Ed Miliband, secretary of state for energy and climate change, visited St Thomas' Hospital on Thursday to open a new combined heat and power (CHP) plant.
Guy's and St Thomas' NHS Foundation Trust has become one of the first healthcare trusts in London to produce its own electricity and heat – saving the equivalent carbon dioxide of around 17,000 passengers flying to New York and enough energy to power Newcastle for a week.
The waste heat generated by this process, in the form of steam and hot water, is collected and used for the hospitals' heating, including space heating and hot water. Because the CHP units are located within the hospital grounds it is also very efficient as virtually no electricity is lost during transmission.
Overall the units will reduce CO2 emissions produced by the Trust by almost 11,300 tonnes per year. It will also save the trust more than £1.5 million in energy costs annually – one of the largest savings from a CHP for an NHS trust.
The units have been funded by a £10 million grant from the Department of Health's Energy and Sustainability Fund.
"We have already been making strides towards reducing our carbon footprint by investing in recycling and low energy technologies," says Steve McGuire, the trust's director of capital, estates and facilities.
"This latest venture is our largest undertaking so far and we are very proud of our achievements.
"As one of the largest employers in London, we see it as our commitment to the community to reduce our energy consumption and to do our bit to protect the environment."
Guy's and St Thomas' was one of the first organisations to sign up to the recently launched 10:10 campaign – a national drive to reduce the country's carbon footprint.
The trust is also a founding member of the Green 500, the Mayor of London's initiative to encourage London's 500 most prominent organisations to contribute to the capital's carbon reduction plan and lead the way in identifying new ways to save energy.