Environmental Engineering Reference
In-Depth Information
of tidal power of roughly 600 megawatts (end of 2011). However, many projects are in
development all over the world, some of them with very large capacities, including in the
UK (Severn Estuary), India, Korea and Russia. The total capacity under consideration is
43 gigawatts (64 TWh per year), the equivalent of roughly thirty conventional coal-fired
power plants.
The Potential of Ocean Energy
Until about 2008, ocean energy was not considered in any of the major energy models,
and therefore its potential impact on future world energy production is just beginning to be
investigated. Some ocean energy resources, such as ocean current converters and osmotic
power, can be used anywhere. Others are more localized: OTEC is mostly available in the
tropics, while the best waves occur at medium latitudes (30 to 60 degrees). The global
theoretical potential for ocean energy technologies is estimated at 7,400 exajoules per year,
roughly fourteen times the global primary energy production (530 EJ per year). However,
there is substantial disagreement about the technical potential, which is estimated between
7 and 331 exajoules per year. Since the upper estimate proposes 'ocean thermal' as the
energywithhighestpotential (300EJperyear)followedby'waveenergy'(20EJperyear),
perhaps in the future, heat and cooling will be the main form of energy harvested from the
4.10 New Frontiers: Science or Fiction?
The Power of the Stars: Nuclear Fusion
When, in 1905, Albert Einstein, unveiled his famous formula (E = mc
2
), proposing that
mass is equivalent to energy, scientists still believed that the sun was a sphere of molten
rock. A few decades later, spectrographic studies showed that the sun is composed mostly
of hydrogen, with some helium. In 1938, the physicist Hans Bethe revealed why: the
pressure at the core of our star is so great that it fuses hydrogen atoms to produce helium.
Every kilogram of hydrogen is converted into 993 grams of helium. The 'lost' 7 grams of
be replicated in a reactor, less than 1,000 tons of hydrogen would be needed to meet the
entire current energy needs of the human race. This is very little compared with the 4.3
billion tonnes of oil extracted every year. It gets even better: hydrogen is so common on
Earth that reserves could outlast the lifetime of the solar system, and helium, the product of
hydrogen fusion, is completely non-toxic. No wonder hydrogen fusion is the energy dream
that has kept generations of physicists awake at night.
