Major Energy Sources on Earth
Since the day that man first made fire, humans have sought out the resources of the earth to power their needs. Whether it’s fuel for cooking, heating or powering, that resource is in high demand. Fortunately, the world provides a vast variety of energy sources for our consumption, though some are better for us and our surroundings than others.
Biomass – Perhaps one of the oldest forms of fuel known to civilization, biomass fuels are any kind of biological matter that people can burn in order to produce heat or energy. In the beginning, biomass consisted of woods, leaves, and grasses, but today, we rely on many more sources. For example, ethanol, an alcohol derived from plants like corn, sugar, hemp, and soy crops, is now blended with gasoline, or used to replace it in some vehicles. While considered more environmentally friendly than some alternatives, biomass still emits particulate pollution when burned.
Production of biomass and biofuels are growing industries as interest in sustainable fuel sources is growing. Utilizing waste products avoids a food vs fuel trade-off, and burning methane gas reduces greenhouse gas emissions, because even though it releases carbon dioxide, carbon dioxide is 23 times less of a greenhouse gas than is methane. Biofuels represent a sustainable partial replacement for fossil fuels, but their net impact on greenhouse gas emissions depends on the agricultural practices used to grow the plants used as feedstock to create the fuels. While it is widely believed that biofuels can be carbon-neutral, there is evidence that biofuels produced by current farming methods are substantial net carbon emitters. Geothermal and biomass are the only two renewable energy sources that require careful management to avoid local depletion.
Fossil Fuels – Fossil fuels are the most commonly used type of fuel in developed nations today. Examples include oil, natural gas, and coal, which are used to power cars, trucks, trains and the majority of power plants around the world. The popularity of fossil fuels initially stemmed from their low prices, but as demand continues to rise, supplies are dwindling and prices have skyrocketed. In addition, fossil fuels are responsible for the majority of particulate emissions today.
Solar Energy – While solar energy does not technically come from the earth, but the sun, it is still considered one of the earth’s most plentiful source of energy. Silicon compounds help to absorb the energy rich rays of the sun and the radiative heat it provides, making possible its use as functional energy for our vehicles, homes, and transportation infrastructure. This is one of the cleanest forms of energy on the planet, but low reserves of silicon, and the price of solar panel production, have rendered it an underused utility.
Hydroelectric Energy – Hydroelectric energy, also known as hydropower, relies on the movement of freshwater bodies of water to move propellers and generate energy. This is typically achieved by building dams at strategic points on rivers. While this provides consistent, clean energy, hydropower is often criticized, as the dams destroy marine habitats and interrupt the mating patterns of key species of fish. A variation of this renewable energy source uses the surface waves of the ocean to generate energy in a similar fashion.
Wind Energy – Wind energy uses giant turbines to harness the natural power of the wind to turn propellers and generate energy for general use. While people can build individual turbines and attach them to homes, this type of energy is more commonly used in flat, plain areas, with the construction of fleets of turbines that are hooked up to a generator that provides for the community. Ruled the cleanest, most environmentally friendly form of energy production, the only complaints against wind energy are that they negatively impact small populations of bats and birds and are accused of causing headaches in humans.
Geothermal Energy – This type of energy is generated by heat from the earth’s core heating water into steam, which turns turbines in order to generate electricity. Typically limited to borders of tectonic plates, new discoveries are, for the first time, allowing scientists to explore the idea of using geothermal power in other areas of the world. The energy is totally clean, although some people have concerns about the safety and reliability of building plants over fault lines. Estimates of exploitable worldwide geothermal energy resources vary considerably, depending on assumed investments in technology and exploration and guesses about geological formations. According to a recent study, it was thought that this might amount to between 65 and 138 GW of electrical generation capacity ‘using enhanced technology’. Other estimates range from 35 to 2000 GW of electrical generation capacity, with a further potential for 140 EJ/year of direct use.
OTEC – Ocean Thermal Energy Conversion (OTEC) relies on the difference in temperature between the different layers of ocean to churn a generator and produce electricity. The result of this pushes warm water to deep levels of the ocean, pushing colder water to the top. Some claim that this results in larger amounts of vegetation and healthy marine environments, whereas others argue that this creates an unnatural setting that throws off the food chain in an area.
COAL – Coal is the most abundant and burned fossil fuel. This was the fuel that launched the industrial revolution and has continued to grow in use; China, which already has many of the world’s most polluted cities, in 2007was building about two coal-fired power plants every week. Coal is the fastest growing fossil fuel and its large reserves would make it a popular candidate to meet the energy demand of the global community, short of global warming concerns and other pollutants. According to the International Energy Agency the proven reserves of coal are around 909 billion tonnes, which could sustain the current production rate for 155 years, although at a 5% growth per annum this would be reduced to 45 years, or until 2051. In the United States, 49% of electricity generation comes from burning coal.
Sustainability – Political considerations over the security of supplies, environmental concerns related to global warming and sustainability are expected to move the world’s energy consumption away from fossil fuels. The concept of peak oil shows that about half of the available petroleum resources have been produced, and predicts a decrease of production. The antithesis of sustainability is a disregard for limits, commonly referred to as the Easter Island Effect, which is the concept of being unable to develop sustainability, resulting in the depletion of natural resources. Some estimate, assuming current consumption rates, current oil reserves could be completely depleted by the year 2050.
Nuclear fuel – Resources and technology do not constrain the capacity of nuclear power to contribute to meeting the energy demand for the 21st century. However, political and environmental concerns about nuclear safety and radioactive waste started to limit the growth of this energy supply at the end of last century, particularly due to a number of nuclear accidents. Concerns about nuclear proliferation means that the development of nuclear power by countries such as Iran and Syria is being actively discouraged by the international community.
Nuclear fusion – Fusion power is the process driving the sun and other stars. It generates large quantities of heat by fusing the nuclei of hydrogen or helium isotopes, which may be derived from seawater. The heat can theoretically be harnessed to generate electricity. The temperatures and pressures needed to sustain fusion make it a very difficult process to control. Fusion is theoretically able to supply vast quantities of energy, with relatively little pollution. Although both the United States and the European Union, along with other countries, are supporting fusion research, according to one report, inadequate research has stalled progress in fusion research for the past 20 years.
Renewable resources – Renewable resources are available each year, unlike non-renewable resources, which are eventually depleted. A simple comparison is a coal mine and a forest. While the forest could be depleted, if it is managed it represents a continuous supply of energy, vs. the coal mine, which once has been exhausted is gone. Most of earth’s available energy resources are renewable resources. Renewable resources account for more than 93 percent of total U.S. energy reserves. Annual renewable resources were multiplied times thirty years for comparison with non-renewable resources. In other words, if all non-renewable resources were uniformly exhausted in 30 years, they would only account for 7 percent of available resources each year, if all available renewable resources were developed.
Solar energy – Renewable energy sources are even larger than the traditional fossil fuels and in theory can easily supply the world’s energy needs. 89 PW of solar power falls on the planet’s surface. While it is not possible to capture all, or even most, of this energy, capturing less than 0.02% would be enough to meet the current energy needs. Barriers to further solar generation include the high price of making solar cells and reliance on weather patterns to generate electricity. Also, current solar generation does not produce electricity at night, which is a particular problem in high northern and southern latitude countries; energy demand is highest in winter, while availability of solar energy is lowest. This could be overcome by buying power from countries closer to the equator during winter months, and may also be addressed with technological developments such as the development of inexpensive energy storage. Globally, solar generation is the fastest growing source of energy, seeing an annual average growth of 35% over the past few years. Japan, Europe, China, U.S. and India are the major growing investors in solar energy.