AL has a Bachelor of Science in Natural Resources and Environmental Studies.
Clean energy is energy extracted from renewable resources with zero environmentally hazardous byproduct emissions. Despite the abundance of renewable resources in the form of water, wind, solar, geothermal, and biomass, dependence on traditional non-renewable energy sources such as coal and oil has not reduced to the levels that can be sustained by the environment.
Renewable resources have the ability to naturally replenish themselves when their stock levels have been reduced or depleted, on the other hand, non-renewable resources are unable to replenish their stock levels within a short period of usage. Non-renewable energy sources are predominantly fossil fuels in the form of hydrocarbons formed from natural processes, these processes occur over a million years' time frame. This energy phenomenon has been known for centuries. It is, for this reason, a lot of investments have been channeled towards reducing the energy dependence and usage of non-renewable energy sources and to increase the production of energy from renewable sources such as wind and solar.
In addition to their limited nature, non-renewable resources are ranked as one of the highest sources of pollution and greenhouse gas contributors. According to the Environmental Protection Agency, the largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation.
Despite the well-established drawbacks of using fossil fuels, these non-renewable energy sources account for a majority share of energy sources in the world today. In 2017, burning fossil fuels generated 64.8% of the world's electricity. (Statista, 2020).
With the rapid progress that has been made in the field of science and technology, energy generation innovations of wind and solar should have already relegated the burning of fossil fuels back to the past, where they belong. This, however, has not happened, the future of energy is still uncertain, non-renewable energy sources are still the dominant energy source.
Cleaner and Renewable Sources of Energy
Cleaner and renewable sources of energy may seem like the future type of energy sources, but in truth, the use of these energy sources predates the use of fossil fuels. Wood, biomass and a renewable resource was the first recorded source of energy to be kept and used by early humans.
In ancient civilizations, the sun was also considered a source of energy. The Egyptians were the first people recorded to have used the energy from the sun to heat their homes. Their houses were designed in a way that allows heat from the sun to be stored during the day, and released at night when it is cold. The Native Americans and Romans also used similar design structures for their houses and were able to harness the energy from the sun.
According to an EIA history report, wind energy was used to propel boats along the Nile River as early as 5,000 BC. By 200 BC. Simple wind-powered water pumps were also used in China, and windmills with woven-reed blades were grinding grain in Persia and the Middle East.
The first innovations in using water for power were conceived in China during the Han Dynasty between 202 BC and 9 AD. Trip hammers powered by a vertical-set water wheel were used to pound and hull grain, break ore, and in early paper-making, (IHA report, 2017).
Fossil fuels like coal were also used as early as 1000 B.C. The 1700's Industrial Revolution was, however, the earliest recorded global scale application of coal as an energy source. Natural gas and Oil are also relatively new to the energy sector, their global scale application didn't start until the late 1800s and early 1900s.
Despite their late arrival, fossil fuels still managed to overtake renewable energy sources and become the primary energy source. The non-renewable nature of fossil fuels only became a concern in the mid-1900s when scientists started raising concerns about the prospects of running out of these fuels. The anxiety of running out of fossil fuels led to conversations about reverting back to renewable forms of energy. This period also saw a rise in solar, wind and hydropower energy structures and innovations, the first full-scale nuclear power plant was also commissioned during this time. The 1900s also saw the development of the first geothermal energy power plants, first in Europe, then in North America.
The first alarm bells about running out of fossil fuels were raised over 70 years ago, during that same period we saw a resurgence of renewable forms of energy sources. 70 years later, non-renewable fossil fuels still account for more than half of the energy sector. Though on a gradual upward curve, renewable forms of energy are still lacking behind fossil fuels and for a foreseeable future, that trend is set to continue. Some important scientific, socio-economic, geographical and environmental factors have hindered the growth of the renewable energy sector. Each renewable energy resource is affected differently by these factors.
The sun is the primary and ultimate source of energy for the planet Earth, without the energy from the sun, life on earth is practically impossible. In fact, fossil fuel energy is also derived from the sun.
According to the University of Tennessee, Institute of Agriculture, the Sun releases an estimated 384.6 yotta watts (3.846×1026 watts) of energy in the form of light and other forms of radiation. The amount of energy from the sun striking the Earth's surface in Texas alone when converted to electricity would be roughly equivalent to 300 times the total power output for all power plants in the world.
The huge bulk of the energy that can be derived from the sun is the reason conversations on environmentally sustainable energy always revolve around solar energy. In addition to being a renewable resource, solar energy has no documented emissions.
Solar power has been used to produce electricity in areas not connected to the energy grid. Solar-powered devices have most recently been on the rise, including vehicles, computers, phones, traffic lights, cookers, pumps, TVs, and many others. The wide distribution and applications for solar energy makes it the most likely clean and renewable energy to replace fossil fuels, however, solar energy is still lacking behind fossil fuels in terms of distribution and global applications.
Solar energy has a well documented financial cost, the initial cost of installing a solar system is fairly high. In addition to installation, the prices of solar panels, batteries, wires, inverters are also relatively high.
Solar energy is also extremely weather and time-dependent. When available, during the day, in the presence of clear sunlight, solar energy can be used right away or stored in batteries. During the night and in cloudy or rainy weather the efficiency of the solar system reduces, and a heavy reliance is placed on the battery to provide power. A large number of batteries would be needed to power several basic household appliances. The batteries require maintenance and replacement after a period of usage, adding an extra cost, also the amount of energy generated by solar panels and batteries per space occupied is relatively low.
A stove with one burner that needs 220 volts to operate requires 400 cells in series. Currently, available panels usually have either 60 or 72 cells in series, therefore, 6 panels that have 72 cell sizes will each need to supply about 150 watts in peak power. Depending on the weather and time of the day, the energy supplied by the panels might reduce, so more panels may be needed in those situations.
The low energy level production of solar equipment, coupled with the expensive cost of setting them up, maintaining and replacing them has contributed to the low global appeal of solar as a primary energy source.
2019 International Energy Agency report shows solar energy accounting for a mere 2.1% of global electricity production.
Wind energy is closely related to solar energy, it is sometimes considered a form of solar energy. It refers to the process of creating electricity using the wind or air flows that occur naturally in the earth's atmosphere. Wind turbines convert the kinetic energy from the wind into mechanical energy, this energy is then converted into electricity by a generator.
Harnessing wind energy dates back to as early as 5000 BC, but it is not until the 11th century that wind energy was used across the whole globe. Different variations of wind turbines still exist today in different parts of the world. Wind energy was predominantly used to pump water and food production in windmills. In the 1970s however, the fuel shortages caused a spike in wind energy usage.
According to an EIA report, wind energy usage for electricity in the United States accounted for less than 1% in 1990, compared to 7% in 2018. Globally wind energy is also on the rise, with China having the largest wind energy production capacity.
According to World Wind Energy AssociationIn data in 2017, Denmark set a new world record with 43% of its power coming from wind. An increasing number of countries have reached a double-digit wind power share, including Germany, Ireland, Portugal, Spain, Sweden or Uruguay. Other regions of the world, however, still record single-digit wind power share.
International Energy Agency 2019 report showed wind energy accounting for 4.6% of global electricity generation.
The lack of global appeal for wind power is owed to its high initial cost of installation, compared to other energy sources, a wind farm might not be cost-competitive.
In addition to its high cost of installation, wind farm sites are usually located in remote open areas, power lines are usually required to transfer the generated electricity, thereby increasing the cost. Wind farms and powerlines connected usually cover a large surface area that could have been used for other competing land uses.
Even though wind energy is considered a clean energy source, it is not without fault. Wind farms are known to produce noise from the spinning turbines. Environmental concerns have also been raised regarding the death of wildlife from the spinning turbines.
Despite the challenges, wind energy is on the rise, in 10 years, wind energy is projected to supply 19% of the world's electricity. Unless most of the core issues of wind energy are addressed, the global appeal of wind energy will remain low.
Hydropower stations convert the energy captured from moving water to electricity. Turbines convert the kinetic energy of falling water into mechanical energy. Then a generator converts the mechanical energy from the turbine into electrical energy.
According to an EIA report, hydropower was one of the first sources of energy used for electricity generation and is the largest single renewable energy source for electricity generation in the United States. In 2018, hydroelectricity accounted for about 7% of total U.S. utility-scale electricity generation and 41% of total utility-scale electricity generation from renewable energy sources.
Globally, Hydropower is the world’s largest source of renewable electricity generation. The IEA report of 2019 shows hydropower accounting for 15.9% of global electricity production.
Hydropower has its advantages, it is an abundant renewable energy source that uses the energy of running water, without reducing its quantity, to produce electricity.
It also has its disadvantages, it can affect land use and natural habitats in the dam area. Reservoirs constructed are very expensive and may cover people’s homes, important natural areas, agricultural land, and archaeological sites. Hydropower is also extremely hydrology cycle dependent. It is highly dependent on available water bodies and precipitation levels, which means not all regions of the world can accommodate hydropower plants. Despite hydropower generation being on the rise, these drawbacks have slowed down its growth globally.
Geothermal energy is one of the oldest types of energy used by humans. Archaeological evidence shows the earliest direct use of geothermal energy occurred at least 10,000 years ago. Associated with cultural, medicinal and spiritual significance, geothermal energy usage was globally renowned, stretching from Native Americans in North America, the Greeks and Romans in Europe, to ancient civilizations in Asia.
Geothermal energy is basically heat derived within the sub-surface of the earth. Water and/or steam carry the geothermal energy to the Earth's surface. The earliest recorded modern industrial application of geothermal energy was in 1904. Italian scientist Piero Ginori Conti invented the first geothermal electric power plant in which steam was used to generate the power.
Over the years, the usage of geothermal energy has gradually increased, but its global appeal still remains very low. Geothermal Fact Sheet 2019, showed geothermal energy accounting for 0.4% net electricity generation in the United States, which also happens to be the largest consumer and producer of geothermal power.
Geothermal energy is a clean and renewable source of energy with zero significant emissions. It is a constant source of energy that is not dependent on the wind or the sun, thereby distinguishing it from other renewable sources like solar and wind power. Regardless, geothermal energy underperforms globally when compared to wind and solar energy.
Analyzing Geothermal Energy 2018 report, attributed the underperformance of the geothermal industry to the fact that there are very limited geothermal power resources and these are further limited only to specific areas across the world, particularly the tectonically active regions. These limitations have hindered the global growth of the geothermal power industry.
Biomass is any organic matter that can be used as an energy source. It is considered a renewable energy source because its inherent energy comes from the sun, and because it can regrow in a relatively short period of time. Plants take in carbon dioxide from the atmosphere, then convert it to biomass, when they die, the carbon dioxide returns to the atmosphere and the cycle continues.
Biomass technologies and plants developed and used today are relatively new compared to other renewable technologies. Biomass energy usage is, however, not a new energy discovery.
Biomass has been used as a source of heat energy since the first discovery of fire by man. Globally, people still burn wood as their primary source of heat during the winter, for cooking and other activities.
Biofuels produced from biomass have also been around for a long time, but cheap and available gasoline and diesel have long hindered the growth of the biofuel industry. Spikes in global oil prices and fossil fuel's negative environmental effects has led to a rise in alternative renewable and cleaner energy sources like biomass.
Globally, the biomass energy industry is growing, IEA 2019 report showed Biomass accounting for 2.5% of global electricity produced, a figure higher than solar energy's global electricity production. In fact, Biomass accounts for 35% of primary energy consumption in developing countries, through firewood.
Though biomass energy is renewable, it has some negative environmental implications. Biomass energy production requires the use of other natural resources like water, plants, and available land. Using up these resources creates other environmental concerns. Biomass energy fuels are also not free from pollution, land degradation, and deforestation.
Biomass is a clean and renewable energy source, but the highlighted challenges have caused the growth of the biomass industry to be relatively slow. The growing interest in environmental conservation also means the future growth of the biomass industry will be highly regulated and measured.
A fuel cell is an electrochemical cell that converts the chemical energy of a fuel such as a hydrogen and an oxidizing agent into electricity. Unlike other common combustion technologies that burn fuel to produce energy, fuel cells undergo a chemical process that converts fuel-rich energy into electricity. A fuel cell does not need to be charged, a steady supply of fuel is all that is required for the cell to produce energy.
These fuel cells are considered renewable energy sources because of the abundance of naturally occurring gases such as hydrogen. They are also considered clean energy sources because the only byproducts of their combustion are electricity, heat and water.
Some common Fuel cells include;
- Alkaline or Hydrogen Fuel Cells (AFC), primarily used in controlled aerospace and underwater applications.
- Molten Carbonate Fuel Cells (MCFC), used in stationary applications, providing high-quality primary and back-up power to utilities and businesses.
- Solid Oxide Fuel Cells (SOFC), used in power generators for homes and sometimes large institutions,
- Direct Methanol Fuel Cells (DMFC), uses range from small electronics, such as battery chargers and laptops, to larger applications like stationary power for telecommunications backup.
- Phosphoric Acid Fuel Cells (PAFC), used in large institutions such as hospitals, schools and manufacturing, and processing centers.
- Proton Exchange Membrane Fuel Cells (PEMFC), typically used in cars, telecommunication and data centers.
The cost and durability of fuel cells have however hindered their global and commercial appeal. They are very expensive compared to other conventional energy technologies and their durability limits the number of applications that can accommodate fuel cells. In addition, some of the fuels used in the cells are known to produce greenhouse gases, though in lower quantities compared to fossil fuels.
It is possible that in the future hydrogen-powered fuel cells could replace the petroleum fuels that are used in most vehicles today. Many vehicle manufacturers are actively researching and developing transportation fuel cell technologies.
As of 2020, fuel cell produced energy accounts for less than 1% of global energy production.
Nuclear energy is considered a clean energy source, however, classifying it as a renewable energy source is still debatable. Although nuclear energy itself is a renewable energy source, the material used in nuclear power plants uranium U-235 is not renewable.
Nuclear power plants produce electricity by nuclear fission or splitting of atoms, this process produces heat, and this heat is used to heat water and make steam. The steam powers turbines which turn generators, then generators produce electricity. Nuclear power generation does not pollute the air or emit greenhouse gases.
According to GEH Nuclear Energy, a single uranium pellet, slightly larger than a pencil eraser, contains the same energy as a ton of coal, 3 barrels of oil, or 17,000 cubic feet of natural gas. Each uranium fuel pellet provides up to five years of heat for power generation. And because uranium is one of the world’s most abundant metals, it can provide fuel for the world’s commercial nuclear plants for generations to come.
Currently, nuclear energy supplies 12 percent of the world's electricity and approximately 20 percent of the energy in the United States. As of 2018, a total of 30 countries worldwide are operating 450 nuclear reactors for electricity generation.
The global appeal of nuclear energy is, however, highly fragmented. The amount of nuclear energy produced from a single gram of uranium U-235 is enough to cause thousands of human casualties. It is for this reason, nuclear energy is usually used to produce weapons of mass destruction. The destruction of Hiroshima and Nagasaki during the second world war is a testament to the destructive nature of nuclear energy.
The production of nuclear energy today is highly regulated. Even though nuclear energy accounts for 12% of global electricity generation, nuclear plants are located in 30 out of 195 countries. Nuclear technology is also extremely sensitive and expensive, developing such technology is highly scrutinized by the International Atomic Energy Agency (IAEA).
Nuclear energy production is also extremely hazardous. The IAEA has developed a large number of tools and methodologies aimed at assisting regulatory bodies of nuclear installations. Consequences of a nuclear disaster are usually considered a global issue. The effects of nuclear radiation from nuclear power plants are usually felt by the environment for many years. Chernobyl and the Fukushima nuclear disasters have contributed far-reaching and long-lasting environmental implications that will continue to be felt for many years.
It is for these reasons nuclear energy will continue to grow at a low and highly regulated and managed pace.
Future Prospects of Clean Energy
Clean energy installations continue to grow. The increase is attributed to a considerable drop in the cost of producing clean energy which has occurred in the last couple of years. Even though initial costs of installations are still relatively high, most countries have shown a willingness to invest in renewable energy sources which have cheaper and long term benefits. The applications and uses of renewable energy have widened and are no longer confined to electricity production, this has provided new solutions for mobility and energy security worldwide.
The growth of clean energy is however not growing at a pace that can reverse or mitigate the adverse environmental concerns experienced today. This is attributed to a lesser global appeal and reach of clean energy compared to fossil fuels. As of 2017, Fossil fuels accounted for 95% of the energy used in the global transport sector and 81% of global energy consumed. Most developed countries can afford to slowly transition their energy consumption from fossil fuels to renewable energy sources and bridge that gap. Approximately 15% of the countries today are considered developed, this means 85% of countries in the world are still developing their economies. To transit their energy consumption from non-renewable to renewable energy sources is not only an expensive venture, but it also slows down their development process. A lot of economies are also built on fossil fuels exportation, switching to renewable energy will adversely affect their economies.
The cost of clean energy can be highlighted as a major source of concern with regard to its global appeal. If the cost of renewable energy sources continues to go down, the growth rate of the clean energy sector will also continue to rise. Hopefully, we might reach a point when cleaner and renewable energy sources are the dominant energy sources in the world.
- Tasneem Abbasi et al. Critical Reviews in Environmental Science and Technology Volume 42, 2012 - Issue 2 "Is the Use of Renewable Energy Sources an Answer to the Problems of Global Warming and Pollution?"
- Stober I., Bucher K. (2013) History of Geothermal Energy Use. In: Geothermal Energy. Springer, Berlin, Heidelberg.
- The University of Tennessee Institute of Agriculture, The Sun's Energy,
Knoxville, TN 37996
- Hydropower Status Report 2019
- U.S. Department of Energy (DOE), National Renewable Energy Laboratory (NREL) (2019) “Geothermal Energy Basics"
- Fuel Cell Market- Growth, Trends, and Forcast (2020 - 2025).
- 'Nuclear Installations' International Atomic Energy Agency (IAEA), 2020,
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 AL
AL (author) from South Equator, East Pacific on February 22, 2020:
Indeed, I hope we attain that goal sooner rather than later. Clean energy is a necessity.
Pamela Oglesby from Sunny Florida on February 22, 2020:
This is an excellent article that has a wealth of information that is certainly well-documented. Energy independence is a worth goal for sure.
AL (author) from South Equator, East Pacific on February 21, 2020:
Exhaustive indeed, Thanks Umesh, the message was too important to easily summarize. I appreciate you taking the time to go through.
Umesh Chandra Bhatt from Kharghar, Navi Mumbai, India on February 21, 2020:
Very exhaustive and informative article. Well presented.