Skip to comments.Iowa wind energy storage project moves ahead
Posted on 03/07/2010 11:15:11 AM PST by newgeezer
DALLAS CENTER, Iowa (AP) Kent Holst stood in front of the Iowa Stored Energy Parks municipal utility members and proclaimed, This time, we have something to show you.
Holst, the parks development director, showed the officials a drill rig behind a house on the south side of Iowa Highway 44, two miles west of Dallas Center.
The rig is drilling a 2,800-foot well, which will be used to test the hardness of a sandstone formation. The energy park hopes the formation can hold energy that has been converted into air.
When the municipal utilities that own stored energy need electricity at peak periods, the air will be released to the surface to power turbines in two 134-megawatt generators, making electricity.
The drilling project is the first tangible sign of activity for the long-discussed energy park, though the project is three years away from becoming a part of Iowas electricity grid.
The energy park would be one answer to a problem that has long confounded the utility industry: the inability to store electricity.
Holst and other company officials say that Iowas bountiful wind energy can be best used if some type of electricity storage is available. For all its popularity and greenness, wind energy can be the least reliable form of electricity generation.
The wind just doesnt always blow at the right times when the electricity is needed, said Thomas Wind of Jefferson, who is a consultant to Iowa Stored Energy Park.
The Iowa Power Fund has put $3.2 million into the project west of Dallas Center in hopes of putting the state ahead of what may be the next big thing in electricity. One other stored energy park, in Alabama, exists nationwide.
Another contribution from the U.S. Department of Energy put the public involvement in the project to about $4.7 million.
Having storage for energy is one of the critical pieces of Iowas energy future, said Roya Stanley, director of the Iowa Office of Energy Independence who spoke at the annual meeting last week.
About 150 Iowa municipal utilities who are members in the project will provide the rest of the financing, probably through bond sales.
Before that can happen, Iowa Stored Energy Park needs to get geological verification that the sandstone dome in Dallas County can hold air at compressed rates of up to 1,400 pounds per square inch and wont crack the underground rock formations.
Holst and Iowa Stored Energy Park officials are confident that tests will be favorable, because MidAmerican Energy stores natural gas in similar underground caverns nearby at Redfield.
Iowa Stored Energy Park plans to drill a second test well later this year within about a quarter-mile of the first well site, Holst said.
Eventually, the project will encompass eight to 10 wells and the 260-megawatt generator.
Driller Klint Gingerich of Kalona said the 2,800-foot deep well dug for the company is about 10 times deeper than the average water well in Iowa. Gingerichs firm drills mostly water and industrial wells in Iowa and neighboring states.
The deepest well dug in Iowa was a test oil well near Red Oak a few years ago, and that was 3,600 feet deep, Gingerich said. That well did not produce oil.
As the drill bit goes down, core samples of rock are pulled for analysis. At completion, the well will be encased in concrete.
The cementing is probably the most nerve-wracking part of the job, said Gingerich, whose grandfather, Paul, founded the drilling company in 1955. Otherwise, its been a perfect project.
Iowa Stored Energy Park is pegged as a backup source of electricity for Iowas municipal utilities. The big investor-owned utilities, MidAmerican Energy of Des Moines and Alliant Energy, can either generate or buy enough electricity to take care of Iowa customers.
But the surplus of wind energy, expected to amount to up to 15 percent of Iowas generating capacity within a half-decade, is a source of spare electricity for municipal utilities.
As for compressed-air storage of the type planned for Dallas County, Gene Berry of Lawrence Livermore Laboratory said in a report last year, The scale and location-specific nature of energy storage in natural formations is likely to render it of limited benefit to renewables like wind.
Oh, c'mon, don't be such a wet blanket. We can dream, can't we?
Besides, it's not as if you're paying for it. /s
...wait a minute!...let me get this straight...they’re gonna store compressed air in the ground and then release it to run a windmill?...there’s gotta be a ‘break wind’ joke in this somewhere.
physics is not my strong suit, but that is how I read the article. I know that the person who comes up with an easy way to store energy like this for later use will make a lot of money.
Guess the forgot compressed air explodes.
A similar approach is a two-reservior system. When electric rates are low, water is pumped from a downhill reservior to a reservoir on top of a hill. When rates are high, the water is released downhill through a hydro-generation system for sale into the grid. Cost to pump has to be lower than the revenue generated for sale, obviously.
The best system for the U.S. would be to allow FIT (feed in tarriffs) for homeowners. These allow homeowners to generate electricity at home, usually by solar but also wind) to power their homes and be able to sell the excess to the grid.
FIT for homeowners becomes a motivator for conservation (the less a homeowner uses the bigger the check at the end of the month).
The problem (as seems to always be the problem with America) is that unless a company making contributions to a lawmaker can make money on it, the lawmakers will not allow FIT for homeowners. Our corrupt system of government.
Why not just set up some big air vessels for the compressed air? Then they can just have them aimed at a couple of the cash shredders, er, I mean wind mills.
This was proposed at a plant in Texas a couple of years ago, don’t know if they did it or not. This plant was going to pump air into salt mines and run compressed air generators during peak demand. From what I understand they use abandoned salt mines to store natural gas as well. I wonder what kind of mechanical efficiency this process yields, probably in the low single digits.
When you see a project funded with PRIVATE money, you can believe it.
That’s what I think.
Your understanding is just sad.
Ya think that would work?
So we burn coal (or uranium) to boil water then use the steam to power a turbine which drives a generator which powers a motor that drives a pump that pushes air down a hole so that we can let the air back out through a turbine to spin a generator to have electricity on demand after the fire in the boiler goes out. Got that?
The overall efficiency of this scheme is the product of all the individual efficiencies incurred at each step in the cascade of converting energy from one form into another then back. Let's be generous and start halfway through the process with electricity (thermodynamics limits the efficiency of a central station power plant to 12 to 15% at best). So we have motors driving compressors driving turbines driving generators, that four conversions. Lets assume 80% at each step (.8x.8x.8x.8)=0.4096 or about 41%. That means that nearly 60% of the energy going into storage is lost and not available for recovery. That guesstimate does not include any pumping losses, friction in piping, nor any leakage from the "high energy" storage reservoir.
Does any of this sound like a good idea? Maybe we should focus on designing plants that can respond to varying demand in real time and stop trying to fool with the "inelastic nature" of electricity.
PS Uranium powered central station plants with natural gas powered turbines for peaking are the most efficient way to do this. Renewable (green) energy is a expensive chimera.
Either this is a ridiculously simplistic statement — or nuclear fusion is involved.
PERHAPS, just MAYBE, they could turn wind power electricity into coal, store the coal in the ground, and then mine the coal when we need the energy, burning it in a coal fired plant.
Might make more sense.
Not really, compressed gasses can contain a lot of potential energy at elevated pressure and can release that energy in very energetic explosions but the air itself is not exploding. Air is very compressible and stores potential by changing volume rather like a spring. Any rupture in the plumbing releases the stored energy very rapidly.
To carry the spring analogy further, liquids have a much higher "spring rate" (water is about 1% per 1000psi) and therefore don't experience the large change in volume when pressurized. Therefore any rupture results in the stored pressure being rapidly reduced to ambient.
Can you comment on a factor in the compression of the air? I think that would generate heat which is almost certainly going to be dissipated, i.e. wasted. Is that loss enough to give the nod to the water pump system?
The rest of the time the wind blows, the power is used to electrolyze water.
The hydrogen is stored, with a bit of it used to fuel a couple of company trucks, and the rest to power a gas turbine generator set when the wind isn't blowing and the power is needed.
The oxygen is bottled and either used in the welding shop (very small amount) or it's (most of it) sold.
Strictly a peaking operation; and underscores the need of backup generation ability if wind or solar is to be used on any scale.
OTOH, this expensive hole in the ground appears to just give the customer the shaft.
When compressing air, a majority of the energy results in heat. These are losses.
I'd hazard a guess that the compression efficiency is about 25%. I've seen projects suggested that would use the compressed air storage to reduce the compressor requirements for combustion turbines.
This really is a way of matching demand with generation, not a green scheme because the losses are so high.
Pumped (water) storage would most likely be higher in efficiency.
Who designed your test project, Rube Goldberg?
It’s actually been running for over a year, unlike the compressed air system in this story. Should be less net energy losses than these compression and pumping schemes. The “testing” involves the economics and reliablity, rather than the physical feasibility.
To be fair, our management HATES this crap, but with government mandates for minimum percentages of “renewables” to be online, they have to do something to satisfy the regulators.
Everything was off-the-shelf equipment, rather than ground up design and prototypes, to hold costs down. The idea was, since they needed the gas-fired peaking generation, this MIGHT produce enough H^2 to furnish all the fuel needed; and being on the nothern plains, MIGHT not need to fire it up a high percentage of the time that the wind is available.
At least the gasses produced are saleable, and there is a buyer for the oxy.
OTOH, the main generation comes from two large company owned coal mines that have coal fired power stations built at the mine sites. “Excess” coal is sold to other utilities, since much more is mined/day than is burned.
Gas &P diesel fired peaking stations.
Compressor “waste heat” powered generation units at gas line pumping stations.
Your right, compressing air causes it to increase in temperature. That is more or less unavoidable when dealing with gasses, the mathematical representation of the "gas law" is (P1xV1)/T1=(P2xV2)/T2 Where P represents absolute pressure, V represents contained volume, and T represents absolute temperature. The subscripts 1&2 represent the beginning and end state of the process. Let's say you are pumping air into a tank of constant volume, you get something like P1/T1=P2/T2 which can be rearranged to give (P2/P1)xT1=T2 which tells us that temperature goes up as pressure goes up.
As to the heat being "wasted", that does not necessarily follow as the compressed air could be passed through a heat exchanger, the heat recovered and used to perform some useful function. The water pump system is not without it's own set of problems. Water passing through a conduit experiences pressure loss due to friction. So does air but not nearly as much as does water. In truth neither system is going to operate with breathtaking efficiency (certainly less then 50%). Like most processes in nature both schemes are reversible but the laws of thermodynamics prevent you from ever getting back the energy that you put in in the first place (increasing entropy wins every time).
Well maybe it would be possible to build a large solenoid coil of superconducting material, place it in a Dewar of liquid hydrogen and start current flowing through the coil. Theoretically the current should circulate for long periods without loss so the process is 100% efficient but only if you ignore the energy used to chill the solenoid to -450°F. DC solutions don't do much to help in an AC world.
The overall efficiency of this scheme is the product of all the individual efficiencies incurred at each step in the cascade of converting energy from one form into another then back
I'm a retired mechanical engineer with forty some years background in design and development of energy conversion devices. MEs are the least specialized branch of engineering so our backgrounds cover a lot of territory, in general we take physics and make something useful out of it.