The original objective of Australia’s ZeroGen project was to build a 80 MW net integrated gasification combined-cycle demonstration facility, before scaling up to a 300 MW net facility with carbon capture and storage (CCS) by 2017. However, the project team has decided to go for broke and is now working towards deploying a commercial-scale 530 MW power plant with CCS by 2015.

J. Cribb, Julian Cribb & Associates & P. Swindells, ZeroGen, Australia

The ZeroGen project, owned by Australia’s Queensland Government, has begun feasibility studies to fast-track the development of the world’s first commercial-scale demonstration of integrated gasification combined-cycle (IGCC) with carbon capture and storage (CCS).

MHI provided a full ‘EPC wrap’ to Clean Coal Power R&D for its 250 MW IGCC plant in Nakoso, Japan
Click here to enlarge image

The integration of IGCC with CCS has the potential to produce baseload electricity with up to a 90 per cent reduction in carbon dioxide (CO2) emissions when compared to traditional coal fired power stations. ZeroGen is proposing a 530 MW IGCC with CCS low-emissions power generating facility to be operational in Queensland in 2015 – two years earlier than originally anticipated and significantly accelerating the development of this internationally important technology.

The technologies of IGCC and CCS have never before been integrated for electricity production. Thus, a fundamental objective of ZeroGen is to demonstrate the technology at commercial-scale, thereby significantly reducing technology risks and costs to enable the deployment of low-emission, coal-based power plants in both Australia and right across the globe.

The integration of IGCC with CCS could offer a new lease of life to coal – the world’s cheapest and most abundant fuel source – converting it from a cause of pollution into an ongoing source of clean energy. In doing so, it could also help preserve the future of an A$24 billion ($20 billion) domestic coal export industry and the 130 000 jobs it supports. As well as supplying low-carbon electricity to the Australian grid, the ZeroGen concept could help lead the world’s emerging industrial superpowers, like China and India, to a more sustainable reliance on coal and curb the impact of climate change.

Focusing on the Technology

While IGCC and CCS have never before been integrated for electricity generation, they are commercially-proven technologies in their own rights. There are currently five coal fired IGCC plants in operation throughout the world – two in Europe, two in USA and one in Japan – and carbon capture, transport and injection into oil reservoirs (the same technologies that CCS will deploy) has been used in the global oil and gas recovery industries for decades. There are more than 2000 km of CO2 pipelines in the USA alone.

IGCC is widely regarded as one of the most efficient and environmentally friendly technologies for producing electricity from coal. An IGCC power plant combines a gasification system with a modern, highly efficient combined-cycle electric power system (i.e. one or more gas turbines integrated with a steam turbine). The gasification part of the process refers to using a commercially proven manufacturing process to convert coal to a synthesis gas (syngas), which can be further processed before finally being combusted in a gas turbine to produce electricity.

ZeroGen’s IGCC plant will include an additional stage where the CO2 will be captured from the syngas prior to its combustion in the gas turbine, thereby preventing its release into the atmosphere. ZeroGen will utilize IGCC technology developed by Japan’s Mitsubishi Heavy Industries (MHI), which is based on air-blown gasification technology that the company has further refined to achieve the world’s highest transmission and power generation efficiency. MHI has already delivered a 250 MW IGCC demonstration plant to a company called Clean Coal Power R&D Company Limited, which was jointly established by ten Japanese electricity providers. The plant, located in Nakoso, Japan, has successfully completed its initial target, i.e. 2000 hours continuous operation, which is an exceptional performance by a coal-based IGCC facility so early in its operational life. The ZeroGen plant will be a scaled-up version of the Nakoso plant, and will include carbon capture for the first time.

A well site geologist on location at a ZeroGen drill rig in the Northern Denison Trough
Click here to enlarge image

Coal is combined with a mixture of oxygen-enriched air and steam under pressure, where it undergoes a chemical change to produce syngas – comprised mainly of carbon monoxide (CO) and hydrogen (H2). The syngas produced in the gasifier undergoes a shift conversion where the CO is converted to CO2, with H2 also a product. The CO2 is then separated from the shifted syngas, producing a clean, low-carbon, high-hydrogen fuel, which powers the combined-cycle gas turbine to produce power. The separated CO2 stream is then dehydrated and compressed for transportation and sequestration. The separation process also removes sulphur compounds as a separate stream, allowing these compounds to be converted to a valuable high-purity sulphuric acid by-product.

CCS is a method of preventing the release of CO2 into the atmosphere by capturing and safely storing CO2 emissions from fossil fuel-based power generation. It is an essential component of all low-emission coal technologies. ZeroGen’s CCS involves a three-step process:

1. CO2 Capture: Concentrated CO2 will be separated, pre-combustion, from the syngas produced by the IGCC plant. It will then be compressed into supercritical form ready for safe transportation.
2. CO2 Transport: The compressed CO2 will be transported via pipeline to the sequestration site.
3. CO2 Storage: The final step in the process is the safe and long-term storage of CO2 up to 2 km underground in deep geological reservoirs.

For millions of years, crude oil and gases (including methane and CO2) have been stored naturally underground, trapped in deep reservoirs or basins. CCS technology duplicates this natural process by safely storing carbon within similar geological formations. The best sites for CO2 storage are deep geologic formations, such as depleted petroleum fields or deep natural reservoirs.

Carbon Storage Exploration Programme

Since 2006, ZeroGen, in partnership with Royal Dutch Shell, has been undertaking an explorative drilling programme in the Northern Denison Trough, near Springsure in Central Queensland, which is at the forefront of geological storage exploration activities for the world. ZeroGen has drilled over 40 per cent of all the wells in the world that are being used for the specific purpose of geological storage of CO2. The drilling programme comprises three phases and the status of each is highlighted in Table 1.

Click here to enlarge image

To date, ZeroGen has drilled 11 wells in the Northern Denison Trough area to define and characterise the geological reservoirs identified for potential CO2 storage. ZeroGen is looking for sandstone formations lying 800-2000 metres beneath the surface, with the right porosity and permeability to receive the CO2 as a gas and hold it in a supercritical state under pressure. These must also be sealed by a cap of impervious shale to ensure its remains securely stored.

The drilling programme has already confirmed the geology’s ability to safely and securely store large quantities of CO2 and investigations are now ongoing to determine the cost of carbon storage and the total quantity that can be stored cost-effectively. Up to two million tonnes will need to be stored annually from the ZeroGen commercial-scale plant, which has a potential operating life of between 25-50 years.

ZeroGen will also complete a CO2 and water test injection this year to confirm the reservoir model and the injectivity of CO2 into various rock types. The process will involve injecting up to 2000 tonnes of CO2 and water into various strata within a test well over a 50–70 day trial period, and is considered essential exploration activity when assessing CO2 storage reservoirs.

Royal Dutch Shell continues to support the injection testing programme as part of its global efforts to develop and deploy CCS technology. A long-term geosequestration partner for the commercial-scale project will be identified in due course. Several major entities, including Royal Dutch Shell, will be considered for the role.

Key Challenges

As the CCS industry in Australia continues to evolve, legislation surrounding the exploration and storage of CO2 is essential. The recent introduction of the Queensland Greenhouse Gas Storage Act 2009 provides one of the first legislative frameworks for onshore storage of carbon and represents a vital and positive step for government and industry.

Developing and demonstrating a new technology will always present challenges, and for ZeroGen, the key ones are those of technology risk, time and funding. A key objective is to minimize technology risks and costs surrounding the integration of IGCC with CCS technology to facilitate its widespread deployment in Australia and around the world.

During the past three years, ZeroGen has undertaken extensive research, exploration and technical investigations, as well as stakeholder and community consultation, to mitigate these risks within the project and for the future deployment of the technology.

Electricity produced by IGCC with CCS will cost more than from traditional coal fired stations initially, and some form of economic incentive – whether via carbon trading or subsidy – will be essential for the technology to take root. However it can equal existing power plants in energy efficiency, while providing the pathway for dramatically lowering greenhouse gas emissions. As IGCC with CCS technology continues to evolve it will inevitably become cheaper.

As the effects of climate change continue to worsen and global energy demand continues to increase, there is pressure for large-scale demonstrations of low-emission fossil fuel and other low-emission technologies. In response, many stakeholders and investors have expressed an urgent need for commercial-scale demonstrations of IGCC with CCS.

ZeroGen had originally planned to first build an 80 MW demonstration plant, however following discussions with project stakeholders a new opportunity emerged to proceed directly to commercial-scale.

The partnership with Mitsubishi Corporation (MC) and MHI has been a key factor in allowing the project to proceed directly to commercial-scale, as it significantly reduces the technology risks for the project and thereby enables a quicker, safer and more cost-effective strategy to deployment.

ZeroGen has been endorsed by a number of leading national and international entities including the Australian Coal Association, WWF-Australia, CFMEU, World Coal Institute and Electric Power Research Institute od the US.

ZeroGen’s commercial-scale project is estimated to cost in the vicinity of A$4.3 billion. In today’s economic climate, there is no doubting the challenges facing every project when it comes to raising funds. However, the imperative of climate change is such that most of the organizations ZeroGen is speaking to regard low-emission technology investment as a non-negotiable area of expenditure, and the project is recognized worldwide as too significant to delay.

Funding partners currently include the Queensland Government and Australian Coal Association Low Emission Technologies Limited (ACALET). MC and MHI are also considering an equity position in the project. Strategic private investors are also expected to make an important contribution. ZeroGen will also be seeking significant support under the Australian Government’s Clean Energy Initiative CCS Flagships Programme.

Where Now?

ZeroGen will begin studies to demonstrate the technical and economic feasibility of the 530 MW power plant. The feasibility studies process is expected to take approximately two years.

The actual location for the commercial-scale plant will be determined through the feasibility studies process, but it is ZeroGen’s strong desire that it is located in Central Queensland, with the sequestration site the Northern Denison Trough. Following the outcome of successful feasibility studies, the plant is expected to commence operations in late 2015 and be fully operational in 2016.

More Powe Engineerimg International Issue Articles