Emeritus Professor Wall has dedicated his career to the chemical engineering area of energy and coal research. He answers a few questions about his work and interests.
Can you please give us a brief introduction to yourself and your background?
I came from Melbourne originally, and after completing a Chemical Engineering Degree at RMIT University, I came to Newcastle to do a PhD on coal combustion with Ian Stewart in the late1960s. I took measurements of thermal radiation in Australian power stations, both in the Hunter and the Latrobe Valley in Victoria.That was great because it meant I was doing measurements on the real thing as well as laboratory measurement, and I have continued on with the collaborations established from that time. After completing my PhD I traveled a bit and spent a year at Imperial College in London, but eventually I came back to Newcastle University in the mid 1970s.
What is your main area of research?
I have worked entirely within the chemical engineering area of energy and coal research – heat transfer, reaction engineering, fluid dynamics – and the associated environmental issues. Initially I focused on using coal in current power stations in a cleaner way, by working out which coals suited and which ones didn’t. Quite a lot of that work was done in collaboration with large coal companies and power companies. However in the last few years there has been a lot more emphasis on carbon capture and storage, and so that’s really been my main priority over the last five years or so.
One of our main recent achievements has been creating interest in Australia of Oxy Fuel as a different carbon capture option, and that has proven very successful. We helped create a partnership between Australia and Japan that has lead to a feasibility study to convert a power station unit in Queensland to an Oxy Fuel demonstration project. That demonstration is starting up as a retrofitted unit at the Callide Power Station in the middle of next year. The process has involved extensive research- we are currently doing research on issues that emerged- and when the demonstration starts we’ll take measurements on the power station to test how the process is working.
Our group continues to work on less applied projects on the science of coal reactions, including both power station coals as well as coking coals. Coal is a wonderfully complicated chemical mixture and there are always chemical combinations arising to give complications to its use, and provide research challenges.
What motivates you in your work?
The greatest pride that I have would probably be in helping students complete successful PhDs and seeing them develop as useful people in our society as a consequence. I’ve supervised more than fifty PhD students. Otherwise, I have enjoyed establishing and maintaining Newcastle University as a centre of excellence in coal usage, through two CRCs and now in a National R&D centre.
What are your interests outside of work?
Well, I came to Newcastle so I could live by the beach. I’ve always been a keen surfer and I still am.
What is the next step for you?
A new coal organisation started just two months ago in mid 2010, called the Australian National Low Emission Coal Research and Development organisation. This focuses on carbon capture and storage, and researches all the CO2 capture options and carbon storage options relevant to Australia. I have been appointed the science leader in coal combustion of that organisation, and it has a seven year life, so that is my immediate activity.
You mentioned Oxy Fuel as one of your research projects- what is it?
In a normal power station you burn the coal with air, which has a nitrogen content of about 70% by volume. The CO2 content in the product gas is not high enough to be compressed to the liquid-like form for geological storage. So, you must increase the concentration of the carbon dioxide. All carbon capture technologies generate carbon dioxide at a high enough concentration so the gas can be compressed efficiently. Oxy Fuel does this by burning the fuel in oxygen rather than air, so the product gas does not have the nitrogen that would be in the gas if you were burning with air. Now, if you burn in oxygen alone the temperature is too high for the plant materials so we recycle CO2 into the burners to replace the nitrogen and recreate similar gas temperatures.
Where is it used?
Coal is the current emphasis internationally for carbon capture and storage technologies as it has the highest carbon dioxide generation per energy. There is one of these Oxy-fuel plants used in France at the moment based on gas, but most of the other demonstrations, including the Australian one, are coal-based. The US Department of Energy has just announced support of US$1.2b for its FutureGen project as an Oxy-Fuel plant, whereas it was being developed as a gasification plant, this being another carbon capture route. This will be a big boost for the Oxy-Fuel option.
What are the main difficulties that you have encountered in your work on Oxy Fuel?
During the feasibility project we helped design the Callide retrofit for its thermal performance using mathematical models, tested candidate coals for reactivity in laboratory simulations, and participated in pilot-scale tests in Japan. The current emphasis that our group has is on the issues associated with the quality of carbon dioxide. For example, we would like to remove the sulfur and nitrogen gases and some of the trace elements because they interfere with the compression process. The challenge we face is to optimise the extent of the removal of these gases so the plant will still run properly, but also so the process would remain economic.
What are the advantages of using Oxy Fuel?
It’s probably the least expensive carbon capture route. It’s also the route where the technology is most similar to a current power station. It’s an adaptation, if you like, and can be retrofitted onto an existing power station as is being done at Callide.
What have you found most rewarding about your work with Oxy Fuel?
I enjoy the process of finding things that are new and that are useful, and working with a range of people; scientists, geologists, chemists, physicists, and also the power station engineers who are involved in the practical plant. In the past few years we have run an Oxy-Fuel Working Group under an Asia-Pacific Partnership (APP) project which interact the 15 or so international demonstrations of the technology. We have also run Capacity Building Courses in Korea in 2009, in China in 2010 and a have a third planned in Queensland in 2011. The support we have had from our colleagues in many countries to make these events successful has been fantastic.