Irene Aegerter, Physikerin, hat ihre Dissertation am Eidg. Institut für Reaktorforschung in Würenlingen (heute PSI) ausgearbeitet, war Mitglied der KSA (Eidg. Kommission für die Sicherheit der Atomanlagen) und ist Vizepräsidentin der SATW.

Simon Aegerter, Physiker, hat seine Dissertation bei Prof. Oeschger, Klimaforscher der ersten Stunde erarbeitet, war Chefphysiker der Schweizer Armee, hat in einem Energie- "Think-Tank" mitgearbeitet und an der Weltenergiekonferenz referiert und ist Mitglied der SPG.

Challenges for the Global and Swiss Energy Sector

Irene Aegerter and Simon Aegerter


Still, more than 80% oft the global energy supply is fossil fuels (IEA, 2012). This is unsustainable for several reasons:

  • Burning fossil fuels add CO2 to the environment, thereby changing the heat balance of the atmosphere and the chemical characteristics of the oceans by acidification.
  • While the remaining resources of fossil fuels are large and possibly growing due to new discoveries and new technologies like hydraulic fracturing (fracking), their extraction gets increasingly expensive both in terms of money and in terms of energy.
  • Besides carbon dioxide, other pollutants are unavoidably linked with fossil fuels: dust, nitrous oxides and in the case of coal, heavy metals and other poisons.

A post-fossil energy economy is needed and it is pursued on many tracks in many parts of the world. There are essentially three paths that are partly complementary and not mutually exclusive:


1. Renewable Energy Sources

So far, only two kinds of renewable energy sources have played a perceptible role: Hydropower and biomass.

Hydropower in its various forms is one of the oldest forms of additional energy besides slaves and animals. Its potential is not fully exhausted, but very limited. Biomass has a large potential, but it has two serious drawbacks: 1) If not used in an industrial class process, its potential for pollution is unacceptable. The smoke of open wood- and dung fires in kitchens kills millions, according to the WHO. 2) It competes with food. The ethanol production from corn in the USA has led to a price explosion for the staple food in Mexico.

New renewable energy sources are required. Solar power and electricity from wind turbines have taken up a lot of attention lately. Their main drawback is that they deliver energy in the form of electricity. While electricity certainly is the most valuable form of energy, less valuable forms of energy like heat, that are mostly provided by fossil fuels are also required and it is economically questionable to transform electricity into lower valued heat. Furthermore, much energy is required for road- ship- and air transportation that cannot at this time be electrified completely.

As a source of electricity, the sun and the wind can substitute electricity that is now produced by fossil fuels. The main obstacles that prevent these sources from taking over the bulk of the supply from fossil fuels:

  • While electricity from fossil fuels and especially from certain classes of hydro power plants can deliver electricity on demand, the production from wind and sun are fluctuating and stochastic and therefore unfit for integration in a reliable grid, unless massive storage facilities like batteries can be developed that don’t increase the already high cost. With current technology the grid needs to be stabilized with backup production facilities that can only be fossil or nuclear. If and when photochemical processes will be available that convert solar energy directly into a fuel (photon-to-fuel processes, PTLs), the sun will be able to contribute substantially in the substitution of fossil fuels.
  • Even with an efficient PTF process in place, there remains the fact that the energy density or more precisely: the power density of solar energy is so low. No technology can increase the solar constant beyond about 1 kW/m2. Whatever the process will be to collect the energy of the sun, it will require large amounts of materials. This makes solar energy – in any form – material intensive and therefore potentially costly and environmentally questionable. The same is true for wind energy.


2. Clean Coal

The era of fossil fuels could be extended for at least a century if it were possible to collect the CO2 at the source – for instance at the stacks of fossil fuelled power plants and the exhaust pipes of vehicles – and store it safely so that it does not become part of the natural carbon cycle. Such a process is called sequestration. It has been demonstrated in one project: the Sleipner gas field off the coast of Norway. There, the CO2 that is extracted together with natural gas, is separated and pumped back into the underground gas reservoir thereby enhancing the productivity of the field.

However, the sequestration of most of the exhaust from all the stacks and tailpipes of the world is of quite another dimension. It has to be remembered that for every ton of coal burnt, 3.7 tons of CO2 have to be sequestered. In the case of oil it is 3.05 and in the case of gas 2.75 tons. So, the whole infrastructure that provides the world economy with fossil fuels would have to be quadrupled in order to be able to handle the CO2 to be sequestered. This would raise the cost of fossil fuels to unknown levels.

This does not solve the problem of the capacity of possible sequestration sites. Several have been proposed, but the sheer amount of waste makes them all look tiny or unsafe.


3. Nuclear Energy

Nuclear Energy has a bad name and is allegedly not wanted by the people. Yet, even after Harrisburg, Tschernobyl and Fukushima it remains the cleanest, safest and most environmentally safe source of energy and – if done right – will become the cheapest.

Nuclear Reactors make heat. That heat can be converted partially into electric energy or used as process heat. Future nuclear reactors will provide much higher temperatures, thereby enabling technologies that can produce synthetic fuels. Perhaps the best path for CO2 sequestration is, to use it as a carbon source to make fuels from CO2 and water using nuclear energy at high temperatures.

In the future, nuclear energy will be provided by a new generation of reactors that offer a number of choices: Large or small and modular, gas- metal- or salt cooled, based on uranium or on thorium, high or low temperature. They all are inherently safe, no conceivable accident can possibly have an impact outside the plant and a mix of the various types of reactors produce a "waste" that can be put to good use as a heat source or source of Gamma radiation in hospitals – or, if deemed waste – is harmless in 5 centuries.

Two of the contenders shall be briefly introduced here:


3.1. The Liquid Fluoride Thorium Reactor (LFTR)

In the Liquid Fluoride Thorium Reactor, the fuel is dissolved in a pool of molten salt and is itself in the form of Uranium Tetrafluoride. The core is self-regulating, that means, the reactivity and energy production drops with increasing temperature and vice versa. The salt serves as cooling agent: it transfers the heat to a secondary salt loop that in turn transfers it to a gas- or steam loop for production. The core sits in a blanket with molten Thorium Tetrafluoride. The neutrons from the core convert Thorium-232 to Uranium-233, which is fissile and can be fed into the core to replace the fissioned fuel.

Unlike in light water- or gas-cooled-reactors there is no high pressure, and the whole nuclear part of the installation can be built without costly high-pressure standards. That makes it safer and cheaper.

The Molten Salt Reactor concept was developed in the Oak Ridge National Labs and a prototype was operated for several years in the 1960s without incident. Presently, the concept is being vigorously developed by the Shanghai Institute of Applied Physics under the direction of Jiang Mianheng. A 10 MW prototype should be ready by 2017.


3.2. The Integral Fast Reactor

The common Light Water Reactors in use today use only U-235, which constitutes 0.7% of the bulk Uranium. The rest is almost exclusively U-238 which is not fissile but can be converted into fissile Pu-239. A reactor called the Experimental Fast Breeder was built and operated for many years at the Argonne National Laboratory in Idaho. In order to avoid transport of spent fuel to reprocessing plants, a reprocessing plant was added to the reactor. Such a reactor can extend the availability of nuclear fuel by a factor of 140. The project was scrapped in 1992 for political reasons, but the concept is being developed in various versions in Russia, China and the USA. A consortium of General Electric (GE) and Hitachi will demonstrate a prototype by 2020.


4. Conclusions

With the new generations of nuclear reactors, all of the perceived dangers and problems of nuclear power will be eliminated: The Generation IV reactors are inherently safe in normal and abnormal operations, they are proliferation resistant and they use the long lived "waste" isotopes as fuel. They utilize Thorium and all of the Uranium, thereby making the available resources essentially inexhaustible.

Taking these insights into consideration Asian and Eastern European Nations (Russia, Korea, China, India etc) and United Arab Emirates have embarked on a coming nuclear age. The USA are hesitantly following suit. In Europe only Germany and Switzerland plan to abandon their nuclear capacity.


5. Recommended actions for Switzerland

Switzerland is at a crossroad to determine the Energy future and that means the people have to decide, which way to go. The proposed "Energiewende" relies on renewable energy sources, mainly solar electricity and wind power. In order to stabilize the grid, gas fired power plants are envisioned. Considering that solar electricity is available, averaged over the year, for only more than 10% of the time, this puts the goal of getting rid of fossil fuels in peril.

Swiss scientist and engineers could play an important role building the energy systems of the future and thereby enable our industrial corporations to profit from worldwide demand for new energy technologies. Sectors, where Swiss research and industry has promising expertise are among others:

  • Artificial photosynthesis (UZH, EPFL).
  • Chemical technology for processing of molten salts (ETHZ and Industry).
  • Electro-chemical storage (ETHZ, Industry).
  • Grid integration of solar power plants (ETHZ, Industry).
  • High temperature solar heat (PSI).
  • Life cycle analyses of various energy supply chains (PSI).
  • Theoretical concepts for and simulation of molten salt flows (ETHZ).

Politics should enable these and other potential contributors for a post-fossil energy age to develop their strengths so that they will be prepared to compete successfully on the world market for a post-fossil fuel age.



  • Robert Hargraves: "Thorium energy cheaper than coal“, ISBN 9781478161295
  • Deutsche Übersetzung von Simon Aegerter: Robert Hargraves: "Thorium billiger als Kohle-Strom“, ISBN 9781497301856
  • Charles E. Till, Yoon Il Chang: „Plentiful Energy“, ISBN 9781466384606



[Released: May 2014]