Which Of These Answers Is Not A Renewable Energy Source?

Energy sources can be divided into two main categories: renewable and nonrenewable. Renewable energy comes from natural sources or processes that are constantly replenished, such as sunlight, wind, water flow, biological processes like wood and agricultural crops, and geothermal heat. Nonrenewable energy, on the other hand, comes from finite resources that do not replenish or that take extremely long periods of time to replenish relative to how quickly they are used up, such as fossil fuels like coal, oil, and natural gas, as well as nuclear power.

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Types of Renewable Energy

There are several major types of renewable energy sources that are commonly used. These include:

Solar Energy

Solar energy comes directly from the sun and is captured and converted in a few ways. Solar panels (photovoltaic cells) capture sunlight and convert it into electricity. Concentrated solar power plants use mirrors to reflect and concentrate sunlight to heat a liquid, produce steam, and generate electricity via a steam turbine. Passive solar heating uses windows and building materials to capture sunlight and heat buildings.

Solar is one of the most abundant renewable energy sources. According to the UN, the amount of solar energy that hits Earth in an hour equals the amount of energy used by all human activities in a year (https://www.un.org/en/climatechange/what-is-renewable-energy).

Wind Energy

Wind turbines capture the wind’s kinetic energy and convert it into mechanical power or electricity. Wind farms consist of many turbines and generate power for utilities. Wind power is one of the lowest priced renewable energy technologies.

According to the EIA, the United States has some of the best wind resources in the world. Wind power is an increasingly cost-effective way to add new power generation, and wind turbines can be built on land or offshore in water (https://www.eia.gov/energyexplained/renewable-sources/).

Hydroelectric Energy

Hydropower uses the energy of flowing or falling water to produce electricity via a turbine connected to a generator. Hydroelectric dams store water in a reservoir and release it to generate power.

Hydroelectricity supplies 16% of the world’s electricity. It’s a stable, low-cost, renewable power source. However, damming waterways also impacts the environment. Fish migration routes can be blocked, and aquatic ecosystems damaged (https://www.nationalgrid.com/stories/energy-explained/what-are-different-types-renewable-energy).

Geothermal Energy

Geothermal energy taps into underground reservoirs of steam and hot water to generate power. It can come from natural geothermal reservoirs or pumping water underground to be heated.

Geothermal power plants generate electricity for utilities, while geothermal heating/cooling systems provide direct use for homes and buildings. The western U.S. has strong geothermal resources, but most areas have some shallow ground energy to leverage.

Biomass Energy

Biomass energy uses organic matter like plants, wood, and waste to produce heat and electricity. Biomass fuels include wood, biogas, biofuels, and trash. As plants grow they capture and store the sun’s energy through photosynthesis. Burning biomass releases this stored solar energy.

Bioenergy is a diverse, sustainable energy source. However, some criticisms exist around harvesting and unintended land use changes. Still, bioenergy reduces dependence on fossil fuels.

Solar Energy

Solar energy comes directly from the sun in the form of solar radiation. This radiation can be captured and turned into useful forms of energy like heat and electricity. According to the Department of Energy, solar technologies use photovoltaic (PV) cells to convert sunlight into electricity.

PV cells are made from materials like silicon that release electrons when they absorb photons from sunlight. This generates an electric current that can be captured and used. Many PV cells together form solar panels, which can be installed on rooftops or other sunny locations. The direct current from the panels is converted into alternating current using inverters so that the electricity is compatible with household appliances and the electric grid.

Solar energy offers a clean and renewable way to harness the sun’s energy for electricity and heat. PV panels can generate power quietly and cause no pollution during operation. However, there are some challenges like the variability of sunlight that need to be addressed through storage and grid integration technologies.

Wind Energy

Wind energy is one of the most rapidly growing renewable energy sources in the world. Wind turbines convert the kinetic energy in wind into mechanical power that can be used for electricity. Wind turbines work by using blades that are shaped like airplane wings. When the wind blows past the blades, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag forces that cause the rotor to spin. The rotor is connected to a main shaft, which spins a generator to create electricity.

Modern wind turbines can operate at wind speeds between about 7 and 55 miles per hour (11 to 25 meters per second). At slower wind speeds, the turbine won’t spin fast enough to generate electricity. At higher wind speeds, the turbine could be damaged or have to be shut down. So turbines are designed to optimize energy production at the most common wind speeds in the areas where they’re installed.

The power available in the wind is proportional to the cube of the wind speed. So if the wind speed doubles, the power available increases by a factor of 8. This is why wind turbines are designed to be tall – to reach stronger winds found at higher altitudes. The average utility-scale wind turbine installed today is about 80 meters (260 feet) tall.

Some key advantages of wind energy:¹

It’s a clean, renewable source of energy that produces no air or water pollution.

New wind turbines can generate electricity at extremely low costs.
Wind energy is abundant and inexhaustible.
It strengthens energy security and reduces dependence on imported fuels.

Hydroelectric Energy

Hydroelectric energy utilizes the power of flowing water to generate electricity. It is considered a renewable energy source because it relies on the water cycle of evaporation and precipitation to replenish the water in rivers and reservoirs.

At hydroelectric power plants, the energy of the moving water is harnessed by turbines and generators to produce electricity. The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir. When the water is released from the reservoir, it flows through a turbine, spinning it, which then activates a generator to produce electricity. The amount of electricity that can be generated depends on the volume of water flow and the vertical distance the water falls. According to the Union of Concerned Scientists, hydropower is currently the largest renewable energy source for electricity generation in the United States.

The main advantage of hydroelectric power is its ability to quickly adjust electricity generation to meet sudden spikes in demand, since the flow of water can be controlled through the dam. It is also inexpensive to operate and does not directly produce greenhouse gas emissions. However, building large dams can be costly and alter local ecosystems. There is also a limit to suitable dam sites based on geography.

Geothermal Energy

Geothermal energy is a renewable energy source that utilizes heat from below the Earth’s surface to generate electricity. The word “geo” means earth, and “thermal” means heat, so geothermal energy refers to tapping into the heat contained within the Earth.^[1]

The Earth’s core is extremely hot, with temperatures exceeding 4,000 degrees Celsius. This heat is contained in reservoirs of hot water and steam located deep underground. Wells can be drilled into these reservoirs to bring the hot water or steam to the surface. The steam can then be used to drive turbines and generate electricity.^[2]

Geothermal power plants are built where these geothermal reservoirs are located. There are three types of geothermal power plants: dry steam, flash, and binary. Dry steam plants use steam directly from the reservoir to turn the turbine. Flash plants take high pressure hot water and convert it to steam to drive the turbine. Binary plants pass the hot water through a heat exchanger to heat a secondary fluid which vaporizes and drives the turbine.

Geothermal energy is considered renewable since the water is replenished in the reservoir, although reservoirs can be depleted over time if overproduced. Geothermal power plants produce minimal emissions and have a small land footprint compared to other power plants. However, suitable geothermal reservoirs are not available everywhere. The western U.S. has the highest potential capacity for geothermal energy in the country.

^[1] https://www.ucsusa.org/resources/how-geothermal-energy-works

^[2] https://www.energy.gov/eere/geothermal/electricity-generation

Biomass Energy

Biomass energy is derived from organic matter such as plants and plant-based materials. Sources of biomass include trees, crops, algae, and waste from plants and animals. Unlike fossil fuels that take millions of years to form, biomass fuels are considered renewable as they regenerate in a relatively short time.

According to the U.S. Department of Energy, biomass is commonly used for electricity generation. It can be directly burned to produce steam which spins a turbine that generates electricity. This process of burning biomass to produce electricity is known as biopower (source).

As plants absorb carbon dioxide from the atmosphere during photosynthesis, the carbon cycle is balanced when biomass is burned. This makes biomass a clean and climate-friendly fuel source. The energy potential from biomass is large as plants generate energy from the sun, and there are abundant sources of organic waste materials (source).

Fossil Fuels

Fossil fuels like oil, coal, and natural gas are nonrenewable energy sources formed from the remains of ancient plants and animals. Over millions of years, the remains were buried under rock and sediment and subjected to intense heat and pressure which turned them into fossil fuels (1).

Oil, also known as petroleum, is a liquid fossil fuel that is found beneath the Earth’s surface and extracted through drilling. Oil is refined to produce transportation fuels like gasoline, diesel, and jet fuel. It is also used to produce chemicals, plastics, and other materials (2).

Coal is a solid fossil fuel that is mined from the ground. Coal is burned to generate electricity, provide heat, and make steel. There are four major types of coal – anthracite, bituminous, subbituminous, and lignite (1).

Natural gas is a gas fossil fuel that is found beneath the Earth’s surface mixed with oil deposits or on its own. Natural gas is used to generate electricity, heat homes, cook food, and power vehicles. Natural gas emits less carbon dioxide when burned compared to coal and oil (2).

Sources:

(1) https://www.nationalgeographic.org/encyclopedia/nonrenewable-resources/

(2) https://www.eia.gov/kids/energy-sources/nonrenewable.php

Nuclear Energy

Nuclear energy comes from the splitting of uranium atoms in a process called nuclear fission. In a nuclear reactor, uranium fuel rods are placed into a controlled environment where nuclear fission reactions can be initiated, controlled, and sustained at a steady rate. The enormous amount of heat generated from fission is used to boil water into steam, which spins a turbine to generate electricity.

During fission, a uranium atom absorbs a neutron, becomes unstable, and splits into two smaller atoms. This splitting process releases kinetic energy, neutrons, and gamma rays. The released neutrons go on to cause fission in nearby uranium atoms, creating a self-sustaining chain reaction. Control rods that absorb neutrons are used to regulate the rate of the nuclear reactions. Water also plays an important role as a moderator to slow down neutrons and make them more likely to cause fission when colliding with uranium atoms. The heat generated from all these nuclear fissions is extracted by the reactor coolant and used to make steam.

Nuclear power plants provide around 20% of electricity in the United States. Nuclear energy has the advantages of emitting no greenhouse gases, using readily available uranium fuel, and producing large amounts of reliable base load power. However, there are concerns about properly disposing of radioactive waste products and preventing nuclear accidents.

Conclusion

In summary, the type of energy source that is not considered renewable is nuclear energy. Nuclear energy relies on radioactive elements like uranium that must be mined and processed. Once these finite resources are used up, they cannot be replaced or replenished in a short period of time. While nuclear power plants efficiently produce large amounts of electricity without emitting greenhouse gases, the waste produced is radioactive and difficult to dispose of safely. Sources of renewable energy like solar, wind, hydroelectric, geothermal and biomass can be naturally renewed and replenished. Among major energy sources, nuclear is the only one not considered renewable.

To conclude, this article provided an overview of different forms of renewable energy such as solar, wind and hydroelectric power. It also covered nonrenewable sources like fossil fuels and distinguished nuclear energy as the nonrenewable exception. Understanding the difference between renewable and nonrenewable resources allows us to make informed energy choices.