DE |EN |FR |IT
Alpiq in: Switzerland
Alpiq Group

Gas-fired combined cycle power stations

Chavalon/Vouvry

Chavalon/Vouvry – possible site for a gas-fired combined cycle power station

Functional principle of a gas-fired combined cycle power station

Gas-fired combined cycle power stations function using a gas turbine and a steam turbine. Gas mixed with compressed air is burnt in the combustion chamber. A hot propellant gas is created that drives a gas turbine. This is connected to a generator that generates electricity. The hot exhaust gases are passed to a heat exchanger in which water is vaporised. This water vapour drives a steam turbine which in turn drives a second generator. A gas-fired combined cycle power station uses the thermal energy far better than an individual gas or steam turbine and instead of 40 percent achieves an efficiency of around 60 percent.


Gas-fired combined cycle power stations in Switzerland

Fossil-fuel-based electricity generation plays only a minor role in Switzerland. Here it has a share of around 3% of the electricity supply. The planned phasing out of nuclear energy is now leading to an actual entry into the fossil-fuel-based generation of electricity. The Swiss Federal Council anticipates the construction of a new gas-fired combined cycle power station by 2020. By 2035 this could become 5 to 6. At that time the Federal Council assumes a share of electricity generated using fossil fuels of around 20%.

In order that this vision can become a reality, policymakers must first define the framework conditions such that it even becomes possible to build gas-fired combined cycle power stations and to operate them economically. However, until now this has not occurred, primarily as a result of climate protection policies, and probably also due to a lack of sites. Admittedly, from 2013 50% of the CO2 emissions can be offset abroad. But that is still a huge obstacle for the economical operation of the power stations.


The Chavalon gas-fired combined cycle power station

A possibility for the construction and economical operation of a new gas-fired combined cycle power station, is the existing site of the decommissioned oil-fired power station at Chavalon in the lower Valais region of Switzerland; namely in September 2012, the operator EOS Holding and the Swiss Federal Office for the Environment (FOEN) were able to agree on a CO2 compensation regime. However, the economic viability is naturally dependent upon whether the new gas-fired combined cycle power stations can be operated to continuously generate electricity or whether they are permitted to be operated only intermittently for the supply of peak-load electricity. Depending on the situation, the calculation looks different. It will become apparent within the context of the consultation process on the Energy Strategy 2050 as to which form of operation is basically foreseen, and whether for the present it is only a question of a single gas-fired power station – namely preferably Chavalon with the advantage of the existing site.