The purpose of this chapter is to provide information about methodological and technological issues in climate friendly technology transfer for the energy supply sector. The discussion is restricted to technologies for climate change mitigation, since technologies for adaptation to climate change (so-called climate safe) in the energy supply sector are not yet discussed in the literature and have little potential for the nearby future.

The total primary energy supply including non-commercial biomass reached 398 EJ² in 1996, of which renewables (excluding hydro) represent 10.9% (43.4 EJ) and total final consumption reached 283 EJ (IEA, 1998). According to other authors (Craig and Overend, 1996) total primary energy supply should be higher (around 435 EJ), since non-commercial biomass supply is probably near to 80 EJ. Global annual energy consumption has grown at an average amount of 2% for almost two centuries (SAR II B1, 1996; SPM, 1996). According to five notable global energy scenarios exercises (IPCC, 1992; WEC/IIASA, 1995; Kassler, 1994; Shell, 1995; IPCC, 1996) forecasts are quite different, ranging by a factor of 2, which means an average growth of 1.96% per year for the most energy intensive scenario to 0.73% per year for the lowest one. The large difference is due to assumptions regarding improvements in energy efficiency, change in user habits, change in the profile of available energy sources and the capacity for development of different regions of the globe. Even so, a significant conclusion is that there are opportunities to improve the standard of living of the world's population with an increase of energy needs below the historical trend.

Energy related CO2 emissions are projected to increase at a slower rate than energy consumption. Historically, CO2 emission intensity of both economic and energy activities has been decreasing by 1.3%/year since the mid 1800s (1% decline in energy intensity per unit of economic value added and 0.3%/year due the replacement of fuels with high carbon content (e.g. coal) by those with lower carbon content (e.g. natural gas) or those with zero carbon content (e.g. nuclear power; sustainable biomass) (Nakicenovic et al., 1993; Nakicenovic et al., 1996). This is a trend with no inducement from environmental concerns. However, with environmental issues gaining momentum, CO2 emission intensity should decline at a faster rate. CO2 emission in the IPCC - IS 92 scenarios from the energy sector moves from the 2.3 GtC/year value of 1990 to 2.3-4.1 GtC/year in 2020 and 1.6-6.4 GtC/year in 2050 (IPCC TP1, 1996).

The energy supply sector is also responsible for substantial methane (CH4) emissions. Out of a total of 535 TgC CH4 emissions per year 100 TgC or roughly 20% is related to fossil fuel use (Prather et al.,1994). Of the fossil fuel related part, two thirds originates in the oil and gas industry (pipe and compressor leakages, venting and flaring) and the remaining in the coal industry (mine leakages and incomplete combustion) (IEA, 1997b; IEA, 1996).

CO2 emissions caused by the energy supply sector can be reduced with the use of some or all of the following options (SAR II, 1996; SPM, 1996):

• More Efficient Conversion of Fossil Fuels;
• Switching to Low-Carbon Fossil Fuels;
• Decarbonisation of Flue Gases and Fuels, and CO2 Storage and Sequestering;
• Switching to Nuclear Power; and
• Switching to Renewable Sources of Energy.

A recent IPCC publication (SAR II, 1996) provides a complete discussion of the many available technologies for each option, while another one (IPCC TP-1, 1996) makes an effort to quantify the amount of CO2 abated for each option. Table 10.1 lists the technical CO2 reduction potential for six different mitigation technologies, by the year 2020. According to Table 10.1 CO2 abatements of more than 10% can be obtained (a more precise figure is difficult to quote since the mitigation potential of the individual options identified are not additive, because the realisation of some option is mutually exclusive or may involve double-counting). The technical potential of each mitigation strategy, in the long term, is much higher. Only replacement of coal by natural gas can reduce overall emission per unit of electricity generated in the range of 50%. The main question is how far CO2 abatement in the energy supply sector is cost effective when compared with other possible actions able to achieve the same reduction. A global evaluation of the optimal mixture of options for 2.4 GtC emission reduction concludes half of it should be performed through increasing carbon sinks (forestry), and a fraction of the other 25% should be obtained by improvements in energy conservation (Jepma and Lee, 1995). Major constraints considered in the figures of Table 10.1 are the long average life of energy conversion plants, and the rate of technology transfer. Most of the growth in the energy sector will occur in the developing countries and these usually are the last to adopt new technologies, due a number of issues, but particularly the absence of binding commitments regarding GHG emissions.

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