We all know the need to change our energy model, change our dependence on fossil fuels to obtain the energy that our cities need for renewable energy sources, such as wind and solar, but if electricity is increasingly renewable, the challenge It will then be to find a way to ensure that the supply is not affected by variations in generation, such as whether the wind blows or not. But, how to store energy when there is a lot of generation and then supply it when there is no sun or wind? The storage challenge is crucial if we want to make full progress towards the decarbonisation of the electricity system.
Storing renewable energy is crucial to advancing decarbonization. Source: pixabay.com.
Renewable energy generation has developed enough to be applied on a large scale, but storing renewable energy in large quantities is still complicated, using batteries would require huge installations, which is why it is the main technology limitation that could slow down the energy transition towards cleaner models . However, there is no shortage of scientists who are dedicated to solving the problem, and interesting proposals are already emerging, from new materials to make batteries more economical and efficient, to the use of fuel cells, to ways of storing energy in the form of heat.
And with respect to this last proposal, researchers from the Solar Energy Institute of the Polytechnic University of Madrid have provided a possible solution, a system that could store large amounts of renewable energy economically and provide energy and heat at the same time. This system was described in an article recently published in Joule magazine, and is based on using excess amounts of solar or wind energy to melt cheap metals, such as ferrosilicon alloys, since when these ferrosilicon alloys are melted they are capable of store large amounts of energy by what is known as the latent heat of fusion.
The molten metal shines like the sun, something useful in this system. Source: pixabay.com.
Basically, when this type of metal is melted at more than 1000 °C it shines like the sun, so the brightness and radiated heat can be used to produce electricity again through photovoltaic cells. This system has been called thermophotovoltaic generators, and essentially they are compact photovoltaic systems that can even take better advantage of radiated heat and produce more power than a conventional solar system, since according to the developers, if a solar panel with an area 1 m2 produces 200W, a thermophotovoltaic panel of the same dimensions would produce 20 kW.
In this way, these thermophotovoltaic systems are expected to store large amounts of energy in the form of latent heat, and then that energy is used to generate electricity. And the largest percentage of the electricity needed to melt the metal will be produced when the demand in the electrical system drops, so it will be cheap electricity to produce and store, so it could be returned very cheaply to the market. And according to the researchers' estimates, this is a very cheap storage system, up to 100 times less expensive than the current lithium batteries used in solar or wind power plants.
General scheme of operation. Source: @emiliomoron, the windmill and the molten metal are public domain images.
And the heat generated by the system does not seem to be a problem, since according to the developers, even if only 30 to 40% of the stored energy is used to produce electricity, it would still be a very economical way to store energy than other options, and In addition, this excess heat could be supplied directly to factories or buildings that require it, which would help reduce natural gas consumption.
And since heat represents a large percentage of the energy demand for some countries, this system could make a lot of sense for them, thus reducing greenhouse gas emissions, this being a good alternative to limit dependence on fossil fuels not only in the electrical sector but also in the thermal one.
Although the first prototype is already in operation and the first results have been published, the technology still needs more research and development to become a large-scale alternative, so the next step for this team of researchers is to scale the technology and prove its industrial viability, we hope that they will continue to achieve good results and this will be an alternative that promotes the decarbonization of the electrical system.
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