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Solar and wind energy would have some merit if we have a way to store this energy. Power distribution in industrialised countries is networked. Meaning that you don’t have one PowerStation supplying electricity only to the surrounding districts, it is connected to other PowerStation’s across the country. In some places (EU and USA) power grid is connected to the grids in other countries. Approximate load on the network for any given time and date is known from historical records. Some extra generating capacity is allowed for the load fluctuations and possible breakdowns. But the economic dictate that extra capacity cannot be too large. If the demand exceeds the supply you have domino effect. One PowerStation overloads and trips out, increasing load on other and tripping it out and so on. The result is countrywide blackout. It has happen in past in America and in Europe. To supply such a network directly from the solar and wind generating plants would require double or triple of required generating capacity to allow for occasions when wind drops out and the clouds cover the sky.
OK many will say, store this power in the batteries and supply it when load on the network needs it. Except, there is a small problem with this proposition.
There is a measurement to tell us how much energy we can get from materials we us as energy sources. It is called Energy density and is expressed in Joules per kilogram.
It doesn’t tell us how much of the energy we are after (electricity) it will provide as there are going to be losses in generating electricity (heat, friction and so on). But it doesn’t matter, as we are interested in the ratio of the power available in different materials and the losses in generating electricity will be approximately same.
Black Coal 32MJ/kg
Petrol 46MJ/kg
Hydrogen 120MJ/kg
Uranium 235 (in fission) 90000000MJ/kg
Capacitor 0.002MJ/kg
SuperCap 0.01MJ/kg
Lead acid battery 0.1MJ/kg
NiCad battery 0.2MJ/kg
Lithium ion battery 0.6MJ/kg
There are some new experimental capacitors with reported Energy density of 1MJ/kg.
From above you will see that replacing 1kg of coal with lead acid battery will require 320kg battery.
Or replacing 250MW power station supplying power for 5 hours will require 45000-tonne battery.
If you want to replace 4kg of petrol in your car using NiCad batteries you will need 920kg battery. Twice as heavy for lead acid battery. And then you have to consider what will happen at evening when 1milion cars are plugged in to be recharged. This is one of the reasons why we don’t have battery-powered cars. But some people will see it as conspiracy by oil companies.
Alex, as you see the Nuclear energy is very enticing. Power available from small quantities of fuel is huge. With Nuclear fusion it is enormous at 300 000 000MJ/kg.
I don’t think Uranium mining lobby is driving the GW debate. They simply saw opportunity to suggest their alternative energy source and they took it.
From all I have written you may think that I’m against Solar and Wind power. Not so. Even in past 20 or so years Solar energy had its place in generating power in remote areas. I’m against wasting money something so inefficient. Although it will work it is going to be so inefficient to cause economical crisis leading to social problems associated with economical crash. Once there is huge unemployment, hunger and treat of revolutions, no one will give hoot about GW and will burn anything in the power stations just to get economy going.
One of possible uses of Solar and Wind energy is to produce hydrogen by electrolysis. It is not very efficient process. Hydrogen would be then stored (similarly to LPG) and used to drive turbines in conventional power station. It may be even possible combust hydrogen directly in turbines without converting it to the steam first. Advantage of this would be that such power station could be put on line and off much faster then steam driven turbines. If salt water would be used for electrolysis it may by possible to extract some rare materials (uranium, gold, silver and so on) from it as by-product of power generation. All the problems associated with feeding Solar and Wind power directly to the power grid, or storing it in the batteries would be eliminated. The pollution emitted by such power station would be mostly water. But as no one seems to go this way there must be some fundamental problems associated with this concept that I’m not aware of.
Regardless of way the application of Solar and Wind energy will take, we are looking on hundreds of square kilometres of Solar panels and thousands of windmills to produce some percentage of our energy requirements. Economic of it? Well I’m sceptical, but I’m not economist.
One unforseen consequence of big blackouts is the big increase of the babies being born nine moths later. Peter Costello there is your solution to declining birth rate!
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