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 by dredging.
• 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.

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