Three hydro power schemes on the River Thames have now been shelved because of a change in Government policy on renewable energy.
But three others at Teddington and Ham, at Runnymede and at Culham are going ahead after beating a Government deadline.
As previously reported on River Thames News backers of a scheme at Abingdon have announced they will no longer go ahead because, among other factors, " the incentives that were designed to encourage groups like ours have been cut drastically."
Now it has emerged that two more hydro schemes at Boulters Lock, Maidenhead, and at Marlow will no longer go ahead.
Renewable energy supporters blame the Government's decision to scrap "pre-authorisation" - a guarantee of the price at which companies can sell the electricity they produce once the plants are built.
David DeChambeau, CEO of SE Power Engineering, whose Romney installation produces power for Windsor Castle, said:"The new rules make it impossible for investors because there is no way of predicting the return on investment.
"It is a great pity because both Boulters and Marlow are ideal sites for hydro projects."
Three schemes with which the company is involved - the community-backed project at Teddington, at Bell Weir, Egham, where a plant will power the Runnymede Hotel, and at Culham in Oxfordshire - will still go ahead because they received approval before the rules were changed. They are expected to produce power by 2016 or 2017.
Mr DeChambeau said: " The Government is pursuing a very short-sighted policy. Its new policy will kill off the hydro industry at a time when it is most needed.
"The only hope is that in two or three years' time someone will see sense and there will be a reversal of the policy. Until that happens the outlook for further hydro schemes on the Thames and elsewhere looks very grim."
The news comes as the Government announced a change of direction for its energy policy. Energy Secretary Amber Rudd indicated moves to favour gas power stations and the phasing out of coal-fired plants.
Besides changing the way renewable energy projects qualify for payments, this country has also scrapped subsidies for onshore windfarms and closed support for small-scale solar projects saying they were becoming too costly for taxpayers.
Meanwhile the Teddington and Ham scheme is currently offering shares for sale. The share offer closes on 26th November.
Once built, the scheme will produce approximately 1.6GWh of electricity - enough to power 600 homes or around 80% of the electricity requirement of Richmond's Schools.
Opponents of the scheme are considering seeking a judicial review over Richmond-upon-Thames council's planning approval.But the trust has guaranteed not to spend any of the share subscription money before the outcome of any court action.
Link to the Teddington and Ham Hydro scheme HERE.
November 30th 2015