The Allam Cycle: the zero-emissions gamechanger to unlock industries of the future?
A revolutionary new zero-emissions power plant could change the way we make energy and think about waste. The Allam Cycle could also be the perfect match for Australia. This is the story of how it started - and where it could be headed.
- New technology promises zero emissions from fossil fuels
- Backers say it could be cheaper than renewables
- Projects planned in US, UK, New Zealand and Australia
Power plants take fuel, burn it and produce energy and emissions, right? Wrong. That’s the old track we went down and it doesn’t have to be that way any longer: a revolutionary new type of power plant is proving it.
The Allam Cycle turns what’s traditionally been a waste product - CO2 - into the power source that drives turbines - and it recycles it again and again. It’s been demonstrated in Texas and projects are in development around the world to expand the reach of the technology. And as well as wasting nothing, it creates products from everything it can.
Best of all, Australia with its coal, natural gas and large-scale carbon storage could be the perfect match.
The eureka moment
“I met Rodney Allam at the Morgan Stanley cafeteria in London back in 2009,” recalls Bill Brown, CEO of 8 Rivers and NET Power, the company behind the Allam Cycle.
“Barack Obama’s Recovery Act had made funding available to stimulate clean coal technologies. But I realised the traditional oxy-combustion path (burning in air) just wasn’t going to work. The problem with steam-driven turbines is that two-thirds of the energy goes up the stack.
“And it was then, sitting in this cafe that Rodney said to me: “Why don’t we use CO2 instead of steam to drive the turbine?” It was a ‘we could do this’ moment - because you can keep more energy in the system if you use CO2 instead of steam.”
How it works
The Allam Cycle (or Allam-Fetvedt Cycle to give its full name) may sound complicated - its inventors call it "a high-pressure, highly recuperative, oxyfuel, supercritical CO2 cycle”. However, it is actually pretty simple. In the Allam Cycle, natural gas or coal syngas is burned with pure oxygen, whereas in traditional power plants, fuel is mixed and burned with normal air.
This oxyfuel - with 95% carbon dioxide - is then combusted at supercritical temperatures and pressures (similar to being 10,000 feet deep in the ocean). This turns the CO2 into a fluid, which drives a turbine at incredible pressure, creating electricity.
And that’s where something amazing happens: what’s left is CO2 and water - and nothing is wasted. These two products can be separated using a heat exchanger; the water can be used for other things (potentially very useful in arid regions), and most of the CO2 is re-pressurised and recycled. No energy lost up the chimney - and zero emissions. In fact, there aren’t any smokestacks at all. And other valuable industrial products can be created too.
This recycling-based thinking is central to the Allam Cycle - “Making Clean Cheaper Than Dirty” is the slogan of Brown’s company NET Power. To the technology’s creators, all that steam from regular cooling towers, and smoke up the chimney - that’s potential energy, products and money and being wasted. What’s so radical is that the Allam Cycle not only turns a power station into a closed loop process - but a chemical plant too.
“The waste product of one system is the feedstock for another,” says Bill Brown. “Why let nitrogen, hydrogen, ammonia, caustic soda, soda ash, quicklime and methanol all escape? It’s all got value for someone.”
NET Power’s breakthrough is also attracting interest because of its ability to marry zero emissions with constant, high-energy power.
“As long as there’s a level playing field, the economics of the Allam Cycle could work out competitively with renewables,” says Rich Powell, Executive Director of ClearPath, a U.S-based clean energy non-profit. “That’s because it has less variable output - meaning the power is more consistent.
“Even with a similar or slightly higher levelised cost of energy (the revenue needed to build and operate a plant), because the Allam Cycle can combine this with higher revenues due to flexible power output, developers could likely earn more with a NET Power plant.”
There are a number of reasons why Australia and the Allam Cycle are a good match. Plans are now in development that could soon help the country in its ambitions to be a major exporter of energy solutions, as well as create new, clean industries in regional Australia.
Fertilisers are one area where the cycle could bring real benefits. They’re an important part of crop production, but at present, these vital chemicals can be carbon intensive to produce. This is where the Allam Cycle comes in. The fertiliser industry’s major ingredient, ammonia, can be cleanly produced through an integration of ammonia synthesis with Allam Cycle plants. So, investigations are now underway into the potential for this new system to use Australian coal and natural gas, creating clean fertilisers for Australian farmers.
The Australian Government has also set out its aims to create a hydrogen hub with “an export focus”: a production centre that could help supply the world with what many believe will be a fuel of the future. Once again, Allam Cycle plants could produce this valuable element, as a by-product of the high-temperature heating - or gasification - of coal that could be one of its key power sources.
And the Allam Cycle has another advantage - one that consumers could feel in their pockets. “Australia is rich in the most power-dense sources of energy, like coal,” says Rich Powell. “This means using it cleanly can be highly efficient.”
The Allam Cycle’s design could also be particularly valuable given the vast and highly dispersed geography of Australia. “So much of the cost of energy is actually in power transmission,” explains Powell. “So if you create local power stations which can also generate products, like valuable hydrogen, then the Allam Cycle gives Australia an opportunity to have some of the lowest life cycle emissions possible.”
The Allam Cycle is, by most measures, a revolutionary technology. Its advocates say that for such a breakthrough to take off, a similarly radical shift in perspectives will now be needed.
“We have to stop focusing on the nature of the energy source and start talking about the emissions,” says Bill Brown. “We need to judge power the same as people: we value diversity so there needs to be a diversity of technology. We should be open to the unexpected.”
Rich Powell thinks this open way of thinking needs to translate into policy shifts. “In my view, NET Power’s technology should be categorised as renewable,” he says. “But still relatively few jurisdictions give preference to zero-carbon, carbon-based fuels. That means there’s a big gap in the market.”
Big names are backing the Allam Cycle. NET Power counts leading power and energy companies like Exelon, McDermott and Occidental’s Oxy Low Carbon Ventures as investors.
The technology has been included in recently-announced plans for a large liquefied natural gas (LNG) plant in the United States which is one project that could show the technology’s potential at scale. Bill Brown says 8 Rivers and NET Power are also planning future projects around the world, including in the UK, New Zealand, as well as Australia: the company is in talks with Low Emission Technology Australia about potential projects in Queensland and Victoria.
It may take this revolutionary technology some time to reach critical mass of adoption and acceptance, but the economics seem to support it. That’s because in order to get to net zero, the world might need to spend USD$50 trillion by 2050, retrofitting and decarbonising existing power systems. To Bill Brown, this presents a problem - and a considerable opportunity.
“I believe we will only reach that 2050 target if the economics work without government intervention,” he says. “But no company can deploy new assets every year at this pace. So we need to create an economic ecosystem of products - from nitrogen and hydrogen to ammonia - and that’s just what the Allam Cycle does.”
If Bill Brown is right, the Allam Cycle could improve not just the way the world produces power, and the environment - it could improve economies as well.
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