In its most recent report the Global Wind Energy Council said that wind power led all technologies in new power generation in 2015. By the end of 2015, China has the most wind turbine capacity installed with 145GW. This surpassed Europe, which has 129GW of wind turbine capacity installed in total.
However, as more wind turbines are installed, operators must begin to tackle their biggest drawback: not knowing precisely when the wind will blow. This leaves wind farm and grid operators with the task of balancing fluctuating wind power and the demand for electricity throughout the day.
Water batteries
In a bid to resolve this issue and increase the efficiency of wind farms, German engineers have developed a solution to use water to store, discharge and modulate electricity output.
GE Renewable Energy has signed a turbine supply agreement with construction, technology and service company Max Bögl Wind to deliver and commission what it says will be the world’s tallest and first ever wind turbine integrated with pumped storage hydro-electric power.
The Gaildorf wind farm, located in southwest Germany’s Swabian-Franconian Forest on the Limpurger Berge uplands, will consist of four of GE’s 3.4-137 wind turbine, with a capacity of 13.6MW. Each turbine has a total tip height of 246.5m, and a 16MW capacity pumped storage hydro-electric power plant will be built.
The base and surrounding area of each wind turbine tower will be used as a water reservoir, holding 1.6 million gallons of water. A nearby valley, approximately 200m below the wind turbines, will house an additional lake reservoir and the 16MW capacity pump/generator hydro plant.
When electricity is needed, water flowing downhill from the reservoirs will power the hydro plant. When the energy supply is high, the hydro plant will pump the water back up the hill to the reservoirs, acting as the giant battery. The hydro plant will benefit from this arbitrage, making power when the price is high and using power when the price is low, while complementing the wind farm.
The combination of the two power sources working in parallel will ensure that electricity is always flowing from the plant, says GE. It is expected to provide balancing power for fast-response stabilisation of the grid, maintaining a low cost of electricity for residents in Germany.
Digital wind farms
GE’s 3.4-137 turbine is part of its new 3MW wind platform unveiled in late 2015, which the company says is suited for a variety of wind conditions across Europe. The units feature software and analytics powered by the company’s Digital Wind Farm system, which runs on Predix – an internet-based analytics service.
The system collects data from different sources, including the wind turbines, the grid and even weather forecast services and analyses it in the cloud. The insights help operators predict maintenance needs, optimise production throughout the day and control how much power can flow into the grid at any given time.
The team behind the farms says the design provides a very fast increase in output, allowing the hydro plant to react immediately to fluctuations in the German energy market. However, for it to work in other locations, the wind turbines must sit at the top of a hill, and there must be room in the valley for a man-made lake — in this case the lake below the wind farm—that will store the water when it’s not being used by the turbines.
“Germans in this area are known as tinkerers and inventors,” says Cliff Harris, general manager for onshore wind in Europe at GE Renewable Energy. “So the mentality of this technology really fits with the population.”
The team behind the farms says the design provides a very fast increase in output, allowing the hydro plant to react immediately to fluctuations in the German energy market. However, for it to work in other locations, the wind turbines must sit at the top of a hill, and there must be room in the valley for a man-made lake — in this case the lake below the wind farm—that will store the water when it’s not being used by the turbines.
“Germans in this area are known as tinkerers and inventors,” says Cliff Harris, general manager for onshore wind in Europe at GE Renewable Energy. “So the mentality of this technology really fits with the population.”
The German project is thought to be the first of its kind and, if successful, could pave the way for future wind-hydro combinations. Max Bögl Wind expects to do one or two projects a year in Germany after 2018. The reservoirs can be freshwater or saltwater, which means the plants can be built close to the sea.
It is hoped that this kind of plant will help Germany move toward its goal of generating at least 45% of its energy from renewables by 2030.
“It’s a bit risky, and it can’t work everywhere,” says Harris. “But the plant will run for several decades, and we expect the benefits will be felt over that time.”
The four wind turbines are expected to be commissioned by the end of 2017 and the full Gaildorf power plant is expected to be operational by the end of 2018.
Additional information in this article was provided by GE Reports.