Your choices so far:
1 Electricity; 2 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 | 2 Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | 2 Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | 2 Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | 2 Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
Electricity is the king of energy carriers and should be treated with due respect.
Electricity shall in the first instance be used for
- Mechanical work such as needed for lawn-mowing, pumping, fanning, compressing as well as evacuating or to run escalators, lifts and alike. In the longer run, this will also include transportation.
- Illumination.
- Operation of home electronics, computers, for communication devices and such.
- To obtain cryogenic/freezing as well as extremely high temperatures.
- For electrochemical operations such as electrolytic plating and alike.
- For operations and processes where the added value from the cleanliness, the simplicity and the precision of process control can be judged to override the thermodynamic arguments against it.
Sometimes there may also be other constraints such as the nature of the process itself that makes electricity the only realistic alternative for the end user regardless of thermodynamics.
For low temperatures – freezing down to cryogenic – as well as for extremely high temperatures (exceeding 1800 °C or so) is electricity the best alternative. For temperatures in between 0 °C and 1800 °C there are alternative ways to achieve these temperatures but since electricity is simple to control and is clean at the user end, it is often the preferred energy carrier with process industry.
The usability of electricity in industrial processes includes all temperatures:
- 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.
When the main aim of the energy supply is to sell electricity to such process industries that really need it, then a thorough investigation and mapping of the real needs should also be included in the contracting process.
There is a number of industrial processes where the use of electricity is not necessary from a process point of view and where the technical development during the last few decades already makes the replacement of electricity not only possible but advantageous and profitable.
When the main aim of the energy supply is to produce and sell electricity to such process industries that really need and fully appreciate it, then only large-scale production will be of interest. The technologies to be considered then become: 1-hydroelectricity, 2-wind-power, 3-solid or digestible biomass in large-scale CHP or tri-generation plants.