The other solar solution to electricity gridlock

Concentrating solar power is indeed a potential network asset in Australia ... if it is deployed astutely.

Renewable energy is frequently characterised as a burden on our electricity networks. But what if some forms of solar power could provide important network services, and reduce network costs overall?

A project by the Australian Solar Thermal Energy Association – AUSTELA – and two universities examined the potential for concentrating solar thermal power to avoid the need for traditional network augmentation at grid constrained locations, and what this would do to the business case for CSP. The results are launched at the beginning of February in a series of workshops in Brisbane (February 6), Sydney (February 11) and Adelaide (February 12). The project quantifies the potential economic benefits from installing CSP at these locations, and maps where CSP could provide cost-effective network support services.

Concentrating solar thermal power has been in commercial operation at utility scale for more than 20 years, and can be entirely dispatchable, due to inherent thermal inertia and the potential for thermal energy storage. CSP is predicted to provide 12-17 per cent of Australia’s electricity in 2030 in AEMO’s 100 per cent renewable energy scenarios. By the end of 2013 more than 3 GW of CSP was installed worldwide, with more than half including thermal energy storage in the form of tanks of hot molten salt.

While the technology is rapidly on its way down the cost learning curve, it is still currently short of commercial viability in Australia’s National Electricity Market. But rarely is CSP discussed as a potential network asset, to replace traditional means of meeting network supply constraints. This would require us to rethink how CSP should or could be developed, in terms of when, where and how big.

AUSTELA, the Institute for Sustainable Futures at the University of Technology, Sydney, the Centre for Energy and Environmental Markets at the University of New South Wales, and IT Power worked with network partners Ergon Energy, Essential Energy, Transgrid, ElectraNet, SA Power Networks, SP AusNet and Powercor to investigate the role CSP could have in grid management, and identify whether network payments at appropriate locations could bridge the cost gap. But connecting to the grid in constrained locations can often place a cap on the potential CSP plant size, requiring a smaller, more modular approach.

The project found that CSP can offer a commercially viable alternative to traditional network augmentation solutions in addressing electricity grid constraints. The study identified $0.8 billion of potentially avoidable network investment, and 533 MW of cost effective CSP which could be installed at grid constrained locations in the next 10 years.

The project also found that CSP could avoid the need for network augmentation in 72 per cent of the constrained areas examined – i.e. in 48 locations. If constraints were limited to only those with solar resources better than 21 MJ/m2/day DNI, CSP could avoid the need for augmentation at a staggering 94 per cent of locations.

The project developed a concept 'Indicative Firm Capacity' to show the probability that a CSP plant would be generating during peak periods by comparing historical weather data to recorded peaks. The modelling showed that IFCs in excess of 80 per cent can be achieved in all seasons and most locations in the National Electricity Market. Ten hours storage is sufficient to reliably meet both summer and winter afternoon and evening peaks in most areas of the NEM. In winter, IFC is less due to the lower solar resource, but high IFCs can still be reached in most locations north of Adelaide with only 10 hours storage.

Jay Rutovitz and Ed Langham are Research Principals at the Institute for Sustainable Futures, UTS. The project was undertaken with funding from the Australian Renewable Energy Agency, AUSTELA and Ergon Energy and supported by advice from IT Power.

*Interactive maps of proposed network investment, the cost effectiveness of CSP at currently identified constrained areas (assuming a network payment), and of the Indicative Firm Capacity throughout the NEM for a range of CSP configurations will be publicly available on the project website.

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