Acorn CCS hub can expand our low-carbon horizons

The St Fergus Gas Terminal occupies a windswept stretch of coastline in north-east Scotland, where natural gas has come ashore since the 1970s. The facility six miles north of the port town of Peterhead is the landing point for several offshore pipelines, which bring around a quarter of all the UK’s gas onshore.

The site, which is the focus of the Acorn project, could become one of the first carbon capture and storage (CCS) hubs in the UK. Using waste CO2 produced on the processing site itself, and access to some of the best offshore storage sites in the world, a sizeable CO2 transport and storage network could be up and running here by the early 2020s.

Yet the real beauty of Acorn lies in its ability to expand from this first phase to provide a number of options for supporting clean industrial growth and decarbonising our society in different ways.

The UK Government intends to set out its deployment pathway for CCS and CO2 re-use by the end of 2018. This will highlight what industry and government should do to reduce deployment costs through demonstration projects in the 2020s and, crucially, enable the technology and infrastructure to be rolled out during the 2030s at large enough scale to properly tackle the UK’s carbon emissions.

The pathway will consider, among other things, the need to develop an industrial carbon capture incentive mechanism and the best way to finance and provide CO2 infrastructure, including storage sites and pipelines.

Research under way within the ACT Acorn project, with funding from the UK and Europe, shows that full-chain CCS, which can handle and securely store industrial volumes of CO2, can be established in north-east Scotland at low cost and low risk.

However, a core part of the work has also been to consider the expansion options for Acorn, which the project partners believe can be done “at marginal cost” to support the Scottish and UK governments’ crystallizing ambitions for clean growth and climate action.

So how would this scaling-up of Acorn happen and what exactly would it deliver?

Refreshing economics

The legacy of the Industrial Revolution, a time of progress and the beginning of the world’s reliance on fossil fuels, has proved a tough nut to crack. We need to decarbonise while bearing in mind the impact this could have on fossil fuel-dependent communities and economies. CCS provides a bridge between the use of fossil fuels and moves towards much cleaner energy and industrial processes.

Previous attempts to deliver CCS have shown that realising economies of scale from the outset of a project is impossible without a huge injection of public or investor cash. However, Acorn has been specifically designed to make best use of existing large-scale infrastructure to kickstart industrial-scale CCS using very low quantities of CO2 and keeping initial capital spending to a minimum.

This does make the unit cost of the small quantities of CO2 high at the start of operations. But with appropriate government and industry backing to become commercially viable – the incentive mechanism referred to earlier – Acorn’s infrastructure can then expand cost-effectively to provide CO2 storage not just for Scotland but for industrial centres south of the border and, as we’ll hear shortly, across the North Sea.

Industrial connections

Our fossil fuel fixation may have led us to unprecedented global warming but, by a twist of fate, the infrastructure it has required could well provide the means of taking the CO2 it creates back to its origins.

Scotland’s industrial centres, including the largest at Grangemouth, lie conveniently close to a major pipeline built to carry natural gas from the North Sea to the Central Belt. Known as Feeder 10, this pipeline begins at St Fergus and runs, without branches, to near Bathgate, just south of Grangemouth. By simply reversing its direction of travel, it could provide a low-cost route for CO2 emissions to flow back to North Sea storage sites.

The pipeline also provides the opportunity for inward investment in Central Scotland for new, low-carbon industry, including hydrogen production or biomass power generation, with CO2 emissions transported, managed and stored through Feeder 10 and the Acorn infrastructure. In the case of biomass power this could also create negative emissions – biomass having already absorbed CO2 from the atmosphere during its growth.

Previous projects have taken a long hard look at the potential re-use of Feeder 10 and concluded that it was a viable route to St Fergus for CO2 currently vented at Grangemouth. Not only that, the Grangemouth industrial cluster presents “the best location in Scotland for developing carbon capture and utilisation (CCU) opportunities”, and with links to high-volume CO2 transport to the Acorn project.

When it comes to transporting those volumes offshore to North Sea storage sites, there are three oil and gas legacy pipelines that can be used. The Atlantic pipeline alone could carry around five million tonnes (Mt) of CO2 every year, a figure that can rise to 16Mt if all three pipelines are deployed.

This, of course, raises the important consideration of protecting these assets from current decommissioning plans. It is worth noting that, rather than building new pipelines, the re-use of existing infrastructure, including Feeder 10, will result in a saving of around £750 million.

International first port of call?

The development of a CCS hub at St Fergus has clear benefits for tackling Scotland’s carbon emissions, but its proximity to Peterhead Port offers an even greater build-out opportunity: importing CO2 by ship from potential export hubs along England’s east coast – such as Teesside – and from other countries around the North Sea basin.

Modelling carried out as part of the ACT Acorn project suggests the port has “ample capacity” for the volumes of CO2 expected in the early build-out phases, and with a maximum capacity of 16.2Mt a year.

Visualise this as more than 400 ship movements every year and an increase in port traffic of around 15-25%. The researchers have estimated that CO2 export hubs around the North Sea basin could supply this quantity several times over.

Modelling is one thing but how would this work in practice? The study suggests that, for import quantities of around 5-10 Mt a year, a fleet of three or four tankers of 30,000 to 50,000 deadweight tonnage would be needed. The CO2 would then be transferred to St Fergus in liquid phase through a new and relatively short purpose-built pipeline.

Other factors do need to be considered, but the ACT Acorn team believes their work has provided much greater understanding of these, which can be further explored. These include technical issues around CO2 pumps and low temperatures, handling an interrupted flow of CO2, and the effects of weather and seasonality on the full chain of operations.

Gas on the grid

There has been much talk recently about the role of hydrogen in providing cleaner heat, power and transport as the UK moves away from fossil fuel for these uses.

The ACT Acorn project has included in its analysis the opportunities for new energy vectors, such as producing hydrogen at St Fergus by steam methane reforming with CCS at the very point where natural gas makes landfall.

Studies suggest that St Fergus is an excellent location in the UK to introduce hydrogen in this way, since the hydrogen can be blended into the natural gas grid initially at low concentrations.

Two scenarios have been modelled by the ACT Acorn team to allow for differing ambition and support by the Scottish and UK governments. In a more cautious scenario, 5% and then 10% of hydrogen would be blended into the gas at St Fergus over a relatively long period. The second, more ambitious approach considered higher levels over a shorter period, and with a full gas-to-hydrogen transition for the Aberdeen and Moray area.

With decarbonised gas and CCS figuring in both Scottish and UK policy – including the UK Government’s Clean Growth Strategy and the Scottish Government’s Climate Change Plan – St Fergus is poised to deliver, should policy development support the move.

CO2 as product, not waste

The use of captured CO2 in making useful products often gets a mixed reception. The focus of CO2 re-use tends to be on generating revenue rather than climate action, it requires energy and other resources, and many current products eventually release the CO2 back into the atmosphere.

That said, the ACT Acorn project believes CO2 re-use offers a considerable opportunity for sites such as Grangemouth and those with smaller industrial emissions; the CO2 can be captured onsite and then used as a feedstock to produce inorganic fertiliser, fuels, certain chemicals and building materials. And this activity has very little need for transport and storage infrastructure.

ACT Acorn’s international team of researchers concludes its work in early 2019, by which time the UK Government will have published its CCS deployment pathway. The hope is that the initial Acorn hub and storage project will be delivered in the early 2020s, proving the viability of CCS technology and enabling the build-out options described here.

The need for effective climate action is becoming ever more pressing. St Fergus and Acorn may be perceived as being geographically remote, but they could end up at the very heart of Europe’s low-carbon transformation.

Read the ACT Acorn Expansion Options report

Words: Indira Mann, SCCS

Main image: NSMP

ACT Acorn, project 271500, has received funding from BEIS (UK), RCN (NO) and RVO (NL), and is co-funded by the European Commission under the ERA-Net instrument of the Horizon 2020 programme. ACT Grant number 691712. ACT Acorn is a collaborative project between seven organisations across Europe being led by Pale Blue Dot Energy in the UK.