A battery to most people is something that goes in a car, or is a cell used in flashlights, toys, video games, controllers, TV remotes, etc. But there is another kind of battery and on a different scale -- a reservoir of energy.
As
a young engineer, I joined a trip organized by a professional society
to a new power station in Wales that also worked on the same principle
as a battery. During off-peak hours when electricity demand was low,
water was pumped up to a higher reservoir -- North Wales is hilly. It
was then allowed to flow down during peak electricity demand times
(usually 6 pm to 10 pm) to drive water turbines and generate power.
While 'pumped hydro' provides over 90 percent of the world's high-capacity energy storage,
it has drawbacks: the vertiginous terrain required together with and
an abundance of water for example. Lithium-ion storage using lithium
salts is also being used and some say is poised to dominate energy storage. And there are new advances to make use safer and cheaper.
Another storage idea being employed is in conjunction with alternative energy sources like solar or wind. Gravitricity is an Edinburgh company that has a small demonstration model. It hoists a 50-tonne iron weight inch by inch before releasing it gradually to generate power.
Their small test system produces enough power to supply about 750 homes. What has been encouraging is the system's longevity, the life of the lifting cable in particular and how the team were able to control it. Also individual components are designed to be easily replaceable giving the whole a decades-long working life with regular maintenance.
Then there is the obvious attraction of disused mine shafts. Obviating the need for building higher derricks, the weight can be dropped down from a much smaller supporting structure. If North Wales has the craggy hills, South Wales has the abandoned coal mines.
However,
there are safety issues in mines with methane gas and the possibility
of flooding. For these reasons plus the greater uniformity of
purpose-built shafts, Gravitricity is proceeding also with sinking new
holes.
At the same time, the attraction of a deep, clean mine shaft is difficult to resist. A full-sized Gravitricity installation with a 300-meter-deep mine shaft is expected to be functional by 2024 -- most likely in the Czech Republic. Clearly a subterranean endeavor is less of a blot on the landscape.
Energy
from a green source, and an installation that stores unused energy for
release during peak loads... plus it is mostly underground. All of it
satisfies the public mood for an equitable transition into a low-carbon
economy. Emissions are reduced and the former mine workers secure
alternative jobs.
(Note: You can view every article as one long page if you sign up as an Advocate Member, or higher).
