David MacKay was a voice of reason in the sometimes crazy world of energy. In his last interview he identified the futility of basing future UK energy supplies on renewable energy.

Today each person in the UK uses on average 125 Kwh/day. Roughly a third is for heating services and food, a third is for electrical power, and a third is for transport. For the UK to have a zero carbon future all this energy will have to be generated by electricity. We will have to electrify all transport and produce synthetic fuel for plastics and air travel. Any reductions through efficiency savings is likely to be offset by efficiency losses in converting electrical energy to chemical energy in the form of hydrogen and methane.

125 KWh/day is the equivalent of an average continuous power supply of 125/24 = 5 Kw per person. For the population of UK this equates to a national output of 300 GW average power perhaps peaking to 500GW in winter. How can this huge demand be met?

Modern society depends on always available power. If power goes down then society stops. There are no phones, no internet, no ATMs, no refrigeration, no sewage pumps – nothing, and if a large city like London is without power for more than 12 hours rioting and looting would quickly take hold. It is therefore inconceivable not to ensure that we have reliable energy at all times. So an energy plan for the UK must be able to meet demand even on the coldest evening of the year in winter with no wind and no solar . For this reason Renewable energy can never under any realistic scenario meet that target. To imagine that battery prices could fall enough to make wind and solar backup such enormous power demands is simply a delusion.

Renewables are very low density and for significant energy supply require vast areas of land. Solar energy is unsuitable for the UK because during winter output is 9 times lower than summer. Since we have to find a reliable zero-carbon solution for the winter, it makes no sense to switch it off in the summer just because we like renewables.

A good analogy for reliance on renewables is the age of Sail. Sailing ships moved goods around the world from the 16th century until the beginning of the 20th century. Technical progress even produced higher speed. However they were limited both in size and especially in reliability. They could become becalmed for a week or hit by ferocious storms blowing them way off course. They really only worked worked well under stable wind conditions, which were unpredictable. As soon as iron clad ships and reliable steam engines became available they quickly replaced sailing ships. Modern container ships today master all weather conditions and move most of the world’s trade on which the global economy depends.

Why is Germany investing so much in Energiewende?.

Germany is really building 2 energy infrastructures. A renewable infrastructure and a backup fossil fuel infrastructure. They recently built 19 new modern coal fired stations in parallel to their investment in wind and solar. The reason is simple.

On a cold December evening when there is no wind the renewable power supply is zero, and all their coal stations must be be ramped up to maximum output. They will have to build yet more coal stations if they go ahead and close their nuclear plants just to please the Green party. Energiewende as currently envisaged will never be able to deliver a zero carbon future, unless they add inefficient CCS to their coal plants. If so then they will need 50% more of them.

The only logical solution for the UK is a mostly nuclear energy future with some CCS coal stations if economic.

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