Energy 2

Having discussed some general topics it is time to get to some specific issues. To recap energy use will increase as our civilisation becomes more sophisticated. Fossil fuels produce carbon dioxide and climate is changing as a result. This change in climate threatens life on the planet.

So what’s to be done? The first part of the answer is to use fossil fuels better. This means burning gas rather than coal and burning it more efficiently. It is slowly becoming clear that it is better to use electricity because even with fossil fuels burning in a power station is more efficient than in ( say) cars.. This is perhaps the place to nail the lie that electric cars are zero emission. They are at the tailpipe but if fossil fuel is burned to create the electricity then mankind benefits only from the greater efficiency of a power station over an internal combustion engine.

It is far from clear whether pure electric cars or hybrid cars ( those having both electric and internal combustion engines ) will succeed. On one hand pure electric have lower emissions and on the other battery limitations mean that pure electric are range limited.

This points to the great problem with electricity. That problem is that electricity is almost ideal as a means of energy transmission but is very difficult and expensive to store. At present our mains electricity must be generated as it is consumed.

There have been big advances in batteries in the past fifty years but even with that batteries are expensive, slow to charge and only barely meet the demands upon them. This is such a problem that in the UK we have resorted to pumped water for large scale storage. Essentially this is a reversible hydroelectric scheme. When demand is low water is pumped by electricity to a high storage reservoir. When demand is high the stored water is released through turbines generating hydroelectricity. This process inevitably loses some energy but it is the only acceptable method at present. There is some suggestion that large batteries might help and US Solar City are planning a 100MW battery in Australia.

As was said earlier all energy ultimately comes from the sun. Photosynthesis powers plants and hence has provided us with fossil fuels. However photosynthesis has a very low efficiency which means that crop based fuels will be of limited use. Crop based fuels are carbon dioxide neutral in the sense that the growing plant consumes carbon dioxide which is then returned to the atmosphere when it is burnt. The carbon necessary for all plants is taken from carbon dioxide in the atmosphere. Plant growth removes C02 from the atmosphere but all that C02 is returned when the plant rots.

Rather than use plants as intermediary solar electric directly turns the sun’s rays to electricity. The problem is that solar panels are not very efficient. Over the past few years prices of solar panels have fallen a lot but they are still quite expensive. However the fundamental problem is that solar panels only generate in the daytime and preferably during a sunny day.

Wind turbines have a similar problem of intermittency ie. they only generate when the wind is blowing. It is unclear whether wind or solar power is fully cost efficient compared to fossil fuel power. There are indications that wind and solar are approaching cost parity with fossil fuels after a long period when they have be subsidised by government. These subsidies were not paid by general taxation but by taking money from existing generators.

Because wind and solar are intermittent there is the question of balancing supply and demand. At present while wind and solar are a small part of total energy production this is a minor issue but as their contribution rises it is set to become a major problem. Managing the national electricity grid will become an issue.

At present the only known none carbon method of steadily generating electricity is nuclear. For well rehearsed reasons this is contentious. It is very expensive using the conventional nuclear station. It is said that “mini nukes” built on a modular basis will be cheaper but  this is a paper exercise as none have been built.

It is apparent that at least some of the supply/demand balancing will demand load shedding. In its modern form this means paying large users a fee for allowing their supply to be cut. As the UK has very little spare capacity this already happens at peak demand.

It is possible that if electric cars become widespread then batteries would only be recharged at times of low demand and there is even the suggestion that car batteries could supply at peak times. This would require complex controls but computers may make it feasible.