When a generator is driven by a turbine, it generates electricity. When the generator is supplied with electricity instead, it works as a motor and can drive a pump. This principle is used in pumped storage plants. They are used to store electrical energy. In the storage process, water is pumped from a reservoir up to a lake located at an higher altitude. This water can then be released at a later time to drive turbines.
Pumped storage power plants can store electricity at times when electrical energy is abundantly available. When demand peaks are high, they can supply electricity by turbining the pumped up water. For this reason, a pumped storage plant is also referred to as a peak energy plant. In view of the limited efficiency, only part of the energy absorbed is recovered. The profitability of a pumped storage power plant results primarily from power market price variabilities at different points in time.
The Limmern pumped storage plant (LPSP) is one of Axpo's most important expansion projects in recent years with investments amounting to CHF 2.1 billion. The ground-breaking ceremony took place in 2009, followed by a construction and planning period of about ten years. With an output of 1000 MW, the LPSP is a huge battery in the Glarus Alps. In contrast to pure storage power plants, pumped storage plants such as LPSP cannot only generate peak energy. They can also convert excess electricity generated during off-peak periods into valuable peak energy (see also: How it works).
The new LPSP, built underground in the rock, can pump water back from the Limmern lake to the Muttsee reservoir located 630 metres higher up, and then reuse it for electricity production when necessary.
With a length of 1054 metres, the Muttsee dam is the longest in Switzerland and lies at around 2500 metres above sea level. It is therefore also the highest dam in Europe. The 250,000 m3 of concrete - that's how much was needed to build the record-breaking dam - is offset by the huge water volume of 23 million m3 that the gravity dam on Muttenalp can hold.
The most important facts about LPSP at a glance:
Rudolf Hug, former member of the Axpo Board of Directors and passionate photographer, published his latest book "Jahrhundertwerk im Glarner Kalk" in 2019. It describes the genesis and operation of the Limmern pumped storage power plant. Impressive pictures over 156 pages underline the importance of this pioneer project.
Order here ISBN: 978-3-9524084-7-6
Follow the construction of the Limmern pumped storage power plant in fast-forward mode.