In long-term projects, scientists of the ETH Domain explore options to guarantee forms of energy supply in Switzerland that are resource-efficient, compatible with the climate, safe and independent. Examples of this include the optimisation and intensification of combined gas power plants with CO2 carbon capture, deep geothermal energy, solar energy, hydropower and biomass.

Thin-film solar cells on a transparent polyimid foil developed by Empa. Thanks to the flexibility of the foil, the solar cells can be mounted on a variety of surfaces. Source: Empa.

Energy research in the ETH Domain has a long-term orientation and plays an important part. Research projects concentrate on the potential, the feasibility and the risks of various energy technologies and thus provide a basis for political decision-making. Researchers do not only focus on increasing efficiency but also on the optimisation of renewable energies such as hydropower, biomass, solar energy and deep geothermal energy, as well as a reduction in the CO2 emission of combined gas power plants. “It is the task of research to demonstrate the options and challenges of different energy technologies. The decisions, however, will have to be made by the politicians,” says Fritz Schiesser, President of the ETH Board.

Environmentally friendly combined gas power plants
A modern combined gas power plant with an output of 400 Megawatts could replace a nuclear power plant the size of Mühleberg. However, this would entail additional greenhouse gas emissions of about one million tonnes of CO2 per year. It is technically feasible today to capture this CO2 before it reaches the chimney and to channel it into the ground instead of into the air. In depths of at least 800 metres, below dense rock strata, it can be permanently stored in a way that is similar to natural oil or gas deposits. Whether and to what extent this process is also feasible in Switzerland is being investigated in the CARMA project headed by Prof. Marco Mazzotti of the ETH Zurich. In this context, the storage capacity and the costs play as much of a role as sustainability and acceptance by the population. For the latter, it is primarily the effectiveness and safety of the CO2 storage that is of central importance. To demonstrate both in a field trial is the researchers’ declared aim. “Speed is of the essence since experience shows that a field trial takes about ten years from planning stage to conclusion. The storage of the CO2 volumes from combined gas power plants should only be realised after a successful demonstration,” says Marco Mazzotti.

Inexhaustible energy in the Earth’s interior
“The heat in the Earth’s interior represents an energy resource that is unlikely ever to be depleted. The potential of deep geothermal energy is not limited by the resources that are available but by technology,” says Marco Mazzotti. Natural strata with hot water which satisfy all the requirements for power generation can only be found in very few locations. Enhanced geothermal systems (EGSs) are capable of providing access to a substantially larger part of the thermal energy that exists deep down in the Earth and of making it utilisable at the surface. In this procedure, the permeability of rock is increased by means of stimulation in order to enable the water to circulate through the hot reservoir. Various aspects of this advanced reservoir exploitation are being further developed in the ETH Domain, including the avoidance of perceptible seismic activity and new drilling processes.

In 80 minutes, the Earth receives as much solar energy as the whole of humankind uses up in a year.

Thin-film solar cells with market potential
It is not only the Earth’s interior that contains immense energy potential; in theory, the sun would also be able to solve our energy problem. “In 80 minutes, the Earth receives as much solar energy as the whole of humankind uses up in a year,” says Prof. Gian-Luca Bona, Director of Empa. In order to make even better use of solar energy, Empa focuses on the development of a new generation of photovoltaic cells that are mounted on foil by means of thin films. In the laboratory, these anorganic thin-film solar cells have already displayed an efficiency level of over 18 per cent. The efficiency level describes the proportion of incoming solar energy that is converted into electric power. To be able to mount thin-film solar cells on different materials of large dimensions at favourable cost, Empa’s researchers are developing a kind of printing technology that might facilitate a widespread application of thin-film solar cells.

Making even better use of hydropower
Hydroelectric power plants produce 55 per cent of electric power in Switzerland. Thus hydropower is this country’s most important renewable energy. Pumped storage power plants, in particular, play an important part in cushioning peak demand, in the generation of power reserves and the integration of new renewable energies into the power grid. At the EPFL in Lausanne, various projects are under way that are concerned with the exploration of efficient modes of operation for pumped storage power plants and their comprehensive monitoring. Massimiliano Capezzali, Deputy Director of the EPFL’s Energy Center, is convinced that the maintenance of power plants must also be accorded a great deal of importance: “A renovation and extension of Swiss hydroelectric power plants could substantially increase their energy production.”

In parallel, the Aquatic Research Institute Eawag is exploring what effects the utilisation of hydropower has on aquatic ecosystems and how negative consequences such as fish migration and the dynamics of river landscapes can be avoided. At the WSL, studies are in progress about future water availability in Switzerland. Researchers are investigating how much water will be available for power generation in a warmer climate with less snow and partially melted glaciers.

Methane for a decentralised power supply
After water, biomass is Switzerland’s second most important source of renewable energy. The term biomass denotes all the organic materials that are produced by photosynthesis and that have not been changed by geological processes like oil and coal. For the purpose of energy production, biomass is converted into fuels, chemicals or methane by means of catalysis or gasification. “Methane could be a driver for a decentralised power supply or used for vehicles with gas engines,” says Prof. Alexander Wokaun, Head of the General Energy Department at the PSI. In energy production with biomass, it is predominantly wood-type waste that is used. According to an Eawag study, the production of methane from wood (biogas) would provide Switzerland with a good complement to established energy technologies.

Much used wood
Owing to the scarcity of fossil fuels in the last few years, the generation of heat and energy from wood has increased in significance. In order to be able to plan a possible expansion in the generation of wood energy, it is important to know the wood reserves available in Swiss forests. This knowledge is provided by the National Forest Inventory (LFI), which is conducted by the WSL together with the Federal Office for the Environment. Forests do not only serve as an energy resource but also as places for recreation and biodiversity, and they provide protection against natural hazards. In addition, wood is an important building material. All this can result in conflicts over use, which is why the WSL is exploring how much wood will be available for energy production in future. To this end, it is developing various scenarios concerning factors such as climate, management and utilisation for other purposes.

Even though waste wood constitutes a sensible type of biomass, Alexander Wokaun and his team are doing research into alternative materials that have a high, still unused energy potential. According to Alexander Wokaun, a promising source is biomass containing water such as liquid manure or sewage sludge, which is converted into methane under high pressure. The researchers at the PSI are currently developing a pilot plant for this procedure.

Energy efficiency is indispensable
Even if Switzerland optimises energy generation, it is indispensable to use any energy available more efficiently. The Competence Center Energy and Mobility (CCEM) at the PSI promotes energy research projects in the ETH Domain that involve more than one institution. In this way, it makes a contribution towards the solution of the great challenges that the Swiss energy system is facing, a system which is expected to provide energy services in a resource-efficient, low-emission, reliable and economical manner. The ways in which these sustainability goals can be achieved are being explored at the CCEM. They comprise an increase in efficiency in all energy conversion steps, energy storage, as well as the replacement of fossil fuels by energy sources that are low in CO2.

In the institutions of the ETH Domain, numerous projects are ongoing for the development of energy-efficient technologies. Thus the PSI is conducting research into more efficient vehicles. In cooperation with industry, PSI researchers have developed fuel cells that might serve as a basis for a marketable vehicle drive. At Empa, scientists are searching for technologies that reduce the energy consumption of buildings;  interesting approaches include plasters on the basis of nanomaterials. Such a high-performance type of insulating plaster developed by Empa provides insulation that is two to three times better than that of conventional plaster and is suitable for both new buildings and renovation work.

Eawag is continuing to develop energy-saving processes for waste water treatment, which are already used in a sewage plant in the city of Zurich, for instance. Finally, the EPFL is cooperating with the cities of La Chaux-de-Fonds, Lausanne, Martigny and Neuchâtel to develop a software that will enable the cities to better plan and manage their energy supply and energy demand.