Reducing greenhouse gas (GHG) emissions from the electricity sector will be a central part of Australia's efforts to make deep cuts in its national emissions. This is because the country has high electricity GHG emissions. In tum, renewable electricity (RES-E) is likely to play a major part in cutting Australia's electricity sector emissions because it is less·resource-constrained, and more mature, than the alternative low emission electricity techologies of fossil-fuel carbon capture and storage and next-generation nuclear technologies; Because RES-E generation is currently dearer than fossil-fuel-generated electricity (even given a politically likely carbon price), support mechanisms are needed to allow it to compete with fossil-fuel-generated electricity. In this thesis I show that there is a case for providing support to RES-E in Australia, above that likely to be provided by carbon pricing; and that currently high-cost solar and geothermal types of RES-E should receive more support than currently low-cost RES-E types. The thesis also shows that the largest 2020 GHG reduction target being considered by the Australian government will make only the least expensive type of RES-E (wind) competitive with coal generated electricity, and will not make other RES-E types competitive with it; In the thesis I examine the lessons Australia can learn from the overseas experience of RES-E support policy, particularly in Western Europe and the USA. The thesis specifically examines the generation and subsidy price performance of Renewable Portfolio Standard (RPS) RES-E support mechanisms (where governments determine how much RES-E will be generated and RPS tradable certificate markets determine its price), and Feed-in Tariff (FIT) support mechanisms (where governments determine RES-E prices and electricity generation markets determine how much will be generated), in the USA, eight Western European countries and Australia. I also examine RES-E subsidies provided by the federal government in Australia as well as electricity transmission in the country compared to Europe and the USA. I show that Australia has modest transmission levels, which hinders the development of its RES-E. The cost of transmission expansion in Australia is large, and may need financing across all electricity consumers. It may also need some government subsidisation, and regulation, if market-based transmission planning is not effective; The thesis's analysis of Australia's RES-E development, compared to that of the European Union and the USA, shows that RES-E has a lower electricity generation share (including a lower non-hydro RES-E generation share), and is less diverse, in Australia than in the other two regions/countries. I also show that Australia's current level of RPS RES-E subsidy compares poorly with equivalent levels of wind and solar subsidisation in Germany, Spain and the UK; Two major conclusions in the thesis, which together form its most significant contribution to knowledge, are that radical RES-E expansion (rapid increases in RES-E generation share) will require RPS mechanisms to adopt some features normally found in FITs. The most important of these are 'type-specific support' (different levels of subsidisation for different types of RES-E), and a high level of RES-E investor certainty about subsidy levels. Achieving radical RES-E expansion will also require FITs to adopt features normally found in RPSs, the most important of which are a high level of generation outcome certainty and a close connection between subsidy levels and electricity generation performance. However, the extent to which the RPS and the FIT can be hybridised will not be known with certainty for another three to four years. Until then, recently established RPS banding (variable traded certificate multipliers), as used in the UK and Italy, carveouts (RPS submarkets dedicated to a particular type of RES-E), as used in the USA, and flexible FIT degression (subsidy reductions linked to RES-E generating capacity changes), as used in Germany and Spain, will not have reliable generation and price histories; Institutional inertia means the RPS will very likely remain the main form of RES-E support in Australia, so the need I have shown for an RPS to adopt features normally found in FITs means that banding should be introduced into its RPS, so that it gives different levels of subsidisation for different RES-E types (particularly for solar and geothermal electricity). It also means that an implicit or explicit price floor is needed to make RPS tradable certificate prices less volatile than at present; Comparison of particular features of Australia's RPS with the equivalent features of the RPSs used in the USA and Western Europe reveals other major flaws in Australia's RPS. To remedy them, the thesis also makes the case that pre-RPS RES-E generation should be removed from Australia's RPS; banking of its tradable certificates should be restricted in it; unusual energy sources (especially solar hot water heaters) should be removed from it; and its target should be a generation share, not an absolute quantity of generation. In the thesis I also show that if Australia is to make deep cuts in its GHG emissions, its RPS target needs to be significantly increased so that it at least absorbs all the projected increase in Australian electricity demand. I also recommend in the thesis that Australia's different state and territory FITs be replaced with a national gross FIT for small to medium scaled RES-E, differentiated according to location; In general, I find that while Australia has made a reasonable start in its RES-E development, significant redesign of its RPS is needed if the country is to make deep cuts in its electricity generation GHG emissions through radical RES-E expansion.