Scottish electricity generators are currently making £millions a year in subsidies (as well as selling the electricity) from hydro-power plant built by the public sector without subsidy 50-odd years ago.

A petition before Holyrood's Petitions Committee calls on the Scottish Parliament to examine how this situation arose and to consider whether the subsidies should be stopped. This web site explains why.

The government introduced the Renewables Obligation in 2002 to promote new renewable generation technology.

In consultation, it had been broadly agreed that new or very small hydro plant only would qualify for the lucrative subsidies on offer.

However, the large hydro-power generators persuaded government to make late changes to the scheme. As a result, irrespective of age, any hydro plant up to 20 MW in size would, if minimally refurbished, qualify for subsidy.

Another late change allowed generators to cut the capacity of plant to bring it below the 20 MW limit.

Nearly all of the plant in question had been operated without subsidy and profitably for the best part of fifty years, some of it for 100 years.

After investing what is believed to be around £100 million in a crash refurbishment programme, Scotland's major hydro-power generators are between them earning around £100 million a year from the subsidies and are set to do so every year until at least 2027.

The money is paid by electricity consumers over and above the normal price of electricity.

If public money is given to a private company to encourage it to invest in projects deemed to be to the public benefit, there should be clear evidence that the investment is for something the company would not have done of its own accord and that there is a clear and transparent equivalence between what is given to the company and what it invests.

Neither test was met when the Scottish Executive agreed that already existing hydro-electric power stations could be accredited under the Renewables Obligation scheme. In practice, it meant (a) a reduction in hydro generating capacity and (b) the generators being paid 20 times over for their investment at a time of widespread fuel poverty.

The petition calling on the Scottish Parliament to investigate the decision and its financial consequences and consider whether the subsidies should be withdrawn can be seen here.