100% renewable power in Jamaica possibleMonday, November 18, 2019
BY Howard Chin
I have read Anthony Chen's Earth Today article on Friday, November 8, 2019 in which he says we should be aiming for 100 per cent renewables for our electricity supply. He recommends the use of batteries to bridge over the times when there is more demand than the power plants, be they renewable or otherwise, can supply.
Just a few days ago we had some unaccustomed load shedding power cuts when Jamaica Public Service Limited (JPS) had a power plant breakdown, as I understand the situation, just when two independent power plants were out for maintenance. This caused the supply to fall under what consumers of electricity had plugged in and turned on, so JPS electricity had to drop consumers off until there was more supply available than demand.
When you aim for 100 per cent renewables the wind can slow and stop so that wind turbines will stop producing electricity, clouds can pass over a solar farm and it will rapidly decrease electricity production. To prevent load shedding as occurred a few days ago, we must have power stored to be able to make up for the electricity shortfall.
Our total peak demand is roughly 700 megawatts, so the power storage probably has to be able to deliver this for a few days in order to tide us over the odd times when it's cloudy and windless. The way this can be done most appropriately now is by large seawater pumped storage; where seawater is drawn from the sea and pumped to a reservoir at a thousand feet or more higher, using excess renewable electricity when it is plentiful, and letting it out through hydroelectric turbines when we need it.
Battery technology is not quite up to that level as yet. Yes, batteries can be useful, if not essential, for short periods of times to take care of sudden upsets in the electricity system, but studies, including the 2013 Worldwatch Institute's Jamaica Sustainable Roadmap, supported by the German Government, in Table 4.1 where various technologies are compared, indicated pumped storage to be “very suitable” and we only needed to identify suitable sites.
Jamaica is particularly suitable for pumped storage because of our hilly terrain, unlike many of our Caribbean island neighbours.
Years ago, with information from the Survey Department of the National Land Agency, I located two sites where multi megawatt-days of power could be stored, one to the west and one to the east.
It would be a relatively trivial design for Jamaican engineers to perform, and the implementation could be performed economically by one of the large Chinese construction firms, with economical Chinese power generating equipment.
For a 100 per cent renewable and reliable electricity supply we would also have to make serious upgrades to our electricity grid and our laws as we immensely ramp up our solar farms, wind farms, and other forms of renewable energy production.
In his further writing, Professor Chen says that “suitable sites” must be reserved. For solar, this is true; for wind this is partially true because offshore wind is far more constant as well as higher speed as may be seen every day on the TV weather report.
It can be done with existing technology, probably economically, and it can be done well before 2055. Can we afford not to?
Another aspect to the seawater-pumped method of storing energy is the use of the high pressure water at the turbines for reverse osmosis production of fresh water. We will need more fresh water as time goes by and global warming reduces the amount of rain we get naturally.
Howard Chin is a member Jamaica Institution of Engineers. Send comments to the Observer or email@example.com.