What Among These Is Not A Source Of Renewable Energy?

Renewable energy comes from natural sources that are constantly replenished, such as sunlight, wind, water, plants, and geothermal heat. Using renewable energy is extremely important as it produces much less pollution than traditional fossil fuels, is sustainable over the long term, and helps combat climate change. The major types of renewable energy include solar, wind, hydropower, geothermal, biomass, and ocean energy.

Table of Contents

Solar Energy

Solar energy is one of the most abundant and readily available renewable energy sources on Earth. It is generated directly from sunlight using a variety of technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants, and artificial photosynthesis.

Solar power works by converting the energy in sunlight directly into electricity through the use of photovoltaic cells. These cells are made of semiconducting materials that are specially treated to form an electric field, positive on one side and negative on the other. When sunlight hits the solar cell, the energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. This process of converting light (photons) to electricity (voltage) is called the photovoltaic effect.

The main advantage of solar power is that it utilizes an abundant, renewable source of energy that is available pretty much everywhere sunlight can reach. It is also a clean source of energy that produces no air or water pollution and very little greenhouse gases. Solar technology requires little maintenance and has a long lifespan. Homes and businesses with solar panels can also reduce their dependence on the grid.

However, solar power does have some limitations. The amount of sunlight that arrives at any location depends on latitude, climate, and weather conditions. Solar output is lower in cloudy conditions and nonexistent at night, requiring storage or supplemental power. Solar panels require a large surface area to collect sufficient sunlight. The manufacturing of photovoltaic cells also requires rare materials. Despite decreasing costs, the high initial investment required still poses a challenge to widespread adoption. Intermittent generation from solar also creates integration challenges with the electrical grid.

Wind Energy

Wind energy is harnessed by using wind turbines to generate electricity. Wind turbines consist of large blades that spin around a rotor when the wind blows. The spinning motion turns a shaft connected to a generator to produce electricity.

There are two main types of wind farms: onshore and offshore. Onshore wind farms are located on land, while offshore wind farms are placed in bodies of water like oceans and lakes. Onshore wind farms are less expensive to build and easier to access for maintenance. Offshore wind farms can generate more power since wind speeds tend to be faster and more consistent over water. However, offshore wind turbine construction and maintenance costs are higher.

Some key pros of wind energy are that it’s renewable, clean, and abundant. Wind power generation produces no air or water pollution. Wind is free and unlimited, and turbines can be built on existing farms or ranches. Some cons are that wind power relies on the weather, so it’s intermittent. Wind farms also receive opposition for perceived negative impacts on birds and the visual landscape.

Hydropower

Hydropower is one of the leading renewable energy sources, accounting for over 16% of total global electricity generation. It utilizes the natural water cycle to generate electricity through water turbines, which convert the kinetic energy from flowing or falling water into mechanical energy. There are two main types of hydropower facilities:

Dams are the most common type of hydropower plant. Dams are built to store large reservoirs of water that can be released to spin turbines and generate electricity on demand. The height of the water behind the dam creates potential energy, which gets converted to electricity.

Run-of-river systems generate power from the natural flow of rivers, without the need for dams or water storage. They utilize the kinetic energy of flowing water by diverting some of it through a pipe or channel to spin turbines before returning the water back to the river.

While hydropower is renewable and produces minimal greenhouse gas emissions, there are some environmental concerns. Building large dams can change natural water flows and habitats. Dams also block fish migration and can flood large forested areas upstream. Run-of-river systems have a smaller footprint but can still impact local wildlife.

Geothermal Energy

Geothermal energy harnesses heat from beneath the earth’s surface to provide renewable energy. The word “geo” means earth, while “thermal” means heat. Geothermal energy relies on the hot rock and fluids found naturally in some areas of the planet.

There are three main types of geothermal energy systems used to produce electricity: dry steam plants, flash steam plants, and binary cycle plants. Dry steam plants use steam from a geothermal reservoir to directly drive turbine generators. Flash steam plants pull deep, high-pressure hot water into lower pressure tanks, generating steam to drive turbine generators. Binary cycle plants pass geo-fluid through heat exchangers, heating a secondary fluid that vaporizes to drive turbines.

Applications of geothermal energy extend beyond electricity generation. Direct heating uses hot water from springs or reservoirs near the earth’s surface to provide heat for homes, pools, greenhouses, and industrial processes. Geothermal heat pumps can tap into shallow ground temperatures for space heating and cooling in buildings.

Biomass Energy

Biomass energy is derived from organic matter such as plants, agricultural waste, and urban waste. It harnesses the energy stored inside plants through processes like combustion, fermentation or decomposition. The main types of biomass energy include:

Biofuels from Plants and Waste

Biofuels like ethanol and biodiesel are produced from crops like corn and soybeans. These liquid biofuels can be used to power vehicles. Waste vegetable oil and animal fats can also be converted into biodiesel. Solid biomass like wood pellets and chips can be burned directly for heating and electricity generation.

Combustion, Gasification, Pyrolysis

There are various processes to convert biomass into useful energy. Combustion involves burning biomass directly. Gasification uses hot air or steam to convert biomass into syngas, which is then burned. Pyrolysis heats biomass in the absence of oxygen to produce bio-oil, syngas and biochar. Overall, biomass can provide clean, renewable energy from waste materials and crops.

Ocean Energy

The ocean provides tremendous renewable energy potential with the power of tides, waves, and thermal energy conversion.

Tidal energy utilizes the rise and fall of ocean tides to generate electricity in coastal areas. Tidal “barrages” act almost like dams by capturing tidal waters and directing flow through turbines.

Wave energy converts the mechanical energy of ocean surface waves into electricity. Technologies like floaters, hinged containers, and other devices capture wave motion for conversion.

Ocean thermal energy conversion uses temperature differences between warmer surface water and colder deep water. The temperature gradient can generate power through cycles similar to geothermal power.

While only a small amount of ocean energy is utilized today, it provides promising future renewable electricity potential. With more research and technology improvements, wave and tidal electricity generation is expected to grow substantially in the coming decades.

Non-Renewable Energy

Non-renewable energy sources come from finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. The two main types of non-renewable energy are fossil fuels and nuclear power.

Fossil fuels like coal, oil, and natural gas are formed over millions of years from the remains of ancient plants and animals. We cannot recreate these energy sources over a short timeframe. Fossil fuels currently make up the majority of the world’s energy supply, providing around 80% of global energy. However, reserves are being depleted much faster than new ones are being formed. Experts estimate that at current rates of use, proven oil reserves will run out in about 50 years and natural gas in just over 50 years.

Nuclear power harnesses energy released from splitting uranium atoms in a process called nuclear fission. Uranium is a non-renewable resource and in finite supply. There are also concerns around safety, nuclear waste disposal, and ties to nuclear weapons that limit growth. Nuclear energy accounts for around 10% of global electricity generation.

Reliance on non-renewable energy sources presents issues around long-term sustainability. As fossil fuel and nuclear resources decline but demand rises with population growth, prices increase dramatically and countries compete for dwindling supplies. The environmental impacts of extracting and burning fossil fuels are also increasingly apparent through climate change and pollution. This heightens the need to transition more of the world’s energy supply to renewable sources that can meet demand indefinitely without supply constraints or environmental harm.

Comparisons

When comparing renewable and non-renewable energy sources, there are several key factors to consider including costs, efficiency, and environmental impact.

In terms of costs, renewable energy can have high upfront capital costs but very low operating costs. The opposite is true for non-renewable sources like coal and natural gas, which have lower upfront costs for power plants but higher ongoing fuel expenses. Overall, renewable energy is becoming increasingly cost-competitive with conventional sources.

Efficiency varies greatly between different energy technologies. Fossil fuel power plants are typically around 30-60% efficient at converting the chemical energy in fuel to usable electricity. Renewables range widely, with solar PV around 15-20% efficient and hydroelectric dams up to 90% efficient. However, efficiency ratios are not the only meaningful comparison.

Regarding environmental impact, renewable sources produce little to no greenhouse gas emissions or air pollution. Fossil fuels emit substantial CO2 and other pollutants when burned. The life cycle emissions of non-renewables are vastly higher. Renewables like solar and wind have minimal environmental impact in operation.

In summary, while no energy source is perfect, renewable technologies provide cleaner and more sustainable options for electricity generation compared to non-renewable fossil fuels.

Conclusion

In summary, there are many sources of renewable energy such as solar, wind, hydropower, geothermal, biomass and ocean energy. These renewable sources can provide clean and sustainable energy for the future. On the other hand, fossil fuels like coal, oil and natural gas are non-renewable sources of energy that will eventually run out. They also contribute heavily to climate change through greenhouse gas emissions.

Some key takeaways are:

Renewable energy comes from natural sources that are constantly replenished, while non-renewable energy comes from finite resources.

Fossil fuels are the main source of non-renewable energy today, but they lead to pollution and climate change risks.
Transitioning to renewable sources like solar, wind and hydropower helps ensure energy sustainability and protects the environment.
No single renewable energy source is a silver bullet – we need a mix of sources to meet energy demands.