What is it?Geothermal energy is derived from the heat of the Earth itself. It can be sourced close to the Earth’s surface, eliminating the need for excessive and destructive digging. However, the heat source itself is derived from deep within the Earth’s core—around 4,000 miles down. At this part of the planet, temperatures may reach over 9,000 degrees Fahrenheit. The heat emanates from the core to the surrounding rock. Humans have utilized geothermal energy for millennia—it is the cause of hot springs, and ancient Romans harnessed its power for space heating.
How is it sourced? Geothermal power plants harness these heat sources to generate electricity. There are three types of power stations—dry steam, flash steam, and binary cycle power stations.
How is it used? Geothermal energy can be part of a commercial utility energy solution on both large and small scales. This may include everything from heating office buildings and manufacturing plants to growing greenhouse plants. It can also be used to heat water at fish farms and aid in several industrial processes, such as pasteurizing milk.
Are there any downsides? Geothermal energy, though sustainable, can cause some minor environmental issues. In the most extreme cases, geothermal power plants can cause small earthquakes. Moreover, there are very heavy costs associated with building and developing geothermal power plants, and the energy availability is highly location-specific. This type of power is only sustainable if the reservoirs are properly managed.
What is it? Bioenergy is a type of renewable energy derived from biomass to create heat and electricity. It is also used to produce liquid fuels used for transportation, such as ethanol and biodiesel. Bioenergy creates “biofuels,” such as ethanol and biodiesel. Biomass is defined as any organic material which has stored sunlight in the form of chemical energy—this can include everything from wood, wood waste, and straw to manure and other byproducts of various agricultural products.
How is it sourced? Bioenergy is sourced in a variety of ways. Users can directly burn the biomass or capture the methane gas produced by natural decomposition of organic material.
How is it used? Bioenergy can be used in vehicles (ethanol and biodiesel) and in farm operations, working to convert waste from livestock into electricity. This is done using a small, modular system. Additionally, manufacturing facilities can be equipped to burn biomass directly, allowing for the recycling and reuse of material (for example, paper mills can use wood waste to produce electricity and steam for heating). If equipped, towns can also tap the methane gas created by the anaerobic digestion of organic waste in landfills.
Are there any downsides? Bioenergy generates the same amount of carbon emissions as fossil fuels. However, the plants grown as biomass remove a roughly equal amount of CO2 from the atmosphere, helping to keep the environmental impact relatively neutral. However, organizations such as Greenpeace and the Natural Resources Defense Council have critiqued the use of bioenergy for the harmful impact it may have on forests and the climate (as a result of the CO2 emissions).
What is it? Hydroelectricity is produced from hydropower, which is derived from the energy of falling or fast-moving water. It is produced in 150 countries and, in 2015, produced nearly 17% of the world’s total electricity. It also produced around 70% of all renewable electricity. Hydroelectricity’s low cost makes it a competitive source of renewable electricity; the power plants consume no water, and the project produces no direct waste and has a considerably lower output level of greenhouse gasses than fossil fuel energy plants..
How is it sourced? The most popular form of harnessing hydroelectric power is by capturing the kinetic energy of flowing rivers. This is done through the utilization of a series of dams, which are constructed to store water in a reservoir. When released the water flows through turbines, producing electricity. The water is cycled between lower and upper reservoirs to control electricity generation. Hydroelectric power can also be harnessed through “run-of-river hydropower.” In this method, a portion of a river is funneled through a channel, thus eliminating the need for a dam.
How is it used? Though the use of hydroelectric power is dependent on geographic location, it is used to supply electricity in a variety of situations—from farm and ranch operations to individual buildings and towns.
Are there any downsides? There are some minor environmental consequences associated with the use of hydropower. Interventions in waterways, such as damming and changing flow, can impact the habitat of thousands of species. Additionally, building the plants themselves is an expensive project, and widespread droughts are likely to exponentially increase the cost of hydroelectric power.
What is it? Solar power is the conversation of energy from sunlight into electricity. This is done by either directly using photovoltaics, indirectly using concentrated solar power, or a combination. With the exception of geothermal and hydrogen, the sun plays an essential role in most types of renewable energy. In capturing the sun’s energy directly, technology can convert this power into heat, illumination, electricity, and cooling systems. Solar power is an extremely reliable source of energy, thus providing essential energy security. It can also provide energy independence to those who purchase personal solar panels. Additionally, solar power creates a lot of jobs—between two and three times more than the coal and natural gas industries.
How is it sourced? Photovoltaic (PV) systems use solar cells to convert sunlight into electricity. This coverts light into electricity using semiconducting materials. Additionally, the sun’s heat can be concentrated by mirror-covered dishes that are focused to boil water in a conventional steam generator to product electricity.
How is it used? The application of solar power is seemingly endless. Users can install personal and commercial solar power systems in the form of rooftop equipment or field array panels. Users can also purchase solar energy generated by an offsite commercial solar installation.
Are there any downsides? When the sun sets or is heavily shaded, solar PV panels stop producing electricity. This necessitates the creation of batteries to store electricity produced by solar panels for later use. Additionally, up-front costs can be intimidating, and personal panels do not work on every type of roof. However, when it comes to environmental impact, or lack thereof, solar energy is peerless.