• Energy Research

Solar photovoltaics (PVs) and wind constitute more than 60% of global annual net new capacity additions. Balancing an electricity system with 30–100% variable PV and wind is straightforward using off-the-shelf techniques comprising stronger interconnection over large areas to smooth out local weather, storage, demand management, and occasional spillage of renewable electricity. The overwhelming dominance of PV, wind, and hydroelectricity in new renewable energy deployment means that renewable electricity is tracking toward near equivalence with renewable energy. A global survey of off-river (closed-loop) pumped hydro energy storage sites identified 616 000 promising sites around the world with a combined storage capacity of 23 million GWh, which is two orders of magnitude more than required to support 100% global renewable electricity. This is significant because pumped hydro storage is the lowest cost storage method and is available off-the-shelf in large scale. Australia is deploying PV and wind at a rate of 250 W per year per capita, which is four to five times faster than in the European Union, the USA, Japan, and China. This is significant because it demonstrates that rapid deployment of PV and wind is feasible, with consequent rapid reductions in greenhouse gas emissions.

Short-Term Off-River Energy Storage (STORES) is a breed of pumped hydro energy storage which incorporates closed-loop pumped hydro systems located away from rivers. Compared with conventional river-based hydroelectric projects, the STORES facilities consume modest volume of water and have little impacts on the environment and natural landscape. A significant feature of STORES is the large altitude difference between upper and lower reservoirs (typically > 300 metres), which enables large amounts of electrical energy to be stored in pairs of medium-sized reservoirs. STORES is capable of large-scale energy time shifting and a variety of ancillary services such as frequency regulation and voltage control, which can facilitate high penetration of photovoltaics and wind in electricity systems. This study investigates the potential for STORES to be deployed in Australia supporting large-scale photovoltaics and wind developments in the Australian electricity markets. The study is comprised of two aspects: 1. Grid integration modelling of photovoltaics, wind and pumped hydro with a focus on the analysis of energy supply and demand balance in 100% renewable electricity systems. Hypothetical scenarios for 100% renewable electricity in the Australian National Electricity Market (NEM) and 90-100% renewable electricity in the South West Interconnected System (SWIS) of Western Australia are modelled. An energy balance model is used to determine the least-cost configuration of generation, storage and transmission facilities based on the hour-by-hour analysis of historical solar and wind data and electricity demand in 2006-2010 (NEM) and 2007-2014 (SWIS). The levelised costs of electricity normalised to 2016 Australian dollars are $75-93/MWh for the NEM and $103-129/MWh for the SWIS, which can be competitive with new-build coal or natural gas-fired power stations in Australia. Importantly, the levelised costs of balancing are only $25-$28/MWh in the NEM and $37-$41/MWh in the SWIS, which are significantly lower than the results from studies using alternative balancing methods such as geothermal or concentrating solar power coupled with high-temperature thermal energy storage. 2. A comprehensive Geographic Information System (GIS)-based site survey for STORES across each state/territory of Australia. Two typical types of sites, dry-gully and turkey’s nest, are modelled and a sequence of GIS-based procedures are developed which highlight the most promising regions for STORES deployments and identify the prospective sites. A national atlas of pumped hydro energy storage is developed which demonstrates Australia has a large storage potential in the form of STORES - equivalent to 67,000 gigawatt-hours (GWh) or 670 gigawatts (GW) with 100 hours of storage; far beyond the storage requirements (about 20 GW, 500 GWh) to support 100% renewable electricity in the Australian energy market. In comparison, Tumut 3, the largest hydroelectric power station in Australia, has a generation capacity of 1.5 GW while the Hornsdale Power Reserve in South Australia, the world’s largest lithium-ion battery, is only capable of 0.1 GW, 0.129 GWh of storage. This study provides a generic, cost-effective approach to decarbonise electricity sectors through a synergy of flexible renewable energy resources, geographic dispersion of photovoltaics and wind, demand response and most importantly, large-scale energy storage, STORES. Significantly, the affordable and reliable low-carbon electricity systems can be built based on existing mature generation, storage and transmission technologies which have already been deployed on a large scale, namely photovoltaics, wind, existing hydro and biomass, pumped hydro and high-voltage direct-current and alternating-current transmission.

Abstract An hourly energy balance analysis is presented of the Australian National Electricity Market in a 100% renewable energy scenario, in which wind and photovoltaics (PV) provides about 90% of the annual electricity demand and existing hydroelectricity and biomass provides the balance. Heroic assumptions about future technology development are avoided by only including technology that is being deployed in large quantities (>10 Gigawatts per year), namely PV and wind. Additional energy storage and stronger interconnection between regions was found to be necessary for stability. Pumped hydro energy storage (PHES) constitutes 97% of worldwide electricity storage, and is adopted in this work. Many sites for closed loop PHES storage have been found in Australia. Distribution of PV and wind over 10–100 million hectares, utilising high voltage transmission, accesses different weather systems and reduces storage requirements (and overall cost). The additional cost of balancing renewable energy supply with demand on an hourly rather than annual basis is found to be modest: AU$25–30/MWh (US$19–23/MWh). Using 2016 prices prevailing in Australia, the levelised cost of renewable electricity (LCOE) with hourly balancing is estimated to be AU$93/MWh (US$70/MWh). LCOE is almost certain to decrease due to rapidly falling cost of wind and PV.

Short-Term Off-River Energy Storage (STORES) is a breed of pumped hydro energy storage which incorporates closed-loop pumped hydro systems located away from rivers. Compared with conventional river-based hydroelectric projects, the STORES facilities consume modest volume of water and have little impacts on the environment and natural landscape. A significant feature of STORES is the large altitude difference between upper and lower reservoirs (typically > 300 metres), which enables large amounts of electrical energy to be stored in pairs of medium-sized reservoirs. STORES is capable of large-scale energy time shifting and a variety of ancillary services such as frequency regulation and voltage control, which can facilitate high penetration of photovoltaics and wind in electricity systems. This study investigates the potential for STORES to be deployed in Australia supporting large-scale photovoltaics and wind developments in the Australian electricity markets. The study is comprised of two aspects: 1. Grid integration modelling of photovoltaics, wind and pumped hydro with a focus on the analysis of energy supply and demand balance in 100% renewable electricity systems. Hypothetical scenarios for 100% renewable electricity in the Australian National Electricity Market (NEM) and 90-100% renewable electricity in the South West Interconnected System (SWIS) of Western Australia are modelled. An energy balance model is used to determine the least-cost configuration of generation, storage and transmission facilities based on the hour-by-hour analysis of historical solar and wind data and electricity demand in 2006-2010 (NEM) and 2007-2014 (SWIS). The levelised costs of electricity normalised to 2016 Australian dollars are $75-93/MWh for the NEM and $103-129/MWh for the SWIS, which can be competitive with new-build coal or natural gas-fired power stations in Australia. Importantly, the levelised costs of balancing are only $25-$28/MWh in the NEM and $37-$41/MWh in the SWIS, which are significantly lower than the ...

Rapid cost reductions have led to the widespread deployment of renewable technologies such as solar photovoltaics (PV) and wind globally. Additional storage is needed when the share of solar PV and wind in electricity production rises to 50-100%. Pumped hydro energy storage constitutes 97% of the global capacity of stored power and over 99% of stored energy and is the leading method of energy storage. Off-river pumped hydro energy storage options, strong interconnections over large areas, and demand management can support a highly renewable electricity system at a modest cost. East Asia has abundant wind, solar, and off-river pumped hydro energy resources. The identified pumped hydro energy storage potential is 100 times more than required to support 100% renewable energy in East Asia. Keywords: Photovoltaics, Wind energy, Pumped hydro energy storage, 100% renewable energy

Abstract Pumped hydro energy storage is capable of large-scale energy time shifting and a range of ancillary services, which can facilitate high levels of photovoltaics and wind integration in electricity grids. This study aims to develop a series of advanced Geographic Information System algorithms to locate prospective sites for off-river pumped hydro across a large land area such as a state or a country. Two typical types of sites, dry-gully and turkey’s nest, are modelled and a sequence of Geographic Information System-based procedures are developed for an automated site search. A case study is conducted for South Australia, where 168 dry-gully sites and 22 turkey’s nest sites have been identified with a total water storage capacity of 441 gigalitres, equivalent to 276 gigawatt-hours of energy storage. This demonstrates the site searching algorithms can work efficiently in the identification of off-river pumped hydro sites, allowing high-resolution assessments of pumped hydro energy storage to be quickly conducted on a broad scale. The sensitivity analysis shows the significant influences of maximum dam wall heights on the number of sites and the total storage capacity. It is noted that the novel models developed in this study are also applicable to the deployments of other types of pumped hydro such as the locations of dry-gully and turkey’s nest sites adjacent to existing water bodies, old mining pits and oceans.

Australia has one of the highest per capita consumption of energy and emissions of greenhouse gases in the world. It is also the global leader in rapid per capita annual deployment of new solar and wind energy, which is causing the country's emissions to decline. Australia is located at low-moderate latitudes along with three quarters of the global population. These factors make the Australian experience globally significant. In this study, we model a fully decarbonised electricity system together with complete electrification of heating, transport and industry in Australia leading to an 80% reduction in greenhouse gas emissions. An energy supply-demand balance is simulated based on long-term (10 years), high-resolution (half-hourly) meteorological and energy demand data. A significant feature of this model is that short-term off-river energy storage and distributed energy storage are utilised to support the large-scale integration of variable solar and wind energy. The results show that high levels of energy reliability and affordability can be effectively achieved through a synergy of flexible energy sources; interconnection of electricity grids over large areas; response from demand-side participation; and mass energy storage. This strategy represents a rapid and generic pathway towards zero-carbon energy futures within the Sunbelt. Here is a summary of the study: https://www.dropbox.com/s/uvd90goh80y9eda/Zero-carbon%20Australia.pdf?dl=0