The world needs to cut carbon-dioxide emissions drastically and urgently. With the process that we have helped NET Power to prove, it is possible to de-carbonise traditional fossil-fuel energy production.
In May, our client NET Power fired up a 50MWt demonstration plant in Texas, USA, using a new process called the Allam Cycle, named after one of its inventors, Bath-based Rodney Allam. We’ve been working with NET Power since 2013, helping to take the technology from conceptual design to a demonstration of the combustor and testing of the process.
NET Power’s plant mixes fuel (natural gas) with pure oxygen, which is combusted with CO2 recycled from within the process, to reach the high temperature and pressure needed to drive a turbine. Using pure oxygen rather than air eliminates any chance of producing nitrogen oxide, one of the world’s worst air pollutants, and enables the plant to generate all of its carbon dioxide as high-pressure, high-purity by-product that can be sequestered underground without further compression requirements.
This approach contrasts with the traditional process where gas is burned with air to create heat and convert water to steam to power the generating turbine, producing a lot of excess CO2 (and NOx) that is vented to the atmosphere. With the Allam Cycle, the CO2 is contained in a semi-closed loop and never enters the atmosphere.
Now that the process has been proven to work, the next step for NET Power is to build a full-size 300MWe plant.
From impossible to possible
"When NET Power first provided us with the details of the system, we thought it would never work as well as it does!” our Oil and Gas Director Steve Milward says. “But we got our teeth into it and the work has been a revelation. It has allowed our worldwide operation to play a part in something truly remarkable."
Well after construction of the demonstration plant had begun, we were asked to deliver a combustion test stand at the facility, and we called on brain power from across the globe. Multiple specialists from 13 WSP offices in different countries contributed, giving us both local focus and the international reach that allowed for breakthrough moments.
The Engineering Manager overseeing the project, Prashant Thapar, and his team built an 8m long, 3m high combustor test rig weighing about 30t which was installed in the middle of an existing facility with minimal disruption to the existing operation. It was then hooked up to all the piping in the NET Power plant, but without any connection to the very expensive turbine.
The day that it was switched on was the day NET Power had the final, undeniable proof that the idea worked.
Zero-emission fossil fuel
Urgent action is needed to cut the world’s carbon emissions if there is to be any chance of keeping global warming to 1.5 degrees C, according to the Intergovernmental Panel on Climate Change. The technology - that we have helped to prove - works, and can be used with coal and natural gas.
Our hope is that it can contribute towards reducing emissions from fossil-fuel power production.
While the bulk of the CO2 produced in the Allam Cycle is reheated and used again in the combustor, there is a CO2 by-product that needs to be removed. This can be used for what is known as “enhanced oil recovery” – whereby it is driven into oil wells to flush out every drop, so as not to waste it – or it can be stored, for instance in the empty wells.
"The world is not going to suddenly be able to switch to 100% renewables overnight," says Steve Milward. “We are still going to need the world’s natural resources as we make the transition, but with this innovation we can generate power and contain the carbon.”