The ground – a significant energy source
Heat that is extracted from the ground and refined using a heat pump today represents around 10% of the heating in our homes and premises. Ground-based energy systems have been around since the end of the 1970s and today constitute an energy sector of their own. The benefits for the environment are considerable, and continued use will significantly reduce emissions of carbon dioxide and other polluting gases.
The ground as a renewable energy source
Winter cold and scorching summer sun mean that ground surface temperatures fluctuate considerably over the year. However, temperature variation decreases with depth, and at around 10 metres deep it is just about constant throughout the year. Here the temperature is more or less the same as the mean atmospheric temperature for recent years, making it approximately 9o in the south and 2o at its lowest in the north. This low-quality heat consists of passively stored solar heat and is thus a genuine renewable heat source, since tapping it in the winter is followed by a resupply during the summer.
Significant gains for the environment
If we make the rough assumption that 15 TWh of natural heat are a substitute for heating oil, around 1.5 million m3 are saved per year. In terms of carbon dioxide emissions, this amounts to around 3.45 million tons of our total emissions of approximately 65 million tons. This is equivalent to around 5.5%.