The Future of Wind Power May Be Underground 223
Posted
by
samzenpus
from the blow-from-down-below dept.
from the blow-from-down-below dept.
Hugh Pickens writes "When the wind is blowing, it is usually the cheapest peaking power available. However utilities need consistent always-on power from large, cheap coal and nuclear power plants that are the backbone of the electric grid. Wired reports that operators are looking at Compressed Air Energy Storage (CAES) using abandoned mines and sandstones of the Midwest to store compressed-air. This converts the intermittent motions of the air into a steady power source by using it to run air compressors to pump air into an underground cave where it's stored under pressure. The first CAES plant in the United States actually went online in McIntosh, Alabama in 1991 where engineers created a geological pocket 900 feet long and up to 238 feet wide in a dome by pumping water into it to dissolve the rock salt. When the (briny) water was pumped back out, the salt resealed itself and they had an air-tight container."
Re:Generate a Vacuum (Score:2, Insightful)
Re:Efficiency (Score:2, Insightful)
Load leveling Vs. Supply leveling (Score:5, Insightful)
The problem with these energy storage techniques for renewables is every single one of them would be more economical if they were used as load leveling systems (suck extra energy during down times, release in peak hours) rather than supply leveling systems (suck extra energy in high production hours, release it in low production hours).
The reason for this is day-to-day and monthly power consumption is a very easy thing to predict, so we know very well how much storage we need and if it will or will not be enough. Using these systems we can level the load and allow the greenest power sources (nuclear, followed by hydro) to produce the vast majority of power we need (because they can run at near 100% 24/7).
The wind is a very much harder thing to predict. So how much storage is needed? Who knows. What we DO know is that every single wind power station is going to need gas turbine backups for when a) the wind doesn't blow, b) demand is high and c) storage is depleted.
Using energy storage to allow nuclear and hydro to run most economically is a far better choice than using it to level the output of wind power.
Re:Load leveling Vs. Supply leveling (Score:2, Insightful)
I think the best way to store the energy long term would be to make synthetic gasoline (maybe natural gas) by reacting hydrogen with carbon dioxides. There has been research in the past about the electrolysis of carbonate solutions to produce hydrocarbons.
Re:Generate a Vacuum (Score:5, Insightful)
Re:Generate a Vacuum (Score:5, Insightful)
Re:Load leveling Vs. Supply leveling (Score:3, Insightful)
You are using a false dichotomy here. In fact the best approach is to use all available flexibility to improve the match between supply and demand. There is no need to smooth out either supply or demand on a one-to-one basis. Instead, you use a smaller amount of flexible assets (hydro, pumped hydro, air storage, fast-start gas generators, electric vehicle chargers, price-sensitive customers, etc.) to fill in the gaps between the two. To the extent that variations in supply and demand (or between different locations) are uncorrelated, you can take advantage of statistical smoothing and get more bang for your buck by smoothing out the whole portfolio.
It is likely that there will be days when loads are fairly high and wind power production in the same region is relatively low. It is less likely that solar would also be low on those days. If you have customers who are willing to use less power on these rare occasions, then you can take advantage of that. If not, it doesn't cost much to build a few natural gas turbines that you only run on these rare occasions.
See, e.g., http://users.ox.ac.uk/~cenv0115/ [ox.ac.uk]
Been thought off and rejected as to complex (Score:4, Insightful)
The problem is that trains need people on board who in general want to breath, spoiled brats they are.
So, the train would need an oxygen supply on board, added weight and explosion risk and a LOT of oxygen because people do a lot of breathing. It would also need to scrub the CO2 out, because it is after all a closed system.
Then the train needs to enter a normal area to let people in and out without explosive decompression.
It can be done, but is just not worth the hassle, especially when aerodynamics don't matter all that much for a train. The nose after all is only a small part of a LOOOOOOOOOOOONG train. The carriages don't add much to wind resistance, you can in a way decrease air-resistance per carried passenger by just carrying more passengers.
Re:Unwater Bags (Score:4, Insightful)
Um, how do you intend to keep bags of air at any depth underwater? Even when highly compressed, the density ratio is going to cause buoyancy, requiring some anchoring mechanism and a bag that is structurally sound enough to handle the stresses. I don't think that you can compress air enough to get it to match the density of liquid water at any depth...the nitrogen will start to liquefy first...and that brings a whole different set of problems.
Re:advantages and disadvantages of compressed air (Score:3, Insightful)
Um, 50 gigawatt hours is about 1.8 * 10^14 joules. That is about 43 kilotons of energy. Now think catastrophic failure.
You seem to think this is a totally untested domain. However we have been doing the same sort of thing with flammable natural gas [wikipedia.org] for decades and I have not heard about any accident. So presumably the underground storage of large amounts of gas is a well tested and understood technology.
Besides you certainly don't need or even want to store your 50 gigawatt hours of energy in just one basket. Instead you'd want multiple baskets either close to production or consumption areas.