94- www. world- petroleum. org 6.3- Understanding oil and gas Carbon capture: explained It's economically and technically speculative, but CCS could be a bridge to a low- carbon future Fossil fuels are set to remain a large part of the world's energy mix for the foresee-able future, so the hunt is on for the best way to carry on using them while drastically cutting the amount of carbon dioxide ( CO2) pumped into the atmosphere. A technology called carbon capture and storage ( CCS) is among the most promising low- carbon solutions; it involves extracting CO2 from power plants, factories and other industrial facilities before it is expelled into the atmosphere. The captured gas is then injected into a secure underground stor-age site - and removed from the climate-change equation ( see box). It's the key to the sustainable long- term use of fossil fuels - helping mitigate the ef-fects of climate change while renewable en-ergy systems are developed. As such it's an " airbag" technology, says George Peridas, a climate scientist at the Natural Resources Defense Council ( NRDC), a US- based envi-ronmental non- governmental organisation. How effective an airbag could it be? The International Energy Agency ( IEA), a multi- CO2 can be captured before or after coal is burned. In post- combustion capture, the CO2 is stripped out of a power plant's exhaust gases with a solvent such as amine or am-monia. Post- combustion technologies can be added - retrofitted - to existing pulver-ised- coal power plants. Pre- combustion carbon- capture technol-ogy can be used in the new wave of inte-grated- gasification combined- cycle ( IGCC) plants. Here, instead of being directly com-busted, the fossil fuel is gasified to produce a synthetic gas ( syngas) - a mixture of hydro-gen and carbon monoxide ( CO). The syngas is then processed in a water- gas- shift reac-tor, which converts the CO to CO2 and more hydrogen. The CO2 is then captured, leav-ing a hydrogen- rich syngas that can be com-busted to generate electricity. IGCC plants are more expensive to build than conventional coal- fired plants and the high hydrogen content of the fuel gas ( over 90%) makes them less efficient than steam-driven plants. However, they come into their own once CCS is factored in, as the CO2 they produce is in a high pressure, concen-trated form that is relatively easy to capture - and that means big cost savings com-pared with post- combustion CCS technology. In another variation, called oxy- combus-tion, fossil fuels are burned in nearly pure oxygen rather than in air. This produces a nitrogen- free flue gas that has water vapour and CO2 as its main components. Although using oxygen increases costs, the highly concentrated stream of CO2 that results from the process again makes capture rela-tively straightforward. Leaders in IGCC technology, such as US company GE Energy, say the cost savings at the carbon- capture stage make IGCC the way forward, but there is still much debate over the pros and cons. One certainty is that post- combustion CCS technology will con-tinue to play a significant role in the power industry for decades to come. That's because you can't retrofit con-ventional pulverised coal power plants with IGCC technology and not only do most ex-isting plants use conventional technology, but many new facilities in countries such as China - which has been opening more than one new coal plant a week on average recently - use it as well. So if we are to tackle CO2 emissions through carbon- capture technology suc-cessfully, a multi- pronged approach will be needed. ?? Capturing CO2: the key to clean coal
95- www. energy- future. com Profile - Mark Nesbitt Name: Mark Nesbitt Company: BP Present job: Process engineer Age: 27 Nationality: British Degree: Queen's University Belfast, Masters in chemical engineering Before I joined BP, in 2005, I'd already spent a year with the company - on an in-ternship programme, between my third and fourth years at university. I worked at the Grangemouth terminal in Scotland that proc-esses oil from North Sea fields, stabilising it for onward transport to refineries. It was a steep learning curve, but a great opportu-nity to take what I'd learned in the academic world and apply it on a practical scale. That experience helped enormously when I joined BP's training programme for new graduate recruits in the Exploration & Production business ( E& P) - Challenge. My first role at BP was in the E& P technol-ogy group at BP's offices in Sunbury as a fa-cilities engineer, providing technical support to business units around the world - help-ing select development concepts for projects and preparing feasibility studies for prospec-tive projects, for example. I provided techni-cal support on the business case for invest-ments in Libya, which the company has since followed through, which is satisfying. I then worked as a commissioning engi-neer on Greater Plutonio, a $ 5 billion, five-field development in deep Angolan waters. Initially, I spent time in South Korea, helping oversee the completion of the giant floating, production, storage and offloading ( FPSO) vessel that is now producing oil from those fields. Then I worked in a rotational role off-shore, until the start- up of the facilities; I was tasked with ensuring vital parts of the facilities were commissioned to the required standard. I won't forget the day we commissioned the first well - seeing equipment I'd worked on processing first fluids from the Plutonio reser-voir was immensely rewarding. Recently, I have moved into a joint venture - In Amenas, a big gas project in Algeria in partnership with Norwegian oil company StatoilHydro and Algerian gas company Sonatrach. It's been interesting to be ex-posed to other companies' ways of working. Initially, I was based in Oslo, Norway, working in an engineering contractor's of-fice. Again, the responsibility was huge: sometimes I was the only BP representa-tive, even though I'd only been with BP for short time. Since completing the Challenge scheme, I've stayed on at In Amenas, as-suming responsibility for all aspects of proc-ess engineering on a new gas compres-sion project. I want to see the project right through the design and build phases to pro-duction. The whole process could take sev-eral years and will involve working in the UK and on- site in Algeria; but it's not often you get the chance to see a project through all the cycles. And, if I stick with it, I could become the lead start- up engineer, which would be a great opportunity. In the long term, I see myself in engineering manage-ment for big projects in the E& P business. Variety is one of the things that makes the job so interesting: one day you can be work-ing with a deckhand offshore and the next you can be presenting to senior management in head office. There's enough diversity in the energy business to satisfy anyone's ambition: if one role isn't to your liking there's the flexi-bility to move into many different disciplines. But you need to be flexible too - pre-pared to travel widely and enjoy interacting with people from different cultures. If you are adaptable and open- minded, the industry of-fers great opportunities. ??