10.2.5 Power Generation
Electric power generation is one of the biggest single sectors emitting CO2.
Major options to reduce GHG emissions are summarised below:
- Replacement of fossil fuelled plant by non-fossil fuel systems with low
GHG emissions. On a life cycle basis renewables and nuclear systems could
release up to 2 orders of magnitude less CO2
emissions than those of fossil fuelled systems (CRIEPI,1995; Uchiyama,1996).
- Fuel switching to less carbon-intensive fuel. Fuel switching from coal
to petroleum or natural gas or from petroleum to natural gas can contribute
to reducing CO2 emissions (OECD/IPCC, 1991;
1995). Switching from fossil fuels to nuclear power can significantly reduce
CO2 emissions. For instance, CO2
emissions avoided by nuclear generation in Japan amounted to 66 TgC, an amount
equal to 20% of the overall CO2 country emission
in 1995 (FEPC,1998).
- Improvement of conversion efficiency by using advanced fossil fuel based
technologies, such as combined cycle or retrofitting inefficient fossil fuel
plants. According to IEA statistics, current average power conversion efficiency
is around 30%, whereas that of most efficient commercial plants with natural
gas combined cycle systems already reach over 55% (IEA,1998a).
- Improvement of thermal efficiency by use of cogeneration to supply process
or district heat. Depending on the circumstances, this can increase thermal
efficiency substantially. District cooling systems can also improve overall
thermal efficiency in megacities with dense population and stable demand.
- Improvement of efficiency of transmission line by increasing busbar voltage
and/or using DC. This could improve transmission efficiency up to 10% in some
situations. More localised power production will also bring less transmission
losses and contribute to local and regional development.
- Improvement of efficiency by maintenance and modification of existing systems.
For example,rehabilitating hydropower plants or recovery of capacity of reservoirs
- CO2 capture and sequestration from power
plants has the potential to substantially reduce CO2
emissions, but more R&D is needed to make it economically viable
and assure that environmental impacts are negligible.
- Utilisation of fuel cell technology when commercially viable. Fuel cells
are able to convert hydrogen to electricity at higher efficiency than through
direct combustion. Hydrogen can be produced from fossil fuels, renewable fuels
or by electrolysis of water. It is also an effective way to cogenerate heat
and power in relatively small quantities. By improving efficiency less CO2
emission will be produced for the same amount of electricity generation.