Renewable integration options for remote New Zealand community

Abstract

About 35% of New Zealand’s population lives in rural and remote areas like Whitianga and its nearby settlements. These areas are facing growing electricity demand due to rising population, business activity, and the shift to cleaner transport such as EV and FCEV. This trend is expected to put additional pressure on existing electricity infrastructure and networks, many of which were not built to handle such loads. A potential solution is to utilize local renewable energy sources, such as solar, wind, and green hydrogen, to reduce reliance on the national grid and delay costly infrastructure upgrades. The first part of the thesis investigates the dynamic behaviour of a PEM electrolyser as a likely component in future integrated renewable energy systems. A Python-based simulation compares the hydrogen production output of dynamic and static models of a PEM under variable solar PV inputs. For the PEM capacity selected, there was a modest difference in cumulative hydrogen output from the dynamic model compared to the static model using one-minute input data over a whole day. Potentially, the dynamic model provides a more accurate way to size electrolyser and associated units like compressor and hydrogen storage vessels with the fluctuating electrical input conditions. The second part evaluates the use of rooftop solar PV, wind, and hybrid solar-wind systems integrated with green hydrogen into a single residential house to achieve various levels of self-sufficiency over a full year. The study models energy balance, hydrogen storage, and levelized cost of energy (LCOE) for a range of system sizes, showing that 100% self-sufficiency is achievable in all three options, but only at extremely high LCOE levels between 0.52 and 0.78 NZD/kWh. Among the options, the hybrid system of solar and wind performs best, achieving complete self-sufficiency (100%) at the lowest cost of 0.52 NZD/kWh while balancing energy generation and storage needs with demand. The third part presents a case study of the Whitianga township and region, exploring the integration of solar PV, Vehicle-to-grid (V2G), and green hydrogen to meet future energy demand. A techno-economic assessment examines residential, commercial, and transport energy needs from 2024 to 2050 and evaluates how a 32 MWp solar PV energy system can supply local demand while reducing reliance on the national grid and the need for local transformer upgrades. Two approaches were investigated: a centralised solar farm approach plus local hydrogen production & EV charging demand, and a decentralised residential rooftop solar approach supported by V2G electricity storage. The results indicate that the centralised approach has the lowest LCOE of 0.107 NZD/kWh, while the local grid upgrade remains unavoidable, even with higher solar penetration to the local grid. But in terms of payback period, the decentralised approach has a significant advantage, even with the higher investment cost, especially when V2G is incorporated into the energy management system. The initial investment amount can be recovered in 12.01 years with 20kWh of V2G battery storage.