Europe leading the way
Jan-Olof Dalenbäck, Professor, Building Services Engineering, Department of Energy and Environment,
Chalmers University of Technology, Gothenburg, Sweden
Countries around the world are
increasingly recognizing the sun’s
tremendous potential as a renewable energy source. According to the U.S.
Department of Energy, every hour, more
energy from sunlight strikes the Earth
than is consumed on the planet in a year.
In Europe, many large-scale centralized
solar heating systems have been taking
advantage of this abundant, environmentally friendly energy source for the
past 30 years.
In Europe today, there are about 20
million sq m (215 million sq ft) of glazed
solar collectors used in a variety of
applications, corresponding to about
14 gigawatts of thermal power (GWth).
Most of those collectors provide heat
for or serve small thermosiphon domestic
hot water systems with just 2-3 sq m
( 21. 5-32. 3 sq ft) of collectors. Perhaps
10 percent of the total number of systems
are hot water plus heating, while very
few are used for heating only. About
1 percent of the European collector market
comprises large-scale centralized heating
applications, with heat loads up to several
GWth. About 9 percent of the heating
loads in Europe is served by large-scale
centralized heating systems (i.e., district
heating and ‘block heating’ systems).
There is thus a need and opportunity
to connect solar heating applications to
large-scale centralized heating systems.
According to the European Solar Thermal
Technology Platform (ESTTP), that is
indeed feasible if Europe adopts a more
progressive solar district heating policy.
In Europe at present, there are about
120 documented centralized heating
plants, each with more than 500 sq m
( 5,382 sq ft) of solar collectors. Of these
120 plants, 30 have a ‘nominal power’
(or capacity) of 1 MWth or more. [The
solar industry defines the nominal
power of 1 sq m ( 10. 7 sq ft) of solar
collector as 0.7 k Wth to facilitate a comparison with the nominal wind power,
photovoltaic power, etc.] The total col-
lector area of the 120 plants – about
200,000 sq m ( 2. 15 million sq ft) and
approximately 140 MWth.
Large-scale centralized solar heating
systems were introduced in Europe the
late 1970s, in response to an interest in
developing solar heating systems with
seasonal storage to cover a larger part
of the heating loads in the northern
latitudes. Sweden played a leading role
in these early projects together with the
Netherlands and Denmark. In the ’90s,
the interest in large-scale centralized
solar heating increased in Germany and
Austria, and about 100 new plants with
more than 500 sq m ( 5,382 sq ft) of solar
collectors have been put into operation
across Europe since the mid-’90s. The
Figure 1. Number of European Centralized Solar Heating and Cooling Plants With More Than 500 sq
m ( 5,382 sq ft) of Solar Collectors (year commissioned).
Source: Jan-Olof Dalenbäck.