What is Renewable Energy?

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    We’ve all heard the buzzwords “renewable energy,” and we know that it’s a good thing. We also know that it is one of the fastest-growing sectors. Its global market was valued at over $928 billion in 2017 and is projected at a $1500 billion value by 2025. But what does renewable energy mean, exactly?

    What is Renewable Energy?

    Renewable energy is an energy that comes from a source that does not become depleted when used. This allows for the continuous harnessing of power. There is a wide variety of sources in this category, and they vary considerably. But, just because a source of energy is renewable does not mean it is good for the environment.

    What is Non Renewable Energy?

    We are moving towards a world where electricity is produced beyond dependence on fossil fuels. Due to this, it is easy to mistake some sources to be renewable.

    In simple terms, renewable sources are not those found inside the earth, and which took millions of years to form. Also, many energy sources that are not ecologically sound are not considered renewable resources.

    Can Coal Be Clean?

    “Clean coal” is one of the popular terms today. The name is misleading, as it implies a clean form of production. While newer technology does produce coal with far less pollution than in the past, these power plants still emit pollutants. For every unit of energy generated, coal emits more carbon dioxide than any other source of fuel.

    Despite efforts to rebrand coal and improve processing technology, coal is still a fossil fuel at the end of the day. It requires millions of years to form and, therefore, cannot be replaced.

    Nuclear Energy

    Since the 1940s, nuclear power has been hailed as an alternative to the burning of fossil fuels for energy. Its cost is considerably low and also provides a stable source of energy.

    But, the risks associated with the resource are high. Radioactive waste is unavoidably produced in nuclear energy production, and it takes several thousand years to become non-threatening.

    Similarly, accidents happen and are sometimes inevitable. An example of this is the Fukushima Daiichi nuclear disaster, which was caused by an earthquake and tsunami.

    Nuclear energy

    The result was nuclear meltdowns, hydrogen explosions, and radioactive contamination at the site. The catastrophe is classified as a Level 7 International Nuclear Event.

    Nuclear power plants also depend upon uranium as a source of energy, which is estimated to last for only 30-60 more years with current demands. Therefore, nuclear energy is a nonrenewable power source since the raw material used is finite.

    Sources of Renewable Energy

    Wind Power

    Wind power is what it sounds like- energy generated by wind. Turbines capture the kinetic energy of the wind, which is then converted into electrical power. It is a sustainable source of energy that has a significantly less harmful effect on the environment than the burning of fossil fuels.

    Arrays of wind turbines installed on wind farms usually harness the energy. The wind farms can span hundreds of square miles.

    Therefore, though these farms tend to produce more clean power than many other sources, they do take up a lot of physical space. Because of this, they are mostly built in rural areas that are host to wildlife. Some claim that this practice leads to loss of habitat. The farms have also been criticized for interfering with radio, television, and radar reception nearby.

    Over 80 countries worldwide are supplying their electric grids using wind power. More nations are also in the process of installing wind farms. Due to this, global wind capacity is expanding each year rapidly. In 2018, it was at 591 GW, and the figure has increased significantly over time.

    Wind turbines produce a relatively consistent amount of energy per year, but the amount they produce in the short term varies. Wind power, therefore, is most frequently used in conjunction with other sources of power so that the power supply is dependable and sufficient.


    Hydropower is the power harnessed from fast-running water. This technology has been around since ancient history- remember the watermills you might have seen as a child? Water is denser than air, and can, therefore, generate plentiful amounts of energy. Hydropower costs very little in maintenance, but initial construction costs tend to be high.

    Hydropower is generated in a few different ways. Hydroelectric dams and reservoirs have historically been built to harness water for energy production. This is how approximately 63% of the world’s renewable energy is acquired, or 19% of total world energy. Smaller-scale hydro systems are usually found on small rivers.

    Hydropower is a plentiful source of renewable energy, but unfortunately, it comes with a cost to the environment. Dams and reservoirs harm ecosystems since they displace wildlife. The changed water flow and sometimes resulting droughts are also devastating to fish populations.

    Furthermore, dams and reservoirs unsettle communities. Studies show that they are responsible for the displacement of 40-80 million people worldwide. Most of those affected never regain livelihoods similar to those before the construction.

    Solar Energy

    Solar energy is the harnessing of radiant light and heat from the sun, which is converted into thermal or electrical energy. Photovoltaic (PV) devices are used to collect and generate electricity from the sun. Semiconductors release electrons that are freed by solar energy. They then pass through an electrical circuit to power a device or send the generated electricity to the grid.

    Thanks to the sun’s abundant rays, there is a massive amount of solar energy available, which makes it a desirable form of renewable energy. According to a 2000 study by the United Nations, solar energy’s annual potential output was found to be between 1,575 to 49,837 exajoules (EJ).

    The world’s total energy consumption was estimated at 559.8 EJ in 2012, meaning the sun’s renewable energy potential is several times larger than that figure. In 2017, solar energy generated 1.73% of global power, and it is only increasing in popularity.

    By 2050, solar energy is expected to become the largest source of electricity worldwide. Solar photovoltaics and concentrated energy are expected to contribute approximately 16% and 11%, respectively.

    Producing solar panels results in some pollution, but during operation, solar power systems give off no harmful emissions, making them an excellent alternative to the burning of fossil fuels, as well as other renewable sources of energy that aren’t as environmentally friendly.

    Read More: How To Install Solar Panels

    Geothermal Energy

    Geothermal energy refers to energy produced and stored within the earth. If you’ve been to a natural hot spring or geyser, then you have experienced geothermal energy escaping to the surface.

    The heat used for geothermal energy often comes from deep within the planet- down to the Earth’s core, about 4,000 miles below the surface. Temperatures at this depth can reach up to 9,000 degrees Fahrenheit.

    The heat is responsible for generating electricity that is used for various purposes, including heating and cooling.

    As heat is continuously produced inside the earth, geothermal is a renewable form of energy. However, there is a debate on whether it is a fully sustainable source. Why?

    Geothermal energy

    The three oldest sites where geothermal energy is collected have all experienced reduced output due to heat and water being extracted at a faster rate than it is replenished. Drawing from the earth in this manner also releases a mixture of gases and trace amounts of toxic elements.


    Biomass refers to organic matter that is used as a fuel to generate electricity. It can be sourced from wood, plant, or animal matter. The mass is then converted to methane gas or fuels such as biodiesel or ethanol, which are burned for energy. Alternatively, solid mass is directly burned to produce heat.

    The burning process tends to affect the environment. It results in the release of pollutants that include sulfurous oxides, nitrous oxides, and particulate matter into the atmosphere. Therefore, biomass is a contributor to air pollution. It means that although it is a renewable energy source, it is not a clean one.

    Tidal Energy

    Tidal energy is a renewable source that is caused by the rise and fall of ocean tides. The power is collected using three different systems, which are tidal streams, tidal lagoons, and barrages. Turbines placed within each of these systems are responsible for harnessing tidal power.

    Opposing forces cause the rise and fall of ocean tides. They are the gravitational force of the sun and moon and the rotation and gravity of our planet. The effects of the sun and moon pull the water from the ocean up while forces of the earth pull it down. The result is the formation of high and low tides. The natural pulling of water up and down will always occur, thereby providing an inexhaustible source of energy.

    Tidal power is not as popular as other renewable energy sources such as solar. Currently, there are only a few tidal plants across the world, most of which are in Europe and Asia. Out of the tidal projects in existence, the largest one is the Sihwa Lake Tidal Power Station. It is located in South Korea and has a generating capacity of 254 MW.

    Wave Energy

    Wave Energy is a renewable source of energy that is caused by the vertical motion of waves on the surface of the ocean. The movement is because of the difference in air and water surface temperatures caused by the heat from the sun.

    The movement of ocean waves creates kinetic energy, which is then harnessed and used to generate electricity.

    Wave power is captured using a wide range of techniques that include submerged oscillating water columns, onshore oscillating water columns, and tapered channel systems. The energy from the waves is converted into electricity using wave energy converters (WECs). The converters differ in design, which also depends on the nature of the tidal system in place.

    The harnessing of wave energy is still not a widespread practice across the world. There are only a few tidal plants found, which can be found in nations such as the United States, Portugal, and Australia.

    Renewable Energy Trends Around the World


    Most of the nation’s energy in Germany is sourced from coal and other fossil fuels, but that does appear to be changing. All existing coal plants are expected to close by 2038, in favor of renewable energy sources.

    The nation currently produces the third-highest amount of wind power worldwide, with a 55.6 GW of installed capacity.

    Residents have mostly been in favor of wind power. But, as plans to further expand this sector grow, more are becoming concerned with the destruction of forests and damage to wildlife.


    China is the world’s largest producer and consumer of energy. Hydropower makes up approximately 20% of the nation’s total energy production, making it the largest source of renewable energy.

    China’s potential hydropower capacity is estimated at 600 gigawatts (GW), with 319 GW installed as of 2019 far more than any other country in the world. The size grants the nation freedom from energy dependence, but it is not without environmental consequences.

    The areas surrounding dam reservoirs have experienced flooding, erosion, and habitat destruction. Additionally, an estimated 15 million people have been relocated over the past 70 years due to flooding at large reservoir sites.

    United States

    In the United States, renewable energy currently makes up 11% of the country’s primary energy consumption, and 17% of domestically produced electricity. The figures are expected to grow significantly in the coming years. Forty-four percent of renewable energy in the U.S. currently comes from hydropower, with wind power just behind at 37%.

    Solar energy is currently the third-highest contributor to the U.S.’s renewable energy. It also has excellent potential to expand significantly in the future given that many states have zero-carbon initiatives, with goals of achieving fully renewable energy.

    Solar is a very desirable source of renewable power, thanks to its clean energy production and the bountiful sunshine in much of the U.S. Solar is frequently thought of as expensive, as the manufacturing of solar panels and the process of installation are costly. However, this is changing. The cost of panels has significantly decreased in recent years.

    Incentives are also available at the federal and local levels, which significantly reduce initial costs. Some of these are only available for a limited time. For example, the generous federal solar investment tax credit that allows U.S. residents to deduct 30% of solar installation costs from their federal taxes. The percentage is reducing each year and will be fully phased out in 2022.

    Renewable Energy Policies and Initiatives

    Most U.S. states promote renewable energy by offering incentives to their residents. Others have laws that require a certain percentage of energy to come from renewable sources.

    All public utility companies are now required to use net metering as part of their power supply, by mandate of The Energy Policy Act of 2005. A vital incentive that came from this act is the solar investment tax credit (ITC). It has to date saved customers an average of almost $9000 towards solar energy systems.

    From 2006 to 2014, federal income tax credits helped U.S. households fund clean energy investments towards their homes worth more than $18 billion total.

    Additionally, The American Recovery and Reinvestment Act of 2009 offered over $27 billion towards energy efficiency investment and renewable energy research. It was the most significant federal investment towards renewable energy in U.S. history, intending to strengthen clean energy initiatives.

    Renewable Portfolio Standard (RPS) refers to the required increase in the production of energy from a renewable source. Out of 50 states, 38 currently have RPS (plus DC), with a variety of standards and goals. By 2032, DC targets to generate 100% of electricity from renewable sources. California, a long-time leader in renewable energy, has a goal of 100% by 2045.


    • John Gathuita

      John is an electrical and solar technician, writer, and blogger who specializes in renewable energy, sustainability, and technology. He seeks to inspire more people to adopt solar energy and to work towards a sustainable future.