Materials solutions for climate troubles

Materials World magazine
,
1 Jan 2008

The Energy Materials Working Group of Materials UK has launched its Strategic Research Agenda (SRA) for the energy sector over the next five, 10 and 20 years.

‘The objectives are to help Government meet its targets of reducing carbon emissions, ensuring the security of our energy supplies and affordable electricity, and providing wealth creation for the UK,’ explained Derek Allen, Chairman of the Group. ‘The agenda covers resources, skills, technology challenges, funding and recommendations.’

The SRA, which was introduced at an event on 4 December 2007 at the Tate Britain in London, UK, was published in conjunction with four reports on fossil fuels, nuclear reactors, renewable technologies, and energy transmission, distribution and storage. Key authors presented their findings to the audience.

Speaking about CO2 sequestration, Dr Colin Small of Rolls-Royce and co-author of Fossil-Fuelled Power Generation noted that, while new carbon capture techniques can reduce 92% of emissions, ‘we will need more kilowatt energy for every pound of coal we burn. This means we’ll need to burn more coal, and plants will need to become more efficient and last longer (for at least 50 years)’. This will require new coatings and stronger materials for boilers, pipes, turbines and gasifiers, and also better joining, repairing and recycling techniques. Small also outlined a need for novel material systems for energy generation, such as corrosion and sulphidation resistant metals for gasifiers. ‘We’re coming to the end of current systems. We need to figure out what on earth we are going to use in our plants in the future.’

Professor George Smith of Oxford University, UK, was next to present on his team’s report, Nuclear Energy Materials. He pointed out that a new plant has not been commissioned in the UK since 1995. This means that, by 2020, nuclear energy will only provide seven per cent of the UK’s electricity, where it currently provides 18%. The goal for the next five years, he said, is to ‘support existing plants and keep the show on the road’. This means improving the lifetime efficiency of existing materials, and updating nuclear waste management.

In the next 15-30 years, Smith hopes to see the adoption of Generation IV reactors, which create hydrogen as a by-product. ‘The ultimate goal of creating fusion energy is at least 30 years away. What are we going to do in the meantime? We can’t rely on a magic bullet, we have to plan it step by step.’ Key areas of R&D to focus on are corrosion and erosion, crack nucleation and creep-fatigue.

All the speakers emphasised common themes of materials needing to last longer and be more efficient in harsher environments, the requirement for improved testing and modelling devices, and more resources to maintain a strong research workforce.

The Energy Materials Working Group intends to liaise with industry stakeholders to disseminate the SRA and create a formal body by spring 2008 to ensure its delivery. It also aims to hold workshops throughout 2008.

Capturing carbon

Following the morning’s SRA launch, an afternoon session held at the Institute focused specifically on carbon transportation and storage.

Dr John Oakey, Director of the Power Generation Technology Centre at Cranfield University, UK, said there will be an inevitable requirement for carbon capture and storage (CCS) technologies. Coal use has grown in the last 30 years. Its emissions made up 38.4% of the total world CO2 emissions in 2003, as opposed to 34.9% in 1973. And new coal plants are continually being built around the world. ‘It’s no good asking the Chinese to switch to windmills – they’ve invested in coal technologies that will last for 40 years. So something needs to be done with them,’ said Oakey.

He outlined the three most investigated methods for capturing carbon – post-combustion, where a solvent separates the CO2 as it is emitted, pre-combustion, where gasification separates the CO2 before it is burned, and oxyfuel combustion, which uses pure oxygen mixed with flue gas to burn coal, producing an easy-to-sequester CO2-rich gas.

Each method has its advantages and disadvantages in terms of cost, complexity and need for corrosive-resistant materials. But, as other speakers pointed out, the question of what to do with the CO2 can be just as complicated.

The ideal approach to storing of CO2 is in a sealed, enclosed area that remains intact for thousands of years without leaking. ‘Oil and gas fields are premium storage sites, as they are well sealed (they have contained oil and gas for millions of years), their pore value is known, and money can be made by pumping out the excess oil and gas [as they are forced from the ground by injected CO2],’ said Sam Holloway of the British Geological Survey. He says there is an estimated 6.2-8.5Gt of storage capacity in the UK’s on- and offshore oil and gas fields – which could hold its entire CO2 emissions for 10-15 years.

A longer term solution, said Holloway, is offered by water-bearing reservoir rocks, called aquifers. However, little is known about them or their capabilities. ‘Whether they leak is a critical question,’ he said. ‘We need much greater resources to figure that out.’

Hopefully by 2014, when the UK’s CCS demonstrator plant is expected to be built, more will be understood about potential storage sites.

For further information on the UK Government-sponsored CCS competition, see Materials World, December 2007, p5. Also see Materials World, July 2007, p25-27 for an article outlining the long-term strategy and implementation plan for energy materials in the UK.

 

Further information:

Energy Materials Working Group