Can Fossil Fuels Achieve Zero Emissions?

A fossil fuel plant which produces zero carbon emissions might seem like a contradiction in terms – but this oxymoronic dream could well become a reality by the end of the year. Invented by a retired British engineer and two born-again American technology buffs, the Allam cycle natural gas power plant is expected to be firing on all cylinders at its Houston location this autumn.

How do you solve a problem like coal?

Beginning with the Industrial Revolution, coal enjoyed pride of place as our chief source of energy for almost two centuries. Recently, concerns about the environment have led many people to question its sustainability, especially given the fact that coal emits twice the amount of carbon that natural gases do and furthermore, that carbon only makes up 14% of the total emissions from the plant, making it very hard to isolate and dispose of.

Even more concerning, the process is also a very inefficient one. Most operational coal plants still generate their electricity through a steam turbine powered by coal combustion, but this necessitates the use of cooling towers to turn the steam back into water and prevent it from powering the turbine in reverse. In fact, only 38% of all coal burned can be turned into usable energy.

Scientists and researchers have been looking for ways to capture steam in order to reduce energy costs and CO2 emissions for many years now, but the boffins at 8 Rivers are trying an entirely new approach: doing away with the steam altogether.

A revolutionary technique

Rodney Allam’s novel turbine doesn’t use coal or water, but rather CO2 compressed to a similar density as that experienced 3km under the sea. Natural gas is used to raise this compressed CO2 to a temperature of 1,150°C, at which point it becomes a supercritical gas and drives the plant’s turbine.

Once it has done its job in creating the electricity, it returns to its previous state – where it can be re-pressurised and reintroduced into the cycle all over again. The small amount which cannot be recycled is extracted and taken away for disposal, already in a compressed state (waste CO2 from traditional plants requires compression before it can be dealt with).

There are, of course, energy losses with Allam’s cycle, as well. Nitrogen must be chilled in order to extract the pure CO2, which then must be compressed repeatedly every time it enters the turbine chamber. However, both of these processes are regularly used and accurately costed, meaning the team have done their sums and worked out they should be able to achieve an efficiency of 56% - and with zero emissions.

Working in tandem with renewables

In Britain, the Industrial Emissions Directive (IED) was introduced in 2013 in order to force power plants and commercial factories to clean up their act with regards to their emissions. If successful, Allam’s cycle could represent a fantastic work-around for fossil fuels and revolutionise our energy generation methods.

But the idea is not without its critics. Firstly, there are those who question the continued pursuit of fossil fuels as opposed to renewable energy sources (such as wind, solar and wave power) when climate change is such a contentious issue. Furthermore, others believe that the principal practice employed in extracting natural gas – which comprises a vital part of the process – is dangerous enough in itself. Protests against fracking have taken place up and down the length of Britain over the last few years, due to fears it could corrupt water sources and cause earthquakes.

However, working hand in hand with renewables, Allam believes that his innovative invention could solve our current carbon crisis. “I’m not knocking renewables, but they can’t meet future power demands by themselves,” he said. “I'm 100% confident it will work.” We should know by the end of the year whether his confidence is well-founded or not.