July 9th, 2019 by Steve Hanley on Clean Technica.com, Researchers In Switzerland Say Zero Emission Society Will Require Seasonal Energy Storage
Researchers Martin Rüdisüli, Sinan Teske, and Urs Elber of the Swiss Federal Laboratories for Materials Science and Technology (EMPA) have studied what will be needed to make Switzerland able to use only zero carbon energy. Among their main conclusions is that the country can produce more electricity than it needs from renewable sources in the summer but will need to import electricity from its more southerly neighbors in winter.
Image courtesy US Green Building Council
In a report published in the journal Energies, they used data provided by Swissgrid to determine the current demand for electricity in quarter-hour increments year round. They then posed the question, “How would demand change once most heating and transportation in Switzerland is electrified?” The answer they came up with is that demand will increase by approximately 13.7 terawatt-hours on an annual basis.
That figure further assumes that significant steps are taken to shift to electric vehicles where possible in the transportation sector and to improve the energy efficiency of existing residences and commercial structures. According to a report in Science Daily, the research assumes heating requirements of all buildings will first be reduced by around 42% through renovation measures and that 3/4 of the remaining heating requirements in houses and apartments will be achieved using electric heat pumps. It further assumes about 2/3 of all private car trips will be in electrically-powered automobiles.
The research focuses on five areas. First, replacing conventional furnaces with heat pumps. Second, because Switzerland proposes to end its use of nuclear power, each nuclear power plant must be replaced with about eight times the photovoltaic output. A nuclear plant delivers around 8,000 hours of electricity per year but a solar cell delivers only about 1,000 hours a year. As a result, solar panels will need to be installed on virtually all available surfaces.
Third, a dramatic increase in electrical storage capacity using all available technologies including batteries and pumped hydro as well as geothermal and technologies that convert electricity into chemical energy sources. Fourth, they recommend heat storage technologies so the use of heat pumps can be reduced as much as possible in winter.
Fourth, create seasonal heat storage facilities so that the electricity requirements of the heat pumps can be reduced in winter. Fifth, new HVDC transmission lines that will bring electrical power from sunnier southern countries to Switzerland in the winter when electrical demand is highest. A bright spot in the analysis for electric vehicle advocates is that EVs will not unbalance the grid as they can be charged when electricity is plentiful, assuming a proper charging infrastructure is created.
“For the sustainable conversion of our energy system to succeed, we need both short and long term — i.e. seasonal — energy storage technologies. That is why we should not play off energy sectors against each other, but keep all technical options open,” says Martin Rüdisüli. Sinan Teske adds: “We must learn from nature how to deal with solar energy, which is not available all year round. We could store as much as possible in summer and limit our needs in winter. Or we could look for partners in the southern hemisphere of the earth who can harvest solar energy and deliver it to Switzerland when winter is here, and vice versa.”
The bottom line is that renewable energy may be abundant at certain times but storage will be key to creating a low or zero carbon society, coupled with robust transmission lines that can transport electricity from where it is abundant to where it is in limited supply.
The most important takeaway from the EMPA study may be the value of improving the energy efficiency of homes and businesses. A kilowatt-hour of energy saved is a kilowatt-hour of electricity that doesn’t have to be generated. Heating and cooling of buildings accounts for more greenhouse gas emissions than the entire transportation sector, according to the US Green Building Council.
The upshot of all this is that decarbonizing the economy is about more than putting up more solar panels or wind turbines. It will take a lot of planning and a lot of work by people, businesses, and governments to make it viable. But we need to get started as soon as possible. There’s no time to lose.
From Science Daily:
If we want to get rid of fossil fuels nationwide, there is a lot to do. It will be a generation project, that much is clear. EMPA researchers Martin Rüdisüli, Sinan Teske and Urs Elber have now calculated how long and steep the road to a sustainable energy system might be; their study was published at the end of June in the journal Energies.
The researchers chose a conservative approach and initially collected real data on electricity consumption, heating requirements and hot water consumption in Switzerland. These data then served as the basis for a thought experiment. Switzerland’s electricity requirements are still quite easy to determine: The Swiss grid operator Swissgrid provides detailed values for every quarter of an hour on every day of the year. Heating energy and hot water requirements are becoming more difficult. The Empa experts used data from the district heating supplier REFUNA, which supplies several communities in the lower Aare Valley with waste heat from the Beznau nuclear power plant. A data analysis showed that the heat requirement of the connected houses correlates quite well with the outside temperature — and at nights warmer than 18 degrees Celsius, the heat is therefore only used for process water and shower water.
Electrifying heating systems and cars
For their thought experiment, the researchers made various presumptions. Firstly, most Swiss residents behave like people in the lower Aare Valley and live in similar buildings. Secondly, in order to get away from heating oil and natural gas, the heating requirements of all buildings will first be reduced by around 42% through renovation measures; then 3/4 of the remaining heating requirements in houses and apartments renovated in this way will be realised with electric heat pumps. And thirdly: Mobility will be electrified to the extent that approximately 2/3 of all private car journeys can take place electrically, which corresponds to approximately 20% of all kilometres driven. Freight traffic and long-haul journeys, 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 Empa study — because the phase-out of nuclear power has been decided since the referendum on the Energy Act of May 2017. Therefore, the researchers expected a strong expansion of photovoltaics; half of all roof surfaces in Switzerland rated as good to outstandingly suitable within the framework of the http://www.sonnendach.ch project are equipped with solar cells. This corresponds to about one third of all roof areas in Switzerland.
How much does the demand for electricity increase?
Next, the researchers determined the resulting electricity consumption, which is likely to rise by around 13.7 terawatt hours per year due to heat pumps and electric vehicles — i.e. by around 25 percent compared to today. Even more alarming than this significant increase in consumption, however, was the temporal gap between electricity generation and demand: solar cells produce the most electricity in summer — but heat pumps and heated cars require a particularly large amount of electricity in winter. This results in a seasonal supply gap.
This could be compensated for by importing electricity from neighboring countries, as is already the case today in the case of shortages. But CO2 balance will probably suffer as a result — because electricity from Europe often massively worsens the CO2balance of Switzerland, which has been so carefully electrified. Heat pumps and electric cars therefore benefit the climate the most if the electricity required for them is also renewable.
What do the researchers suggest?
The EMPA study also provides some valuable information on how to implement a low-CO2 energy system. Firstly, it makes most sense to replace oil-fired heating systems with heat pumps if the buildings are insulated using state-of-the-art technology. Because a heat pump without appropriate insulation is significantly less efficient. Secondly, each nuclear power plant must be replaced with about eight times the photovoltaic output. Why? A nuclear power plant delivers around 8,000 hours of electricity per year — a solar cell, however, only 1,000 hours. This means a large number of solar panels — on all available surfaces. Thirdly, we need as much storage capacity as possible for solar energy — both local battery storage facilities and pumped storage facilities as well as other storage technologies, in particular (geothermal) heat storage facilities, but also technologies for converting electricity into chemical energy sources. This is because the sun shines strong enough only a few hours a day to fill the storages. For the rest of the time, the stored energy has to last.
Fourthly, we must create seasonal heat storage facilities so that the electricity requirements of the heat pumps can be reduced in winter. Fifthly, we need to better match energy supply and demand. There will be plenty of solar power and heat in summer, but in winter renewable energy in particular will be a rare (and therefore expensive) commodity in the future. Sixthly — and this is the good news: electromobility does not make the balance tilt. Under the assumptions made, the daily charging of electric vehicles at home, at work or when shopping generates only relatively low peaks in electricity demand compared with the electrical heat supply. A prerequisite for this, however, is appropriate networks with sufficient capacity.
If further renewable energies such as wind power, geothermal energy, more biomass and a little more hydropower are realised in winter in the future, the coverage gap will shrink, however, it will probably not be possible to close it completely. The electrification of heat and mobility alone will therefore not solve the problem. “For the sustainable conversion of our energy system to succeed, we need both short- and long-term — i.e. seasonal — energy storage technologies. That is why we should not play off energy sectors against each other, but keep all technical options open,” says Martin Rüdisüli. And Sinan Teske adds: “We must learn from nature how to deal with solar energy, which is not available all year round. We could store as much as possible in summer and limit our needs in winter. Or we could look for partners in the southern hemisphere of the earth who can harvest solar energy and deliver it to Switzerland when winter is here, and vice versa.”
Swiss Federal Laboratories for Materials Science and Technology (EMPA). “Thought experiment: Switzerland without fossil fuels. Can that succeed?.” ScienceDaily. ScienceDaily, 8 July 2019. <www.sciencedaily.com/releases/2019/07/190708122332.htm>.
Martin Rüdisüli, Sinan L. Teske, Urs Elber. Impacts of an Increased Substitution of Fossil Energy Carriers with Electricity-Based Technologies on the Swiss Electricity System. Energies, 2019; 12 (12): 2399 DOI: 10.3390/en12122399
Impacts of an Increased Substitution of Fossil Energy Carriers with Electricity-Based Technologies on the Swiss Electricity System
Martin Rüdisüli *, Sinan L. Teske, and Urs ElberSwiss Federal Laboratories for Materials Science and Technology (Empa), Überlandstrasse 129, CH-8600 Dübendorf, Switzerland*Author to whom correspondence should be addressed.Energies2019, 12(12),2399; https://doi.org/10.3390/en12122399 Received: 13 May 2019 / Revised: 14 June 2019 / Accepted: 17 June 2019 / Published: 21 June 2019 Full-Text PDF [2129 KB, uploaded 3 July 2019] |Figures
Electrifying the energy system with heat pumps and battery electric vehicles (BEV) is a strategy of Switzerland and many other countries to reduce CO2 emissions. A large electrification, however, poses several new challenges for the electricity system, particularly in combination with a simultaneous substitution of nuclear power plants (NPP) by volatile renewables such as photovoltaics (PV). In this study, these challenges in terms of additional electricity demands, deficits and surpluses as well as effective CO2 mitigation are assessed in a dynamic and data-driven approach. To this end, electricity demand and production profiles are synthesized based on measured data and specifications and assumptions of the key technologies at a high temporal resolution. The additional electricity demand of heat pumps is estimated from hourly measured heat demand profiles of a Swiss district heating provider, while for BEV different recharging patterns are combined. For electricity production, NPP are deducted from the current electricity production profile, while PV is added at an hourly resolution. In order to estimate CO2 emissions, life-cycle analysis (LCA) CO2 intensities of the different technologies are used. It is shown that with a BEV and heat pump penetration of 20% and 75%, respectively, there is an almost 25% (13.7 TWh/year) increase of the electricity demand and—just as challenging—an additional maximum power requirement of 5.9 GWh/h (hourly-averaged power). Without additional storage options, large amounts of electricity must be imported in winter and at night, while in summer at noon there is a large surplus from PV. Due to their high CO2 intensities—at least for the next decades—electricity imports and PV may—depending on the reference scenario (with or without NPP) and assumptions on other key parameters—even offset the overall CO2 savings of a highly electrified Swiss energy system. View Full-Text Keywords: electrification; energy strategy; Switzerland; mobility; heating; nuclear phase-out; PV▼ Figures
Graphical abstractThis is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
Rüdisüli, M.; Teske, S.L.; Elber, U. Impacts of an Increased Substitution of Fossil Energy Carriers with Electricity-Based Technologies on the Swiss Electricity System. Energies 2019, 12, 2399.