Environmental Engineering Reference
In-Depth Information
60
Waste heat
Heat pumps
Electric boilers
Biofuel & peat
Refuse
Coal
Natural gas
Oil
50
40
30
20
10
0
Figure 2. Development of heat supply to the district heating networks between 1970 and 2003 (Swedish
Energy Agency, 2004).
Palm (2004) shows that also institutional factors can connect the waste management
system and the DH system. In the city of Linköping, one reason for the introduction of waste
incineration was that the same municipal utility operated both the waste management system
and the DH system and saw that with waste incineration they could solve two problems at the
same time: both an acceptable waste treatment method and heat production for the DH
system. A study by Sahlin et al (2004), which is an overview of the consequences of using
waste as fuel in Swedish DH systems, also shows that waste incineration enables DH
networks to expand due to the low cost of the heat.
Waste incineration and combined heat and power production
One disadvantage of waste incineration is the low electrical efficiency in the plants.
6
This
is due to the many impurities in the fuel; the temperature of the steam in the boiler can not
exceed 400ºC without entailing high maintenance costs due to corrosion, as stated e.g. by
Korobitsyn et al (1999). Combined heat and power (CHP) production is an efficient way to
use resources and is recognized by the European Union as one of the measures needed to
meet the demands in the Kyoto protocol (European Union, 2004a). Many utilities have
chosen not to invest in electricity production in their waste incineration plants due to
difficulties in producing electricity in combination with historically low electricity prices in
Sweden.
7
However, electricity production at waste incineration plants is forecast to increase,
from 0.7 to 1.7 TWh between 2002 and 2010. (Swedish District Heating Association, 2005).
6
The electrical efficiency of waste incineration plants is around 23% at capacity 30 MW
e
(Elforsk, 2003). By way
of comparison, a natural gas fired CHP plant has an electrical efficiency of 46-49.5% at capacity 150 MW
e
and
biomass fuelled power plants 34% at capacity 80 MW
e
(Elforsk, 2003).
7
A more detailed explanation of this can be found e.g. in Trygg and Karlsson (2005).
