Alternative reduced CO2 wind back up systems

The work of Warren Katzenstein and Jay Apt, Peter Lang, and Peter Hawkins all seems to demonstrate that natural gas beck up of wind generation imposes choices and inefficiencies, that almost or completely the CO2 emissions benefits of wind. It would appear from their work that stand alone natural gas systems using combined cycle gas turbines, are either nearly as efficient at lowering natural gas emissions or actually more efficient as a wind plus open cycle gas turbines. Supporters of wind generation have noted that that wind generators are well matched to hydro-electricity, and indeed that seems to be the case in a few parts of the world, for example Scandinavia where wind generators in Denmark appear to compliment hydroelectricity from Norway and Sweden. In the United States, hydro resources have been almost entirely utilized, and are currently inadequate for wind back up in most high wind areas. Pumped Storage has been suggested, the the high cost of past pumped storage facilities suggest that the cost of nuclear reactors is competitive with the cost of pumped storage facilities with similar rated capacities, while the nuclear facilities would be far more flexible, and produce as much as 2 times as much electricity on an annual basis as pumped storage would. Compressed air energy storage (CAES) is a second form of backup proposed for wind generators. My investigation, however, revealed a surprising problem from CAES, radioactive radon gas would be brought to the surface with returning compressed air. The problem appears to be far more serious than the release of radioactive gases associated with nuclear power generation. My case study of proposed CAES project presented by the Ridge Energy Storage & Grid Services company to Texas State Energy Conservation Office in 2005 showed that 40% of the energy for the project would come from the burning of natural gas. CASE systems are huge geothermal heat pumps, and they return cold air. Humidity in the air freezes, and the ice can damage generator turbines. Heat lost in the CAES process represents lost energy from electricity used to compress the air. In evaluating the cost of wind generated electricity I stipulated

a cost for new West Texas wind of $2250 per name plate KW in 2009. Since the capacity factor of West Texas runs around .40, the adverage output West Texas wind producer can expect to pay $5625 produce KWs of electricity his windmill will average producing. Since only 70% of the electricity entering the CAES facility reaches the consumer, the wind producer must add 30% more capacity to compensate for the energy loss. Thus the price of the wind generated electry entering the CAES facility must compensate the wind producer for something like a $8000 capitol investment for every average kW sold to the CAES facility.

In addition the estimated cost of the Ridge Energy CAES facility was $765 per KW of electrical output, Thus we are looking at an investment of nearly $9000 per kW of electrical capacity and this does not count the cost of new electrical transmission lines from West Texas to energy hungry Dallas. In contrast

the 2008 cost of nuclear power is somewhere between $4000 and $5000 per kW (as opposed to an estimated $8000 to 12,000 figure during the middle of the next decade).

And nuclear plants can be located close to electricity markets. In addition, the nuclear plant would be far more flexible, and would produce more electricity on an annual basis than the wind + CAES combination. In addition I noted an alternative employment of the CAES system that no one seems to have thought of, the used of CAES in in nuclear cooling, that would produce a low cost nuclear CAES combined cycle:

It seems to have escaped the notice of most CASE advocates that CAES casn be teamed with nuclear power plants in innovative ways. Since it is more economical to keep reactors running at full power all night, suplus electricity produced at night could be used to store compressed air. During the day, compressed air can be used to expand the reactors daytime power output by as much as 40%. The air does not have to be heated with natural gas. Indeed the compressed air can be heated from the reactors waste heat, killing two birds with one stone, and conserving the water used for daytime reactor cooling, and the use of compressed air in cooling the reactor, would creat significant water use savings, allowing reactors to run even during drought conditions.

Just a thought, mind you.

I also looked at battery backup for wind, that was of course, way too expensive. In fact it was so expensive that I conducted a thought experiment,

Assume that the system operators chose to back up the 1 GW wind system with nuclear power rather than a redundant wind system plus batteries. The cost of the wind system would then drop to $2.7 billion plus $5 billion for nuclear backup or $7.7 billion. Quite obviously the nuclear backup would be cheaper, but now the wind is totally redundant, because the backup system can operate full time for just the added price of fuel. Thus the purely nuclear system would simply be a lower cost than a reliable wind system. The nuclear system would be more reliable, and could be counted on with a fairly high degree of certainty to produce at 100% of its rated capacity during peak electrical demand summer months.

Thus my conclusion was that Pumped Storage, CAES, and battery backups for wind were more expensive, less flexible, and would produce less electricity over time than electricity producing nuclear reactors.

Is Pumped Storsage Practical with Renewables?

Sometime ago, I undertook a limited review of energy storage technology. Since my choice of batteries as a viable energy storage technology to be used to in connection with wind projects has been challenged, I have decided to do another review of alternative storage technologies. Pump storage is by far the most viable alternative to batteries, since pump storage facilities have been built around the world. The primary objective of this study is to determine current pump storage costs. In order to do that I have looked at a number of pump storage facilities and tried to produce an estimate of costs if they were built today. For example the Northfield Mountain pump storage facility which is rated at 1080 MWe. It can produce electricity for 10 hours at a stretch. The Northfield Mountain facility was completed in 1972 at a cost of $685 Million.

In 2008 dollars the Northfield project would have cost about $3.7 billion, probably about 25% less than the cost of a nuclear plant with similar rated capacity. The nuclear plant at $5 Billion in 2008 would be a far better buy, for while the Northfield Mountain pump storage facility. The Northfield facility produces electricity for 1o hours a day, while the reactor could produce power for 24 hours a day over long streaches of time. The reactor produce power over 90% of the time, thus its power would be lower cost. But a head to head comparison of the pump storage facility and the reactor would not demonstrate true cost.

In order to produce electricity for the pump storage facility, a wind generating array would have to be built. The cost of that array would be paid for when electricity from the pump storage facility was sold. Pump storage operates at 75% efficiency. That is 25% of the energy input is lost before electrical output. Thus assuming a capacity factor of .40 for the wind array with a rated output of 1400 MWs operating 24 hours a day would be required to fill the pump storage facility. Lets assume costs at the low end of the 2008 range for windmills, say $2250 per KW. Thus the wind array required to fill the pump storage facility full would cost $3.150 billion. That would give us a figure of close to $7 Billion to be financed by the sale of peak electricity from the pumped storage facility. Seven billion dollars is a lot of money to spend for electricity that would be only available for 10 hours a day.

Pumped storage is a better match to wind generated electricity, than to solar generation systems. Solar power tends to be generated at periods of peak electrical demand. Thus pumped storage would only be desirable as a match to solar if solar power with storage were to be a candidate for base load electricity. It is clear that the economics of solar base with pumped storage would not be good. Solar in California produces about 20% of rated power. To produce base power for the rest of the day. a pump storage facility would have to be able to store twice the water that the Northfield facility holds or alternatively have a much higher head.

Matching pumped storage to wind would seem a much better deal. Wind costs less than solar per KW of rated capacity, and it is not impossible to find locations at which wind capacity would be double the natural limits of solar capacity. With wind it makes sense to use the pumped storage facility to produce peak electricity. Wind generated electricity is more likely generated in of peak night time hours, and thus sold at a relatively low price. Do the benefits of putting wind generated electricity to work pumping water uphill at night, and then using the water to power generators during peak day time electrical demand hours? Peak electricity can be sold at a higher price than of peak electricity, but the cost of storage has to be included in the cost benefits equation.

The California LEAPS project was conceived of as a matching of pumped storage with renewable electrical sources. In practice this might not have been the case. Although the LEASP project was described as having a 500 MW generating capacity, and providing 18 hours of storage. The LEAPS scheme proposed to used the existing Lake Elsinore as a lower reservoir, and to build an upper reservoir on a hill above the lake. The total project was estimated to cost $1.1 Billion. Serious objections have been raised to the project. First the input electricity would not come from existing renewable, but rather from fossil fuels power generators. Secondly, the inefficiency of pumped storage was over estimated by project backers. They estimated 13% energy loss in the pumping process, but failed to note that energy from pumping would be lost when water in the upper lake evaporated in the hot dry California air. Finally project economics did not work. The project promised to return only seventy five cents for every dollar it cost to build and operate. A plan to combine the pumped storage project with a money making power line would yield a project that might break even. Critics pointed to other defects in the project's design. The LEAPS upper reservoir is designed to contain 16 to 17 hours’ worth of water for hydroelectric generation under normal operations. But LEAPS cannot generate electricity for such a long period, while refilling itself with off-peak electricity. The LEAPS project also will draw on fossil fuel fired power plants, rather than renewables for electricity. Critics have calculated that when constraints are added to the output equation, the LEAPS facility was only capable of generating about 333 MW during peak electrical demand periods not the 500 MW capacity expected.

The LEAPS project then raises serious questions about the financial viability of pumped storage. It should be noted that many pumped storage facilities involve the construction of both upper and lower reservoirs. Because the LEAPS project involved the construction of only an upper reservoir, it would cost less than two reservoir projects like Northfield Mountain. Yet cost benefits studies have shown that the pumped storage part of LEAPS project will loose money.

In addition significant environmental issues have been raised about the LEAPS project which would be located in an environmentally sensitive national forest area, the Cleveland National Forest. Retired Cleveland National Forest supervisor, Anne S, Fege wrote in 2007, that the project would desecrate two pristine canyons, create a serious risk of fire in a fire prone national forest cause by high voltage transmission lines, would be built in an earthquake area, necessitating more expensive construction standards, would cause daily fluctuations to the water level of Lake Elsinor, and would decrease recreational opportunities available in the national forest. Advocates of pimped storage, although often flashing their "Green" credentials seldom pay attention to the environmental impact of the energy projects they support. Greens seem to believe that simply calling something green is enough to prove how pristine it is, without the need of further evaluation. Green who look no further than the word "Green" are no more friends of the environment than advocates of clear cutting are.

I must conclude then, that a substantial case can be made against the use of pumped storage as an electrical backup for renewables generation. The case against the use of pumped storage with solar is considerably stronger than the case against its use with wind, and the combination of wind and pumped storage appears to be more expensive than the cost of nuclear generating facilities. In addition, a wind pumped storage system, while more flexible than wind alone, would be neither as flexible nor as reliable as a nuclear generating system.

Thus the case that pumped storage would be an acceptable low cost alternative to batteries seems implausible at best.