Wye Valley NHS Trust在本月初在Hereford的The County Hospital安裝了兩個地源熱泵。
信託公司的戰略和規劃官員Alan Dawson說，將所需的47個鑽孔沉入地下200米（650英尺）深處，是一個 "重大項目"。
A hospital is being converted to renewable energy to start heating the site without using fossil fuels.
Wye Valley NHS Trust installed two ground source heat pumps at The County Hospital in Hereford at the start of the month.
The trust is planning to install more heat pumps to heat the rest of the site with the help of a £21m government grant.
It said the move to renewable energy will reduce the amount of carbon produced to heat the hospital by about 97% and save 3,715 tonnes of carbon a year going into the atmosphere.
The pumps work by extracting heat from the ground and passing it through machinery to warm the water which circulates in the heating system.
Solar panels have also been installed by the hospital, which has already switched to LED lightbulbs.
Alan Dawson, strategy and planning officer for the trust, said it had been a "major project" to sink the required 47 boreholes 200m (650ft) deep into the ground.
The trust said it hoped to become one of the greenest in the UK and its work far so had already reduced the hospital's carbon footprint by about 600 tonnes a year, saving about £90,000 in fuel bills.
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