Can “solar hydro" replace coal and gas-fired power stations?

Organic Rankine Cycle (Source: Applied Sciences, 9 (1) 49, 2019)

RayGen, with the support of AREA (Australian Renewable Energy Agency) and in collaboration with other companies, is on-track to test a 50MWh “solar hydro” project in NW Victoria. The plan is to eventually develop a 200MW solar power plant with around 100MW/1000MWh storage. This is enough to help replace retiring coal and gas fired power stations.

The plant will consist of mechanical mirrors on the ground concentrating sunlight and heat to RayGen’s efficient collector on a raised tower. The collector consists of mirrors and super-efficient PV modules which can collect both light and heat. The specialist panels convert about 30 per cent of the sunlight to electricity and capture around 60 percent of the excess heat. 

The heat is stored as hot (92^°C) water in one reservoir while the electricity is used to chill water to 2^°C, which is stored in a cold reservoir. Between the two tanks is the Organic Rankine Cycle system (see above diagram), which has a special organic fluid circling within it. At the evaporator, the fluid is heated to a gas by the stored hot water which then drives a turbine to generate electricity. The organic gas then passes to the condenser where it is cooled back to a liquid by the stored cold water. 

With the organic fluid coming to boil at a lower temperature than water, it means that the system has a high efficiency. Since the water temperature differences are stored like a battery in the reservoirs, the system can generate electricity when required. “The temperature difference of about 90^°C has a similar energy storage capacity as pumped hydro with a height of 1000 metres – so really, really big pumped hydro.” says RayGen’s Will Mosley. “RayGen is able to deliver the economics of pumped hydro and the flexibility of batteries.” (RenewEconomy) 

Read more: 
- RayGen edges closer to “solar hydro” success with new strategic partnerships. RenewEconomy, April 16, 2020. 
- World-leading solar technology born in Melbourne, that’s ultra-cool. ARENAWire, September 28, 2017. 
- Solar power plant phase 1. ARENA, January 2020. 
- Renewable energy storage, solar power technology. RayGen

Australia's chief scientist says we can be a world leader in energy storage.

Australia has the most MW of storage = navy bar graph (source RenewEconomy)

A new study led by chief scientist Alan Finkel has emphasized Australia’s role as a leader in the home battery storage sector, and says Australia can, and should, be a leader of energy storage of all types, including renewable hydrogen as an export opportunity.

The two most mature energy storage technologies in Australia are pumped hydro and lithium-ion batteries. There are other storage technologies being explored or adopted, such as renewable hydrogen, solar thermal, electrical thermal and flow batteries.

Battery technology is improving such that it can be used to provide back-up electricity if there is not enough power generation to meet demand. Batteries also play a crucial role in stabilizing the grid by helping to keep a constant frequency. Large-scale batteries and virtual power plants from home battery storage are starting to perform these roles.

One advantage of batteries is that once installed as small units they can be added to as needs and funds arise. Also, they can be installed close to where they are needed, reducing the transmission costs. In some cases, batteries can save investment costs by avoiding the need to upgrade power lines in cities and similarly support the large grid at its extremities without new lines.

Read more:
Finkel says Australia can, and should, be world leader in energy storage. RenewEconomy, July 6, 2018.
Taking charge: the energy storage opportunity for Australia. Office of the Chief Scientist - Occasional Paper, July 2018.
Also in this blog:
SA’s big Tesla battery goes full discharge (100MW) …... December 2017.
Australia’s biggest solar farm switches on …... (Including solar thermal storage). May 2018.
...Hydrogen as a storage of renewable energy for export. October 2017.
Australian virtual power plants to date.

"Australia's biggest solar farm switches on in Port Augusta"

Artist's impression of the Bungala solar farm (RenewEconomy)

“Australia’s biggest solar farm – the 220MW (AC) Bungala solar project near Port Augusta in South Australia – has begun production marking the important first stage of the transformation of a former coal city into a major renewable energy hub.

The first output from Bungala – which could end up being a 300MW project if all three stages are built – was injected into the local grid last week, as final commissioning of the 110MW first stage continues.

Bungala, located 12kms from Port Augusta, is one of a number of major renewable projects being built, or about to start construction, near the city which once hosted the state’s two brown coal generators.

Near Bungala, the 212MW Lincoln Gap wind farm, along with at least 10MW of battery storage, is under construction, and the 150MW Aurora solar tower, with 8 hours of molten salt storage, should start construction later this year about 30kms north of the town.......”

Read more at: Australia's biggest solar farm switches on in Port Augusta. Renew Economy, May 15, 2018.