Your choices:
1 Electricity; 2 Water; 3 Process heat
| 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) | 1 Electricity | 3 Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | 3 Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | 3 Process heat (150 - 1000 °C) |
| 2 Water | Fuel: Solid | 3 Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
In many cases, electricity is assumed to be the main energy carrier desired by the end users, but this is not necessarily true.
The high share of exergy in flowing water means that the production of electricity can be done at exceptionally high efficiencies. At the same time – since electricity cannot be stored – the fast control of traditional hydropower installations makes hydropower the best source imaginable for electricity production. Hydropower is also already a significant part of the total electricity balance.
Hence; if the end user desires and really needs electricity, the best source is hydropower stations.
In case process electricity is produced using hydropower as the main resource it may well represent a significant share of the total electricity in the regional or local grid. In those cases, local industry may well find it worthwhile to contract the local electricity producer so as to improve their green profile in marketing.
For the end user, the unique thing with electricity is its flexibility or, in thermodynamic terminology, its high share of exergy. This makes the use of electricity in industrial processes suitable for all temperatures and a variety of processes:
- Freezing temperatures at process industries, such as a food processing industry, must be produced locally, on-site. This is not necessarily the same as to say that the production of freezing temperatures must be seen as an isolated or stand-alone process, but a system perspective must be adopted.
- Cooling and refrigerating temperatures can be produced basically in two different ways, by absorption cooling where the main energy supply is heat and only minor amounts of electricity are needed, or by compressor cooling machines where all the help energy is supplied as electricity.
- Many industrial processes, like food manufacturing, washing and several biotechnological and/or chemical processes require only modest temperatures like 0-150 °C. In very many cases will the companies themselves have their internal energy supply system, often centred around one or two small hot-water or steam boilers producing a heat carrier (hot water or steam) that is distributed around the production site.
- Temperatures ranging from 150 to some 1000 °C are common in many types of industries like asphalt works, metal manufacturing and heat treatment, metal casting, glazing of ceramics end numerous others. CHP-plants and hot water boilers for the production of district heating, district cooling and electricity also fall into this category.
- For temperatures exceeding 1000 °C, such as glass melting, steel reheating for rolling, the burning of ceramics, building brick, cement and household stoneware alike, fossil fuel firing and electricity are the major sources of energy supply today. The drawback with electricity for some of these high-temperature processes is the absence of a hot gas which is often used to attain temperature uniformity. With electricity as the energy carrier, such gas (if needed) must be produced or provided by external means.