Fuel cells and electrolysers in future energy systems - VBN

per cent reduction in greenhouse gas emissions, depending on the commitment of other developed countries.
In a previous agreement, the target for the renewable energy share of electricity generation was defined as
21 per cent by 2010. In Fig. 1, the level of renewable energy sources and CHP in the EU countries in 2005 is
illustrated and compared with targets for the RES share of electricity production in 2010.
Percentage
80
70
60
50
40
30
20
10
0
Renewable energy and combined heat and power in the EU
70
RES 2005
RES 2010 target
CHP 2005
CHP 2010 target
Fig. 1, Renewable energy sources (RES) and combined heat and power production (CHP) of the electricity supply in 2005
and targets for 2010. The target for CHP in 2010 is for EU‐15 and is not specified for each country (from Eurostat [3]).
One of the technologies in focus in EU research programmes is solid oxide fuel cell (SOFC) for power plants
(PP) and for combined heat and power production (CHP). This is due to the fact that these have higher
efficiencies than other power generation technologies and higher efficiencies than other fuel cells.
Furthermore, they have no or very low local environmental effects [4]. Another technology which attracts
high attention is electrolysis, which is also being developed on the basis of solid oxide electrolyser cells
(SOEC). These have higher efficiencies than traditional alkaline electrolysers. Most publications about both
SOFC and SOEC are concerned with the status of research in new materials; which is hardly surprising, as the
technology is still at the early development stage. Literature has also been published on the development of
fuel cell stacks, small and large‐scale SOFC or hybrid SOFC combined with gas turbines as well as modelling
and testing of the operation of SOFC systems [5‐10]. The demonstration of SOFC is moving into the next stage
in the Danish village Vestenskov on the island of Lolland, where SOFCs are introduced in connection with
electrolysers. Electrolysers have already been operated in connection with other types of fuel cells and wind
turbines on the Norwegian island of Utsira [11].
When identifying the suitable applications of fuel cells and electrolysers, it is insufficient to analyse these in
the current energy system designs. Rather, they must be analysed in relation to both contemporary and
future energy systems. With the increased focus on intermittent renewable resources, CHP and energy
savings in Europe, future energy systems may involve considerably more CHP and intermittent resources in
the future. Worldwide, similar policies can be expected for CHP due to high fuel prices and aims of reducing
greenhouse gases, and many initiatives have already been taken in promoting intermittent renewable
resources. Future energy systems may look very different from the systems we know today.
The Danish energy system is a practical example of one configuration of such a future energy system. Approx.
20 per cent of the electricity supply comes from wind turbines, and 50 per cent is produced by CHP plants.
Energy savings, especially in the heating sector, combined with a large penetration of CHP and wind power
production have kept the primary energy supply at a stable level since the early 1970s [12]. The Danish case
reflects many of the challenges faced by the international community within the energy supply sector. Until