat flows by convection from lower to upper layer then from water surface to air. The surface area is very big. And the temperature differential is small from 80C to 30C (air temp.) There is little energy you can extract from 50C temp. differential and heat loss is big.
Reply | Report Abuse | Link to thisMy adiabatic storage system is enclosed and insulated and heat flows by conduction. So heat loss is minimized. More energy can be stored as temp. is higher about 600C and energy is also stored as pressure over 690 bars.
The laws of physics are on my side. Conduction is least efficient heat transfer. Convection and radiation are much faster. That's why the earth's interior is still molten rock and hot as hell after 4.6 billion yrs. Because heat flows by conduction to the surface. That's very slow. If it were convection and radiation, maybe in a few hundred yrs earth's interior would already cool and solidify.
Thanks for your advice. Technology has gone a long way since 1980s. I was in mid school then.
You are right. I did not check the critical temp. since it is not necessary to liquify it to store energy. Enthalpy is a function of temperature and pressure not the state of the substance.
Reply | Report Abuse | Link to thisErm... Isn't the Earth still hot at the inside because of ongoing radioactivity? Else it would have cooled down long ago.
Reply | Report Abuse | Link to thisSo you are proposing a pressure vessel that must be huge to be practical, contain fluctuating pressures to 1000 PSI & store temperatures of 600C. It must be built in modules because the failure of one huge pressure vessel discharging gas at 600 c would be catastrophic. To act as a backup system for a utility the capacity would need to be in the multi millions of litres. Every square foot of the pressure vessel would have to be able to withstand 144000 pounds of pressure. The material would have to be something like titanium, capable of withstanding repeated thermal shock as well as flexibility to cope with huge swings in pressure. In fact something like a submarine shell capable of repeatedly diving to 2300 feet & resurfacing. That is about the collapse depth of a US nuclear submarine after one cycle, not repeated cycles & many times the size. We have not even got to the insulation yet. To thermally insulate a 600 C vessel to a point of near zero heat loss then encase the whole thing in concrete which also must be totally water sealed for reasons I can not bother to explain, would be heading for moon launch costs for the scale required. Starting to get a little expensive I would say. As for geothermal heat traps, the hot rocks, usually granite, which by the way derive their heat from radioactive decay within the granite, not heat from the interior of the earth, are insulated by thousands of metres of overlaying rock. You can do the remainder of the calculations yourself, we are already well into fairyland territory.
Reply | Report Abuse | Link to thisYour insinuation that my experience is of no value because of advances in technology is arrant nonsense. Two & two still make four & the laws of physics have not changed. I tried to lead you gently to a more enlightened place. Looks like I was wasting my time.
Another illustration of the folly of venture socialism. Instead of 'investing' millions of tax dollars in new technology, the government should just get out of the way and let an industry which earns billions invest in its own technology. The profit motive, if allowed to operate, will find the technological solution which is most profitable. All government can do is interfere with and distort that process while wasting tax money.
Reply | Report Abuse | Link to thisEfficiency of Compressed Air Energy Storage plants operating today (the two so far) is about 55% if you include both the electrical and fuel components, energy in to energy out. This is quite good compared with other fossil units. In terms of fuel, they consume half the amount of gas per kWh than a combined cycle plant, and can also operate on a much wider range and faster ramp time than combustion turbines. Storage times can be exceptionally long (20-30 hours or more) because the incremental cost of building more storage is low (if using salt caverns, which the two existing plants use). And the total capital cost of CAES is not much higher than combined-cycle. CAES combined with wind can produce firm capacity with mostly renewable content at a price lower than combined cycle. But you need the right geology.
Reply | Report Abuse | Link to thisPumped storage hydro is now about 80% efficient. Most engineers consider this to be pretty good.
Reply | Report Abuse | Link to thisIncorrect. First, most of the newer wind projects going in are getting capacity factors of 35-45%. Contract prices for the electricity are 3.5 to 4 cents a kWh, which is getting extremely competitive for energy alone (not firm capacity, of course). But by combining a larger wind project with smaller pumped storage capacity (and 80% efficiency), coupling the two in a way that minimizes the amount of energy cycled through storage yet maximizes the flexibility of the pumped storage plant, you get firm renewable capacity that is cost-competitive with fossil alternatives when environmental benefits are taken into account. And in some cases, even when they're not taken into account.
Reply | Report Abuse | Link to thisAnd those two plants in operation consume half the gas of a conventional turbine. Why? The hybridization of off-peak electrical input driving the compressors and the gas that no longer needs to waste energy compressing its own air. Today's CAES technology is relatively efficient compared with fossil generation, and provides much more dynamic response to the grid.
Reply | Report Abuse | Link to thisPerhaps you didn't read the details about a solar thermal gradient pond. The brine in the water creates a thermal barrier that prevents the sun-heated water at the bottom from losing its heat to the surface. The water at the bottom reaches a near-boiling temperature, which can be drawn off and used to drive a turbine. It is very inexpensive technology. But the previously cited challenges - such as mixing caused by wind - remain.
Reply | Report Abuse | Link to thisOn the Beacon bankruptcy, the timing is ironic because changes that FERC recently made to improve the fairness of compensation to fast-responding storage will significantly increase the revenue that flywheels will be able to garner in their target markets.
Reply | Report Abuse | Link to this"...most of the newer wind projects going in are getting capacity factors of 35-45%..."
Reply | Report Abuse | Link to thisWhat a crock. Back those numbers up. From what I've seen, CF is dropping, not increasing. CF in the entire USA dropped from 30.3% in 2008 to 26.5% in 2009.
In Ontario, the average province wide average CF is 25.3% and the MORE IMPORTANT median CF is 14%. And note that as usual, the actual CF of the Wind Farms is 15-30% lower than projected by Wind Farm lobbyists and Government Apologists/Spin Doctors.
http://ontariowindperformance.wordpress.com/2010/09/14/over-all-performace/
In Britain:
"...Average output from wind was 27.18% of metered capacity in 2009, 21.14% in 2010, and 24.08%
between November 2008 and December 2010 inclusive..."
http://www.jmt.org/assets/pdf/wind-report.pdf
European Capacity Factors are abysmally low, averaging 20.8%.
"...Contract prices for the electricity are 3.5 to 4 cents a kWh..."
That's not what Wind is getting. Wind in Ontario is getting 13 to 19 cents per kwh, with CPI indexing, plus additional subsidies and incentives. The latest Cape Wind project, off Nantucket Sound, National Grid is going to have to pay 20.5 cents per kwh, increasing by 3.5% per yr for 15 yrs to 33.8 cents per kwh by 2028. Plus 2.1 cents per kwh federal subsidy. So 22.6 cents per kwh rising to 35.9 cents per kwh. This compares to the highest Peak power rate currently at 4.5 to 9 cents per kwh.
"...you get firm renewable capacity that is cost-competitive with fossil alternatives..."
Reply | Report Abuse | Link to thisWhat a ridiculous and absurd statement. Pumped Hydro runs ~$2000 per kw of capacity and ~$90 per kwh of storage. Wind is running $2.5k per kw at an optimistic 30% CF that's $8.3k per avg kw. Add long distance Transmission to that and Grid Stabilization and backup power OCGT power plant and you are over $11k per kw avg output. So storing Wind just to level out the daily peaks, making Wind somewhat viable as an energy source would add ~$1.2k per kw of capacity or or $1.2k/.3CF/.8eff = $5k per kw of avg output.
So now we are up to $16k per kw of avg output. But pumped hydro sites are not easy to locate, so maybe avg 500km transmission. At $0.85 per kw-km for transmission that's 750km X $0.85 X .5kw/kwcap = ~$1k per kwavg. So that brings us to $17k per kw of avg output. That's for the very best & cheapest pumped hydro storage that will only moderate the daily wind variation enough to make it somewhat compatible with actual demand. It will not moderate the weekly or seasonal variation of Wind, which typically craps out during long, high power demand cold spells or heat spells. And the Environmental destruction of the Massive Wind Turbines, long distance transmission lines, and HUGE pumped hydro storage reservoirs.
A ridiculous idea, we would quickly go bankrupt pursuing a Nutty Scam like that. $17k per kw for an unreliable power source, with reliable 24/7, summer or winter Nuclear at certainly less than $5k per kw, and certainly $2k per kw can be achieved. And 60-80yr lifespan vs 15-20 for the Wind Turbines.
And now it seems Wind Energy will be limited to 1 TW maximum vs current energy demand of 15 TW. So Wind CANNOT & WILL NOT be an Energy Solution, Global wind power potential - Physical and technological limits, by Carlos de Castro:
http://www.sciencedirect.com/science/article/pii/S0301421511004836
The infuriating thing is engineers must know to a high degree of accuracy what the actual costs & outcomes of these schemes will be. If the chief engineers & executives of the companies promoting & constructing them were held personally financially responsible for the real life outcomes we would see realistic & truthful projections. As it is, no one is responsible & the mistakes & lies continue. This is inherent in just about any government funded enterprise.
Reply | Report Abuse | Link to thisBrine is not a good thermal barrier since it is in contact over a large surface area with fresh water which can transfer heat via convection to the surface air. How do you heat brine at the bottom of the pond? Not by convection, since heat comes from the sun at the surface and hot water is lighter and goes to the surface. Brine is heated by conduction which is a poor way to transfer heat, and cooled by convection which is efficient heat transfer. That's why heat loss is big.
Reply | Report Abuse | Link to thisDirect solar radiation heats the brine. The ponds are giant solar collectors. If you think you know more about the heat losses than those who spent years studying the problems we must have indeed been stupid. All losses were recorded. Latent heat of evaporation or phase change in the top layer of water, small convective losses past the brine layer, so called black body radiation from the whole system plus the surprise which was the conduction of heat from the bottom of the pond. The heat drew moisture out of the apparently dry underlaying sandy desert soil via capillary action. This then evaporated carrying the heat away out the sides & also into the deeper soil. My original point was that even 80 C temperature is hard to contain. Cement is quite a good conductor for similar reasons. Trying to contain 600 C is infinitely more difficult. But then we were all stupid back then apparently.
Reply | Report Abuse | Link to thisI just re read your post. For goodness sake go back & follow the link I gave about solar ponds. You obviously have never heard of them. Brine & fresh water stay separate. If there was convection between them you would soon have brackish water, not two distinct bodies. Similar things even happen in the atmosphere & in the oceans. In the atmosphere it is called an inversion where cold dense air overlays hot air & suppresses convection. The phenomenon was first discovered when people walked into what they thought was fresh water, I think in Israel. As they got a little deeper they encountered the underlaying briny water, suffering severe burns.
Reply | Report Abuse | Link to thisSo don't waste your time in fairy tales. Compressed air cars have 300 bars pressure tanks. Fabricators are making 4,000 bars high pressure tanks. Foundries have insulators for molten iron at 1500C. But no it can't be done it's impossible it's beyond present technology. You must be right.
Reply | Report Abuse | Link to thisLord Kelvin calculated the rate of cooling of a molten earth without radioactivity. It would cool solid in about 100 million yrs. Earth's thermal conduction is 0.1 W/m^2. A molten rock at 1200C will radiate heat at 266,000 W/m^2. Conduction is slow because solid layers act as insulators.
Reply | Report Abuse | Link to thisCompressed Air cars? Now you are being ridiculous.
Reply | Report Abuse | Link to thishttp://depletedcranium.com/no-sherlock-air-powered-cars-are-ineffecient/
"...New research from UC Berkeley and ICF International puts a period at the end of the discussion, showing that compressed air is a very poor fuel, storing less than 1% of the energy in gasoline; air cars won’t get you far, with a range of just 29 miles in typical city driving; and despite appearing green the vehicles are worse for the environment, with twice the carbon footprint as gasoline vehicles, from producing the electricity used to compress the air. Given these barriers, manufacturer claims should definitely be taken with a grain of salt..."
Try standing on top of one of those iron foundary furnaces & you will soon discover how much heat is escaping. The new insulating materials reduce the heat losses over previous systems by about 20%. There may be some that claim 30% or more but they go no where near eliminating heat losses. If they shut an iron foundary down without first removing the molten iron, how long would it take to cool to a solid block of iron? Not long I can tell you.
Reply | Report Abuse | Link to thisEnormous pressures can be contained in small vessels. The hydraulic plumbing on a small earthmoving machine typically contains pressures of 3000 PSI. Translating this to the industrial scale tanks you are talking about is an entirely different matter.
Reply | Report Abuse | Link to thisIt is people like you who simply can not grasp these realities that are demanding action on projects that can only fail, costing us billions. Our education system has a lot to answer for too.
When the government "gets out of the way" we have financial collapse, pollution and unsafe products harming us. The short-term profit motive is too strong compared to the long-term view that is highly discouraged in private industry nowadays. See the Ford Pinto, Credit Default Swaps, salmonella outbreaks in our food supply, fracking contamination in drinking water and The BP Gulf Oil Spill for examples.
Reply | Report Abuse | Link to thisHey, the guys that lost billions of ratepayer's and taxpayers dollars on building money-sucking nculear reactors got off scot free. The polluters using our atmosphere as an open sewer get to do so for free as well. The paltry and inconsistent subsidies to clean energy don't even begin to capture he value they provide by not ruining our environment!
Reply | Report Abuse | Link to thisI see we have now attracted verbal polution.
Reply | Report Abuse | Link to this"...the guys that lost billions of ratepayer's and taxpayers dollars on building money-sucking nculear reactors..."
Reply | Report Abuse | Link to thisThat's right, religious greenies like yourself, who blockaded Nuclear Power development, and were quite happy to accept huge funding from Big Oil/Gas & Coal sources, in order to do their bidding. If the Nuclear Expansion of the 70's & 80's had continued unimpeded, there would scarcely be a Coal Power plant running in the USA, and Global Warming would be a theoretical study of what might have been, but thanks to your buddies, the largest source of clean & green energy in the USA has been stifled, and we stand on a Runaway Global Warming/Peak Oil Precipice.
But, of course, the typical Religious Greenie, is hoping for that to happen, although they won't admit it, they want to see our civilization collapse, and believe the New World Order will replace it, run by a Greenie Priesthood and the low-life's such as myself will be starving or dead. But Sault and his greenie buddies will be living the lap of luxury in their Greenie Temples, served by the ignorant, proletariat who have been punished for their resource gobbling sins against the Greenie Religious Edicts.
I would like Scientific American to publish an issue dedicated to the physics/engineering/economic realities related to all forms of publicly available "energy", green and otherwise. It is all very well to promote renewables, but to do so absent considerations of economic reality and universal ignorance of technical limitations merely provides fodder for political meddling and nourishes unrealistic expectations by an unsophisticated public. I am all for conservation and reduction of CO2, but think we really need to step back and consider the strategic perspective, what will actually have a significant impact on global warming: e.g. increasing efficiency, natural gas, nuclear, hydro, coal, solar, wind, storage, intelligent grid, CO2 markets, R&D prospects, population ...... In the meantime I am not putting solar panels on my roof.
Reply | Report Abuse | Link to thisAin't going to happen, Scientific American & Nature magazines are owned by the Eco-Mafia Holtzbrincks Aristocratic Family in Germany. You've heard of the military-industrial complex, well in Germany they have the Eco-industrial complex, of which the Holtzbrincks are a part of. Large German Industry and Banking are heavily invested in Eco-Industry, Wind & Solar Energy, Organic Farming etc.
Reply | Report Abuse | Link to thisBefore being taken over, SCIAM regularly published excellent articles on Nuclear Energy, both Fusion & Fission, now such articles are non-existent. Notice not one article, as in ZERO, ZIP, NIL in SCIAM on such Hot Nuclear Tech like LFTR (Liquid Flouride Thorium Reactor) or Polywell Fusion. Thousands of articles on Nutty Green Tech. Read all about the German Eco-Mafia & the history of SCIAM & Nature magazines here:
http://ecofascism.com/article22.html
Hear! Hear!
Reply | Report Abuse | Link to thisSpeaking about Germany, the IPCC and the WWF (one of the World's biggest ENGO's based in Germany), this is JUST UNBELIEVABLE. The WWF did a widely publicized study for the IPCC that showed CO2 emissions from Electricity Generation for Germany & France about equal. Since France is almost all Nuclear & Hydro vs Germany being mostly Coal & NG, some people were alarmed. Reading the fine print:
Reply | Report Abuse | Link to this"...1 WWF does not consider nuclear power to be a viable policy option. The indicators “emissions per capita”, “emissions per GDP” and “CO2 per kWh electricity” for all countries have therefore been adjusted as if the generation of electricity from nuclear power had produced 350 gCO2/kWh (emission factor for natural gas). Without the adjustment, the
original indicators for France would have been much lower, e.g. 86 gCO2/kWh..."
As far as I am concerned the WWF should be declared a Terrorist organization, and subject to the appropriate sanctions, and all tax exempt status revoked.
Don't be surprised that compressed air cars store 1% of energy vs. gasoline. Lithium ion batteries store only 2% of gasoline's energy density but Tesla Roadster can easily beat your Altis gasoline car on a race track.
Reply | Report Abuse | Link to thisYou should take your quoted source with a grain of salt because gasoline engines are only 25% efficient and MDI compressed air engine is 90% efficient and Tesla's electric motor is 97% efficient.
BTW compressed air cars have low energy density because of their diabatic storage which losses heat to the environment. Adiabatic storage has energy density matching or exceeding lithium ion batteries.
I never suggested convection between brine and fresh water. I was refering to convection within fresh water and the layer exposed to air. But there's also heat loss by conduction in the interface of brine and fresh water. This is about 60 W/m^2 for every 1C temp. differential.
Reply | Report Abuse | Link to thisIt's hot inside foundry plants because molten iron is exposed to air to cool the iron. What you feel is heat convection and radiation. Touch the furnace with your bare hand. That's heat conduction. Place a phone directory book between the furnace and your hand. You can't feel the heat. That's heat insulation.
Earth's heat conduction is 0.1 W/m^2. There's still molten rock down there. 5-meter perlite insulator at 600C will conduct heat at the same rate. A well-insulated tank can retain heat as good as 30 km of earth's crust and better than solar ponds.
Before the Great Pyramid, Eqyptians thought big pyramid is impossible. Before the Hoover Dam, people thought big dams are impractical. It's impossible and impractical until somebody builds it.
Not familiar with Adiabatic storage, but it sounds dubious to me. If you are going to compress a gas why not just compress DME or NG and get a serious load of energy? Or just use Methanol, dirt cheap, make it from water & waste/biomass/flue gas/volcanic CO2/atmospheric CO2 - burns in 43% eff engines or in fuel cells. Easiest fuel to store, and low emissions. Batteries work very well, energy density is pretty good now, just need to get costs down, learning curve, mass production will accomplish that. Your compressed air storage is about as simple as it gets and yet nobody is doing it that I've ever heard of. Home hobbyists routinely convert cars to battery-electric, haven't heard of one - none - zero who have converted their car to compressed air, though it should be easy to do.
Reply | Report Abuse | Link to thisAdiabatic process is described in all thermodynamics textbooks. The whole idea is to store grid electric power. How do you convert electricity to natural gas? I don't think you can make methanol from water. Watch Disovery Channel or National Geographic. I've seen hobbyists make compressed air bike from junk in their garage. But I'm suggesting adiabatic storage not compressed air vehicles.
Reply | Report Abuse | Link to thisMany things work on a theoretical level but are devilishly difficult to harness on a practical level.
Reply | Report Abuse | Link to thisTake nuclear fusion. There are billions of fusion reactors in space, our sun being one. Billions of dollars have been spent trying to tame this process yet still with no sign of commercial reality. As I have not visited a foundry recently I can not tell you what the exterior temperature of the furnace wall is. However, one of my jobs as a young man was as a matte tapper in a copper refinery. The radiant heat from the exterior was tremendous. No doubt modern insulation methods could reduce the losses considerably but at what cost. Your pressure vessel will suffer thermal & pressure variations, each causing expansion & contraction of the pressure vessel & the surrounding insulation. Your pressure tank must be huge to do the task you are looking at, magnifying the problems of metal fatigue & causing deterioration of your insulation. The cost benefits will never stack up. Allowing your compressed air to cool & liquefy then pass through a heat exchanger on the expansion side in front of your turbine would be more practical especially if a gas burner was also added. Still not practical but feasible.
Nuclear fusion is much more complex technology. Compressed air engines and tanks had been assembled by hobbyists in their garage. Scaling up is the challenge. Radiant heat in copper refinery is tremendous because the furnace is made of steel, a heat conductor. Cooling and heat exchanger would increase energy loss. Gas burner? To heat the air? True cost and benefit will be known once a prototype is built.
Reply | Report Abuse | Link to thisOh. I was sure it was refectory bricks we were using. They looked like bricks & that was what the labels on the pallets said when I helped refurbish a furnace. We even used what we called a lance to cut them with when we needed to cut into a furnace. The lance was a 6 metre length of 12mm ID steel pipe which was connected to an oxy bottle. You heated the end of the pipe with an oxy torch until it was white hot, and then turned on the oxy. The hot end then burned so fiercely that it would cut anything including furnace bricks Even if they had been steel. Funny how old age has messed with my memory. Or it could be that you simply do not know what you are talking about.
Reply | Report Abuse | Link to thisActually, not as much energy is lost by cooling to the atmosphere via a heat exchanger then re heating via a heat exchanger as you decompress, as you would believe. Also, additional gas heating acts like a turbocharger adding very efficiently to your output. That has been done where vast underground salt dome caverns have been used to store compressed air. Not really viable either but at least they did not try to build super tanker sized highly insulated pressure tanks.
Reply | Report Abuse | Link to thisIt must be your memory gap. It's not refectory bricks. It's refractory bricks. It's an insulator used in the inside wall of furnaces. The thickness and thermal conductivity of refractory bricks are not enough to prevent a lot of heat from escaping, and furnaces have a lot of metal components that conduct heat. That's why it's hot around a furnace.
Reply | Report Abuse | Link to thisCooling to the atmosphere is heat loss. Reheating requires energy input, lowers your energy efficiency. If you're talking of the thing, heat loss = energy input, where do you store the heat before it is used again? The process is not simultaneous like a turbocharger. You store energy because you need it at some future time.
Enough of this. We're not going to build this anytime soon so we'll have plenty of time to study it.
Some important points missed. These fly wheels are for frequency regulation. They store energy for that purpose and are not intended to replace a battery at this stage. What they do that no battery can do is handle rapid charge and discharge for an estimated useful life of 20 years. Secondly, they deploy in a modular way with virtually no environmental impact except for their footprint and compared to batteries no chemical waste to recycle. You can put them anywhere the grid operators need them and are well suited to densly populated areas. Not so for pumped hydro, compressed air and the like. Thirdly, by providing an alternative to traditional frequency regulation they free up the expensive generating capacity currently used for this purpose. Which synergistically allow the freed up generators to run in a more efficient mode. Also, by absorbing excess energy on the grid to spin up the flywheel as a way of damping the highs, the installation is using energy that would otherwise just go to ground and be lost. Beacon is not an alternative energy company. It is a grid service company with measurable demand in place and a market eager for their entry. Perhaps the next generation flywheel being developed will provide an entry into the energy storage market, but that is in the future and it is then that the kind of comparisons to batteries and such may be appropriate. As for having Beacon sell the Stephentown plant at this point when revenues are sure to rise on new pay for performance rules from FERC is shortsighted, counterproductive and in no one's best interest, least of all taxpayers who will see payback in their electricity bill for having this technology in place.
Reply | Report Abuse | Link to thisAn excellent explanation & appraisal of the technology. My criticism was directed at its usefulness as an energy storage method as indicated by the article headline. Another case of poor editing.
Reply | Report Abuse | Link to this"For truly green wind/solar the cheapest storage available at $200/kwh is pumped hydro" -- I think this is a typo for $20/MWh? Surely $200/kWh is ridiculously high. In general, I find that both hydro and other types of storage are practical and cost-effective, but highly dependent on the market, and the "next-best-alternative" that's available. Hawaii is very different from Iowa in many ways - also electrically!
Reply | Report Abuse | Link to thisCAES is indeed very promising. However, the new generation of technologies do NOT need natural gas to release the energy again. That was the first generation, such as in Alabama. And we can (and will have to) do much better than that.
Reply | Report Abuse | Link to thisI can't imagine why an EV owner would want to do this. Batteries have a limited number of cycles before they have to be replaced. The cost of having to buy a new set of batteries would far outweigh any financial benefit of allowing them to be used as grid storage. I would rather use the limited number of charge cycles for my EV battery to power the vehicle.
Reply | Report Abuse | Link to this