Can renewables fill the power gap?

Lots of potential – but not unlimited

The conclusion of our work is clear: a future electricity supply for Switzerland that is as climate-friendly as today’s will only be possible with a rapid and massive expansion of photovoltaic generation. Because this is where the far widest potential for renewable electricity production lies in Switzerland – large enough to almost replace the nuclear power plants. At least in annual energy production. However, a part of the electricity from photovoltaic plants must be stored, to be transferred from mid-days to evenings, and from summer to winter. Here the appropriate means are still partially missing: while batteries can supply short-term storage today, the question of optimal seasonal storage still remains unanswered. In addition to photovoltaics, wind, biomass, geothermal energy and hydropower also must use their additional potential, which, however, are already today pushing against social reservations. In general, the biggest question is the potential for geothermal energy. Deep geothermal energy is currently in the research stage and it is still unclear whether, when and how much electricity this technology will produce in Switzerland in the future. If one looks at the limited total opportunities for renewable electricity production here, then it is clear that future electricity consumption should not increase. This is an ambitious goal in the face of the trends towards electric mobility, more heat pumps and increasing population. Otherwise, Switzerland will probably not be able to do without gas-fired power plants or more electricity imports.

"Exploitable potentials" for Swiss electricity supply in 2050 (in addition to production 2015/16). Exploitable potentials basically correspond to technical potentials reduced by environmental and economic constraints. To some extent, also social aspects are taken into account as limiting factors.

Green electricity is worth its price

It is certainly foreseeable that electricity from photovoltaic installations and wind turbines will continue to become cheaper in the future. But for biomass, hydropower and the other alternatives this is likely not the case: as soon as more biomass will be used, biomass prices in Switzerland will climb; the same holds true for natural gas according to international trends; for gas power plants the separation and geological sequestration of the CO₂ emissions will bring additional costs, and deep geothermal energy is also not yet an economical technology. Overall, our results suggest that electricity bills will be higher in the future than they are today. It seems quite justifiable to me, however, that a wealthy country like Switzerland should be willing to afford a sustainable and secure power supply.

Levelized costs of electricity generation in 2050.

This is all the more true when one recalls the so-called "external costs" that represent negative environmental consequences. It is not the polluter but the general public who must pay for these external costs. These include, for example, the consequences of climate change, which we are causing with our CO₂ emissions today and which will burden future generations. These CO₂ emissions – even taking into account the emissions that are incurred in the production of the power plants – are significantly lower for most renewables than for gas power plants. The remedy could be the capture and permanent geological storage of CO₂. However, it is still not clear today whether CO₂ storage will ever be feasible given the prevailing conditions in this country. The recently launched EU research project "ELEGANCY" seeks to answer this question, where, among others, ETHZ and PSI from Switzerland are involved.

Life-cycle greenhouse gas emissions of electricity generation in 2050.

Bundle activities

What is needed now after our work is a systemic perspective: how can these individual technologies best work together in the future? What types of energy storage are needed and how can the move towards electric mobility best be made? The "Joint Activity Scenarios & Modeling" effort, which bundles the know-how from various SCCERs, has recently been dedicated to addressing questions of this kind. First results are expected by the end of this year.