Question: Of all the renewable sources of energy available, which do you think will have the biggest impact in terms of changing the world?

Bruce Alexander answered on 18 Jun 2012:

There are two main answers to this question. The first considers where we get the energy from in the first place.

Solar energy really has the promise to deliver enough energy to more than meet our demands many times over. The only down sides are the fact that it currently is a little too costly to be widely used and that some parts of the globe are more sunny than others. Fine for sub-Saharan Africa, not so fine for Aberdeen or Wick. We could use solar energy to do other things, not just supply electricity. We could use it to drive certain chemical reactions to make useful chemicals – this is the idea behind “solar fuels” which is about to become more well known.

The other answer relates to how we deal with the energy once we have it.

One of the things that will probably have the biggest impact is something that will “smooth out” energy as we make it. To explain…We will have to use different forms of renewable energy depending on where we are and what we are trying to do – solar power for sunny places, wind or tidal for not-so-sunny places (like the north of Scotland!). Each renewable source of energy has different peaks in energy supply (we can predict that solar power will give energy during daylight hours, for example, but wind is a little more unpredictable) We need a power network that can cope with all of these different forms of energy adding in power to the national grid at different times. One possible way of coping with this is to use what is called a super-capacitor. These act like giant rechargeable batteries (although they are not the same). SO the idea is that as you produce energy from (say) wind or solar, then the bits that you do not use, you can use to charge a capacitor to “store” for the times you need it when the energy supply is not so high, such as during night time.

Our current power grid copes (almost! – I live in the South East, where it creaks quite a bit) with our current energy supply – coal and nuclear power stations are reasonably predictable in when they supply power, but is nowhere near suitable to be used with renewable energy – we need to address both the supply and distribution of energy at the same time.