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Trade-offs in switching to renewable electricity

 

Switzerland plans to replace nuclear power with renewable electricity as part of the Energy Strategy 2050 (ES 2050). This turnaround may lead to new risks of power losses in a country that expects a very reliable supply of electricity. The researchers have found that many different mixes of domestic and imported wind and solar power can work, and a large majority of Swiss citizens support these mixes.

Background (completed research project)

Hydropower and other sources currently supply some 70% of Swiss electricity, which leaves around 30% of Swiss production to be shifted from nuclear to renewables. The new risks that brings include:

  • intermittency (e.g. sun not shining, wind not blowing or rivers being frozen),
  • extreme weather damage to our electricity grid (e.g. storms, icing, landslides, etc.), and
  • public opposition limiting the renewable generation capacity (e.g. solar panels or wind turbines) and power lines that can be built.

Possible options for renewable electricity trade off these risks: wind turbines in Switzerland are not very popular and get erratic wind but are easily connected; solar power from North Africa is predictable and accepted but needs power lines that cross several countries.

Aim

This project supports policymakers in deciding how much renewable generation Switzerland should target and where. For this, the aforementioned risks of four main options for increasing renewable electricity were examined: wind power in Switzerland, photovoltaics (PV) on Swiss rooftops and in solar farms, offshore wind in the North Sea and concentrating solar power (CSP) in North Africa.

Results

It was found that Switzerland can phase out nuclear and switch to renewables without risk of intermittency, if it does not rely solely on PV. This is because Swiss hydropower can compensate for limited intermittency, though less so in winter when PV output is low and Swiss rivers get limited water. Wind power from the North Sea is especially suited to the Swiss electricity system, as it is more stable than solar power and produces more electricity in winter. Furthermore, both North Sea wind and North African solar are likely to be cheaper than using natural gas.

The risk of outages due to extreme weather depends on the sources: for a future with a large share of imports, sufficient redundancy in transmission corridors, high-quality equipment and good procedures can minimise the risk, and Swiss hydropower provides some short-term buffer.

The team did a survey among Swiss citizens and found a consistent preference for solar electricity and, to a lesser degree, wind, to be built in existing industrial and commercial areas, including e.g. ski resorts. There are five distinct groups of voters, three of which have a very specific profile: “Pro Renewables”, “Pro Switzerland” and “Pro Landscape”. The largest two groups are “Moderates” and a group that is “Contra Status Quo” of using nuclear power. All groups except “Pro Landscape” (95% of respondents) prefer electricity from Switzerland, and all groups except “Pro Switzerland” (84% of respondents) accept imports of renewable electricity, preferably from plants operated by Swiss utilities. Natural gas is less popular than domestic or imported renewables.

For solar farms in Switzerland, there is inherent tension between using land for nature or agriculture and infrastructure. Furthermore, the need for permits and grid connections makes them unattractive to utilities at current bulk electricity prices. Rooftop PV only needs to compete with residential electricity prices, which are higher due to included grid fees and taxes. Installing PV on non-building infrastructure like avalanche protection barriers is possible, but such projects are still experimental and expensive.

Relevance

Implications for research

The scientists see two new directions for research:

  • developing ways to visualise energy infrastructure in the existing landscape to analyse acceptance, and
  • empirical study of grid vulnerability by GIS-based analysis of spatial-temporal correlation of weather patterns and grid faults.

Implications for practice

Two major implications for the implementation of ES 2050 can be identified:

  • ES 2050 can be broadened to include imports of wind and solar, as these look to be cheaper. Swiss ownership and operational control would be preferable.
  • Interpretations of ES 2050 differ among local, cantonal and national stakeholders. While there is no forum to resolve these diverging priorities, conflicts and delays are to be expected.

Original title

New risks: Potential supply interruptions and stakeholder views on the growth of renewable electricity in Switzerland

Principal Investigators

  • Prof. Anthony Patt, Institute for Environmental Decisions Natural and Social Science Interface, ETH Zürich
  • Dr. Oscar van Vliet, Departement Umweltsystemwissenschaften, ETH Zürich