The infrastructures enabling the delivery of electricity will play an essential role in the decarbonization process. But it will not be enough to simply reinforce them: they will need to include new functions and various synergies will need to be exploited.
We reproduce here this decryption on the Swiss electricity networks, an article published at the beginning of February 2025 in the magazine "Le Bulletin Electrosuisse" and signed by Roger Nordmann, the former national councillor, now strategy advisor at Approche Nordmann, president of the Swiss Smart Grid Association (VSGS), member of the Board of Directors of Groupe E SA and chairman of that of Planair SA.
The electrical grid is the most important infrastructure for achieving climate neutrality. It is indeed indispensable for carrying electricity produced from renewable energy sources, which is not only expected to cover our current electricity needs but also, as decarbonisation progresses, to replace most of the fossil fuels currently used.
Electricity will thus become our main energy source. A solution all the more attractive as replacing fossil fuels with renewable electricity is often accompanied by a significant efficiency gain.
Over the coming decades, Switzerland's annual electricity consumption will therefore increase sharply, mainly in the mobility, buildings and industry sectors. For example, in order to replace the entire roughly 55 TWh of energy currently consumed as diesel and petrol in the mobility sector, the annual electricity consumption induced by vehicle electrification could rise from 0.4 TWh today to about 17 TWh in 2050. Because electric motors are much more efficient than their thermal predecessors, this represents a reduction of nearly 70% in the energy used.
Next, the renovation of buildings heated by fossil fuels will, to a substantial extent, involve replacing old boilers with heat pumps. Here too it will be possible to divide heating energy consumption by a factor of three or four. If insulation efforts are continued and other renewable sources such as wood are used, the additional electricity needed for this transition could be around 6 TWh/year, consumed mainly during the winter. Note that this figure also takes into account savings that will be made thanks to the progressive replacement of direct electric heating.
Finally, the electricity required to decarbonise industry must also be taken into account. This involves replacing about 17 TWh of energy coming from fossil fuels. This area is more delicate, because two thirds of this energy is consumed in processes requiring temperatures well above 100°C, and therefore out of reach of heat pumps. There will thus be no automatic efficiency gain when substituting gas and oil with electricity. Moreover, to decarbonise high-temperature processes, the use of renewable gas is often unavoidable. Since the biogas potential is by far insufficient, the renewable gas will have to be produced from summer surplus electricity production.
The seasonal balance will also have to be taken into account. Thus, Switzerland will need 76 TWh of solar power per year after the shutdown of the last nuclear plant for age reasons, which corresponds to about 13 times current photovoltaic production. In addition, dams will have to be raised quickly, in accordance with the popular decision of June 2024, to provide an additional 2 TWh of winter storage.
Finally, it will be necessary to produce 6 TWh of electricity annually from wind power, this production being mostly wintertime. It is indeed mainly on this last point that Switzerland is very behind: wind power production there currently reaches only about 0.17 TWh/year, compared with 9 TWh/year in Austria.
In view of these figures, it is obvious that the electrical grid is a determining element of this transformation. In its current design, however, its functions are limited: unable to store electricity, it is traditionally sized so as to be able to cope with the largest peak power to be transported, including a safety margin.
The conventional approach to meeting future requirements would be to reinforce the grid according to the "more of the same" logic. However, expanding the grid's functions would be far more promising, knowing that an increasing share of electricity will be produced close to its point of consumption. If the grid is equipped with elements allowing electricity storage near production facilities, the need for transport – and therefore for grid extension – decreases. This creates a trade-off.
Concretely, for short-term storage, the grid can be equipped with decentralised batteries that will store electricity temporarily and redistribute it a few hours or a few days later. The grid can also be equipped with electrolysers that transform surplus electricity into hydrogen.
This renewable gas can then be used as such in industry or converted into methane and injected into the natural gas network. This operation opens the way to longer-term storage, since methane is easy to store, even though Switzerland currently does not have the appropriate reservoirs. This interconnection of electricity distribution with the gas network sets up what is called the convergence of energies.
Thanks to these approaches, the grid can do much more than transport electricity. In summer, batteries allow storage of the solar power produced during the day and spread its transport over 24 hours. Thus, an isolated farm equipped with batteries can, for example, have a photovoltaic installation significantly more powerful than the capacity of its connection line and make electricity available during the night.
In all seasons, batteries also make it possible to cope with power peaks generated by electric vehicle charging at the end of the day, without having to reinforce the grid. In summer, they store locally the photovoltaic power produced when the sun shines. In winter, their recharge from hydroelectric and wind production is spread over the whole day. This then allows them to relieve the strong evening electricity demand.
Batteries can also serve redundancy and grid security: given the growing share of electricity in the energy mix, this aspect gains importance. They also absorb unexpected variations, which are very costly in terms of balancing energy. Finally, having photovoltaic-origin electricity available at night also allows electrolysers to operate 24/7 during the six summer months – and not only for a few hundred hours per year – which massively reduces the unit costs of hydrogen.
To enable the short-term local storage necessary for the energy transition, these stationary batteries should have a total capacity on the order of 70 GWh, which corresponds to one fifth of the future volume of electric car batteries. And since they do not need to be lightweight, lithium-free technologies are quite conceivable, for example sodium-ion technology.
These new capabilities of the grid make it possible to address the decarbonisation of industry and winter electricity supply in a much smarter way. There is indeed an unsuspected synergy in mastering these two challenges. But before returning to this point, it is appropriate to put into perspective a route often mentioned but unrealistic for ensuring winter supply.
This questionable option consists of transforming a summer electricity surplus into gas, storing it for months, then reconverting it into electricity in winter. However, this is a false good idea, and for two reasons. On the one hand, this double transformation induces very large losses. It takes about 3 kWh of summer electricity to end up with 1 kWh of electricity available in winter. On the other hand, the quantities of gas to be stored are enormous: to have 10 TWh of winter electricity, it would be necessary to store 20 TWh of renewable gas, given the losses associated with reconverting renewable gas into electricity. And yet this figure does not include the storage of renewable gas needed for industry.
This approach is therefore not the right one. The key to the synergy is rather to reserve synthetic gas for high-temperature use in industry. The "solar, syngas and industry" (SSI) strategy avoids the losses related to reconversion into electricity. This choice implies sizing annual electricity production more generously, so as to have enough in winter without having to produce it by means of synthetic gas. By reserving for industry the synthetic gas produced from the summer excess of electricity production, the decarbonisation of high-temperature industrial processes can be achieved almost without increasing winter electricity consumption.
The electricity grid equipped with these new capabilities, and in particular with stationary batteries, will become a major asset for producing synthetic gas. It will then become possible to spread the use of summer peak electricity over 24 hours to valorise it in the production of synthetic gas. Given the geographic dispersion of industrial zones and the countless solar roofs, it is worthwhile to decentralise electrolysers in order to use hydrogen as locally as possible. This avoids having to strengthen the capacities of the electricity grid for medium- and long-distance transport. Capacity reserves in the decentralised parts of the grid are, for their part, generally larger, because individual connections are generously sized.
In small quantities, hydrogen surpluses can be injected and transported in the natural gas network. When they become larger, they can be converted into methane and transported in that form via the natural gas network to larger reservoirs, possibly located abroad, for seasonal storage. This approach based on the extensive existing natural gas network avoids the costly construction of a vast national hydrogen network.
Note that there is an even simpler local use of summer photovoltaic production surpluses. When these appear, they can temporarily replace the use of gas in industry, as well as wood or gas in district heating networks. Indeed, these systems are also operating in summer to produce domestic hot water. By installing an appropriate heating element and providing a very low temporary network tariff to valorise the surpluses, it becomes possible, on the one hand, to reduce emissions related to the combustion of fossil gas and, on the other hand, to avoid wasting wood in summer and reserve it for winter.
Implementing this strategy implies shifting investment priorities in the grid. Instead of devoting most of the effort to strengthening lines and transformers, it will be important in the future to find an optimal distribution between copper, batteries, electronics and the new uses of surpluses.
This strategy also requires establishing a regulatory framework serving these objectives. It will be just as essential to admit that these new functions of the grid are of general interest and should not be financed only by the stamp. This is yet another reason to establish a national climate fund.
In the era of decarbonisation, the role of the grid is no longer limited to transporting electricity. It becomes a multifunctional, flexible and high-performing actor in a complex energy equation. This evolution is part of the changes in perspective that politics, the economy and citizens will have to make. The preservation of the climate depends on it.
Roger Nordmann is also the author of "Emergency: energy and climate – Investing for a rapid and just transition", Éditions Favre, 2023.
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