A pathway to decarbonised energy
Creators: name: Cheng, Cheng
Publisher: name: The Australian National University
Year: 2023

description: The energy sector accounts for three quarters of global emissions and needs to be the primary focus of decarbonisation. This thesis examines an affordable pathway to decarbonised energy, enabled by 100% renewable electricity and the deep electrification of transport, heat and industry. The proposed pathway is built upon off-the-shelf technologies that are widely available and can be readily deployed, namely solar photovoltaics, wind, off-river pumped hydro, electric vehicles and heat pumps. Costs of solar photovoltaics and wind have been reducing rapidly over the past decade and this trend is likely to continue in the foreseeable future. This provides opportunities for accelerated large-scale deployment of solar and wind around the world. A vast amount of off-river pumped hydro energy storage potential is identified in most countries, some of which could be developed to balance variable generation from renewables at low cost. This thesis examines the technical feasibility and cost-competitiveness of this pathway in several contexts. This thesis first looks at the electricity sector, because 100% renewable electricity is the basis for further decarbonisation of other energy sectors. A case study is presented of Bolivia. A 10-year hourly energy balance optimisation model showed that the levelized cost of 100% renewable electricity in Bolivia for increasing levels of per capita energy consumption is lower than the cost of new hydro or gas generation. Future demand increase arising from rising living standards and population growth can be incorporated with little impact on wholesale electricity prices. The thesis then extends to countries in East Asia. The available solar, wind and pumped hydro resources in East Asian countries were assessed. Sufficient land and water areas with good solar photovoltaics and wind resources in East Asian countries were found to support 100% renewable electricity, and only a small proportion of the identified pumped hydro potential would be needed to balance the variable solar and wind generation. The thesis then conducts a detailed analysis of an affluent East Asian country, Japan, as an example to understand the potential role of solar, wind and pumped hydro in a developed and densely populated country. It was found that Japan can be self-sufficient for 100% renewable electricity supply at competitive cost compared with (for example) importing "green" hydrogen. In the last two Chapters, decarbonisation extending beyond the electricity sector is explored. Full renewable electrification of land transport in Australia was investigated to understand the impact additional electricity demand from electric vehicles would have on a 100% renewable electricity system. The study found that electrifying transport would result in a 40% increase in electricity demand, and that this could be incorporated (without vehicle-to-grid technology) with only a small increase in the cost to generate 100% renewable electricity (in $/Megawatt-hour). A second analysis focuses on the residential and commercial heating sectors and introduces a novel methodology for generating high-resolution electrified urban heating load profiles. A case study was performed using the urban heating sector in Australia and demonstrated that electrified urban heating can be incorporated quite easily in Australia with minimal required updates to infrastructure. The thesis concludes that many regions in the world have access to sufficient solar photovoltaics, wind and off-river pumped hydro energy storage to make a zero-emission, affordable, and widely applicable decarbonisation pathway achievable. These mature technologies can be readily deployed at vast scale with known costs. Future improvements in other technologies (e.g., batteries, high voltage DC transmission, water electrolysis, carbon capture and storage) will likely lead to lower costs of energy than those estimated in this thesis.