As an energy-efficiency adviser, I was interested to read the article about Brighton and Hove City Council buying "green electricity" (The Argus, July 16).

However, the council will not be using only green electricity - unless it has run a separate cable from the Town Hall to the power station.

Electricity supply is much like a lake. Rivers pour into the lake from various sources, some of which are green.

You can pull out a bucket of electricity from the lake but cannot identify its source.

I am, however, impressed by the council's wish to pay for the amount of energy it uses from a green source.

Most energy suppliers, including our local one, have some form of green tariff.

-Steve Coppard, stevelyn@whsmithnet.co.uk