Grids dominated by solar and pumped hydro in wind-constrained sunbelt countries

Three-quarters of the global population lives in the sunbelt region (±35o latitude) with excellent access to solar resources. Wind resources at the equator are very limited, while supply chain and permitting delays are slowing wind deployment at a global scale. This paper investigates the potential for solar photovoltaic-dominant 100% renewable grids to be developed in sunbelt countries through a case study of Malaysia. It was expected that the technical potential for solar photovoltaics and off-river pumped hydro would be far in excess of what is required to decarbonise Malaysia's electricity grids. A Geographic Information System analysis determined that Malaysia has the potential to deploy approximately 8.5 Terawatts of terrestrial photovoltaics and 25 Terawatts of marine floating solar on calm oceans. There are roughly 450 Terawatt-hours of energy storage available in the form of off-river (closed-loop) pumped hydro energy storage. A least-cost, 16-year hourly energy balance model was used to determine that an affluent, fully electrified, highly interconnected Malaysia could greatly reduce emissions through the deployment of 660 Gigawatts of photovoltaics and 2200 Gigawatt-hours of pumped hydro, supported by small amounts of hydrogen-based gas peaking. All-in costs for such a fully decarbonised energy system were modelled to be in the range of 95–103 USD per Megawatt-hour. A Sarawak-Peninsular Malaysia interconnected grid could produce a similar electricity cost to two separate grids while reducing the long-term energy storage needs by approximately 33%. Inclusion of about 3 Terawatt-hours (0.1% of average annual generation at 20 Megawatt-hours/capita/year demand) of hydrogen, synthetic methane, or legacy fossil fuels could further reduce long-term energy storage needs by about 30% by helping to ride through occasional prolonged cloudy periods. Policymakers in sunbelt countries should be highly sceptical of technical potential estimates that suggest limited area for solar photovoltaics. Sunbelt countries can comfortably proceed with the development of cheap, reliable solar-dominant grids primarily supported by pumped hydro energy storage and inter-regional transmission.