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Types Of Renewable Energy

Intro and Context

Homo Sapiens have rapidly advanced by using creative thinking and adapting to their environment to their advantage. This creative thinking has lead us to discover that many natural fuels can be extracted and then converted into an energy source, which we now rely on in so many facets in our everyday lives. The main fossil fuels, coal, oil and natural gas, have been mined and exploited since the early 18th century in the western world. During the 20th century, the industrial revolution gave us technological breakthroughs such as the steam engine that resulted in coal being the preferred fuel, as it enabled large scale growth for industrialization. (The history of oil 2018). However, we are living on a finite planet and the use of fossil fuels is an unsustainable energy source in the long run. Not only because there are limited resources to mine, also science taught us during the 20th century that they have a disastrous effect on the Earth’s atmosphere, causing anthropogenic global warming. In order to continue our high standard of living, Homo Sapiens now need to adapt to the rapidly changing environment and transition from the harmful use of fossil fuels, to the more sustainable alternative: renewable energy. There are three common types of renewable energy, including solar, wind and hydropower, and two alternative, less common types: geothermal and biomass. (Renewable Energy Introduction 2019). This essay will discuss each renewable energy method and the sustainable implications they help address on a global scale, in relation to environmental impacts, economic factors, advantages, disadvantages and unsuitable climate conditions for each renewable energy type.

Solar Power

Solar energy is derived from natural sunlight and heat and then converted into electricity. (Solar Energy, n.d.). There are currently two different types of solar power, solar photovoltaic and solar thermal. Solar photovoltaic (PV) technology uses photovoltaic cells to convert sunlight directly into electricity, and are usually assembled as panels. Photovoltaic cells are the most common electricity generators for rooftops, buildings, vehicles and large scale facilities allowing for economies of scale. The cells operate by using “fields of sun-tracking mirrors called heliostats to concentrate sunlight onto highly efficient PV cells located inside a receiver at the top of a mast of tower” (Solar Energy 2019). PV systems transfer the energy into a grid inverter that converts the DC current into AC current, that can then be used to power home appliances. (Solar Energy Education 2018). Figure 1 below shows the predicted amount of solar PV generated and cumulated by global region. (Solar Energy 2018). The main disadvantage of solar PV systems is that power is only generated from sunlight, therefore, limited to hours when the sun is shining.

The solar thermal technique is used to create thermal energy for appliances like hot water systems, space heating and refrigeration cycles, as well as producing steam for steam turbine generated electricity. (Solar Energy 2019). A field of mirrors are used to harvest the suns heat by “reflecting sunlight onto a thermal receiver, which transfers the heat to a thermal energy storage system” (Solar Energy 2019).  Figure 2 below shows that solar thermal heat consumption is expected to grow by over one-third, mostly driven by installations in the buildings sector. (Solar Energy 2018).

The main advantage of solar power is that it is entirely sustainable once installed, as it does not emit any pollution or greenhouse gasses when producing electricity, unlike the fossil fuels. This renewable method is a free source of energy from the sun, making it completely inexhaustible. (Solar Energy Education 2018).  Both technologies can be stored and released as required. Solar power is already used in many countries since its discovery in 1839, and the solar cell in 1941. (Solar Panel History 2018). Australia currently has the highest average solar radiation per square metre, with over 2 million households having solar systems on their rooftops. (Solar Energy, 2019). On a global scale, solar PV capacity reached about 2% of the global power output, with 60% generated in large utility-scale projects. (Solar Energy 2018) .

There are some major factors that need to be considered with the installation of solar power, which could lead to future disadvantages if the climate and economic conditions are not ideal. Firstly, solar technology has high initial start-up costs. The cost of an average size system for a standard household connected to an energy grid, is between $15,000 to $29,000. If a battery storage system is used to supplement energy instead of taking electricity from the local grid, costs can increase up to $47,000. (The Disadvantages of Solar Energy 2016). Many people from lower social economic areas and poorer countries will not easily be able to afford the installation costs, or the ongoing costs of monitoring and maintenance. Solar power is known to be somewhat inefficient, with the average household only converting 14-22% of their available energy into power. (The Disadvantages of Solar Energy 2016).

The location, latitude and sunlight availability play a significant role in the solar technology’s sunlight to electricity conversion rate. Countries like Canada and Russia are at a disadvantage as “the efficacy of solar power drops dramatically the farther you get from the equator”. (The Disadvantages of Solar Energy 2016). However, equator location can also be irrelevant for countries with a high average of clouds and rain, such as Hawaii, as they don’t receive enough natural sunlight. (The Disadvantages of Solar Energy 2016).

There are several negative environmental impacts associated with solar power, including land use and habitat loss, as economies of scale facilities can be enormous. Extremely hazardous materials are used in the manufacturing process, such as: lead, cadmium, gallium arsenide, several acids and acetone. (The Disadvantages of Solar Energy 2016). First world countries have regulations in place to ensure these toxic substances are properly recycled, however, other countries such as China, Taiwan and the Philippines, that are responsible for over half of the world’s solar PV manufacturing, are irresponsibly disposing of these materials, polluting the air, soil and water. (The Disadvantages of Solar Energy 2016).

Wind Power

Wind power has been adopted for thousands of years, with the first known record dated back in 5000 BC, where wind energy was used to propel Egyptian boats along the Nile River. (The History of Wind Power 2019). During the 19th century, globalization spread wind technology around the world, seeing countries using windpumps and windmills to generate electricity for agriculture, food production and water management. During the 1970s an oil shortage in the USA facilitated a surge in alternative energy sources. In most western and European countries, it wasn’t until the early 2000s that Government incentives and subsidies were granted for renewable energy infrastructure, after growing concerns for the environment. (The History of Wind Power 2019). China now holds the title for the world’s largest wind electricity generation capacity of 221GW, followed by the USA with 96.4GW. (Unwin 2019).

Wind technology creates energy by harnessing naturally occurring air flow (kinetic energy) in the atmosphere. Wind turns the turbine blades, which is converted into mechanical power, and the mechanical power “is used to spin the shaft connected to a generator that makes electricity” (O’Donnel 2018). The technology is considered renewable because it has minimal environmental impacts when generating power, and the power source is infinite as long as there is wind. Ecowatch Organisation states the wind industry has grown around 26% per year over the past 18 years, and predicts that by 2030 19% of the world’s electricity will be supplied by wind power, which would reduce carbon dioxide by over 3 billion tonnes (Spear, 2014).

There are several advantages of using wind power as a primary energy source. Wind technology is easy to access and implement due to its reliable nature, proven success and scalability capability. Windmills and other wind infrastructure are fast to build and implement, making it more attractive than the years of debate and construction associated with coal and nuclear power plants. (Spear, 2014). Studies have shown that “a wind turbine ‘pays back’ all of the carbon dioxide emissions from its manufacturing, installation, servicing and decommissioning in its first three to nine months of operation” (Spear, 2014). Therefore, the wind power that results from the other 20 years in its projected lifetime is considered 100% sustainable.

Wind power is considered one of the most cost-effective renewable energy methods, with the average electricity conversion rate being 45%. (Sendy 2018). Wind power’s advantage over solar power, is that the wind turbines can generate electricity 24 hours a day as they aren’t dependent on sunlight. They are more effective because one single wind turbine can generate the same amount of electricity as thousands of solar panels. (Sendy 2018). However, the initial start-up expense of manufacturing and installing the turbine large enough to power one standard house, has an average cost of $15,000 – $20,000. Therefore, it wouldn’t be easily affordable to those in low-income households. (Sendy 2018).

There are disadvantages that need to be considered when considering how appropriate wind technology is for a certain region. The wind turbines take up considerable space and require sky high positioning far away from trees and other buildings. They are well suited for agriculture and farming businesses rather than suburbia or cities due to their requirement of large, unobstructed open spaces. They can also be noisy and require ongoing maintenance for their mechanical parts, which can be costly. (Sendy 2018). One extremely windy country – Scotland, is currently building the world’s largest floating wind farm. Wind power currently generates 98% of its electricity needs. (Climate Council 2019). Current climatic wind conditions need to be taken into consideration if this renewable energy is to be effective those regions.


Hydroelectric power (Hydropower) generates electricity by the energy of moving water. Similar to a wind turbine, “the pressure of the flowing water on turbine blades rotates a shaft and drives an electrical generator, converting the motion into electrical energy” (Hydropower – Australian Renewable Energy Agency 2019). Hydropower technology is the most advanced type of renewable energy. According to Renewables 2018 Global Status Report, hydropower is currently the most common renewable energy source in the world, as shown in the figure below.  (Renewables Global Status Report 2018).

The advantages and disadvantages associated with hydropower are similar to solar and wind power. Firstly, the construction of the power plants impacts the land and natural habitats in the waterway. For example, they can obstruct fish migration and affect the populations of native plants and species. (Hydropower And The Environment 2019) The facilities only need to use fossil fuels in the construction; therefore, they will only emit pollution until they are fully operating. Once implemented, hydro technology is highly reliable and flexible, as it is simple to adjust the water flow and electricity output. (Hydroelectric Energy Pros And Cons 2019) Hydropower also solely relies upon the presence of water, therefore, the technology is only recommended for countries with an abundance of waterways, such as Canada and Alaska. Due to the technology’s expensive and complex installation, it would be impractical for residential households to privately build a hydropower facility. This renewable technology is mostly for commercial and large scale Government projects.

Geothermal Power

Geothermal power is natural heat derived from below the Earth’s surface from resources such as hot spring water, steam or molten rock. This is done by installing a ‘heat exchanger’ pipe system 3-5 metres below the ground surface filled with water or anti-freeze solution, which is connected to a geothermal heat pump to heat or cool buildings. (Geothermal Energy 2019) Direct-use applications of geothermal power “include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk” (Geothermal Energy 2019). Geothermal technology is still quite underdeveloped, as there is currently no method to allow recovery of heat directly from molten rock, which is the most powerful resource of geothermal energy. Plus, the heat pumps require a power source to function. (Geothermal Energy 2019).

Although geothermal electricity is considered environmentally friendly, a negative impact from the extraction is that greenhouse gas stored below the Earth’s surface can potentially be released into the atmosphere. (Meyers 2019). Geothermal technology can also be dangerous to install; Switzerland triggered an earthquake with a 3.4 magnitude from their construction of a geothermal power plant. (Meyers 2019). This renewable energy is completely location specific, as good geothermal reservoirs are difficult to come by, and prime sites are often far from highly populated areas. Iceland and the Philippines are two countries that use geothermal electricity for nearly one-third of their electricity demands.

Biomass Power

Biomass power (biopower) is the oldest form of energy generation, and has been used since before homo sapiens dominated the other homo species, in the form of heat generated from wood fires. Over time this method developed and became classified controversially as ‘renewable energy’, due to the fact that organic, plant, manure and municipal waste residues will always exist. (What Is Biomass 2019). However, there are still emissions from burning biomass. Supposedly, there are less greenhouse gas emissions than fossil fuels, however a toxic ash is left behind which then needs to be effectively disposed of. The US Department of Energy Information mentions that “Ash from waste-to-energy plants can contain high concentrations of various metals that were present in the original waste. Textile dyes, printing inks, and ceramics, for example, may contain lead and cadmium” (Biomass And The Environment 2019) Due to the type of waste burned in biopower plants, most first world countries, such as the USA, have air pollution control devices such as fabric filters, scrubbers, and electrostatic precipitators to help capture air pollutants. (Biomass And The Environment 2019). Other countries from poorer regions may find it difficult to regulate emission controls. On the basis of a poor sustainability standard, Biopower is not recommended as an alternative for fossil fuels.


Renewable energy is essential for meeting the global future energy needs while maintaining a sustainability standard, as fossil fuels are finite and damaging to our planet. Currently 73.5% of the world’s energy is generated by non-renewable sources, as seen in figure 4 below. The four current renewable technologies: solar power, wind power, geothermal power and hydropower are all supreme alternatives to fossil fuel generated power, due to their unlimited resource input, and zero emissions while functioning. Each technology has several disadvantages and initial negative environmental impacts while they are being manufactured and implemented, however, their advantages certainly outweigh their disadvantages. The climate, location and cost are important when considering which technology is the most efficient method in each circumstance. As those variables can make the technologies economically unfit and not effective in certain countries and regions. Biopower is not a recommended energy option as it is the least sustainable technology due to the greenhouse gas emissions, air pollution and toxic ash it generates. Homo sapiens would do well to continuously adapt to their changing environment and further their renewable energy technology through creative thinking.


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  1. Unwin, Jack. 2019. “The top 10 countries in the world by wind energy capacity. Power Technology.
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