Geoscience Reference
In-Depth Information
Alternative, renewable, or clean energy
Fossil fuels are an amazing discovery, and they have allowed the world to develop at a
faster rate than it has at any other time in history. The high standard of living in the deve-
loped world is based on cheap and relatively safe fossil fuels. But as we have discovered
burning fossil fuels has the unintended consequence of changing global climate. So in the
21st century we need to switch from fossil fuel energy to carbon-neutral energy. These in-
clude solar, wind, hydro, wave, and tidal energy. There are other reasons to switch to re-
newable sources of energy. First is the concern that we have reach 'peak oil' and 'peak
coal' resource levels, and that the world is now running out of both. This is highly unlikely
given all the new reserves of oil and high-grade coal that have been discovered over the last
20 years. Nonetheless, as great colleagues of mine who are chemists keep on telling me, the
greatest crime you can do with oil is to burn it, with our whole industrial society being built
on plastics made from petroleum. Moreover, given the fracking revolution, there is now al-
most unlimited supply of natural gas. Second, countries have in the 21st century become
very aware of 'energy security'; most developed countries' economies are heavily reliant
on the import of fossil fuels, making them very vulnerable to volatility of the markets and
international blackmail.
There now follows a brief discussion of the main alternative energy sources. Straight away
we can see how different portfolios fit different countries. For example, the UK has the best
wind resources in the whole of Europe, while Saudi Arabia has excellent conditions for sol-
ar power. Almost all the technology for these alternatives exist, except for nuclear fusion.
Solar
. The Earth receives on average 343 W/m
2
from the Sun, and yet the Earth as a whole
only receives a two-billionth of all the energy put out by the Sun. So the Sun is in many
ways the ultimate source of energy, energy which plants have been utilizing for billions of
year. At the moment we can convert solar energy directly to heat or electricity or we can
capture the energy through photosynthesis by growing biofuels. The simplest approach is
through solar heating. On a small scale, houses and other buildings in sunny countries can
have solar heating panels on the roof, which heats up water, so people can have carbon-free
hot showers and baths. On a large scale, parabolic mirrors are used to focus the solar en-
ergy to generate hot liquid (water or oil) to drive turbines to create electricity. The best
places to situate solar heat plants are in low-latitude deserts, which have very few cloudy
days per year. Solar heat plants have been built in California since the 1980s and are now
being built in many other countries. Solar photovoltaic panels convert sunlight directly into
electricity. The individual rays of the Sun hit the solar panel and dislodge electrons inside
