Energy Sources

Modern life is completely dependent on energy. We need energy to move our cars, to power our homes and businesses, to get water delivered to our houses, to use our computers ... very few things can be left out of a list of activities that we take for granted and which, whether we remember it or not, depend on energy. Since the industrial revolution, our main energy sources are non-renewable and dirty, such as fossil fuels and coal, which emit heat-trapping greenhouse gases that cause climate change. Since the 1980s humanity has been more acutely aware that it needs to shift its energy sources towards cleaner, renewable technologies such as wind, solar, geothermal, biofuels, hydrogen etc. The energy revolution is taking place, perhaps not as fast as it should, but public opinion and political will are building an irreversible momentum towards a cleaner type of economy.

Oil (fossil fuel) still is the biggest source of energy. In America, it supplies more than 40% of the total and more than 99% of cars and trucks in the country run on oil. Besides emitting harmful gases, oil will eventually run out so finding alternatives is not only an environmental issue but also a logistic imperative. Hydropower is one of the most significant energy sources already in place. In Norway, it provides 99% of the country’s energy demands. In Brazil, it contributes around 80% of the country’s energy matrix. In the United States it can generate enough power to supply 28 million households with electricity. Worldwide, it plays in an important role in many countries.

Wind and solar are two of the most promising renewable energy sources. Both have been used for centuries and now state-of-the-art technology is allowing us to harness their natural power. They still account for a small percentage of the energy generation total, but the future is bright for both of them. Bioenergy is another popular option being explored. Made out of biomass, it can be sourced from agricultural crop wastes and residues, wood wastes, municipal wastes etc. Biofuels, a type of bioenergy that attracts a fair share of controversy over their green credentials (competition with foodstocks, replacement of forests with monocultures etc), are increasingly popular as part of a fuel mix available at commercial gas stations.

Geothermal is another very promising energy source. It consists of energy harnessed from the heat of the Earth, extracted from shallow ground, hot water or hot rock that exists a few miles beneath the Earth’s surface. Natural gas is used to serve alternative fuel vehicles. It is derived from fossil fuel but is clean burning and emits fewer harmful gases than gasoline. It can be stored as compressed gas (CNG) or cooled to a liquefied state (LNG). Nuclear energy is a very controversial energy source due to disposal risks. Despite that, it accounts for around 14% of the world’s total energy output. Clean energy advocates do not consider it green while some argue that it will be necessary in the transition period to a 100% renewable future. Hydrogen is one of the cleanest sources of power and can be made from renewables such as solar, wind and geothermal, nuclear power and fossil fuels. There is considerable research on the use of hydrogen to fuel passenger vehicles, although on-board hydrogen storage remains a challenge to be overcome.