Technology that removes carbon dioxide from the atmosphere

February 13, 2016 - 05:00
Article from Gemini, SINTEF

You may as well learn the expression “carbon-negative technology”, or Bio-CCS, right away, because it has become a talking point in technological circles.

If we capture, transport and deposit the carbon dioxide that is liberated when biomass is burned, and store it permanently in the ground, we can actually remove carbon dioxide from the atmosphere. (Illustration: Doghouse.no)

Bio-CCS can reduce the level of CO2 in the atmosphere.

“In practice, the method captures CO2 emitted by “climate-neutral” processes such as the combustion of organic waste, pellets or sawdust,” explains SINTEF research scientist Mario Ditaranto, a specialist in combustion technology.

It is then stored safely underground for ever, thus reducing its concentration in the atmosphere, because it has been eliminated from the natural CO2 cycle. This is the only method we have to lower the level of atmospheric CO2, which is an important cause of our climate problems.

The method is not new. Until now Bio-CCS has suffered from a rather mixed reputation as insignificant, expensive and limited in its range of applications. However, in the light of climate change and the recent COP21 summit in Paris, it is on the of everyone in the climatology field. In Norway, it has led to SINTEF, the environmental organisation Bellona and certain branches of Norwegian industry working together for a rapid breakthrough.

“Superlight geoengineering”

The reason for the growing popularity of Bio-CCS is that at the very least it can be regarded as an extremely mild and non-hazardous form of geo-engineering. The aim of geo-engineering is to counteract anthropogenic climaste changes by means of physical interventions. Launching huge sunshades into space and spraying tonnes of sulphur into the atmosphere to filter sunlight are a couple of suggestions.

These have naturally led to heated debates about both the ethics and safety of such solutions. After all, what might be the consequences if we fix things in ways that only make them worse?

Unavoidable

More than 1000 estimates brought together in the latest report from the Intergovernmental Panel on Climate Change (IPCC) show that even a significant but gradual brake on CO2 emissions will not be sufficient if we are to avoid a serious climatic crisis.

If we are to stay on the right side of the two-degrees threshold, we will also have to remove some of the CO2 that is already in the atmosphere, and that is where Bio-CCS enters the scene.

Need of negative thinking

“The Paris Summit has made it clearer than ever that zero emissions will not be enough. Even if we stopped all CO2 emissions tomorrow, the Earth would still have a climate problem,” says Bellona’s Marika Andersen, who was among those who followed the climate negotiations in Paris at close hand. Her day job is at Bellona’s European office in Brussels, where she works on energy and climate policy, with special focus on bioenergy and carbon capture and storage (CCS).

“We simply cannot avoid using Bio-CCS. Today, we can see that more and more people are thinking in carbon-negative terms, which is just fine, because CO2 remains in the atmosphere at levels that will have to be reduced,” says Andersen.

According to Andersen, we now need to make active efforts to identify partners who are prepared to adopt this technology. For their part, the politicians need to take responsibility for developing infrastructure that will enable industry to deliver and transport CO2 to safe storage sites.

Facts

This is Bio-CCS
Biomass, i.e. plants and trees, bind CO2 from the atmosphere as they grow.
When biomass decays or is burned, the carbon is released to the atmosphere. These two stages thus make up a carbon-neutral circuit.
If we capture, transport and deposit the CO2 that is liberated when biomass is burned, and store it permanently in the ground, we can actually remove CO2 from the atmosphere.
The method known as BioCCS is now more than ever relevant as a result of the climate crisis.

“All this will have its price, though it will be lower than putting out the fire that climate change will bring on if we don’t do what needs to be done.”

Too expensive, and a source of fear?

But is the world ready to adopt technology based on storing CO2 underground?

Yes and no, says Mario Ditarando of SINTEF, who brings up two factors that have meant that this technology has yet to be adopted on a large scale:

This first is cost. As with all new technology, it needs to be priced in such a way that it can carve out a viable place in the market. It costs a great deal to capture CO2 from electricity generation or industrial processes. Optimistic estimates suggest that energy production will be about seven per cent more expensive than it is today if we capture CO2 from emissions. But it may cost as much as 10 to 15 per cent more before the technology has been fully commercialised.

We also need to take into account the cost of investing in constructing the capture facility and amortising these over the lifetime of the whole plant. This is a major risk for an energy supplier to take in a market for CO2-free energy that has yet to be established.

“In practice, this means that society will have to compensate the difference in price between cheap coal and clean energy with CCS. This will require political decisions that have a price in both financial and rhetorical terms,” says Ditaranto.

The other factor is human fear, i.e. what the experts call lack of public acceptance, which is largely a matter of collective psychology and insufficient knowledge.

Not 100 per cent sure

“But do we know that storing CO2 in the ground is completely safe?”

“No-one has stored CO2 in the ground for thousands of years, so we cannot be 100 per cent sure that it is completely safe. But the natural gas, of which Norway is the world’s third largest exporter, has been safely stored by nature for millions of years, so I am in no doubt that the concept is quite safe. Technically speaking, while there are certainly risks involved, as in all industrial processes, geophysicists and engineers are capable of managing these."

"We ought really to be more afraid of the climate changes that are on their way. And these are what are going to go off the scale of what we regard as expensive today,” he adds, and points to a scenario for the future that could become extremely relevant:

“We can already see how difficult it is in political and economic terms to deal with refugees from war-zones that we can only hope will become more peaceful as time passes. What is it going to be like when the flow of refugees increases because parts of the world become uninhabitable as a result of climate change?”

Facts

Facts about CLC
Nordic Energy Research funded a project with the name of “Negative CO2, to be carried out by a consortium led by Chalmers University of Technology that also includes SINTEF Materials and Chemistry, SINTEF Energy Research, VTT Technical Research Centre and Åbo Academy, University in Finland, Sibelco Nordic AB (Sweden) and the Norwegian environmental group Bellona.

The project is based on using biomass as a fuel and Chemical Looping Combustion (CLC), which is a combustion process in which the fuel is kept out of direct contact with air. In its place, a metallic oxide carries oxygen from an air-filled reactor to another reactor that contains the fuel.

The only combustion products are water and CO2, which can easily be separated out by condensing the water.
Ditaranto challenges the politicians to give industry and energy suppliers unambiguous signals that society is now ready to take responsibility, so that the scientists can get on with making Bio-CCS a reality.

“What is the difference between “ordinary” CCS and Bio-CCS?”

“The principles involved are identical, but the technology needs to be adapted to suit each individual area of application, and what is just as important, it will have to be tested,” says the SINTEF scientist.

One place where it would be useful to start is ethanol production, which is big in both the USA and Brazil, because among other applications, it is used as fuel for vehicles. When we produce ethanol from biomass, pure CO2 is a by-product, which means that we are spared the costs of capturing this greenhouse gas.

“However, we are working on all potential solutions. One important area of focus for us is identifying where it would have the biggest payoffs in terms of technology, logistics and not least, sustainability. In other words, how can we get the most for the climate and our environment out of the least effort, and what are the technological challenges involved,” says Mario Ditaranto. For example, bio-waste requires different solutions from wood and sawdust.

Waste pioneers

Some big players are already preparing to put these concepts into practice very soon. At the Klemetsrud energy recovery plant in Oslo, for example, Oslo City Council decided in July last year to construct a bio-CCS plant. Last month they opened a test facility that will collect CO2 from parts of the plant, with both the press and politicians attending.

Klemetsrud is currently the biggest emitter of CO2 in Oslo. The plant recovers household and industrial waste from Oslo and several nearby towns and produces almost 6 00 GWh of renewable district heating energy and about 160 GWh of renewable electric power a year. Aproximately 60 percent of the waste is organic. The plant could potentially capture about 400 000 tonnes of CO2 a year, this would make it the first carbon-negative power plant in the world.

These plans have made Bellona rejoice and have caused Johnny Stuen, the City of Oslo’s technical director, to roll up his green shirtsleeves:

“We are already going full speed ahead with a feasibility study of full-scale CO2 capture, financed by Gassnova,” says Stuen on the phone from London, where he is giving a talk about the Klemetsrud plant.

“We are one of three participants in this study: the Norcem cement plant in Brevik and Yara’s fertilizer plant in Porsgrunn also want to adopt Bio-CCS.

Wants the politicians on board

“Technologically speaking we are a little bit behindhand, because this has not been the most wide-open door for CCS. But now it is time to tell the world that Bio-CCS is the most effective method at hand to do something about the level of CO2 in the atmosphere. By adopting Bio-CCS, we can accelerate the reduction of our CO2 emission,“ says Mario Ditaranto, adding that the Nordic countries are pretty active in this area: Nordic Energy Research recently funded a research project led by Chalmers University of Technology, in which SINTEF is also a participant.

This project aims to look at how biomass can be utilised in one of the most promising CCS technologies, known as Chemical Looping Combustion (CLC).

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