Giant 'Water Battery' Provides Power and Capacity

­I’m very proud of the enthusiasm that my home country, Scotland, has shown in embracing the green transition. It already has a strong capability for conventional renewable generation, such as through wind turbines and hydroelectric power. In the coming years, it will also have the potential to lead the entire world in new renewable technologies, such as tidal generation. It is estimated that the country could have a quarter of the potential tidal power for the whole of Europe, which is estimated to reach 6GW by 2050.

Until these new, more reliable, generation technologies come on board, we have to work around the drawbacks of our current solutions, and the main drawback of wind power is its intermittent nature. Wind generates lots of energy when it is strong, but when it calms down or stops, then very little or no energy is produced. To be useful for the vast majority of applications, those peaks and troughs need to be levelled out. Various ways have been attempted to even out the supply, but many of these have fallen short in one way or another, either by been too expensive, too dangerous, or not being powerful enough. However, there is one alternative that is ideal for Scotland in particular.

Pumped storage hydro (PSH) is a technique that uses two reservoirs, one at a low altitude and another at a higher one. When excess power is available, such as when wind turbines are working well, water can be pumped from the lower reservoir to the higher one. When power levels drop, the water can then be released to the lower one, through turbines that generate electricity in the process.

The reason that I picked this subject for this column is that Scotland’s latest and largest PSH installation has just been given the go ahead. Situated in the north of the country, it will use Loch Leamhain as the upper reservoir, and Loch Earba as the lower one, with a 3km tunnel connecting the two. When finished, it will provide significant quantities of power and stored energy. Both of these statistics are important for PSH. Power signifies how much energy the installation can supply immediately, for times when a power station goes offline suddenly for example. Stored energy signifies how much energy is available when there is a longer term demand, for example, when there is a lack of wind. In this case, the PSH can supply up to 1.8GW in power in the short term and has storage to supply up to 40GWh over a longer period.

PSH is an elegant solution that fits very well with Scotland’s green agenda. It uses the country’s geography and environment in a way that benefits the country, while doing little or no damage. It is also a long term fix, that can produce low-cost energy for over a century once installed.