Environmental Engineering Reference
In-Depth Information
Consuming our solar capital
For the longer term, there was always going to be a problem of sustainability
with fossil fuels, even without the global warming problem. Except for geo-
thermal heat and the decaying radioactivity of minerals like uranium from the
interior of the earth, all energy sources come from the sun (or moon, in the
case of tidal power). But some are constantly replenished by solar radiation,
such as wind, wave and of course solar power itself, while others coal, oil, gas
are stores of solar energy that have fossilized over millions of years. Even if
the necessary heat and pressure for the creation of such fossil fuels could be
replicated - which they can't be - it would take centuries to replenish these
stores of solar energy.
So in using fossil fuels, we are, as the science writer Vaclav Smil puts it, drawing
down on our solar
capital
, a never-to-be-repeated inheritance that cannot last
forever. What we should be doing, regardless of climate change, is living off our
solar
income
, the winds, waves and solar photo voltaic cells that are replenished
by solar radiation, like pay cheques replenishing a bank account. This solar
income does not arrive as regularly as we would wish, but the intermittency
of wind, wave and even solar power is more than compensated for by the fact
they do not contribute to global warming as burning up the stocks of our solar
capital does.
The burning of coal, in fact, created an environmental movement well
before climate change was considered a risk. Action had to be taken to
curb coal-use to mitigate smog in cities such as London, and also to deal
with the problem of emissions from the sulphur in coal in areas such as
America's upper-Midwest and in Germany and central Europe. Falling
to earth as acid rain (rain, or any other form of precipitation made espe-
cially acidic by sulphur dioxide), these emissions had the effect of strip-
ping trees of their leaves. In the 1980s, when the share of coal in power
generation declined and that of nuclear, natural gas and renewables rose,
the world's energy sector actually started to “decarbonize” a little. So it is
possible: there has been a modicum of decarbonization in the past.
But this positive trend began to slow and reverse in the 1990s, and the
energy sector has, thanks to the big burners of coal - which include the
US, Russia, Japan as well as China and India - started to re-carbonize.
This is why a great deal of faith is being placed in a generic technology
known as carbon capture and storage (CCS) as a way of cleaning up coal.
As its name suggests, CCS (see p.81 for details) involves taking carbon
dioxide out of coal before or after it is burned, and storing it underground.
There is, however, a risk that some of this faith may be wishful thinking:
