5. HEAT AND DISTRICT HEATING

few heat and power plants in cities connected to the gas transmission grid in the southwest of the country, mainly in Malmö and Gothenburg. Coal is used mostly for peak generation in a few remaining heat and power plants, plus as base load in Värtaverket in Stockholm, which the owner has decided to phase out by 2022. Oil boilers mainly supply peak load in some DH systems, and, in some places, bio-oil has replaced fossil fuel oil.

Co-generation in DH

Co-generation of heat and electricity enables a more efficient use of energy resources compared to separate production in power plants and heat boilers. Furthermore, co-generation contributes to a stable power supply. The electricity certificate system, which was introduced in 2003, encourages co-generation rather than heat-only boilers when burning biofuels.

In 2016, co-generation accounted for 73% of the total DH generation and 10% of the total electricity generation in Sweden (Figure 5.6). For DH generation, this corresponds to a large increase, from 57% in 2002 when the certificate system had not yet been introduced. Until 2010, the share of co-generation in power generation also increased. In recent years, however, the rapid increase in wind power has led to a lower share of co-generation in the total power generation.

Figure 5.6 Share of co-generation in DH and electricity generation, 1980-2017

The share of co-generation in DH has increased in recent decades, supported by the electricity certificate system since 2003.

Note: The lines refer to the share of total production of DH and electricity that comes from co-generation plants (which can be operated in different ways, e.g. to maximise electricity generation or for pure heat generation).

Source: IEA (2019 forthcoming), World Energy Balances 2019 preliminary edition, www.iea.org/statistics/.

District cooling

District cooling (DC), used in some of the larger cities in Sweden, is mainly supplied to industries, offices and commercial buildings and public services, e.g. shopping malls and hospitals. Stockholm has the largest DC network, which accounts for close to half of the total DC supply in Sweden, supplied by efficient heat pumps in connection with DH production. In 2016, DC supply amounted to around 1 TWh (Figure 5.7). Nearly all DC networks were installed in the past two decades, but the growth has stalled in recent years.

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