Energy bills at Oxfordshire's largest hospitals have more than doubled in three years and managers are considering ways of generating their own electricity including solar and wind power.

The Oxford Radcliffe Hospitals NHS Trust, which oversees Oxford's John Radcliffe Hospital, Churchill Hospital and Radcliffe Infirmary, and The Horton, Banbury, uses the equivalent electricity every year to 8,600 homes.

It also uses the same amount of gas and oil as about 9,700 homes.

Although its consumption has not risen in recent years, its fuel bill has gone up by 136 per cent, from £3.6m in 2003-4 to an estimated £8.5m for this financial year.

Unlike residential customers, who are charged five per cent tax on their fuel, the ORH is charged 17.5 per cent because it is classed as commercial.

Now senior directors are reviewing the way they generate energy. Facilities and estates director Ian Humphries, pictured, said: "There are three things we have to take into consideration. We need to buy energy efficiently, use it efficiently while maintaining the right environment for our patients and staff, and be environmentally friendly.

"To try to fit those things together doesn't always work, but our current focus, with ever-spiralling price increases, is to manage our use of energy in the best way."

Mr Humphries and ORH energy manager Mike Frankum believe their best option would be to use combined heat and power units (CHP), which create in-house electricity from gas, and have been used at the RI since 1993.

But they are also considering solar power and wind turbines at the JR site in Headington.

Mr Humphries said: "At one stage CHP didn't look economically viable for our other sites, but now we're reassessing the equation, and CHP is an attractive proposal.

"We're also reviewing solar and wind turbine systems at the JR, where there are slightly better opportunities than the Churchill or The Horton. For solar power, for example, you need a huge building like the JR.

"At the moment though, these options are not making as much sense financially, but we have a little bit of work to do before we abandon that altogether. We're looking for energy solutions that are cost effective and have no future financial implications."

Mr Frankum, who has day-to-day responsibility for maintaining and overseeing energy use, said the ORH was already part of a consortium of 100 NHS trusts which bulk-bought much of its energy in advance.

He added: "Site managers have energy targets, just like financial targets, and since April we've asked for a seven per cent reduction. This is difficult as we have more and more patients to care for and use hi-tech equipment, like scanners in radiology, and areas like operating theatres and laboratories have to be carefully temperature controlled.

"But we're making changes in basic housekeeping, which is practical and allows everyone to help. We run regular campaigns and have an energy website.

"We've already saved about £1m of energy, with things like high-efficiency lightbulbs and movement-controlled lighting.

"Everything we buy is energy efficient. Just like when you go to the electrical showroom and see the energy efficiency ratings on fridges and washing machines, we do the same.

"In our case, efficiency is one factor of many, including cost and shelf-life, but if we can avoid buying anything that's energy-aggressive, then we will."