The Archer attempted to examine the current situation and possible prospects of renewable energy in Wales. Last week we examined Wales’ ‘love/hate relationship’ with wind power. Many enthusiasts and opponents of the alternative means of energy supply still seem to create a futuristic and unrealistic vision of renewable energies.
Despite this, Wales has been benefiting from its eco-friendly, pumped-storage hydroelectric power station for nearly thirty years. Let us have a look at one of the most revolutionary and efficient solutions preventing the environmental pollution and unexpected power cuts.
Dinorwig is Wales’ first pump-storage power station. It was built in 1984 in an abandoned quarry located inside the Elidir Fawr mountain in Snowdonia, north Wales and is still considered the most imaginative engineering and environmental project in the world.
Even today, Dinorwig is the largest scheme of its kind in Europe and second largest hydro-electric power station in the world. The power station generates electricity by using innovative principles of the water pump-storage which uses all the leftover of electric energy and transforms it to the more efficient gravitational energy.
Dinorwig consists of 16km of underground tunnels, deep below Elidir mountain. Its construction required 1 million tonnes of concrete, 200,000 tonnes of cement, 4,500 tonnes of steel and 6 pump turbines. All of this is located inside a mountain, in the Europe’s largest man-made cavern.
Although some might raise concerns about the environmental impact of the power station, Dinorwig assured that the company is environmentally aware of impacts on the community, and attempts to prevent possible damages.
Sue McLaren, the quality, environment, health and safety manager, said: “when we’re doing any work within the plant on the mountainside, we need to consider our impact on any vegetation or pollution of water, releases and temperature.”
The concept of the ‘electric mountain’ requires two reservoirs. Both of them are located at different altitude and are connected to each other with a series of tunnels. To generate electricity, the flow of water released from the upper reservoir (called Marchlyn Mawr) to the lower one (Llyn Peris) fuels the generators.
Then, the generators transform the electric energy to the gravitational potential energy. When the process finishes, the water is pumped back from the lower reservoir to the upper one. This happens during the surplus of production and low demand for electricity, for example at night. The next day, during the peak time, the process is reversed.
Pumped-storage power stations imply high economic efficiency. The electric energy is purchased at the time of a day when it is much cheaper. And it is given back to the system (sold) at the time of high demand, for example during the day.
The main purpose of the power station is to provide an alternative means of energy when the unexpected power cut happens. In a situation when there is a sudden demand for power, the pumped-storage power station is more efficient than standard stations which cannot generate more power immediately causing, at once, power cuts around the country.
The pumped-storage stations are a very efficient power pack of large capacity. Dinorwig’s crew predicts how much electricity is going to be needed at a certain moment. The crew monitors every power station across the UK in order generate more electricity within several seconds only.
Alan Smart of Dinorwig said: “we have to keep the frequency of 50Hz. That’s a bit like driving your car 15 mph, except you’ve got to go up and down hills and you don’t know the route and you don’t know when the next hill comes from.
“So as you go downhill you’ve got to slow the car down and you’ve got to apply the brakes. As the demand goes down we have to keep the system speed at 50Hz. For an increase in demand we need to increase generation,’ explained Mr Smart.”
Pumped-storage stations seem to be a solution that can go from zero to full power immediately, and keep us supplied for the time until the other power stations catch up.
Although the pumped-storage reservoirs seem to be efficient enough to replace standard power station, they should not be mistaken for a means of generating electrical power. They are a way of storing energy instead, so that the station can release it quickly when we need it.
Since hydroelectric power stations do not burn fossil fuels, they do not directly produce carbon dioxide which is also an advantage. Such power stations, however, are efficient only when they cooperate with other ones which produce periodic surplus of energy.
The surplus of energy, stored during the night at a standard power station is often wasted. In the pumped-storage power stations it does not happen as the surplus is stored in the form of potential energy of water.