Capturing CO2 in your walls

October 15, 2018
Contributed by: Christin Schmidt, PhD

Pulling carbon dioxide (CO2) from the air to produce synthetic fuels will be the golden bullet in the fight against climate change and against a worldwide shortage of energy resources, at least according to proponents of CO2 sequestration technologies. New companies are on the horizon and have come up with great ideas to copy the nature’s way of dealing with high amounts of carbon dioxide gas. Novel innovations are emerging to make CO2 capture more cost-effective and a part and parcel of our everyday life.
In 2016, 81.6% of all gas emissions in the U.S. were CO2, constituting 6,511 million metric tons of it. Burning fossil fuels by industry and transportation systems are the main human sources of CO2, followed by electricity, solid waste, trees and wood products. With a significant increase of global carbon emissions caused by humans since 1900, we contributed massively to climate change by adding heat-trapping gases, such as CO2, to the atmosphere.

The carbon cycle
Carbon compounds are fundamental components for life on earth. They can be found everywhere: in the air, soil, plants, water and in dead and living organism. As one of the major energy sources in nature, carbon is stored in fossil fuels in form of coal and natural gas, for decades and centuries. From here it can be taken up again by organisms. The rapid carbon exchange among living organisms and long-term carbon capture by geological processes is described as the natural carbon cycle and the model for carbon biomimicry. This cycle has been brought out of balance by the human population through the large and sudden release of CO2 into the atmosphere by large-scale burning of fossil fuels and deforestation. CO2 emissions have been on a steep increase since the last century with 2 billion tons of global carbon dioxide emissions in 1900 to over 36 billion tons in 2015.

Carbon levels and global warming
Increasing gas emissions raised the Earth’s surface temperature by 1.4˚F (0.75˚C) over the last 100 years. This seemingly small number has a big effect – increased melting of snow and ice, sea level rise, desertification and stronger storms and extreme weather events. Furthermore, since our oceans serve as a sink for carbon dioxide, the high CO2 levels are causing ocean acidification, harming the biosphere.
Reducing carbon dioxide emissions and atmospheric CO2 is one of the biggest challenges in combatting climate change. The main strategies include the reduction of burning fossil fuels and usage of electricity through improved energy efficiency and conservation, fuel switching by the usage of renewable sources with lower carbon content and more recently carbon capture and sequestration.

Carbon biomimicry
Using natural processes to capture carbon is where business ideas come into play. The goal is to use captured carbon to produce energy supplies or even commercial products. Besides the existing ways of CO2 sequestration by urea production and enhanced oil recovery, many gas technology companies are exploring novel ways of capturing CO2. One approach mimics nature’s ways of using CO2 for chemical processes and building materials: Under the high concentrations of CO2 in the water, marine organisms start to use the CO2 to build durable calcium carbonate structures, such as their shells or inner skeletons. The process is called marine calcification, where dissolved carbon ions in form of carbonic acid reacts to form carbonate, bicarbonate and hydrogen ions. Reacting with calcium, it forms the long-lasting and stable mineral calcium carbonate.
Scientists and companies have developed promising technologies to capture the high amount of CO2 in the atmosphere.  The aim is to store it or re-use it as an energy supply, or even for the production of commercial products. Some of these technologies are processing CO2 to produce syngas or ethanol and eventually liquid fuels, to generate carbonate or bicarbonate materials, growing algae to convert them into liquid fuels or electricity.
Initially, carbon technologies were criticized as being too expensive with an estimate of $600 per ton in 2011 by the American Physical Society. Making them economically competitive and commercially available are the main goals for the next years. One of the large air capture technology companies, Climeworks in Zurich, Switzerland, expect to dip the price below $100 per ton in 5-10 years while operations ramp up. Overall, business analyses estimate the price for one ton of captured CO2 to be between $94 and $232 nowadays, not bad so far. To put this in a commercial perspective, a cost of $100 per ton CO2 sequestration and energy conversion would increase the price of one litre of fuel for vehicles of around $0.22 cents.

A new era of startups
The startup company Calera has picked up on a natural process of CO2 re-use with 2 goals: 1) reduce atmospheric CO2, and 2) provide sustainable and useful products. Calera is a profit-oriented Californian-based company founded in 2007. With a total funding amount of $45.5 million, including $1.68 million funding from the Office of Fossil Energy for Innovative Concepts for Beneficial Reuse of Carbon Dioxide. Calera is capturing CO2 gas from industrial emitting sources, and they produce vaterite polymorph, a calcium carbonate, by adding alkalinity and calcium. This is done by a CO2 capture and conversion technology, where flue gas from power plants is contacted in a scrubber with an aqueous alkaline solution to remove the CO2 and a calcium source that will form the calcium carbonate powder. This technology allows Calera to capture up to 2 tons of CO2 containing calcium carbonate product per day.
This powder is stable when stored in absence of water, but when water and other additives are mixed with the calcium carbonate it transforms into a cement, called aragonite. Calera uses these processes to produce cement or binder system for concrete. They also developed wallboard and cement board products using only vaterite polymorph in a much simplified process.
Most importantly, introducing CO2 gas in this chemical reaction will capture it permanently, even if the final cement is broken down again – providing a perfect solution to irreversibly sequester CO2. Additionally, adding the CO2 containing calcium carbonate to cement mixes, Calera is able to reduce the carbon footprint of traditional concrete production.
Other ideas for regenerative CO2 processing are being pursued by more companies, like the Gas Technology Institute or Phycal LLC, who are using CO2 to grow algae biomass, which can be further processed to produce electricity, biofuel, fertilizers, and recover nutrients.

The contribution of carbon technology accelerators
Although vast ideas and technologies for carbon removal and sequestering are emerging, this alone with not guarantee the success of a business. Carbon180, a NGO residing in Oakland, CA picks up there and aims to accelerate business solutions for carbon removal, policy actions and regulations. It is a non-partisan, non-profit organization with the mission to clean up carbon pollution from the air. One of their main programs Carbontech is their accelerator for carbon technology laboratories and startups. With their first recruitment round opening up soon, they intend to assist startup concepts from discovery to demonstration of feasibility. Their outlook is very promising. Many scientists are approaching Carbon180 with smart ideas: “Business ideas are ranging from carbon capture through fermentation, minerals and even garbage conversion, in order to produce building elements, furniture and other products”, according to Matt Lucas, Associate Director of Carbontech. The accelerator program includes a 3-phase-program with up to $250,000 in funding, access to lab spaces, entrepreneur mentoring and final testing at test sites. This will help young and creative carbon scientists to become successful entrepreneurs and to make their product ready for the market.
As inexorable rising atmospheric CO2 levels change the Earth’s climate, there is an urgent need to develop CO2 reducing technologies and sustainable sources of power. Atmospheric concentrations of CO2 have exceeded the 410 parts per million (ppm) margin beginning of 2018, reaching a critical level according the National Oceanic and Atmospheric Administration. The use of renewable energies is becoming more common, but it will only reduce CO2 emissions if energy demands will not increase further. The need for carbon capture and re-use is greater than ever and the business market is opening up for new technologies and concepts. But there are still a few questions to be figured out: Is carbon capture in form of cement actually profitable in the long run? Where and how can we store all the captured CO2? Exciting and promising times lie ahead.

Christin Schmidt, PhD is a science communication fellow at Biotech Connection Bay Area. She’s also a postdoctoral scholar at the University of California, San Francisco.
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