In my last letter, I asked John Tomblin what subsidies the government gave to fossil-fuel companies.

He replied (14th Dec) rather vaguely that “these can take the form of tax breaks or subsidies for exploration as well as research & development.”

I’m not quite sure what he means, but suspect that he is referring to the fact that exploration and R&D are paid from untaxed income.

But a company is taxed on its profit: that is, on the difference between its income and its legitimate costs. Fossil-fuel companies sell gas, coal, petrol, etc, and so have an income; they prospect, drill wells, drive mines, build new and more efficient refineries, etc, which are costs.

They pay tax on the difference between income and costs. The same is true (the details differ) of all businesses: farmers, factories and fashion-houses as well as fossil-fuel companies. That costs are netted off against revenue before the tax calculation is not a tax break: it’s basic accounting/taxation practice and quite fair. So I don’t accept that this is a “subsidy.” John Tomblin can, of course, show me where I am mistaken or have misunderstood his meaning.

He later cites a 100MWh battery near Shaftesbury, presumably because he considers that its energy-storage is significant.

But a back of an envelope calculation shows that this battery could support Dorset’s households for less than three hours (180 thousand homes, assuming 5kWh/day each).

If account is taken of non-domestic use, if more electric cars need charging and if domestic heating is from heat-pumps, we’re down to a few minutes backup support from this battery. In a winter anticyclone, when solar is insignificant, the wind doesn’t blow and there is no baseload supply from conventional power-stations, a fortnight’s electricity from storage would be a minimum.

A few minutes is derisory. That’s why I claim that his much-vaunted energy-storage solutions are wishful-thinking.

Tony Fisher