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This Project set out to examine some options for developing new approaches to solar thermal energy storage.

Report extract

This Project set out to examine some options for developing new approaches to solar thermal energy storage. Our starting hypothesis was that we needed stronger forms of metal to use to build a new form of storage device. The device itself would also need to be designed in a different way to enhance efficient generation and storage of solar thermal power.

A technically feasible approach to the construction of a new concentrated solar thermal power system concept that involves a novel high-temperature thermochemical energy storage system was developed. This storage system promises to store thermal energy at temperatures of over 1,000°C, enabling the use of a combined power cycle, which reach the highest thermal power cycle efficiencies of up to 60% or more. The storage system is based on the reduction/oxidation cycling of a new mixed iron-manganese oxide thermochemical energy storage material.

A power system design concept was developed, including technical concepts for a two-stage solar tower concentrating system, solar receiver-reactor for the thermal reduction step, oxidation reactor heat exchanger for heat recovery, high-temperature particle storage tanks and material handling systems for particles and gases.

A literature review was conducted to compile data for the performance and cost of combined cycle power blocks. From this, the Levelised Cost of generated Energy (LCOE) has been determined. Based on the current cost-optimised system design with a 75 MW-e net power block and thermal energy storage system with 18 hours full-load storage capacity, an LCOE estimate of 224 AUD/MWh results (including 30% tax). This estimate is ~8% higher than that for a current state- of-the-art system.

To achieve LCOE close to targets such as the SunShot and ASTRI targets (below ~0.1 $/kWh), depends on the long-term cost reduction learning curve of the industry as a whole, driving cost reductions in solar field and construction that would automatically transfer to a future development using a new receiver and storage approach such as this. Based on historical trends of deployment growth this can realistically be contemplated over the coming decade.

Further research is required to achieve additional cost reductions for the Fe67 system. This technology is currently undemonstrated. Hence, large efforts would be required to demonstrate the predicted performance of this technology at a relevant scope and scale (~100 kW or above).

Last updated 10 July 2020
Last updated
10 July 2020
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