Rapidly growing renewable technologies are at the heart of the energy transition. Thanks to continuous innovation, they are becoming increasingly efficient and competitive. And new technologies are on the horizon.
Not only do they make it possible to generate electricity without emitting greenhouse gases, they are also virtually inexhaustible. Renewable energies are at the heart of the energy transition.
In fact, the energy used is never renewed, but is transformed into electrical energy. They are sources such as wind or sunlight that are renewed independently of the use, we make of them, unlike, for example, fossil fuels such as coal or oil.
Mature technologies: hydropower and geothermal energy
The oldest form of electricity generation from renewable sources is hydroelectric power (the first plants date back to the end of the 19th century), which is also the most important, with a worldwide installed capacity that exceeds the total of the others.
It is a mature technology that does not lend itself to an explosive revolution, but new technologies can increase plant efficiency and extend plant life. Moreover, in many countries, especially developing countries, there is still significant room for growth in the use of water resources.
Geothermal energy is also an established technology, which saw the light of day at the beginning of the 20th century: the world's first power plant, the Larderello plant in Tuscany, was inaugurated in 1911, but the first experiments had already begun in 1904.
Today, geothermal energy still plays a secondary role globally, because only a few regions of the world have significant geothermal resources. However, innovative technologies, such as low-enthalpy plants, can significantly increase the number of countries suitable for geothermal development.
The strong growth of solar and wind energy
Solar energy, together with wind energy, is the major player in the current energy transition. Marginal until a few decades ago, it is now experiencing rapid growth: global photovoltaic capacity has increased from 40 GW in 2010 to 580 GW in 2019.
The merit is basically due to technological innovation, mainly in the materials science sector, which has made photovoltaic plants competitive also from an economic point of view compared to fossil sources: according to IRENA (International Renewable Energy Agency), the costs of photovoltaic electricity production have fallen by 82% in the last decade.
And the outlook is even more encouraging: with new-generation technologies, the efficiency of solar panels can be increased by 30% compared to today and productivity by more than 20%.
In the wind energy sector, too, technology has made great strides forward: wind blades now have a diameter of 200 meters, and their dimensions are expected to grow even larger. Here, too, higher productivity lowered costs: between 2010 and 2019 they fell respectively by 39% for onshore and 29% for offshore wind power.
The result is impressive growth: the total capacity of onshore wind farms rose from 178 GW in 2010 to 594 GW in 2019. Offshore plants had a slower development, with only 28 GW installed in 2019, but with a huge growth margin.
Emerging technologies: marine energy, hydrogen and storage
Among the renewable energy sources of the future is the sea, with its immense potential: the most intuitive way to generate electricity is to use wave energy, but it is also possible to harness the tides, with the advantage that these can be accurately predicted. Other methods are based on the difference in temperature between surface and deep waters or on the difference in salinity between different bodies of water.
The technologies to valorize these energy sources have not yet been developed enough to allow their widespread commercial use, but some experimental plants and prototypes have already been realized with good results, mainly for wave and tidal energy. Their respectable theoretical potential has been estimated at 700 GW and 200 GW respectively.
Another resource of the future deserves a separate mention: hydrogen, which is not an energy source but an energy vector and, if obtained from renewable sources, is 100% environmentally friendly.
Its contribution could be valuable, especially in making sustainable sectors that are difficult to electrify, such as heavy industry, shipping, aeronautics and road transport with heavy vehicles.
Hydrogen technologies are also at an early stage and are not yet ready to be commercially deployed, but the time required for their launch could be much shorter than for other technologies.
A decisive role will also be played by energy storage systems, which are needed to remedy the intermittency of renewable sources such as the sun and wind. Historically, the most important storage technology has been pumped-storage hydroelectric power plants, but batteries, especially lithium batteries, which can be installed anywhere, are currently experiencing major growth.
The diffusion of storage systems is still limited, but is increasing rapidly thanks, also in this case, to technological innovation that is constantly improving the quality and performance of batteries and reducing their cost.
When storage is fully integrated into power grids, intermittent sources will be able to supply power to the grid at any time, regardless of atmospheric conditions: it will then be possible to have a completely emission-free power generation mix. A not-too-distant future.
