Atkins, Martin JohnO'Leary, Jack2024-05-202024-05-202024https://hdl.handle.net/10289/16559A significant amount of New Zealand’s greenhouse gases are emitted through the use of fossil fuels to generate process heat. New Zealand is well-placed to provide renewable energy for process heat, with a well-established plantation forestry industry that generates large amounts of renewable biomass fuel sources, and a high percentage of renewables in the electricity generation stack. Biomass and electricity could be used to reduce and eliminate reliance on fossil fuels. The important criteria for these fuel switches are to ensure that they are economic and have sufficient supply over the coming decades. This thesis presents a method to model and optimise the allocation of resources to give foresight around the extent biomass can provide economic process heat across regions in New Zealand. A diverse range of case studies was employed, encompassing individual sites, regional energy systems, and the South Island. These case studies were modelled and optimised in P-Graph studio and examination of the results gave key insights into several important areas: regional diversity in energy supply and demand, impact of the demand scale and temperature profile, and finally demonstrated the economic potential of interregional transport of energy dense biomass to alleviate supply deficits and reduce the Levelised Cost of Energy (LCOE). The largest impact on the LCOE was the temperature profile of the heat demand. The more heat demand below 100°C, the lower the final cost of energy. This was due to the high Coefficient of Performance of High Temperature Heat Pumps (HTHP), which were the ubiquitous fuel switching choice for below 100°C heat demand, providing LCOEs under 11 $/GJ in 2023. At these prices HTHPs are able to match or surpass the current prices for coal at 10 – 14 $/GJ. For heat demand above 100°C, biomass was the dominant choice as it provided much better economics. However, there was a wide range of LCOEs for biomass energy. This was caused by the wide range of resource, collection, and transport costs for the various biomass sources. These LCOEs ranged from 13 – 14 $/GJ for processor residues, to over 25 $/GJ for low grade export logs. As the size of a plant or region increases, the demand exhausts the supply of low cost biomass and must source from a larger radius, or from more costly biomass sources. This resulted in a large spread of LCOEs for the regions in the South Island, with Otago, the West Coast, and Nelson-Marlborough seeing some of the lowest weighted average LCOEs for above 100°C heat demand of between 20 and 22 $/GJ, whilst the three largest energy users, Southland, South Canterbury, and North Canterbury saw LCOEs of between 26 and 28 $/GJ for 2023. A key trend was established that regions with higher biomass supply saw lower LCOEs for heat demand above 100°C. Interregional transport of energy dense biomass was able to reduce the LCOE in the three regions of high demand and low biomass availability, bringing the weighted average for above 100° demand down to between 25 and 27 $/GJ for 2023. The use of interregional transport also saw the proportion of biomass used for heat demand above 100°C rise from 60% to over 90% in 2023. Supply constraints impact the use of biomass in 2037 and see the maximum economic use of biomass in heat demands above 100°C drop to 72%.enAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.Thesis