The 21st century has witnessed the rise of awareness of global ecological problems. Organizations such as Greenpeace advocate for conservation of nature and non-damaging ecological behavior. For sustaining change on a global scale, people’s wish cannot be enough. Technological solutions have to be established in order to prevent adverse effects of progress on global natural balance. Air and water pollution have become a significant problem due to the heavy use of coal and oil for heating buildings and powering mechanisms. Above that, the resources of oil are limited, which enables people to seek other solutions. Presently, the percentage of renewable energy use globally does not exceed 13.8% (IEA, 2017). The scope of the study is limited to renewable energy solutions in the field of generating electricity and heating. As the main methodology, a systematic review was chosen. The relevance of this study is dictated by the high dependence of the world economy on fossil fuels, which negatively affects health and wellbeing of people and harms the environment. The present research aims to explore the extent of the contribution of different renewable energy forms to the global energy profile in the present and future.
To discover and compare the contribution of various renewable sources of energy, the research used academic literature on specific topics such as solar, waste, wind, and water energy. In total, 12 sources were picked for analysis, 3 for each energy source. Google Scholar was used as the primary source engine, where articles were found using the following search terms: “solar energy perspectives,” “waste energy perspectives,” “bioenergy,” “wind energy effectiveness,” water energy perspectives,” “renewable sources of energy.” In each case, the search engine produced 30,000 to 100,000 results in more than ten pages. Sources were then handpicked from the results according to the relevance of the title to the current study.
The present contribution of solar energy is rather small judging from the share it has in the overall global energy profile. According to REN21 (2016), solar power occupies approximately 1.4% of all energy market. Despite being drawn from the practically unlimited source, solar energy has so little use due to the fact that the establishment of proper infrastructure could be costly (Hernandez et al., 2014). Nonetheless, solar energy practically generates zero CO2, which is why it is considered one of the ‘green’ energy sources (Sharma, Tiwari, & Sood, 2012). Reducing the harmful effects to the planet is a task that solar power does effectively. It is often said that each kilowatt of power generated through solar panels saves half a kilogram of CO2 emissions (IEA, 2017). However, it may be wrong due to the fact it is not guaranteed that when a solar module is installed somewhere in the world in another place, a coal furnace stops working.
Global energy demand is rising with the amount of gadgets that need to be charged. Therefore, solar power’s contribution into saving planet from CO2 emissions is limited. It merely generates additional power that does not pollute the planet. It also saves the Earth from the harm that is done each day by coal-burning power plants. In addition, certain researchers tend to argue that the environmental cost of production and installation has to be considered when assessing the impact of the technology on nature. This seems to be somewhat illogical due to the fact that technology of producing solar panels and the technology that solar panels use to produce electricity are two different technical solutions that cannot be assessed collectively. Currently, the technology of gathering solar energy is somewhat unreliable due to the low amount of solar activity in some regions. In many places, the cost of the panels, installation, and maintenance costs are too great to be able to let the user regain the costs for a reasonable period of time, which is why present contribution is somewhat limited.
Energy generated from waste constitutes the most of the global renewable sources of energy production and amounts to about 2% of all global energy generation (REN21, 2016). The amount of contribution of this source to global energy profile seems similar to that of solar energy. However, apart from generating energy, it saves the CO2 and other emissions that come from waste if it is untreated. The extent of this is rather small because most of the countries continue to burn their waste while letting CO2 into the air (EIA, 2017). According to EPA, the US generates 6.82 billion tonnes of CO2 emissions from burning waste (EIA, 2017). Given the absence of emission-cleaning filters installed, waste energy is not that ‘green’ as it may seem, which limits its contribution.
However, waste incineration generates immense amounts of heat, which in European countries is used for boiling the water used for heating residential facilities. The percentage of coverage reaches 37% (see Figure 2).
It may be argued that the onset of cheap heat generated from waste incineration reduces the share of coal energy needed for the same purpose. Despite the high affordability, it cannot currently be used interchangeably with fossil fuels. The reason for this is that the highest recycling rates reach around 50% of total waste production. Also, the share of waste energy in global energy profile amounts to 2%, as it was said earlier. Such amount is simply not sufficient to replace the traditional cheap coal or gas heating. Therefore, the present contribution of waste energy on the global scale in terms of reducing harm to the atmosphere is low due to the overall insignificant usage and considerable prices for its effective use. There are only a few counties who actively develop this source, which does not allow to positively evaluate its global significance.
Water is an essential component of the Earth’s ecosystem that is also used to generate electricity. The capacity of various hydroelectric power plants to produce cheap power is immense. The combined share of the electricity generated from renewable sources amounts to 23.7% (see figure 3).
From figure 3, we can see that Hydropower contributes the most to global energy profile. According to most of the sources drawn for this research, hydropower stays a cheap and reliable source of energy for more than 150 years (Ansar, Flyvbjerg, Budzier, & Lunn, 2014). As it was argued earlier, despite the wide usage of water energy it does not mean that the demand for coal power is dwindling. Additionally, the damage to nature is also present, and such power plants distort natural river flows and destroy the natural habitat of wildlife in the vast areas. It also obstructs the migration of fish.
According to Renewable Energy Organization, the prevalence of water-generated electricity amounts to 16% globally (REN21, 2016). This energy source has the most share among all renewable sources constituting 70% (REN21, 2016). The average lifespan of a hydroelectric plant is around 30-50 years provided proper maintenance is in order, and no major natural disasters occur (or the plant is well-protected against them). From another point of view, such prevalence may decrease the demand for coal use, because burning coal direly affects the quality of life in urbanized areas, while water energy has no such effect. Therefore, it may be argued that to some extent, water energy contributes to global energy profile by being cheap and relatively safe substitute for coal.
Another sustainable energy solution that uses water as a power source is a geothermal plant. Geothermal energy is presently not very widespread because not every land satisfies the requirements for its production. Its contribution to global energy profile in numerical values is about 0.4%. The largest users of such power source are China and the US who draw around 17,000 megawatts of geothermal electricity annually. If we assume that one megawatt of power is enough to provide energy for 1000 households, then 17 000 000 households could be supplied with such an amount (NRC, 2012). This amounts to a huge city that uses renewable energy and does not harm the nature. This contribution may be small on a global scale, but has a huge impact on urban dwellers’ quality of life. Given the above-mentioned facts, the overall present-day contribution of water power regarding its harm-preventing capabilities and role as a substitute for traditional sources is considerable.
Wind seems to be one the most permanent and reliable sources of power that has been providing its services as a power source since the Middle Ages. Presently, wind turbines are used on private farms in the U.S. and as one of the main source of electricity in some Scandinavian countries such as Denmark, where wind power accounts for roughly 42% of total power generation. On a global scale, the share of wind energy constitutes 3.7% (REN21, 2016). Due to that fact, its contribution to reducing the effects of global warming can doubtfully be called significant.
Each kilowatt of power produced by wind generators prevents 0,5 kg CO2 emissions as compared to coal equivalent. In case with Denmark and UK, it does plenty because, given the above-cited numbers, it can be said that roughly a half of the energy is produced through renewables, which reduces the need for harmful and unsustainable coal plants. It is a great contribution for those countries, but on a global scale it practically non-existent due to a small geographical area of those countries.
On the other hand, the environmental contribution of wind energy is deemed questionable by some researchers. Thus, Leung and Yang (2012) note that birds often become victims of the rotary blades. However, this can be deemed insignificant due to the infrequent occurrence. Due to noise pollution, wind turbines can be harmful to wildlife and disturbing for humans (Arvesen & Hertwich, 2012). The offshore installation helps mitigate negative side effects such as noise pollution.
The humanity has a practically unlimited supply of solar energy as the lifespan of the “generator” is estimated at four to five billion years (Nelson, 2011). The market for solar energy seems to be growing substantially in the spheres of utility, residential and non-residential use (see Figure 1).
However, the full potential of solar energy could be utilized only in regions with high amounts of solar activity such as southern and eastern states of the US, countries such as UAE, Singapore, Italy, and other. This cannot be changed, so even if solar energy were used in 100% of the countries with high solar activity, the extent of its contribution to energy profile would still be limited by the fact that other countries are unable to use it. Nonetheless, with the technological upgrades that will allow to maximize electricity gains even within the shortest periods of solar exposure, this situation could be alleviated, and the global contribution will grow (Armaroli & Balzani, 2016).
Presently, the market for biomass energy seems to be growing slowly, witnessing an annual increase of only 3.5% (Scarlat, Dallemand, Motola, & Monforti-Ferrario, 2013). This source of energy is considered renewable due to the assumption that humanity will always generate, recycle or destroy its waste. Therefore, biofuel will always be in abundance. Prospectively, if the recycling rates reach 80 or even 100% in future, then the use of waste energy as a replacement of coal or gas-burning would be possible.
The cheap and ‘green’ electricity produced by water energy cannot be used extensively in the dry regions such as Saudi Arabia, Oman, African Countries, and others, which limits the possibility of its future contribution. The regions where people can construct geothermal plants are limited to areas situated close to lithospheric plate boundaries. Few universal solutions limit the potential of this particular energy to prevent or at least slow down the onset of global warming. It could, however, be used in combination with other renewable sources such as solar energy or waste energy, which would be potentially beneficial for the global profile.
With the development of the technology of offshore wind turbines which are considered more efficient and sustainable, wind power is projected to outgrow onshore turbines in ten to fifteen years (Leung & Yang, 2012). On a global scale, such developments could be used to construct massive amounts of such generators in oceans, where the wind is non-obstructed, which could potentially produce massive amounts of energy. In reality, the whole industry is believed to occupy 30% of the power market in the world as projected to 2025 (Caduff et al., 2012).
The research of options for drawing renewable energy showed that there could be plenty of opportunities. However, since each country and location has its own geographical, economic, and cultural properties, the variety of renewable power sources and, therefore, their contribution is limited. The impact of renewable sources on global energy profile could be maximized if each country has its own plan for the development of renewable energy development. Provided, the technological advancements could make renewable energy sources cheaper, more reliable, and easily constructible their share in the global profile would grow and slowly replace the use of coal or gas. The word ‘non-renewable’ best describes the situation with coal and natural gas. Their use is temporary due to their limited amounts. However vast they may be, their use will eventually cease to exist. The question is whether our planet will still be suitable for living by the time the natural reserves of gas, oil, and coal are depleted.
Presently, fossil fuels stay objectively cheaper than other sources of power with outputs higher or comparable with energy from renewable ones (IEA, 2017). This again limits the contribution of renewables due to the economic inability of developing countries of implementing sustainable energy solutions for contributing to global energy profile. There are many countries in the world where people still struggle to fulfill their basic needs. When a person experiences a scarcity of food in his or her household, they are less likely to concern themselves with the problems of global warming, environmental friendliness of domestic and world energy profile.
Presently, the share of all renewable energy from all sources combined accounts for 23-26% (IEA, 2017). This means that about 75% of total energy production is provided by ‘dirty’ sources. That fact does not allow to conclude that in the present day renewable sources of energy are highly impactful in terms of reducing climate change effects.
Despite somewhat grim picture drawn by statistics and the state of global economy, the influence of renewable sources continues to grow. For a period from 2000 to 2017, the global share of renewable sources of energy grew from approximately 10 to 23%, which is a 43% increase (REN21, 2016). Future could speed up that growth. The internet as a means of fast idea sharing can contribute to raising awareness of global society of the modern environmental problems enabling more and more individuals and government officials to advocate for renewable energy. In addition, successful stories of Denmark, Britain, and other countries could inspire other nations to develop a partnership, share and adapt technological solutions. As an example, China is currently a huge importer of sustainable technological solutions from the West, planning to build a gigantic Gansu wind farm with 20,000 megawatts of power output (Leung & Yang, 2012). The fast-passed development of technology contributes to making sustainable power solutions cheaper and more effective. A few years ago, solar panels were luxurious and a ‘show-off’ house electricity sources. Now even the low-income family in California could afford it, which means the global energy profile could significantly change in 20 or 50 years.
All things considered, the studied literature provides a well-rounded view of the representation of different renewable sources of energy. Each of them is peculiar to certain geographic, climatic or economic environments. Currently, hydropower seems like the top performing renewable energy solution and its present-day impact as compared to other sources is the most significant. The others seem to have the potential to contribute to global energy profile in the nearest future provided the world continues to be mindful of nature preservation and develop sustainable solutions in cooperation.
The factors that can undermine that process can be of political, social, and economic nature. They dictate overall low current representation of renewable energy on the global scale. It gives the reason to conclude that statistically they are not very significantly contribute to the cause of saving the environment. Around 75% of the energy in the world is still non-renewable and continues to change the climate of the earth in the course of its production and usage and diminish the planet’s resources. However, the representation of renewable sources continues to grow annually and, in 20-50 years, it may account for at least 50% of the global energy production in the absence of major technological breakthroughs. This inspires the belief that the future ecological state of our planet will be brighter than its present one. Therefore, the global community needs to help developing countries to overcome energy transition difficulties, which would be a great benefit to the cause of spreading the influence of renewable energy and eventual climate change awareness.
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