Surface geothermal science. Presentation and heat pumps

Heat pumps make the most of "low-temperature" heat sources, such as ambient air, groundwater, soil, etc., to cover heating and/or air-conditioning needs.

In the early 1980s, after the second oil crisis, the high cost of fossil fuels led to a boom in these heating systems. For a few years, the number of heat pumps sold was very high. Primarily using ambient air as a heat source, they were generally installed to heat residential homes as a complement to existing oil-fired boilers.

The appeal of this original energy technology, like others developed at the same time (solar thermal, geothermal, methanization, etc.), faded with the collapse of energy costs in the mid-1980s. What's more, the heat pump craze quickly led to a number of unintended side-effects, with a number of poorly installed, unreliable and mediocre-performing products coming onto the market, ultimately damaging the image of the entire sector.

It wasn't until the early 1990s that the market for heat pumps in the residential sector was revived in countries such as Switzerland and Sweden, where proactive public policies were put in place to promote the quality of products and their installation by professionals. Thanks to these technical efforts, new, better-designed, more reliable and higher-performance products are gradually taking their place. Better sized in relation to needs, better installed, they will enable the market to become more sustainable. In the commercial building sector, the boom in air conditioning in the early 1990s also encouraged the development of reversible heat pumps.

As the market developed, new concepts began to emerge, such as harnessing the energy resources of the subsoil at shallow depths using heat pumps on horizontal or vertical buried collectors. These new concepts gave rise to a new energy sector in its own right: surface geothermal energy.

More widespread in terms of exploitable resources than traditional geothermal energy – limited to the development of deep aquifer resources through direct use of the heat extracted – and requiring less heavy underground investment, surface geothermal energy offers promising development prospects. It calls on a wide range of technical solutions:

• Canadian and Provençal wells, heat pumps on buried collectors – horizontal, vertical – geothermal probe fields, which are covered in the [BE 8 592] file;

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