What is renewable energy?
This is why, over time, renewable energy sources have begun to be developed. Interestingly enough, such sources were often already in use in the past and are now being expanded on a large scale.
Types of renewable energy sources
Renewable energy encompasses a broad range of solutions, each with different characteristics, pros and cons. We will therefore discuss them briefly, one by one.
Solar energy: how it works and where it is used
- Solar energy is probably the most instinctive kind of energy for us. After all, we feel the heat produced by the sun's rays on our own skin every time we leave the house. However, much has changed since the days when our ancestors used the sun to light fires, and solar energy now accounts for more than 5% of global energy production. [1]
The most common use of solar energy is in photovoltaic (PV) panels which convert sunlight into electricity using the photovoltaic effect. This effect occurrs in silicon crystals whose electrons begin to move when exposed to light, thus creating electricity. Due to their relatively small size and simple installation, PV panels are used not only by the industry, but also by individual households.
Production of energy by a photovoltaic system depends on its capacity and location. In Poland, it is assumed that one 1 MW PV installation generates on average about 1000 MWh of energy per year, which corresponds to the annual electricity requirement of about 250-285 households [2]
In Poland, solar energy accounts for approximately 1.4% of electricity production from renewable sources. [1]
The biggest limitations of solar energy include the dependence on weather and season of the year, and the challenges related to storage of the generated electricity. The first issue makes solar PV most viable in warmer climates with longer days. The solution to the second limitation is, for instance, energy cooperatives, which help communities share the electricity generated according to needs.
Wind energy: advantages and limitations
- Windmills and wind turbines are nothing new. For centuries, people have used wind energy to grind grain and wind-powered pumps were used to drain floodplains or power sawmills. Now, the giant wind turbines that make up wind farms convert the movement caused by the wind into electricity, which is then supplied to the power grid. This green solution already accounts for more than 8% of the world's energy. [3]
1 MW of wind power generates approximately 2,000-2,500 MWh of energy per year, depending on the location and wind conditions [4]
However, like solar energy, wind energy is unfortunately weather-dependent and works best in regions with a high number of windy days.
In Poland, wind energy accounts for approximately 13.72% of renewable energy generation. [1]
An additional challenge which stirs up a lot of emotions is the impact of wind turbines on birds and bats. Birds often fail to notice the rotating turbine blades which leads to collisions, especially in the case of migrating species. Solutions to this problem are offered by modern technologies such as radar systems that detect incoming birds and temporarily stop turbines. Moreover, painting one of the blades a contrasting colour significantly reduces the risk of collisions, as field studies have shown. [5]
The challenges related to excess energy storage are similar, but cannot be solved by cooperatives due to the fact that this solution is not available to individual consumers. Hence, wind turbines are often combined with hydroelectric plants, which can temporarily stop the flow of water on a windy day and increase it when the wind stops to create a kind of living battery.
Hydropower: the use of rivers and oceans
- Another source of energy we have known for many centuries is hydropower. It may come as a surprise to some that hydroelectricity is the most popular renewable energy source, accounting for 15% of global energy production. [6]
A 1 MW hydropower plant produces an average of 3,000-4,000 MWh of energy per year. [7]
Hydroelectric power plants are most often built as impoundment power plants on rivers, using the natural flow of water to produce energy. There are also tidal power plants, using the tides of the seas and oceans to produce energy.
In Poland, hydropower accounts for around 10.5% of renewable electricity production. [1]
Undoubtedly, the biggest advantage of hydroelectricity is the flexibility mentioned earlier. Provided there is no drought or flood, the water flow can be adjusted to meet energy needs and, when stopped, can be deposited in a reservoir without losing potential energy.
Unfortunately, the construction of dams also has its downsides. Changes to the natural course of rivers have serious consequences for local ecosystems, as well as for local residents, who often have to be displaced due to the scale of the project. Impoundment power plants are usually effective in reducing the risk of flooding, and proper design and protection systems minimise the risk of damage to the dam even in the event of extreme weather events.
The largest hydroelectric plant in the world is the Three Gorges Dam in China, with an installed capacity of as much as 22.5 GW. This power plant is capable of generating enough energy to power around 85 million households per year. What’s more, this project not only generates electricity, but also effectively reduces the risk of flooding in the downstream sections of the Yangtze River.
Few people know that the highest dam in the world is located in Tajikistan. The Nurek Dam has an impressive height of 300 metres. Although less known than other monumental engineering projects, this dam plays a key role in electricity generation, satisfying 75% of Tajikistan’s total energy requirement. Due to its location in the mountains, efficient use can be made of the Vakhsh River flow.
Hydroelectric power plants are very efficient, but their construction requires significant capital expenditures and suitable site conditions, which limits the possibility of their development in some regions.
Biomass and biogas: Potential in agriculture
- If you know someone who burns wood in a fireplace, you can tell them that they are burning biomass! Biomass is simply organic material that stores solar energy. For example, wood, straw or agricultural waste. Biogas, on the other hand, comes from the decomposition of these organic materials (usually waste) and, following purification, becomes biomethane with similar properties to traditional natural gas
However, the renewability of biomass is often conditional. For example, if we use wood, we need to make sure that we are not clearing the entire forest and that we are managing the forest wisely. In addition, wood releases more carbon dioxide into the atmosphere than even coal. That’s why it’s so important to take care of forests, because they absorb carbon dioxide from the atmosphere, helping to reduce the amount of carbon dioxide in the air.
Biomass can also be stored and used when it is needed most, making it a more flexible energy source than, for example, wind or solar power. However, the disadvantages of this solution are equally significant.
Biomass combustion, although renewable, is still associated with carbon dioxide and particulate emissions, which can have a negative impact on air quality, especially in areas with high levels of this type of energy. In addition, intensive use of biomass can lead to depletion of natural resources if not carried out in a sustainable manner.
The advantage of biomass is its availability and versatility - it can be sourced from agricultural residues, forestry or even urban waste, allowing waste reduction and energy production at the same time.
Therefore, despite its numerous advantages, biomass requires responsible management and investment in modern technologies such as high-efficiency boilers or biogas plants. Only in this way can it become an efficient and environmentally friendly element of the renewable energy mix.
Geothermal energy: harnessing the heat of the Earth
- The last type of renewable energy to be discussed here is geothermal energy. Its origins can be traced back to the Palaeolithic period, when our ancestors discovered hot springs, but the technology has evolved considerably since then, with advanced systems of boreholes and installations being used today to extract heat from deeper layers of the Earth. Although it currently accounts for less than 1% of the world's energy production, the rapid development of the technology could significantly increase its share of the global energy mix in the future [8]
The most common application of geothermal energy is in heating systems. Heat pumps take advantage of the higher ground temperature compared to the air temperature in winter by pumping water through it and generating heat without the need to burn fossil fuels. In industrial systems, similar technology is used, but geothermal water is accessed through deeper boreholes and can be used to produce electricity in addition to heating.
Benefits of renewable energy
Despite the challenges, renewable energy has numerous benefits. On the level of individual users, renewable energy from an appropriate source can reduce the costs of electricity or heating. On a macro level, the use of RES protects the environment and also reduces dependence on fossil fuels and thus potential price fluctuations related to the global geopolitical situation
Unlike fossil fuels such as coal, oil or natural gas, whose resources are finite and can run out in a few decades, energy from the sun or wind will be available for as long as the planet exists. This characteristic makes RES a long-term and stable solution, especially in the face of the challenge of depleting traditional raw materials.
The environmental impact should not be forgotten either. The production of energy from fossil fuels accounts for as much as 75% of global carbon dioxide (CO₂) emissions, which is the main greenhouse gas contributing to climate change. Meanwhile, RES, such as wind and solar power, emit no CO₂ during operation. For example, an average wind farm that produces energy for 100,000 homes in a year means 200,000 tonnes of avoided CO₂ emissions. This is an equivalent of the amount emitted by 50,000 cars in one year, that is the number of cars found in an average Polish city.
An additional benefit is the creation of jobs. The development of the RES sector generates thousands of jobs in areas such as the installation of solar panels, the construction of wind farms or the development of energy storage technologies.
In this way, RES not only have a positive impact on the environment, but also support local economies, especially in regions where the development of traditional industries may be difficult.
Challenges in the development of renewable energy sources
There are many challenges related to the development of RES, the most important being the cost of building the infrastructure, the problems with storage of weather-dependent energy, or the limited application of a particular method of energy production due to changing climatic conditions.
However, the biggest barrier to development is political. Many countries and companies in the world have built their economies on fossil fuels. Reducing their consumption, therefore, will potentially have dire consequences for their economies, which in turn causes them to invest big money to fight the idea of RES.
The future of renewable energy worldwide
However, these barriers should not stop the development of RES worldwide. Analysts predict that renewable energy production could potentially double by 2030 and by 2035 account for up to 100% of some countries’ energy output, significantly reducing global carbon emissions. In addition, technologies for capturing and storing renewable energy are being developed all the time.
Currently, the biggest worldwide leaders in the use of renewable energy sources are Iceland and Albania, which generate 100% of their electricity from RES. Iceland relies on geothermal energy and hydropower, while Albania almost entirely on hydroelectricity [9]. Sweden also stands out againts other European countries with RES accounting for more than 62% of total energy consumption, making it a leader in the European Union.[10]
Compared to these countries, Poland still has a lot of catching up to do. According to a report by the Energy Forum, the share of renewable sources in Poland’s electricity generation was around 27% in 2023, a clear increase compared to previous years.[11] However, when total energy consumption (electricity, heat and transport) is taken into account, the share of RES drops to 17.1%. [12] This result shows that, although the energy sector is growing rapidly, other areas, such as transport and heating, need further development.
[1]https://www.iea.org/data-and-statistics/charts/global-electricity-generation-by-renewable-energy-technology-main-case-2023-and-2030?
[2] https://www.cire.pl/pliki/2/2019/fotowoltaika_producent.pdf
[3]https://www.iea.org/data-and-statistics/charts/global-electricity-generation-by-renewable-energy-technology-main-case-2023-and-2030
[4] https://pl.wikipedia.org/wiki/Energetyka_wiatrowa_w_Polsce
[5] https://onlinelibrary.wiley.com/doi/epdf/10.1002/ece3.6592 An experiment carried out in Norway at the Smøla wind farm, one of the largest in Europe, showed that painting one of the turbine blades black reduced the number of bird collisions by 70%. The study was conducted by researchers from the Norwegian Institute for Nature Research (NINA) and was published in 2020 in the journal Ecology and Evolution. The black colour of the blade increases the visual contrast of the turbine, which helps birds to better perceive the moving parts of the structure, especially in poor visibility.
[6]https://www.iea.org/data-and-statistics/charts/global-electricity-generation-by-renewable-energy-technology-main-case-2023-and-2030
[7] https://pl.wikipedia.org/wiki/Elektrownia_wodna
[8]https://kongresgeotermalny.pl/viii-ogolnopolski-kongres-geotermalny/stan-wykorzystania-energii-geotermalnej-na-swiecie-i-w-europie-w-2022-2023/
[9] https://android.com.pl/tech/866302-europa-prad-oze-albania-islandia/
[10] https://www.teraz-srodowisko.pl/aktualnosci/udzial-oze-w-calkowitym-zuzyciu-energii-w-ue-2023-dane-eurostat-16108.html
[11] https://www.forum-energii.eu/transformacja-edycja-2024
[12] https://www.iea.org/countries/poland/energy-mix
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