In Wales, National Grid has an energy storage system and electric generating facility set into a national park. It has two lakes, one near the top of a mountain and one nearer the bottom. The lakes have typical Welsh names. The lower one is called Llyn Peris. Its neighbor up the mountain is named Marchlyn Mawr. What goes on here is the stuff 8th grade science projects are made of — the relationship between potential and kinetic energy.
Electricity is ephemeral. It has to be used immediately or it is lost. At Electric Mountain in Wales, excess electrical energy is used to pump water uphill from Llyn Peris to Mrachlyn Mawr. When the grid needs an increase in available electrical power, that water is allowed to flow downhill through a network of giant tubes that feed 6 enormous hydroelectric generators.
The English have a thing for tea. That passion was largely responsible for much of the British Empire. In the 19th century, British fighting forces were dispatched to the far flung corners of the earth to protect the nation’s access to its tea supply. Today, we do something similar with regard to oil. In the future, nations may use their military might to preserve access to lithium deposits.
In the evenings in Jollye Olde Englande, the denizens have a habit of viewing television programs from the BBC on the telly, what civilized people call a television. A curious thing happens several times during each show. As soon as a commercial comes on, Britishers rush to switch on their electric tea pots to brew up a nice cup of Darjeeling or Earl Grey. More adventurous types may partake of some Red Zinger if they are feeling particularly feisty.
All those heating devices being activated at the same time causes a spike in the demand for electricity. In most parts of the world, meeting the surge in demand would mean bringing an auxiliary generating plant online, but that can take hours. At Electric Mountain, the flow of current can begin in just 12 seconds.
Engineers at National Grid are provided with programming schedules by the BBC. Shortly before each commercial break, they begin the flow of water downhill and into the turbines at Electric Mountain. That way, there is enough electricity to make tea for millions of Brits so they can watch the rest of their television shows in quiet contentment.
Electric Mountain was built between 1976 and 1982 by the Central Electricity Generating Board. Its construction required the removal of 3 million tons of rock. Some of its internal passageways are 10 miles long. During a typical day, the water level in the lower lake, Llyn Peris, can rise or fall up to 121 feet. The entire system is 72% efficient, which is pretty good for 20th century technology.
We think of battery storage as the way to go when it comes to storing electricity today, but pumped hydro has been around much longer and still works pretty well. Small electric generating facilities– called peaker plants — that are used to meet spikes in demand can take a long time to get up and running. They also generate maximum carbon emissions during the start-up phase. Any system that keeps them from being called into service helps limit the amount of carbon emissions from making electricity. That’s a good thing, even if it means moving 3 million tons of rock to make it happen.
Tune in tomorrow for more about rocks and energy storage.
This story is sourced from The Register, a British news site whose slogan is “Biting the hand that feeds IT.” Photo credits: First Hydro Company