Energy and Climate

Without computer simulations, the operation of nuclear power stations would be very difficult. Whether it is a question of installing new components or conducting safety tests, virtually everything has to be calculated and analysed on the computer first. At the Laboratory for Reactor Physics and Systems Behaviour of the Paul Scherrer Institute PSI, computational models and methodologies are developed with precisely this in mind. Through this, PSI researchers also act as an independent partner to the national regulatory authority ENSI and contribute thereby to support safe operation of the Swiss nuclear power plants.

The idea of producing fuel for nuclear power stations in form of a package of spheres instead of today’s customary pellets was already born back in the 1960s. There was promise of a subsequent simplification of fuel production and a considerable reduction in the amount of radioactive waste both in the production of the fuel itself and after its use in a nuclear power station. However, the spherical fuel was never implemented as the fast reactors for which it was conceived were never built at a large scale. The Paul Scherrer Institute (PSI) has also been involved in the research on spherical fuel in the past. Now several projects partly funded by the EU are currently underway at the PSI again to refine the production of fuel spheres further. This form of fuel could either be used in special plants to reduce waste or in fast generation IV reactors, which in a closed cycle also produce less long-lived waste.

Researchers at the Paul Scherrer Institute (PSI) are currently involved in an international project aimed at reconstructing what happened to the reactor units during the nuclear accident at the Japanese nuclear power station, Fukushima Daiichi in March 2011. In particular, the estimate of the core end-state will help the owner of the damaged plant, the Tokyo Electricity Power Company (TEPCO) to plan the removal of components from the reactor containment and the final decontamination. Besides, the exercise is intended to contribute to further refinement of the computer programs used to perform nuclear accident simulations

Fuel cells that convert hydrogen into power and only produce pure water as a by-product have the potential to lead individual mobility into an environmentally friendly future. The Paul Scherrer Institute (PSI) has been researching and developing such low-temperature polymer electrolyte fuel cells for more than 10 years and initial field tests have already demonstrated the successful use of these fuel cells in cars and buses. However, further research is still required to improve the durability and economic viability of the technology. An international team of researchers involving the PSI has now manufactured and characterised a novel nanomaterial that could vastly increase the efficiency and shelf-life of these fuel cells à as well as reduce material costs.

How do radioactive substances move through the host rock in a deep repository for nuclear waste? Researchers from the Diffusion Processes Group in the Laboratory of Waste Management at the Paul Scherrer Institute (PSI) have been investigating. The transport properties of negatively charged radionuclides, which are repelled by the negatively charged surfaces of clay minerals and thus hardly adhere to the rock, are well known. An EU project in which the PSI is also involved is now yielding similar insights into positively charged and therefore highly adherent radionuclides.

The manipulation and examination of irradiated and therefore radioactive objects, be they from nuclear power stations or research facilities, requires strict safety measures. Tests may only be conducted in so-called “hot cells”, where the radioactivity is hermetically enclosed and shielded behind concrete and lead walls up to 1 metre thick. In the hot cells of the PSI hot lab, the burnt-off fuel rods from the Swiss nuclear power stations are studied from a materials science perspective. The insights gained help nuclear power station operators to optimise the efficiency and safety of their plants. Besides this service, the hot lab is involved in several international research projects.

The supply of a vapour saturated gas mixture plays a crucial role in many industrial processes. In this way, for example, the emission of nitrogen oxides during diesel combustion can be reduced by ensuring high vapour saturation of the gas mixture. A scientist at the Paul Scherrer Institute has come up with an invention which enables this to be implemented industrially in the future via a simple, flexible and robust technique.

Neutrons are an excellent tool for the non-destructive imaging the interior of objects. They can provide a valuable complement to the more widely used x ray radiography. For some materials that are virtually opaque or for those that cannot be distinguished by X-rays, neutrons provide the only informative ‘dissection tool‘. However, neutron radiography is mainly confined to the laboratory and fixed facilities, because neutron generation relies on equipment like nuclear reactors or particle accelerators, which are costly, complex and cannot be moved. Scientists at the Laboratory for Thermohydraulics at the Paul Scherrer Institute PSI want to develop a more flexible imaging technique based on fast neutrons.

The life cycle inventory database ecoinvent forms the basis for life cycle assessment projects, eco-design, and product environmental information. Since 2003, ecoinvent has enabled companies to manufacture their products more in harmony with the environment, policymakers to implement new policies, and consumers to adopt more environmentally friendly behaviour. The new version 3.0 is a further milestone in life cycle assessment: new and updated data offer ecoinvent users a greater number of possible applications in the areas of e.g. chemical production, foodstuffs, vegetables and electricity.

Household waste always used to end up left untreated in landfills, and the effects of this practice are well-known: these waste disposal sites were quite often ecological "death zones". With the incineration of municipal waste, there was some mitigation of this problem: despite the overall increase in quantities of waste, the areas claimed by landfill have been limited in recent decades thanks to waste recycling and incineration. However, waste incineration remains far from a panacea. Some combustion products that are already present in the burnt materials or that arise just during the combustion process itself are harmful to human health and the environment and some of them still find their way out of waste incineration plants and into landfill sites as their final destination.

Megacities are often perceived by the public to be major sources of air pollution, which affect their surroundings as well. However, recent studies show that the environmental credentials of cities with over one million inhabitants are not so bad after all. An international team of researchers, including scientists from the Paul Scherrer Institute (PSI), has now confirmed, on the basis of aerosol measurements carried out in Paris, that so-called post-industrial cities affect the air quality of their immediate surroundings far less than might be thought.

For the discovery and characterisation of the miraculous material graphene à a layer of carbon exactly 1 atom thickà two Russian born physicists were awarded the Nobel Prize in 2010 and got a huge amount of media attention. Ever since graphene was first isolated, scientists all over the world have been rushing to find applications. Recently, scientists at the Paul Scherrer Institute PSI laid the foundations for a graphene-based super capacitor. With its help, the lifespan of batteries in hybrid cars could be extended significantly

Lithium-ion batteries are high performance energy storage devices used in many commercial electronic appliances. Certainly, they can store a large amount of energy in a relatively small volume. They have also previously been widely believed to exhibit no memory effect. That’s how experts call a deviation in the working voltage of the battery, caused by incomplete charging or discharging, that can lead to only part of the stored energy being available and an inability to determine the charge level of the battery reliably. Scientists at the Paul Scherrer Institute PSI, together with colleagues from the Toyota Research Laboratories in Japan have now however discovered that a widely-used type of lithium-ion battery has a memory effect. This discovery is of particularly high relevance for advances towards using lithium-ion batteries in the electric vehicle market. The work was published today in the scientific journal Nature Materials.

Exhaust gases produced by diesel combustion are freed from harmful nitrogen oxides with the aid of an aqueous urea solution. That’s the state of the art. The urea decomposes into ammonia and this, in turn, reduces the nitrogen oxides into harmless nitrogen. However, the urea solution can produce undesirable solid residues and, in addition, freeze in extremely cold weather. Now researchers at the Paul Scherrer Institut (PSI) have developed a catalyst which can be used with better reducing agents than urea for nitrogen oxide reduction.

In nighttime photographs taken from space, the large cities of the world can easily be recognised by the flood of their public lighting. However, probably only the trained eye is able to see, as well as New York or Tokyo, the locations of many oil-producing wells . The light in these cases originates mainly from the combustion of methane. This huge waste of an energy-rich gas has devastating economic and ecological consequences. Reasearchers at the Paul Scherrer Institute PSI are looking for a solution: the conversion of methane into the liquid energy carrier methanol

Researchers in the Energy Economics Group at the Paul Scherrer Institute PSI have used their model of the Swiss electricity system —called STEM-E — to analyze various electricity supply scenarios. They have concluded that alternatives to today's electricity supply are associated with different costs, risks and opportunities. Realising sustainability objectives such as climate protection while phasing out nuclear generation and making Switzerland's electricity supply independent of foreign countries raises many challenges. Furthermore, their analysis suggests that costs of electricity production are likely to increase by at least 50 percent by 2050

Lithium-ion batteries are one of today's best technologies for storing electrochemical energy. They have a high energy density and specific energy and a sufficiently long lifetime to allow them to be used in microelectronic devices and cars. The commercial rise of Li-ion batteries in the last two decades is impressive. However, further improvements are possible and this is a field in which researchers at the Paul Scherrer Institute (PSI) are working. Nevertheless, the potential of the Li-ion battery is limited chemically and it will only be possible to achieve an even higher energy density, which is crucial for electric mobility in particular, by using other new types of batteries.

Ice and snow have fundamental significance for our climate. Generally speaking, one assumes that science knows everything that is important about such everyday phenomena. Yet, as soon as one looks at the whole at the molecular level, many questions remain unanswered. This knowledge is essential for predicting the future of our planet. Thorsten Bartels-Rausch in an interview about the great unknowns.

Switzerland is facing a potentially radical restructuring of its energy system in the light of the Federal Government's Energy Strategy 2050. One particular challenge associated with achieving the goals of the Strategy is realizing an electricity supply sector that responds to uncertain developments in electricity demand, national climate targets and the decision to phase out nuclear power. In order to investigate options for this transformation of the electricity sector, researchers at the Paul Scherrer Institute (PSI) are developing and analyzing a range of alternative scenarios of the future electricity system in Switzerland. These scenarios are developed, quantified and explored with an analytical tool built at PSI that simultaneously examines long-term developments (to 2050 and beyond) while accounting for seasonal and daytime fluctuations in electricity demand and supply.

Researchers at the Paul Scherrer Institute PSI have gained valuable insights into one of the most common ageing mechanisms of polymer electrolyte membranes in hydrogen fuel cells. The robustness of these membranes is crucial in determining the lifespan of a fuel cell. The new findings contribute to longer-lasting cells by a better understanding of one of the main challenges for the commercialisation of these clean energy converters.