Fuel cells and electrolysers in future energy systems - VBN

112
B. V. Mathiesen & H. Lund
In relation to distributed generation, FC technologies are very often
connected to the use of hydrogen, which has to be provided e.g. from
electrolysers. Decentralised and distributed generation has the possibility of
improving the overall energy efficiency and flexibility of energy systems.
Therefore, energy system analysis tools and methodologies must be thorough
and careful when identifying any imbalances between electricity demand and
production from CHP plants (Combined Heat and Power) and fluctuating
renewable energy sources. This chapter introduces the energy system analysis
model EnergyPLAN, which is one example of a freeware tool, which can be
used for such analyses.
Moreover, the chapter presents the results of evaluating the overall system
fuel savings achieved by introducing different FC applications into different
energy systems. Natural gas-based and hydrogen-based micro FC-CHP,
natural gas local FC-CHP plants for district heating and hydrogen fuel cell
vehicles have been evaluated in different energy systems with or without largescale
wind power and with different means of house heating.
The overall result shows that the fuel savings achieved with the same
technology differ very much from one system to another. The FC technologies
have different strengths and weaknesses in different energy systems, but often
they do not have the expected effect. Specific analyses of each individual
country must be conducted including scenarios of expansion of e.g. wind
power in order to evaluate where and when the best use of FC technologies
can be made. However, some general points can be made. In the short and
medium term, natural gas-based FC-CHP systems seem to be best practice in
most energy systems, while hydrogen-based systems including vehicles only
seem to be relevant in systems with considerably larger imbalances between
electricity demand and supply.
1. Introduction
Renewable energy sources and distributed generation play a crucial role in
supporting key policy objectives of combating the greenhouse effect, reducing
the atmospheric pollution and improving the security of energy supply in may
countries around the world. Consequently, there is a strong trend of supporting
decentralised energy production and supply in many countries. Both the
increase in decentralised production and the use of wind power will result in a
growing number of small and medium-size producers which will be connected
to energy networks and, in particular, to electricity grids originally designed
for monopolistic markets. Therefore, many new problems will arise related to
the management and the operation of energy transfer and to the efficient
distribution of wind power and other renewable energy sources into the grids.