Opinion by Dr. Gregor Giebel, Head of the DTU TotalEnergies Centre for Clean Energy, DTEC. Published in Energy Supply, May 2024.
Some say we should conduct research into new technologies that will be able to meet tomorrow's energy requirements and also stop climate change. I understand that it may be comforting to believe that a new technology can save us. But for every new technology that sees the light of day, the question is no longer just whether it works and is sufficiently inexpensive to use. With the speed at which the climate crisis is developing, the question is also how quickly the new technology can install the first gigawatt in the electricity grid.
We emit too much CO2 into the atmosphere. We have known this for 130 years. If we are to believe the five-year forecast issued by the International Energy Agency (IEA), we need to install just as much renewable energy globally as we have done in the past 20 years. The electricity grid must also be expanded correspondingly. Otherwise, we will not only fail to meet the 1.5°C goal that the world has proclaimed as a target, but also the 2°C goal.
Loads of renewable energy available
Fortunately, there is no need for a new miracle technology. We already have all the technology we need. We have technologies that can harvest wind, sun and hydropower, and, in combination, if they are installed in the right way and with the necessary volumes, we already have a solution to the problem.
There are also abundant volumes of renewable energy waiting to be harvested. The sun constantly sends 175,000 terawatts towards the Earth. In comparison, the global electricity requirement is approximately 3.4 terawatts. If we harvested solar energy in the Sahara Desert on an area equivalent to Zealand and Funen, this alone could cover the world's electricity consumption.
There will also be sufficient renewable energy available by harvesting the wind. This alone can generate about 68 terawatts on land. If this did not mean in practice that the wind turbines would block each other, it would be sufficient to cover the world's electricity consumption if wind turbines were installed back-to-back in the entire North Sea.
Existing technology is profitable
What we need is more industrialization. It is far cheaper to scale existing technology than to invent new technology.
The production of wind turbines and solar cells has been industrialized, making the technologies economically available. Both solar cells and wind turbines onshore and offshore are already cheaper to invest in than coal-fired power. And much cheaper than nuclear power.
According to OurWorldInData, electricity from solar cells has, for example, gone from costing DKK 2.62 per kilowatt hour (kWh) in 2010 to costing as little as DKK 0.16 per kWh at best in 2019. In comparison, the price of coal was DKK 0.75 per kWh in 2019.
Unlike coal, the price of solar cells and wind turbines continues to fall. According to the American think tank Lazard, a kWh from solar and wind energy cost at best DKK 0.17 per kWh last year. This corresponds to DKK 765 for a Danish family's annual electricity consumption of 4,500 kWh before adding grid tariffs and taxes.
Connect the technologies is the challenge
Individual technologies can and must still be improved and industrialized. But we have the technologies needed. The real task lies in integrating all these technologies in a large cohesive system so that a stable green electricity supply can match the demand and so that the demand can adjust to the supply. And this requires development.
It requires that we work to connect technologies so that they can supplement each other.
We are already doing this: When the wind blows so much in Denmark that the wind turbines harvest more energy than needed, we send electricity to Norway. When there is no wind, we buy electricity from the hydropower plants in Norway. With this kind of exchange, Denmark has days when the share of energy from renewable energy sources exceeds 120 percent.
But if we are to make the 100-percent mark throughout the year, and not just on selected high-wind days, we must be able to transport energy from multiple technologies simultaneously via the existing electricity grid. And here hybrid power plants are part of the solution. A hybrid power plant has installed several technologies at the same grid connection point, as opposed to, for example, a wind turbine, solar power plant, or a coal-fired power plant.
Hybrid power plants part of the solution
So far, the demand has driven a large part of the development of wind turbines to the current level. With countries such as South Africa, whose existing coal-fired power plants are so run down that they are facing massive investments in their energy system, there are also prospects of high demand for hybrid power plants—the so-called energy parks.
In Korea, there is an example of how the existing electricity grid infrastructure—currently one of the two major bottlenecks globally—can be reused. They have built a large plant with floating solar cells handled by the existing hydroelectric power plant.
At DTU, we are currently working on connecting solar power and wind energy. In DTEC, which is a partnership between TotalEnergies and DTU, the first sod was cut this year for the construction of a test hybrid power plant connected to the electricity grid, which will contribute to our ability to utilize and store renewable energy across energy sources such as wind, sun, and hydrogen in the future. A floating solar plant is also being constructed in Roskilde Fjord near Risø.
The hybrid power plant will be part of the NEST Facilities research infrastructure, which is a national collaboration project across test facilities in Denmark: two in Risø, two in Aalborg, and one in Aarhus. These facilities produce electricity in different ways and can also store the electricity and convert it into new molecules, such as hydrogen, methanol, or ammonia.
The tests we can perform will bring us a big step closer to ensuring 100 percent renewable energy. We do not need to be saved by miracle technologies. Investing in the existing technologies and getting them to interact will undoubtedly help us save ourselves.
