Evaluation of glaciothermal engines for the generation of polar renewable energy

Providing reliable power services to remote Arctic and Antarctic locations presents a formidable task. Delivery of fossil fuel poses expensive logistical challenges, especially for sites subject to restricted seasonal access. Locally renewable wind and solar energy resources help to supplement diesel and other hydrocarbon fuels, but the search continues for viable energy alternatives. Latent heat from freezing seawater or meltwater can be used to boil a high pressure organic working fluid and drive a fluid expander to generate electrical power. The extreme chill of cold polar air provides the essential heat sink to recondense the exhaust vapour. These sources provide an opportunity to generate power from seawater using glaciothermal power cycles. Ambient temperatures may fall below -80 °C during winter at elevated interior sites, and as low as -60 °C at high latitude ice shelf sites. A large amount of heat is released when water freezes (~335 MJ per tonne of ice formed) – equivalent to energy released from a liquid water heat source with a temperature difference of 80 °C. Nett thermal efficiencies of 9—11% at interior sites could be achieved if ice-slurry and tube-fin condenser technologies are properly adapted for use in glaciothermal power cycles. This thesis reviews earlier research work and proposes specific designs for a practical glaciothermal engine that can generate power from freezing water. The performance of a 250 kW engine was studied and the feasibility of using such an engine to provide power at remote cold climate sites was investigated. The conceptual device provides a convenient way to explore the behaviour of various processes intrinsic to the operation of a glaciothermal engine cycle. The analysis includes investigation of underlying physical processes and device working principles, heat transfer modelling, and optimisation of an ice-in-tube glaciothermal boiler, twin-screw expander, tube-fin condenser and associated devices. Year-round performance of the glaciothermal power generator was investigated around Antarctica, providing an overview of potential applications of such a device in Antarctica. Mean annual temperatures across the Antarctic continent were mapped using regression analysis of ice sheet temperature data. The analysis demonstrates that glaciothermal power generation can potentially contribute to providing sustainable energy in very cold climate conditions