Understanding the potential of ammonia-based thermochemical energy storage

The Solar Thermal Group at the Australian National University (ANU) has been working for over two decades on a system for dissociating ammonia with concentrated solar energy so that the products can be stored and recycled through a conventional ammonia synthesis converter to achieve 24-hour power production.

In 2000, the team reported on the successful testing of a world first closed loop system that operated at a solar input level of 1kW. A detailed study of a 10MWe base load power plant in central Australia, has indicated that Levelised Electricity costs less than AUS$0.15/kwh are potentially achievable.

As per the information available, a complete solar driven closed-loop thermochemical energy storage system using ammonia has been demonstrated and this pilot-scale system has shown that ammonia dissociation receiver / reactors are well suited for operation through solar transients and ammonia synthesis heat recovery reactors are capable of stable, predictable operation with heat recovery at temperatures suitable for high-quality superheated steam production.

In addition, reactant storage and handling, for the ammonia system at pressures up to 30 MPa, can be achieved using standard components and manufacturing techniques.

In 2005, Wizard Power entered into a licencing agreement for the commercial deployment of the technology.

In May 2007, the Australian Government acknowledged the significance and commercial potential for the ammonia-dissociation solar energy storage system with a grant of A$7.4 million under the Advanced Electricity Storage Technology programme. This funding contributes to the Whyalla Solar Oasis demonstration project that will showcase a multi-dish power plant using the new second generation Big Dish technology with integrated ammonia-dissociation solar energy storage in Whyalla South Australia.

It is said that the project will be the world's first demonstration of emission free baseload solar power and peak-following power-on-demand.

Providing an insight into the current status, Artur Zawadski, manager, business development and project delivery, Wizard Power, told CSPToday.com that the Whyalla demonstration project is in the detailed design phase, with geotechnical surveys underway and construction scheduled to start in November 2008.

The Big Dish solar thermal concentrator field (six dishes) is expected to be completed in September 2009 and the ammonia thermochemical energy storage is expected to be completed in early 2010.

Zawadski, who is scheduled to speak during the 2nd Concentrated Solar Thermal Power Summit, to be held on 12-13 November in Seville, shared that Wizard Power is working with an energy retailer, Sanctuary Energy, for its plans to build a commercial power plant, co-located with the demonstration plant.

The first stage of the commercial plant will be a 30MW direct steam generation system (no integrated storage) and 100MW in the second stage.

"Once the energy storage demonstration plant is demonstrated successfully, then it is planned to retrofit the storage solution onto the commercial plant," said Zawadski.

The ammonia based thermochemical energy storage system is designed for utility scale power plants with tens to hundreds of megawatts capacity. The storage solution is capable of providing load-following power on demand on a 24x7 basis. "Because the storage is done thermochemically and not thermally, the storage time is indefinite with no energy losses at the point of storage," said Zawadski.

He added that the ammonia synthesis technology and its integration to steam turbine power generation systems is an industry standard technology used within the ammonia production industry and based upon the Haber-Bosch process that has been used for over 100 years for the manufacturing of ammonia.

"Therefore, this component of the solution is very mature, low technical risk and widely supported worldwide. The innovation, which was originally developed by the Australian National University and which is now being commercialised by Wizard Power is the ammonia dissociation, i.e. solar energy storage component," said Zawadski.

He further added that this is the reverse of the Haber-Bosch thermochemical reaction and is therefore expected to be able to achieve economic performance as good as the well developed synthesis process when built at sufficient scale i.e. minimum of tens of MW of storage.

According to Wizard Power, the project will integrate an array of Big Dishes with the exceptional ammonia-based solar energy storage system to power a thermochemical process that stores concentrated solar energy until it is required to generate electricity - at any time day or night, in any weather conditions and on a continuous baseload or on-demand peaking basis.

Last year, it was shared that the international interest in technology is not only because it can deliver large-scale base load and on-demand electricity from solar energy but also because the high temperature thermochemistry use makes possible an array of other energy conversion opportunities.

On the status of commercialisation of this unique Australian energy technology, Zawadski said the company is undertaking R&D into gasification of carbonaceous materials (coal & biomass e.g. algae) and also into brayton cycle gas turbine technology.

And he added that the industry interest in very strong with discussions underway on partnerships for commercialisations and/or demonstration projects in all of these areas.

2nd Concentrated Solar Thermal Power Summit

Artur Zawadski, manager, business development and project delivery, Wizard Power is scheduled to speak during the 2nd Concentrated Solar Thermal Power Summit, to be held on 12-13 November in Seville.

For more information, click here: www.csptoday.com/eu/programme.shtml


Contact Belen Gallego by email: belen@csptoday.com