CLIMATE change activists are saying that we should stop using gas to heat
our homes – in order to reduce our CO2 emissions. The goal is a good one,
but the proposed remedy is absolutely not. If the alternative is to heat
using electricity, then switching is exactly the wrong thing to do in
current circumstances.
That is because the efficiency of a typical gas boiler is much better than
that of conventional fossil-fuelled electricity generation – 80 per cent as
against 40 per cent. (We should also factor in the loss in transmission,
which for electricity is five per cent and for gas is 0.05 per cent). On
those figures, we would have to have 68 per cent of our electricity
generated by non-carbon systems (nuclear + renewable), before the CO2
emissions would be equal for heating by gas and by electricity. The 2018
figure for non-carbon generation is 52.9 per cent for the UK. There are
some factors that would alter those basic figures: there is quite a lot of
gas-turbine/dual cycle generation, where the efficiency can be up to 50 per
cent, and modern condensation boilers can give up to 90 per cent. Using
those numbers, we would have to have in excess of 80 per cent non-carbon
generation. It is clear that it will not, for many years to come, make any
climate sense to switch from gas to electricity for heating.
There are of course other low-carbon alternatives for domestic heat: solar
PV, heat pumps, wood chip, possibly bio-gas. The first two are particularly
expensive (solar for our electrical devices can make sense, but not for
heating – for example my electricity consumption is 3000Kwhr. pa. and my
heating consumption is 43,000Kwhrs; I would hardly have enough roof area).
Also, heat pumps need about 30 per cent electricity. Wood-chip and bio-gas
both produce CO2, and while the former is in principle a sustainable system
– in that the trees are replaced by replanting, which absorbs CO2 – that is
a long-term process while the new trees grow large enough; and we are told
we should be trying to be carbon neutral by 2025.
So, at present, the best thing we can do for the climate by way of heating
our homes at reasonable installation cost, is to install a condensing gas
boiler. (I have absolutely no financial interest in the boiler or gas
industries.)
Professor James McKelvie, Glasgow G76.
DR Hamish Maclaren did a service by reminding us that the UK contributes
only around one per cner of global carbon dioxide emissions (Letters,
October 16). Scotland’s contribution is one-tenth of that, that is, 0.1 per
cent. Bearing this figure in mind, I would welcome a rational explanation
as to why Scotland needs to do more to tackle climate change, which is
asserted by environmental lobbyists and politicians on a daily basis. As a
lifelong supporter of Scottish independence it gives me no pleasure to know
that this is a case where (pace Greta Thunberg) Scotland is too small to
make a difference.
Dr Iain Wilkie, Strachur.
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