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NUCLEAR HYDROGEN USING HIGH TEMPERATURE ELECTROLYSIS AND LIGHT WATER REACTORS FOR PEAK ELECTRICITY PRODUCTION
Introduction
There is a renewed interest in the production of hydrogen using nuclear energy for industry and
transportation (Forsberg, 2008, 2009a). Nuclear hydrogen production technologies were initially
investigated in the 1970s. Since then, one option for nuclear hydrogen production technology has
made considerable progress – high temperature electrolysis (HTE). This technology is based on the
development of high temperature fuel cells that contain an internal membrane through which oxygen
can be transported. In a high temperature fuel cell, hydrogen and oxygen produce electricity and
steam. In HTE, this process is reversed so electricity and steam yield hydrogen and oxygen. The same
equipment can operate in either mode – a capability demonstrated in the laboratory but not a
commercial technology. The characteristics of these systems potentially create new options for
production of intermediate and peak electricity from nuclear reactors.
Electricity demand varies daily, weekly and seasonally. In higher latitudes, there is also an
approximately three-day cycle associated with weather patterns. Today fossil fuel power plants are
the primary technology to match electricity production with fluctuating electricity demand. Fossil
fuels are used for intermediate and peak electricity production because: i) they are inexpensive to
store until needed (coal piles, oil tanks and underground natural-gas storage); ii) the technologies for
conversion of fossil fuels to electricity have relatively low capital costs.
The use of fossil fuels to meet variable electrical demands may be limited in the future because
of concerns about the price of natural gas and climate change. With any deep reduction in greenhouse
gas emissions, carbon dioxide emissions will likely be limited to transportation, consumer products
and other mobile applications – not stationary applications such as peak power production. While
carbon dioxide from fossil power plants may be sequestered underground, such fossil power plants
are likely to be uneconomic for the production of intermediate and peak electricity because of their
high capital costs (MIT, 2007) and the difficulties in operating such plants with variable output.
Renewable forms of electricity (wind and solar) compound the challenges of intermediate and
peak electricity production. These energy sources are highly variable on a day-to-day basis and have
large seasonal swings in energy outputs. In many parts of the world (particularly in northern climates),
the large seasonal variations in electricity demand do not match the large seasonal swings in renewable
energy production. The increased use of renewables will require additional intermediate and peak
electricity production capacity. The existing non-fossil methods to produce peak electricity have
major limitations:
• Hydropower. Hydroelectric power is used for peak electricity production. In a few locations,
there is sufficient hydroelectricity to meet seasonal swings in energy demand – but not
world wide. Hydroelectric pumped storage can be built in many places to meet the variable
daily demand for electricity; but it is not practical to build storage reservoirs for weekly and
seasonal swings in energy demand.
• Compressed air energy system (CAES). CAES uses compressed air as the storage media. When
excess low-cost power is available, air is compressed and stored in underground caverns.
When there is a need for peak electricity, the compressed air is fed to a combustion gas
turbine to produce electricity. In a gas turbine, 40 to 50% of the energy produced by the
turbine is used to compress incoming air; thus, the gas-turbine electricity output is increased
by a factor of 2 by using compressed air from storage caverns rather than compressing the air
as needed. However, the energy content of compressed air is low, making it very expensive to
use CAES except for daily swings in the demand for electricity.
This leads to the conclusion that one of the major electricity challenges is finding low-cost
methods to meet variable electricity demands. This paper describes one such system for intermediate
and peak electricity production using LWR and HTE.
156 NUCLEAR PRODUCTION OF HYDROGEN – © OECD/NEA 2010