Located in the Upper Hunter Valley of New South Wales, the project aims to reduce the amount of coal needed to generate electricity at Macquarie Generation’s Liddell Power Station by approximately 2,000 tonnes each year, and will create an annual saving of 4,000 tonnes of carbon dioxide.

Liddell’s background

Commissioned in 1972, the Liddell Power Station has been a critical component of the NSW electricity system. Liddell was the first major power station to be located inland, away from abundant salt water supplies traditionally used for cooling purposes, and therefore required construction of an artificial lake. Each year Liddell Power Station produces around 10,000 gigawatt hours (GWh) of electricity, or enough power for over 1 million Australian family homes.

While it is a crucial component of the NSW energy system, the power station has not been averse to change and has a history of supporting innovative environmental projects involving biomass, liquid alternative fuel and turbine replacements. In recent years, power station owner Macquarie Generation has been undertaking an upgrade program with the aim of improving Liddell’s operational efficiency in order to reduce its environmental impact.

In 2002, Solar Heat and Power approached Macquarie Generation looking for a power company to partner in testing and developing their solar thermal technology in a real setting. The then Manager of Liddell, John Marcheff saw an opportunity to integrate solar with the feedwater heating system of the power station and the rest is history.

“Macquarie Generation recognised this as an opportunity to contribute to the development of solar thermal technology, and maturity of the renewable energy industry in Australia,” says Liddell Power Station Manager Peter Sewell.

The project uses Solar Heat and Power patented compact linear Fresnel reflector (CLFR) technology, which uses mirror arrays to reflect solar energy onto overhead tubes containing water to produce steam.

Project development

Development of the project has been divided into two phases, with the first aiming to demonstrate that the mirror system could produce steam, and the second stage aiming to show that the steam can be utilised in the power station in a fully automated process.

Work on the first stage of the project commenced in July 2003. It involved construction of a pilot solar mirror array at Liddell to test mirror design and confirm solar energy collection rates. This mirror array covered an area of 1,300 square metres - approximately the size of an Olympic swimming pool.

Tests conducted during August 2004 proved that solar energy could be captured to produce steam to the temperature of 285°C – an ideal temperature to integrate with a coal-fired power station.

In 2005 development of the second stage began. This involved construction of a mirror array site to cover an area of 18,000 square metres or approximately four football fields, with around 500 mirrors each 12 x 2 metres. The reflected solar energy will be used to heat feedwater supplying the boiler of one of the power station’s units, replacing steam currently taken from the turbine.

Refining the second stage and beyond

In refining the design for the second stage, a number of improvements were made based on learning from the first stage. Particular attention has been given to decreasing both construction costs and time, in order to improve capacity for the technology to be rolled out for large-scale solar plants.

Speaking about the development, Mr Sewell notes that the second stage has required innovative techniques for controlling steam supply in a fully automated system.

“Irregular heating, for example, the difference between day and night, winter and summer, as well as cloudy and sunny conditions poses particular control challenges,” Mr Sewell says.

Admission of steam into the power station cycle also posed a design challenge, says Mr Sewell. He adds that the use of high pressure steam always increases cost and complexity due to the pressure ratings required for steam.

Despite these challenges, work on the development is progressing on schedule for commissioning in August this year, with the Liddell Power Station team currently checking electrical systems, flushing pipework and testing components.

A further expansion may be on the books as there is sufficient land available at Liddell Power Station for the current project to be expanded to a maximum 180,000 square metres. This expansion will be dependent on the success of the existing project, economic viability, business priorities and available funding. Plans for future stages will be determined after testing of the second stage later this year.

Given its significance to the NSW grid, a projected annual production of 4,400 MWh of renewable energy, and carbon dioxide savings equivalent to taking about 750 cars off the road, Liddell Power Station has considerable environmental potential in its own right. However, if it is proven operationally successful through the second stage trials, this project might just pave the way for greener coal-fired stations throughout Australia.