Promoting Green Power in Canada - Centre for Human Settlements

Promoting Green Power in Canada Pollution ProbeBiomass regrowth can occur naturally (e.g.,forests) or artificially, through the planting oftrees or energy crops. Organic waste fromprocessing plants or animals, as well as fromhousehold activities, is also a form ofbiomass. The differences here are whether ornot growth-enhancing activities take place(extensive vs. intensive agriculture), orwhether biomass is purposely grown for useas an energy fuel or whether it is a wastederived from other economic activities. Themain difference between fossil and nonfossilenergy sources is that the non-fossilones require additional input, apart fromsunlight, in the form of nutrients that needto be replenished over time, either throughnatural processes or through the addition offertilizers. The use of biomass for energyproduction is also linked to air emissions,although the carbon cycle may be more orless closed, depending on the case.2.4 Conclusions About ExistingDefinitionsBox 2.2 — Is Geothermal EnergyRenewable?Available data from the CaliforniaDepartment of Conservation’s Divisionof Oil, Gas and GeothermalResources and industry sources showthat operating capacity at The Geysershas declined by about 30–40% (about700 MW) since 1988, representingsome 5 billion kWh of lost generationfrom peak production levels. It isphysically impossible to reverse thisdecline, which, in colloquial terms,resulted from developers putting “toomany straws in the soda,” depletingthe naturally generated geothermalsteam at a much faster rate than theearth is able to renew it. The economicpractice of curtailing production duringthe winter and spring has the sidebenefit of slowing the rate of decline ofthe resource [RADER 1998, p. 17].2.4.1 “Conventional” vs. “Alternative”There is little disagreement that “conventional”power sources include energy productionfrom fossil fuels and nuclear energy. Somecontroversy has developed as improvedtechnologies come into play. For example,co- or trigeneration, fluidized bed, very highefficiency gas, and co-firing of biomassimprove the environmental performance ofconventional sources, but do not necessarilyturn them into alternative sources.Clarification is also needed concerning largeand small hydropower generation. Largehydropower, although clearly renewable, isoften seen as unsustainable due to itsdamaging effects on ecosystems. Small hydroplants are generally seen as “green” powersources, although their life-cycle impacts canbe higher, especially if they have a reservoir,as opposed to run-of-river hydro. However,the delimitation of small and large hydro isunclear. It has often been based solely on thegeneration capacity of power plants, but thethreshold has varied from one country toanother (generally, it lies between 10 and 30MW). Recently, the tendency has been toassess the effects of a plant according toenvironmental and social criteria, replacingthe former evaluation scheme based oncapacity. Whereas non-emitting powersources, such as large hydro and nuclear, aresometimes called “clean,” they haveenvironmental and societal problemsattached to them that disqualify them frombeing considered “green.” Also, they do notneed the financial support mechanismscurrently discussed to promote green powersources.19