Callide oxyfuel project: throwing coal a lifeline

Callide oxyfuel project: Throwing coal a lifeline

There are about 22 carbon capture and storage projects in operation or under construction around the world, but now it’s the developments in Queensland that are under the spotlight.

Heralded as the coal industry’s real shot at battling climate change, it’s no wonder the eyes of the nation – and the world – are on Biloela, home to the Callide Oxyfuel Project.

The Callide Oxyfuel Project is a world-leading demonstration of how carbon capture technology can be applied to an existing coal-fired power station to generate electricity with low emissions.
At a time when the coal industry has never been under more pressure, carbon capture and storage (CSS) offers a lifeline; a place for coal-fired power stations in tomorrow’s diverse energy landscape.

The technology is not targeted at the Australian market, where coal-based generation has lost its appeal and its financing. Rather, it’s designed for those countries that have held on to their appetite for coal, particularly China and the US and, to a lesser extent, Japan, South Africa and Russia.

Globally, there are about 22 CCS projects in operation or under construction with a 582MW commercial-scale Integrated Gasification Combined Cycle Project in Mississippi, US, due for completion this year. For now, however, it is the Callide Oxyfuel JV-owned 30MW Callide retrofit in Queensland that’s in the spotlight. It’s the world’s largest – and first-of-a-kind – industrial-scale demonstration of oxyfuel combustion and carbon capture technology. What’s more, after drawing to a close in March, it achieved more than 5500 hours of carbon capture from the coal-fired electricity generation facility, putting 150,000MW of energy on to the grid.

The Callide site comprises three power stations – Callide A, Callide B and Callide C. Collectively they have the capacity to generate 1630MW, which is enough to power approximately two million homes. It is Callide A Power Station that has been transformed into one of the world’s first coal-fired low emission technology demonstrations.

Advancing the generation industry’s investigations into the viability of carbon dioxide storage is a no-brainer, according to the project’s director Dr Chris Spero.

“It’s an absolutely essential path the energy industry must go down to continue economic growth and to meet the community’s demand for reliable, cost-effective electricity,” he said.

“The US and China account for about 51.7 per cent of global emissions. Imagine if we could export what we’re developing at Callide to these two countries alone?

“It’s really a whole new ballgame and there’s a great deal of interest overseas, particularly from those big coal consumers.”

The idea was conceived in 2003 and, from there, the right place, the right time and government support became available.

“From 2004 to 2008 we were doing the feasibility study work on the project and in 2008 we started to sign all the formal agreements and started an international joint venture.”

Oxyfuel technology builds on earlier technologies that were established in the steel and glass industry utilising oxygen to enhance combustion, and in the boiler industry in utilising recycled flue gas to control furnace temperatures and reduce NOx formation.

“In terms of the technology selection, we wanted to develop and concentrate on a technology that wasn’t going to be too great a step forward too quickly, so we chose oxyfuel technology. This technology application is essentially a bolt-on,” Dr Spero said.

“We’ve taken unit number four at Callide A, which had been mothballed, and we did the basic modifications required to do this oxyfuel combustion.”

The process involves carbon dioxide capture by modifying the combustion process to reduce the volume of gas going up the chimney by two-thirds. The carbon dioxide is separated from other gasses that aren’t harmful, such as nitrogen, and then liquefied and stored.

“Normally you burn the coal in the air, all the flue gas goes up the chimney stack and people can see that,” Dr Spero said.

“That CO2 is going into the atmosphere. The concept behind this is about what we refer to as near-zero emissions.

“In applying this technology, it’s not only the carbon dioxide we address but it’s the other waste gasses that normally go into the atmosphere. These have potential environmental impact if they’re too high.”

Dr Spero said there were three main aspects to the legacy of the project. The first is the research that’s come out of it, where industry has learnt a great deal about CCS technology and how effective it is in achieving environmental goals. The second is the project’s innovation: it’s world-first initiative that has overcome challenging technical problems and modifications. The third is the people: the local talent who have been trained in operating new technology.

“Our focus was always about improving environmental performance for the electricity industry and the coal industry, and having a mandate licensed to operate from the public so we are taken seriously,” Dr Spero said.

“It’s an industry effort – an international effort.”

The Callide Oxyfuel Project is a joint venture between CS Energy, the ACA Low Emissions Technologies (ACALET), Glencore, Schlumberger Carbon Services, and Japanese participants, JPower, Mitsui & Co., Ltd., and IHI. The project has also received financial support from the Japanese, Australian and Queensland governments and technical support from the Australian coal industry.

Cleaner, greener pioneering technology

Oxyfuel is the term given to a process that involves firing a conventional coal-fired power station boiler with oxygen and recycled exhaust gases, instead of regular air. This produces a concentrated stream of carbon dioxide (CO2) that can be captured and stored – suitable for rail or truck overland and pipeline transport, and injection into a safe underground geological formation.

The main difference between a conventional coal-fired power station and Callide A is around the boiler area, where an oxygen plant and a CO2 capture plant have been retrofitted. Of course, new build with the latest technology is more attractive, however, the size of the coal fleet means retrofitting will be essential if coal-fired plants continue to be used.

Callide A Power Station has been operating in oxy-firing mode since January 2012 – making it one of the most advanced carbon capture projects in the world.

Storing carbon nature’s way

Carbon storage underground is known as geological storage or geosequestration. There are a number of natural examples of large quantities of CO2 existing in underground geological formations, on its own or in association with oil or natural gas. There are many underground formations around the world where CO2 can be safely stored. The oil and gas industries have been successfully injecting CO2 underground for almost 50 years.

In fact, modelling studies have shown up to 20-60 per cent of injected CO2 could be dissolved within 1000 years, according to BP alternative energy advisor for CO2 storage Tony Espie.

The Callide Oxyfuel Project has helped advance the generation industry’s investigations into the viability of carbon dioxide storage through its collaboration with the CO2CRC.

Carbon dioxide from the project was transported by road to Victoria in late 2014 and injected underground at the CO2CRC’s Otway Project site in South Western Victoria. Building on the large body of work already done by CO2CRC, the injected carbon dioxide was used to evaluate the geochemical and physical behaviour of carbon dioxide within the storage rock.

The project has also been able to advance the understanding of transport and storage options by contributing to a number of feasibility studies and investigations.

A small place making a big contribution

Callide Power Station is located in the Callide Valley near the small town of Biloela in the Banana Shire of Central Queensland. Coal is sourced from the nearby Callide Mine.

“Callide A was suitably placed and a good size of plant, and so on. In all this sort of criteria you would look for to do such a project, modest scale and so on, this one ticked all the boxes,” Dr Spero said.

The Intergovernmental Panel On Climate Change (IPCC) estimates worldwide geological C02 storage capacity is likely to exceed 2 trillion tonnes – more than 60-times total global annual emissions and equivalent to the lifetime output of about 4000 large (1GW) coal plants.

Project milestones

Mar 2006

MoU signed with Japanese participants

Oct 2006

Australian Government’s Low-emissions Technology Demonstration Fund funding announcement

Aug 2008

Refurbishment of Unit A4 at Callide A Power Station Commenced

Oct 2008

Official launch

Jan 2009

Refurbishment of Unit
A4 completed

Mar 2011

Boiler modifications completed for oxyfiring at Callide A Power Station and commissioning commenced

Apr 2011

First coal firing in air mode after boiler oxyfiring modifications

Dec 2012

Demonstration of CO2 begins

May 2014

Project passes halfway mark, achieving 6000 hours of operation in oxyfuel combustion mode

oct 2014

The first of four test injections of Callide Oxyfuel carbon dioxide undertaken at the CO2CRC Otway Basin test site in Victoria

March 2015

Demonstration phase comes to a close after two years, proving 10,000 hours of oxyfuel combustion and 5500 hours of carbon capture