Your choices:
1 Geothermal; 2 Electricity
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| Biomass (digestible sludge) | District cooling | Comfortable indoor climate |
| Biomass (fermentable sludge) | District heating | Electricity |
| Biomass (solid) | 2 Electricity | Process cooling (< 0 °C) |
| 1 Geothermal | Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
In volcanic areas there may be high-temperature sources for geothermal energy, either so that steam is available directly from the ground or so that the injection of water into a geothermal well may produce steam.
In both cases, the steam must be assumed saturated and it must also be assumed to be contaminated with gas components that may be corrosive such as sulphur compounds. Hence this steam should always be isolated and used only via a heat exchanger to raise "fresh" steam to be used in the steam turbines.
The electricity efficiency with this type of systems will be limited because the steam will be saturated but if the resource is big enough it may still be an economically favourable production technology.
In Europe as a whole, the options for electricity production using geothermal energy are so limited that this route is – from all practical points of view – negligible.