The white building at the right of the picture is Loch Striven hydroelectric power station. It generates a maximum of 8 MW – not continuously, but for a few hours most days. It’s very quiet, and unobtrusive in the landscape – about the size and general appearance of a large house. The penstocks (pipes) carrying the water to it are more obtrusive, but not really very objectionable. They could have been buried, but would it be worth it?
A hydroelectric scheme like this could be fairly easily converted to a pumped storage scheme. You’d need a bigger, dual-purpose pump/turbine, and it would be housed in an excavated hole below low tide level. You might perhaps have six times the present capacity, and be able to generate 48 MW at times of peak demand or limited supply from renewable sources such as wind and solar power, pumping water back up to the upper reservoir (Loch Tarsan) at times when supply exceeds demand. From full to empty, a scheme at this site could deliver 48 MW continuously for almost three days. (With larger turbines, it could deliver more power, but for a shorter period.)
This particular location would need the turbines, pumps and penstocks to be designed for salt water, and Loch Tarsan would become brackish or even salty. It would be a change in the environment. Some species would suffer; others would gain. Would the change constitute an environmental disaster? I very much doubt it, by any objective standard.
The construction of the dams for Loch Tarsan were significant costs, and Loch Tarsan itself was a significant change in the environment. Whether that change constituted environmental damage I’m not sure. The environment there is not unattractive now.
©Clive K Semmens 2017