Overview of renewable energy technologies
In a decade (from 2011 to 2020), the world's renewable energy capacity has increased from 1330 GW to 2799 GW (IRENA, 2021), mainly driven by the Asian countries which increased their renewable capacity by over 850 GW. In 2021, 260 GW of additional renewable capacity was installed (IRENA, 2022) and the IEA expects new renewable energy capacity to reach 320 GW in 2022 (IEA, 2022). Those figures reveal how the renewable energy industry is dynamic.
However, according to the IEA (2021), energy consumption from renewable sources (wind, solar, geothermal, marine, biomass, and hydro) represents only 14.1% of the worldwide energy mix in 2021. If we include nuclear, which is still a very controversial subject in many countries, this share reaches 19.1%. Furthermore, the projection of the IEA revealed that the share of renewable energy will continue to increase but the energy produced from fossil fuels will remain dominant.
In this article we will give an overview of renewable energy and give some figures and information.
Hydropower
The hydroelectricity is the most developed renewable source in the world for a long time and represents 40% of the renewable capacity generation. The construction of dams on lakes and rivers allows to hold back water and channel it to a turbine that produces electricity. One of the main advantages of hydropower is its modularity. Indeed, it is possible to increase the power capacity of a dam by opening valves to increase the amount of water in the process. However, building a dam can cause huge damages to the ecosystems. To create the reservoir upstream of the dam, the surrounding environment is completely flooded. Moreover, it causes important displacement of population. In China the construction of the Three Gorges Dam, the biggest dam in the world (22.5 GW hydro plant), has displaced more than 1.2 million people. Therefore, to avoid the negative social and environmental impacts of the construction of such infrastructure, the construction of smaller dams should be preferred after a thorough environmental impact assessment has been conducted.
China, Brazil, and Canada are the countries with the largest installed hydropower capacity. On the other hand, hydropower represents a significant part of the national energy mix in countries like Norway (93%).
The main manufacturers of hydro turbines are GE, Andritz and Voith, accompanied by a strong growth from Chinese competitors Dongfang Electric and Harbin Electric.
Wind power
Wind power facilities know a quick growth lately in order to expand renewables capacity. In 2021, new wind power capacity has reached 97 GW (WWEA, 2022) mainly led by China.
There are 2 types of wind farms: onshore and offshore. Onshore wind farms are located on land while offshore wind farms are located off the coasts. It is interesting to specify that offshore windmills are larger than onshore ones because wind power is stronger in the sea so that the power generation capacity is also larger with offshore windmills. Onshore wind farms are directly connected to the grid while offshore farms require a sea cable to join the costs and be connected to the grid.
Both China and the US represent more than 55% of the total wind power capacity in the world. Denmark was a pioneer in the development of offshore wind farms in the 90’s but the UK and Germany have the world's largest offshore wind capacity installed (respectively 10.4 GW and 7.7 GW) (Vinci, 2022). The construction of offshore wind farms will know an important growth in the coming years as a result of the strong will of governments to develop this technology.
Europe’s industrial competitiveness in the wind industry is strong thanks to windmills manufacturers like Vestas and Siemens-Gamesa but is facing increasing competition from Chinese manufacturers like Goldwind and Mingyang.
Solar power
While wind energy grew by 14% in 2021, solar energy production grew by 19% to reach 133 GW of new capacity (IRENA, 2022). Solar energy is used in 2 different ways. Solar thermal panels are used to create heat while photovoltaic panels produce electricity. Solar thermal panels use mirrors to concentrate sunlight which heats a fluid that creates steam. On the other hand, photovoltaic panels directly convert sunlight into electricity thanks to the silicon presents in the cells of the panel. Solar farms are perfectly suitable for regions with a lot of sunshine in order to get an optimal power generation.
China and the US are once again leading both the new solar capacity and the installed solar capacity in the world, representing respectively 55% and 47% in 2021 (IRENA, 2022). Japan also has a large installed solar capacity (74 GW in 2021) while India is building more and more new solar parks (+10 GW in 2021) (IRENA, 2022).
The main solar panel manufacturers are from China (LONGi Solar, Tongwei Solar, JA Solar) thanks to very attractive prices, but Northern American producers Canadian Solar and First Solar are still in the competition.
Geothermal power
Geothermal energy is an underutilized energy source with only 16 GW installed worldwide in 2021 (IRENA, 2022). A geothermal power plant works thanks to the heat contained in the subsoil. The latter makes it possible to heat the groundwater. Groundwater is piped to the plant through wells and converted into steam that then drives a turbine and generates electricity. Steam can also be recovered in heating systems. Geothermal installations differ depending on the depth, temperature and use of the heat. There are 3 different types: low energy, medium energy and high energy.
In 2021, geothermal capacities knew an exceptional growth led by the US and Indonesia. In a country like Iceland, 90% of heat and almost 27% of electricity is produced from geothermal sources. In Kenya, it represents 46% of the energy mix.
Biomass
Biomass is the oldest renewable energy source. However, a large part corresponding to traditional biomass (using charcoal) is not considered renewable. Therefore, it is essential to develop modern biomass through biogas, electricity and heat production. Biomass has an unlimited capacity as it uses plant and animal materials. Those materials come from forest residues, agricultural activities, or waste (from individuals and industries such as restaurants or wood). A biomass plant works by burning these materials which generates steam and then drives a turbine to produce electricity. A cogeneration plant can produce both electricity and heat. Indeed, hot steam produced from biomass can also be distributed in the form of heating or domestic hot water in heating networks. A biogas plant produced a gas from the degradation of organic waste in an oxygen-free environment. This plant of plant is very interesting in agricultural areas.
New bioenergy capacity increased by more than 10% in 2021 mainly led by China and the Asian continent. Many African countries depends on biomass in their energy mix even though this biomass is not entirely renewable.
There are several forms of renewable sources, and most of them are still underused while the need to decarbonize our economies is critical. Technologies like solar or wind have proven track record and are quickly expanding all around the world. Others like geothermal or biogas plant are still growing at a slower pace because of technical and costs issues. Finally, marine energy or biofuels are just at the beginning of their potential and require important investments to make them a real alternative and an efficient power production.
Sources
IEA. (2022). Renewable Energy Market Update Outlook for 2022 and 2023. International Energy Agency
IEA. (2021). Key World Energy Statistics 2021. International Energy Agency
IRENA. (2022). Renewable capacity highlights. The International Renewable Energy Agency
IRENA. (2022). Renewable Energy Statistics 2022. The International Renewable Energy Agency
IRENA. (2021). Renewable Energy Statistics 2021. The International Renewable Energy Agency
Vinci. (2022). Éolien offshore : où en est-on dans le monde ?. Vinci. https://www.vinci.com/vinci.nsf/fr/actualites/pages/eolien_offshore_ou_en_est_on_dans_le_monde.htm
WWEA. (2022). World Market for Wind Power Saw Another Record Year in 2021: 97,3 Gigawatt of New Capacity Added. WWEA. https://wwindea.org/world-market-for-wind-power-saw-another-record-year-in-2021-973-gigawatt-of-new-capacity-added/