Musings, politics and environmental issues

Archive for June, 2019

Heavy industry in Iceland looks to CarbFix to become carbon-neutral

Iceland’s four largest CO2 emitters, three of which are aluminium smelters and the other a ferro-silicon plant, have signed a Letter of Intent with the Icelandic government to look for ways to become carbon neutral by 2040. The PCC silicon metal smelter at Bakki, which is another large emitter, is also expected to sign – “although our first priority is to get the operation running properly,” according to the environmental officer there.

The aim is to thoroughly investigate whether the CarbFix method for storing CO2 can become a viable option, both technically and financially, for storing CO2 emissions from these companies.

CarbFix was set up originally in 2007 in conjunction with the Hellisheidi geothermal power station, where CO2 is captured from steam and dissolved in water at pressure. The water is then injected into underground basalt rock at a depth of 500-800 m, where it forms carbonate minerals such as calcite within a few years. These carbonate minerals are stable on a geological time-scale.

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Annual capacity at the Hellisheidi plant is around 12,000 tonnes CO2, which accounts for about a third of the plant’s CO2 emissions. The Hellisheidi plant also removes hydrogen sulphide (H2S) from the steam, but this will not be an issue with the companies intending to become carbon-neutral by 2040.

In 2017, a pilot-scale Direct Air Capture unit was added to the system: this process is independent of location as it mostly relies on energy in the form of heat, which is available as a by-product in numerous industrial processes. Unfortunately the technique is currently too expensive to be used  for making heavy industry climate-neutral.

The project with heavy industry, which is expected to span five to ten years, will involve analysing the concentration of CO2 in emissions, so that similar removal techniques can be applied to those at Hellisheidi. The next step will involve design and manufacture of experimental equipment for capturing and injecting CO2, followed by design and manufacture of similar equipment on a larger scale.

The standard method of carbon capture and storage (CCS) involves pumping oil into old gas fields or using some form of carbon capture and usage (CCU). Edda Sif Aradóttir, who is project manager of CarbFix, says there are both advantages and disadvantages to traditional methods.

“The CarbFix method transforms CO2 into minerals within two years through a chemical process that happens naturally in nature, while traditional methods store CO2 in gas or liquid form. The procedure is thus of a completely different nature and CO2 is permanently removed,” she says.

She says that the main disadvantage is that it requires a considerable amount of water to dissolve the CO2 where chemical changes occur between water and rock. “On the other hand, the water needed by the procedure may be reused, which we in fact do up at Hellisheidi … we are working at developing the process even more so that seawater can be used,” she explained.

Funding for the CarbFix2 project has come from various programmes within the EU, including Horizon 2020, with collaborators in Toulouse, Barcelona and Zurich. CarbFix2 is designed to move the project on from a demonstration phase to one which will lead to an economically viable, complete CCS chain that can be used within Europe and globally.

Future research involves exporting the method to new injection sites in Germany, Italy and Turkey as well as Iceland, and further developing the method so it can be used offshore for permanent mineral storage of CO2 on the sub-sea floor. CarbFix proponents say that there is far more storage available in porous sub-marine basalts than required for the geologic storage of all the anthropogenic CO2 that will ever be produced.

I also wrote about this for ENDS Europe Daily today.

 

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Carbon-neutral liquid fuel developed from sunlight and air

Swiss researchers in Zurich have managed to manufacture synthetic liquid hydrocarbon fuels from sunlight and air. Whether it will ever be commercially viable is another story as they can currently only make about 100 ml of fuel a day. Still, the press release quotes Philipp Furler, a former doctoral student in the research group who now heads Synhelion, a spin-off company that aims to commercialise solar fuel production: “A solar plant spanning an area of one square kilometre could produce 20,000 litres of kerosene a day … Theoretically, a plant the size of Switzerland – or a third of the Californian Mojave Desert – could cover the kerosene needs of the entire aviation industry.”

The process only produces the same amount of CO2 that is extracted from the air. The process works like this: CO2 and water are extracted directly from ambient air and split using solar energy. This process yields syngas, a mixture of hydrogen and carbon monoxide (CO), which is subsequently processed into kerosene, methanol or other hydrocarbons and can be used in planes and other forms of transport.

The research is being carried out at ETH Zurich technical university. One of the researchers, Aldo Steinfeld, Professor of Renewable Energy Carriers at ETH Zurich, says that “the thermochemical process utilises the entire solar spectrum and proceeds at high temperatures, enabling fast reactions and high efficiency.”

For those with a technical bent, this is a description of the technology used:

The process chain of the new system combines three thermochemical conversion processes: Firstly, the extraction of CO2 and water from the air. Secondly, the solar-thermochemical splitting of CO2 and water. Thirdly, their subsequent liquefaction into hydrocarbons. CO2 and water are extracted directly from ambient air via an adsorption/desorption process. Both are then fed into the solar reactor at the focus of a parabolic reflector. Solar radiation is concentrated by a factor of 3,000, generating process heat at a temperature of 1,500 degrees Celsius inside the solar reactor. At the heart of the solar reactor is a ceramic structure made of cerium oxide, which enables a two-step reaction – the redox cycle – to split water and CO2 into syngas. This mixture of hydrogen and carbon monoxide can then be processed into liquid hydrocarbon fuels through conventional methanol or Fischer–Tropsch synthesis.

Five years ago, Steinfeld and his team sent out another press release along similar lines, producing “solar kerosene” via a thermochemical process using concentrated solar energy. More on this technology can be read here.