Thursday, September 15, 2005

Solar Power is Not Needed at Night - Baseload Nuclear Power?

Stephen Gloor: Solar Power is Not Needed at Night

June 26, 2005
Solar Power is Not Needed at Night
For most sensible people our future power needs will be filled by nuclear power and clean coal. These two technologies are seen as the saviors of our technological society however, several large problems remain. Intermittent renewable power is seen as sop to the environmentalists while real power generates the base load.

OK so lets start demolishing this conventional fuel future. I will do the figures for Australia as I have these to hand. First of all Australia generated approx 220 000 GWHrs in 2002. With this scenario no attempt will be made to conserve power as why should we. So 220 000 GWHrs equates to approx 25 GW of installed electricity generation capacity. Now the little secret that most fossil fuel proponents don't tell you is that Peak demand can be up to 60% more than than the base load - about 60 GW. Herein lies a problem as both nuclear power plants and coal plants are very bad at responding to peak loads. They cannot be ramped up and down in response to changing loads nearly as well as gas turbines that can start and stop in time frames of minutes. Large nuclear power stations can take many hours to change. Also if we went all nuclear then we would have 35 1 GW plants sitting around doing nothing at night. As nuclear plants cost 2 or 3 billion each then this is 100 billion dollars worth of power plants sitting idle. This problem for an all nuclear future is that it would require expensive electricity storage to cope with the time difference between demand rising or falling sharply and when the nuclear plant can react. Steam coal plants also suffer from this problem.

The supposed solution to this and the CO2 output of coal is a real mouthful. Integrated Gasification Combined Cycle. IGCC is a process where the coal is gasified using steam produced from the exhaust of the gas turbine. The CO2 is collected at this point. The plan is then to sequester the CO2 in the ground. These gas turbines could be the fast reacting peak power that is required. Problems remain. The places that CO2 is supposed to be stored are distant from the power plants. We would have to build CO2 pipelines to carry the gas to the storage. If it was carried in trucks then how expensive would this be as there would be millions of tons of CO2 is involved. Coal produces approx 900 tons of CO2 per GWHr. Lets say that nuclear provides 30% of our power needs then 225 000 GW Hrs X 0.7 = 157 500 GWHrs of clean coal power needs to be generated. This would generate 141 750 000 tons of CO2 that would have to be sequestered. 140 million tons per year !!!!!!!! These are the numbers that the Clean Coal power people don't want you to see.

OK so what is the alternative? How do those numbers stack up? Right - first of all the main argument against solar power is that it is not present at night. WELL IT IS NOT NEEDED AT NIGHT. As you can see from the previous paragraph the nighttime demand is 60% of the daytime demand. Solar power neatly follows the peak. Lets say that we have a reasonable blend of Solar Thermal plants and Wind Power. Rooftop solar panels are also part of the energy mix avoiding the massive transmission losses that characterizes the current grid. Demand side management is also very important in a renewable mix.

To start with 220 000 GwHrs would be reduced to about 180 000 GwHrs with demand management. So we would need about 20 GW of base load and roughly 45 GW of peak. I will talk about the base load later so we are talking here about about 25 GW of peak demand. Solar Thermal plants could be up to 500 MW so lets allocate about 50% of the peak demand to them which equates to 25 solar thermal power plants. If we allow a 30% load factor for wind farms then we would need approx 100 or so 200 MW wind farms. This is a long long way from covering all the available land surface with solar plants and wind farms. I am sure that 100 reasonable sites can be found for large wind farms and we certainly have enough land area for the solar plants. With these plants geographically dispersed the bad weather problem is minimized. With the solar plants in a statewide grid then it is very unlikely to be overcast all over the whole state at the one time. Perhaps we would have to build 30 or 40 large Solar Thermal plants to cope with this. Also the new electricity grid would be flexible with storage from electric cars providing smoothing. Also with an electric car in the garage and solar panels on the roof if the worst happens and the grid has to give up because of really unusual weather conditions then your house would continue as normal as you have local storage in your car battery. A pluggable hybrid car would be capable of generating its own power to cover the shortfall for extended periods. This flexible grid is also much less venerable to outages and attack. There are no high value targets, no toxic fuel transported on our roads and consumers that can exist on stored power for extended periods.

The status quo of coal and nuclear offers no solution to the liquid fuel transport problem. A renewable solution by design incorporates battery electric cars and a solution for our oil woes. The best that nuclear/coal solution can offer is fuel cell cars. Now this depends on the new nuclear reactors that can generate hydrogen to be designed from scratch. We also need to wait for a roadworthy fuel cell and hydrogen storage. A practical fuel cell car is about 10 years away and the hydrogen producing nuclear plant is at least as long if not 20 years away. Now of course battery electric cars can use electricity from nuclear and coal power plants. The syn-gas from the gasification of coal can be converted to liquid fuels such as methanol however this is not the philosophy of the business as usual people. From conversations that I have has with these people battery electric cars are inextricably linked with renewables. The fuel cell car is a much better fit for with the corporate model that these people want. Large Oil Companies are fighting for their very existence. They are trying to make themselves into energy companies however at their heart they remain oil producers. A renewable society does not have oil companies. These companies therefore are fulfilling their legal obligation of returning money to shareholders by promoting a solution that will ensure their continuing existence. It is not a conspiracy as some people think but just the way that corporations are setup. Large oil companies see the future as a seamless transition from oil to hydrogen. The timetable is right for them as fuel cell cars are about 10 to 15 years away which nicely dovetails with the fact oil supplies should be getting really tight then.

The other fact is that oil companies are not electricity producers. Their core competence is oil not electricity. Most companies that move away from their competency and knowledge base fail miserably. Electricity is very hard to brand. Hydrogen by contrast can be for example Shell hydrogen at a Shell filling station. Also when you fill up with Shell hydrogen you also go into the store and buy a couple of things. Most service station operators do not make much on the fuel they sell. Most of their profits are in the chewing gum, smokes and drinks they sell when people buy petrol. With PHEVS and BEVS doing most of their filing up at home the brand is difficult to reinforce. Sure the oil companies can market alcohol however the BEVS do not need it and the PHEVS will fill up once a month or so.

So the way forward for these large corporation is hydrogen fuelled fuel cell cars. To this end they have actively discouraged electric cars with cooperation with the car companies. Oil companies and car companies have a close and symbiotic relationship and they cooperate. Car companies do not like battery electric cars as they do not have many components to fail. Electric cars in practice are extremely reliable and do not need oil changes or tune ups. Fuel-cell cars have pumps and membranes and are much more complex that a simple battery - controller - motor. The current maintenance infrastructure can easily find new work servicing fuel cells. So for these reasons I would find it difficult to envision a nuclear/clean coal solution that would include BEVS. This is not a conspiracy simply corporations that are protecting their shareholders money as the are legally obliged to do.

Now for the renewable base load. To bring a natural gas field on line is a complex and expensive business. First the gas has to be found. If it is offshore, as most new discoveries are, then a special ship has to be built to anchor over the field to extract the gas then it has to be piped or shipped to shore. All of this is very expensive. Now consider a series of solar thermal plants built in the Western Australian desert near the pipeline that runs from Carnarvon to Bunbury. These plants would produce hydrogen using the new high-temperature electrolysis process that is being developed for nuclear power plants. The hydrogen would be converted to methane using CO2 extracted from the air. This methane (Natural Gas) would be fed into the pipeline to be used in conventional gas turbine power plants. The methane could be stored easily in vast quantities for times that wind and solar are not available. The latest generation of gas power plants will have a lifetime of 30 years and these plants can be used without modification to supply the 24 X 7 base load from solar natural gas. Also the expense of the solar thermal plant producing methane would not be much more expensive than building natural gas extraction plants especially as it get more and more difficult to find new gas fields. You do not need to find the sun, just a sunny area with a gas pipeline. There are many such areas in Australia - consider the gas pipeline that runs from South Australia to NSW and Victoria.

Contrast the two futures. One, business as usual, trying to dispose of millions of tons of CO2 and thousands of tons of nuclear waste but not requiring us to change in anyway. Or the scenario where we rely on the sun to produce our energy. Yes we will have to change a bit. We will still have private cars and most, if not all, of our electronic goodies. We will not however, have the problems of CO2 and nuclear waste.

Now you decide if the small disadvantage of solar power no being available at night is such a showstopper after all.

Update 28/06/2005 - some people seem to have misunderstood the CO2 bit. There is no attempt to scrub CO2 to offset CO2 emissions. The CO2 is just extracted to react with hydrogen. If this proves impracticable the we will just have to bite the bullet and upgrade the pipeline to carry hydrogen or build a new one.

Update 2 - Cold Hard Facts made me realise that I had omitted references. All figures are from!OpenView&Start=1&Count=1000&Collapse=3#3

Any other references are in hyperlinks.


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