Switzerland without fossil fuels. Can it succeed? – ScienceDaily

The researchers chose a cautious approach and initially collected real data on electricity consumption, heating needs and hot water consumption in Switzerland. These data were then used as a basis for a thought experiment. Switzerland's electricity needs are still fairly easy to determine: the Swissgrid grid operator provides detailed values ​​for each quarter of an hour every day of the year. Heating and hot water requirements are becoming more difficult. Empa experts used data from the REFUNA district heating supplier, which supplies several communities in the lower Aare valley with waste heat from the Beznau nuclear power plant. An badysis of the data showed that the heat requirements of the connected houses are very well correlated with the outside temperature. Therefore, on nights when the temperature is above 18 degrees Celsius, heat is only used for process water and showers.

Electrifying heating systems and cars

For their thought experiment, the researchers formulated various hypotheses. First, most Swiss residents behave like inhabitants of the lower valley of the Aar and live in similar buildings. Second, in order to move away from oil and natural gas, the heating needs of all buildings will initially be reduced by approximately 42% through renovation measures; then, 3/4 of the remaining heating needs in the houses and apartments thus renovated will be achieved with the help of electric heat pumps. Thirdly, mobility will be electrified to the extent that about two-thirds of all private car trips can be done electrically, which is about 20% of all kilometers traveled. Freight traffic and long-haul travel, on the other hand, are not so easy to convert, which is why they were excluded from the electrification of mobility in the study.

Nuclear power plants no longer play a role in the study of Empa, since the elimination of nuclear power has been decided since the referendum on the energy law of May 2017. The researchers so were expecting a strong expansion of photovoltaics. In Switzerland, as part of the http://www.onnendach.ch project, half of the roof areas clbadified as satisfactory to outstanding are equipped with solar cells. This corresponds to about one third of all roofs in Switzerland.

How much does the demand for electricity increase?

The researchers then determined the resulting electricity consumption, which is expected to increase by about 13.7 terawatt-hours per year from heat pumps and electric vehicles, about 25 percent more than today. The time gap between electricity production and demand is even more alarming than this significant increase in consumption: solar cells produce the most electricity in summer, but heat pumps and heated cars require a particularly high amount of electricity. significant electricity in winter. This results in a seasonal supply deficit.

This could be offset by the import of electricity from neighboring countries, as it is already the case today in case of shortage. But our CO₂ The equilibrium will probably suffer – because electricity in Europe often makes mbadive CO₂ Swiss balance, which has been so carefully electrified. Heat pumps and electric cars therefore benefit more from the climate if their electricity is also renewable.

What do the researchers suggest?

However, the Empa study also provides valuable information on how to implement a low-carbon system.₂ energy system. First, it is a good idea to replace oil heating systems with heat pumps if the buildings are isolated with the help of advanced technology. Because a heat pump without proper insulation is significantly less efficient. Secondly, each nuclear power plant must be replaced by about eight times the photovoltaic power. Why? A nuclear power plant provides about 8,000 hours of electricity per year, but a solar cell only represents 1,000 hours. This means a lot of solar panels – on all available surfaces. Thirdly, we need the largest possible storage capacity for solar energy – local battery storage facilities and pumped storage facilities, as well as other storage technologies, especially from a remote location. heat storage facilities (geothermal), but also technologies for converting electricity into chemical energy sources. . Indeed, the sun shines only a few hours a day to fill the reserves. For the rest of the time, the stored energy must last.

Fourth, we need to create seasonal heat storage facilities to reduce the heat pump power requirements in the winter. Fifth, we need to better match energy supply and demand. Solar energy and heat will be abundant in summer, but in winter, renewables will be a rare (and therefore expensive) product in the future. Sixth, and this is the good news: electromobility does not tip the scales. According to the hypotheses adopted, the daily loading of electric vehicles at home, at work or during purchases generates only relatively small peaks in electricity demand compared to the supply of electric heat. A prerequisite for this is, however, the establishment of appropriate networks with sufficient capacity.

If other renewable energies such as wind, geothermal, more biombad and a little more hydraulic energy are realized in winter, the coverage gap will shrink, however, it will probably be not possible to close it completely. The electrification of heat and mobility will not solve the problem alone. "To achieve the sustainable conversion of our energy system, we need energy storage technologies in the short and long term – that is, seasonal. That's why we should not not play the energy sectors against each other, but keep all the technical options open, "says Martin Rüdisüli. And Sinan Teske adds, "We must learn from nature how to use solar energy, which is not available all year round. We could store as much as possible in the summer and limit our needs in the winter. Or we could look for partners in the southern hemisphere, able to capture solar energy and deliver it to Switzerland in winter, and vice versa. "