Abstract
Taking the United Kingdom as a case study,
this paper describes current energy use
and a range of sustainable energy options for the future,
including solar power and other renewables.
I focus on the the area involved in
collecting, converting, and delivering sustainable energy,
looking in particular detail at the potential role of solar power.
Britain consumes energy at a rate of about 5000 watts per person,
and its population density is about 250 people per square kilometre.
If we multiply the per-capita energy consumption by the population
density, we obtain the average primary energy consumption per unit
area, which for Britain is 1.25 watts per square metre. This areal
power density is uncomfortably similar to the average power density
that could be supplied by many renewables: the gravitational
potential energy of rainfall in Scottish highlands has a raw
power per unit area of roughly 0.24 watts per square metre; energy
crops in Europe deliver about 0.5 watts per square metre; wind farms
deliver roughly 2.5 watts per square metre; solar photovoltaic farms in
Bavaria and Vermont deliver 4 watts per square metre;
in sunnier locations,
solar photovoltaic farms can
deliver 10 watts per square metre;
concentrating solar power
stations in deserts might deliver 20 watts per square metre.
In a
decarbonized world that is renewable-powered, the land area required
to maintain today's British energy consumption would have to be
similar to the area of Britain.
Several other high-density,
high-consuming countries are in the same boat as Britain, and many
other countries are rushing to join us. Decarbonizing such
countries will only be possible through some combination of the
following options: the embracing of country-sized renewable power
generation facilities; large-scale energy imports from country-sized
renewable facilities in other countries; population reduction;
radical efficiency improvements and lifestyle changes; and the growth of
non-renewable low-carbon sources, namely ``clean'' coal, ``clean'' gas, and nuclear
power.
If solar is to play a large role in the future energy system, we need
new methods for energy storage; very-large-scale solar would either need to
be combined with electricity stores,
or it would need to serve a large flexible demand for energy that
effectively stores useful energy in the form of chemicals, heat, or cold.