Wind

Windmills turn in the breeze at Horns Rev 2, the world’s largest wind farm, 30 kilometers (19 miles) off the west coast of Denmark near Esbjerg, on September 15, 2009. Source: Bob Strong/Reuters.

Windmills turn in the breeze at Horns Rev 2, the world’s largest wind farm, 30 kilometers (19 miles) off the west coast of Denmark near Esbjerg, on September 15, 2009.

Source: Bob Strong/Reuters

Origins and Uses

Wind spins a turbine, which generates mechanical energy that can be converted and stored as electrical energy. Turbines can generate wind power on land and offshore in the oceans.

Tradeoffs

  • Susceptible to outage
  • Noisy, negative visual impact
  • High land use if onshore
  • Construction can reduce local bird and fish populations
  • Production may involve use of rare earth minerals which can release harmful chemicals

Did you know?

In 2017, wind power supplied Denmark with roughly 45 percent of its electricity supply. One day that year, wind power generated enough electricity to satisfy the entire country’s demand.

Solar

Workers install photovoltaic solar panels at the Gujarat solar park in the village of Charanka in the Patan district of the western Indian state of Gujarat, on April 14, 2012. Source: Amit Dave/Reuters.

Workers install photovoltaic solar panels at the Gujarat solar park in the village of Charanka in the Patan district of the western Indian state of Gujarat, on April 14, 2012.

Source: Amit Dave/Reuters

Origins and Uses

Solar power encompasses a growing range of technologies and systems that harness the sun’s energy for human use. Common technologies include photovoltaic (PV) energy conversion, which directly converts the sun’s light into electricity using solar panels. Solar thermal electric (STE) energy generation concentrates the light from the sun to create heat, which turns a generator to make electricity. Solar thermal collectors are well suited for large-scale energy projects.

Tradeoffs

  • Renewable with low carbon emissions
  • Cost-effective with prices continuing to decline
  • Can be installed on single homes, reducing reliability on a vulnerable and expensive centralized grid
  • New strides in battery technology enable more efficient storage of solar energy at night and in winter
  • Solar cell production often depends on the dangerous and environmentally harmful mining of quartz
  • PV solar cells only generate energy during daylight hours, and storing electricity is currently not particularly efficient or affordable
  • Large arrays can use vast tracts of land, though this land does not typically have other viable uses

Did you know?

One of the largest solar power parks in the world resides in Kamuthi, India. It stretches over 2,500 acres where 2.5 million solar panels generate enough electricity for an estimated 750,000 people.

Hydro

A man rides a motorcycle carrying his children along the top of a dam, which is flooded by an overflowing river near the Junyue township of Pengzhou, in the Sichuan province of China, on September 12, 2013. Source: Reuters.

A man rides a motorcycle carrying his children along the top of a dam, which is flooded by an overflowing river near the Junyue township of Pengzhou, in the Sichuan province of China, on September 12, 2013.

Source: Reuters

Origins and Uses

Water moves a turbine, fueling a generator that turns the water’s kinetic energy into electrical energy that can be stored. To properly generate electricity, water must move at a high velocity, so dams are built in bodies of water. The water builds up on one side and is funneled through small tubes in the dam to create higher pressure.

Tradeoffs

  • Renewable with low carbon emissions
  • Hydro plants can go quickly from zero output to maximum capacity, relieving grids during power outages
  • Hydroelectric power typically represents a domestic energy source, which allows countries to reduce their dependence on foreign energy
  • Flooding land for hydroelectric reservoirs can displace communities, destroy wildlife habitats, and degrade aquatic ecosystems
  • Susceptible to droughts
  • Damming rivers can cause economic and environmental problems for downstream communities or nations
  • Lack of maintenance could be dangerous for the water supply and those who live nearby

Did you know?

Four of the top ten highest capacity dams in the world and half of all mega dams, or dams over 15 meters tall, are in China. By 2020, China hopes to raise its capacity to 290 GW, which would surpass the capacity of all of Europe’s dams combined.

Nuclear

Steam rises from the cooling towers of the Electricite de France nuclear power station of Le Bugey in Saint-Vulbas near Lyon, on April 13, 2015. Source: Robert Pratta/Reuters.

Steam rises from the cooling towers of the Electricite de France nuclear power station of Le Bugey in Saint-Vulbas near Lyon, on April 13, 2015.

Source: Robert Pratta/Reuters

Origins and Uses

Nuclear energy is produced at power plants through the process of fission, in which atoms are bombarded by neutrons. When bombarded, the atoms split, releasing neutrons which in turn collide with other atoms, and so on. This chain reaction releases energy which is harnessed to create heat and produce electricity. (The word “nuclear” refers to the nucleus of an atom.) Often, uranium is used in fission, as it is easy to split. It is collected through mining and is powerful: one pound of it has an equivalent amount of energy as three million pounds of coal.

Tradeoffs

  • Nuclear energy production and use release few greenhouse gas emissions
  • Uranium fuel is abundant; some experts estimate reserves will last another 200 years at current consumption
  • Nuclear power typically represents a domestic energy source, which allows countries to reduce their dependence on foreign energy
  • Nuclear waste poses a risk to humans for hundreds of thousands of years, and governments are unsure of how to dispose of it
  • Nuclear power plants are typically placed in marginalized communities, so risks disproportionately affect those populations
  • Nuclear power carries a risk of accidents or meltdowns that can be immensely harmful for generations

Did you know?

After a decision to rapidly expand its nuclear energy capabilities following an oil shock in 1974, France now attributes 75 percent of its electricity to nuclear power. But by 2022, France will face an energy crisis when the 40 year lifespan of 22 of its 58 nuclear reactors will expire.

Biomass

Logs are arranged for milling at Okobaba sawmill at the edge of the Lagos Lagoon in Nigeria, on September 25, 2014. Source: Akintunde Akinleye/Reuters.

Logs are arranged for milling at Okobaba sawmill at the edge of the Lagos Lagoon in Nigeria, on September 25, 2014.

Source: Akintunde Akinleye/Reuters

Origins and Uses

Biomass is organic material such as wood, agricultural crops and waste, food waste, and animal manure, which contain stored energy from the sun. Humans have utilized biomass since they discovered how to burn wood to make fire. Wood represents a solid form of biomass, but liquid derivatives like ethanol also release chemical energy in the form of heat.

Tradeoffs

  • Biomass energy comes from organic material which is renewable
  • Low greenhouse gas emissions
  • Waste products from biomass energy production can be recycled for other use
  • Large potential supply of available land for biomass conversion in some areas
  • Not all biomass fuels are carbon neutral or even lower carbon than some fossil fuels
  • Biomass energy production requires large amounts of space and land to grow biomass, with further need for nearby power plants to cut down on transportation costs
  • Using land for biomass production instead of for growing food can negatively impact food production

Did you know?

A 2015 United Nations University report concluded that if all human feces generated annually was converted into biogas, the resulting energy could power 138 million households and the residual slurry could power an additional 130,000.