Global warming and energy technology choices: An approach to weighing the alternatives

Responses to global warming must be fashioned in the face of great uncertainty as to the actual costs and benefits of the actions. Yet the possible consequences of inaction are so great that policy makers are having to move ahead on the basis of science's incomplete knowledge of the true impacts of global warming. Energy technology is a key component of any response becauseof fossil fuels' dominant role in generating the gases that are the cause of the greenhouse effect. This paper presents an approach to analyzing CO2 emissions from both fossil fuel and alternative energy technologies on a basis that normalizes emissions as a function of useful power output over the life of a generating technology, and over its entire fuel cycle. A scenario for analyzing wood-fired electricity generation from a short-rotation wood plantation is developed in detail to illustrate the application of the approach to assessing the CO2 impact of biomass energy. The paper concludes that wood energy supplied by a short-rotation woody plantation not only balances the emissions during the operation of the generating plant, but also sequesters CO2 in the 'infrastructure' of growing biomass that remains on the plantation after harvesting. The paper finishes with a caution that this analysis tends to highlight only the environmental issues involved in technology selection; economics, technical feasibility and important technical parameters are intentionally simplified in order to focus attention on emissions and power output. However, if used properly this approach does provide useful inputs for policy makers concerned with integrating environmental concerns into energy decisions