Environmental impacts of renewable energy

Abstract

This PhD study addresses the question of whether the environmental impact of renewable energy sources is related to the power flux density. The object was to examine whether there are some general rules concerning the environmental impact from renewable energy sources, and whether a common factor could be the power flux density, of unit kW/m2 as an underlying principle. The background and nature of the study are described with definitions of key concepts. The role of energy in the environment, powering the natural world and having a set of functions, are explained. The need for a general theory and the rationale is considered for eight primary renewable energy sources. The literature on environmental impact from these sources is reviewed. The theory and the hypothesis are explained with questions raised. A test devised to explore the relevant interactions (sediment transport and land use) is outlined, using data from a selection of well known hydro electric power developments. The 'Stream Power' concept and a variety of parameters were used for identifying losses of energy and power to a river's natural processes, resulting from impoundment dams. The test was carried out on the reservoir reach and the river downstream. It is concluded from applying the hypothesis to hydro electric power, that the environmental impact may indeed be related to the power flux density, for the two main impact parameters investigated, land use and sediment transport, though this is not conclusively statistically confirmed due to the small sample size. The hypothesis is extended in the Appendix to the other water based renewable energy sources, tidal barrage, marine current, and wave power, and to the lower energy flux density sources such as wind, solar and biomass. It is concluded tentatively that there is a qualitative argument that the environmental impact of all renewable energy sources may be related to power flux density, in terms of both land use and some functions in nature of the energy flow