District heat from combined heat and power or simple combustion

The core element of many district heating systems is as a heat-only boiler station. Additionally a cogeneration plant (also called combined heat and power, CHP) is often added in parallel with the boilers. Both have in common that they are typically based on combustion of primary energy carriers. The difference between the two systems is that, in a cogeneration plant, heat and electricity are generated simultaneously, whereas in heat-only boiler stations – as the name suggests – only heat is generated.

In the case of a fossil fueled cogeneration plant, the heat output is typically sized to meet half of the peak heat load but over the year will provide 90% of the heat supplied. The boiler capacity will be able to meet the entire heat demand unaided and can cover for breakdowns in the cogeneration plant. It is not economic to size the cogeneration plant alone to be able to meet the full heat load.

The combination of cogeneration and district heating is very energy efficient. A simple thermal power station can be 20–35% efficient, whereas a more advanced facility with the ability to recover waste heat can reach total energy efficiency of nearly 80%.

Waste heat from nuclear power plants is sometimes used for district heating. The principles for a conventional combination of cogeneration and district heating applies the same for nuclear as it does for a thermal power station. Russia has several cogeneration nuclear plants which together provided 11.4 PJ of district heat in 2005. Russian nuclear district heating is planned to nearly triple within a decade as new plants are built.

Other nuclear-powered heating from cogeneration plants are in the Ukraine, the Czech Republic, Slovakia, Hungary, Bulgaria, and Switzerland, producing up to about 100 MW per power station. One use of nuclear heat generation was with the Ågesta Nuclear Power Plant in Sweden closed in 1974.

Дата добавления: 2015-08-03