not possible to determine at this time what the specifics of a working reactor will be, although most of the research effort to this date has been directed at the Tokamak design of magnetic confinement.®^ Estimates of the climatic impacts of fusion power generation are thus somewhat conjectural. It is unlikely that any appreciable amount of any pollutant will be emitted under normal operating conditions. Heat releases can probably be assumed to be similar to those from nuclear fission technologies. The size of fusion systems and the method of cooling will determine to a large extent whether local climatic perturbations of temperature, humidity, cloudiness, and precipitation will be significant. 3.6 COMPARISON OF THE CLIMATIC IMPACTS OF THE FIVE TECHNOLOGIES There are potential risks of climatic impact from coal technologies, nuclear technologies, and the SPS. Table 3.4 contains a qualitative summary of the potential severity of impact of these energy technologies on climate. The intent of this table is not to predict but to identify which energy technologies are most likely to play a role in climate change. An attempt is made to classify whether or not each technology will play an important role, a minor role, or no role at all in each type of impact on climate. The most serious impact appears to be that of coal combustion on CO2 levels and the resulting greenhouse effect. Coal combustion will also add to the production of primary and secondary particles, but to a much smaller extent. The impact of particulate loading may also be less severe than that of C02”induced warming, although the impact of a global increase in particles has not been well documented. Coal and nuclear technologies will release water vapor to the troposphere, which may increase the total greenhouse effect, as well as the formation of clouds at lower levels. The injection of water vapor into the stratosphere from HLLV emissions may increase upper-level cloudiness, which could have a definite effect on surface temperatures. Coal combustion may release small amounts of greenhouse gases other than CO2 and H2O, but this should not occur to any great extent from SPS, photovoltaics, or nuclear technologies. HLLV emissions may have a significant impact on stratospheric ozone concentrations, particularly in the latitude belts where launches are being made.$l
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