Carbon Utilization

Carbon utilization is a broad term used to describe the different ways capture carbon oxides, generally carbon dioxide and in some cases carbon monoxide, can be used or recycled to produce economically viable products or services. The idea behind carbon utilization is that carbon dioxide is a raw material that can be captured from industrial flue gas and reused in a variety of products and processes and provides an alternative approach to storing carbon dioxide.

Visualization of carbon utilization processes and technologies.

In recent years, several institutions and programs, such as the U.S. Department of Energy, the NRG COSIA Carbon X-PRIZE, Natural Resources Canada, and Emissions Reduction Alberta have expressed interest in, and supported, the development of new technologies using carbon dioxide emissions through funding and grant facilities. At the same time, there is an increased recognition of the importance of such technologies in the context of climate mitigation in academic, regulatory, and corporate environments.

There has also been an increase in the emergence of companies incorporating carbon dioxide emissions into their feedstock for polymers and concrete, among other products. These companies have emerged as the demand for low-carbon construction materials has expanded. The prospective use of waste carbon in the construction of those materials will increase and where these materials will find wider acceptance. Concrete is an example where low-carbon concrete, and low-carbon concrete aggregate, is used to decrease the overall environmental impact of the use of concrete and to market projects as low-carbon.

Carbon utilization technologies can transform waste streams of carbon into value-added products, including the development of enabling technologies such as life cycle analyses and the use of waste carbon for the production of hydrogen. The four main technological pathways from carbon utilization including carbon uptake, carbon conversion, carbon mineralization, and services.

Visualization of enhanced oil recovery.

Services, or carbon direct use, describes the use of captured carbon dioxide without any conversion or technological manipulation and is the most widely practiced form of carbon utilization. Enhanced oil recovery (EOR) is one of the more common carbon direct uses. In EOR, the waste carbon dioxide is injected into an oil well to force out the crude oil and deplete the oil field. Other uses of captured waste carbon dioxide include making the bubbles in carbonated drinks, the foam in fire extinguishers and refrigerants, and use in the pharmaceutical industry and water treatment.

Carbon uptake is often done through algae or other efficient photosynthetic organisms. The biomass produced in algae systems can be processed and converted into a variety of products, including fuels, biofuels, specialty chemicals, soil supplements, and animal feed products. Carbon uptake is a technology that has reached commercial maturity. The technology has yielded small high value-added productions of pigments, omega 3, and have prospects for biological utilization.

Carbon conversion includes conversion pathways such as thermochemical, electrochemical, photochemical, and microbially-mediated approaches. Some technologies also require catalysts or integrated processes to lower the energy needed to drive these systems. Through conversion, waste carbon can be turned into synthetic fuels, chemicals, plastics, and solid carbon products. One of the main chemical utilizations of carbon dioxide is to produce urea, a substance used in nitrogen fertilizer in farming, and it can be used to produce salicylic acid, from which aspiring is derived. Captured and converted carbon dioxide can also be used in the manufacturing of polycarbonates and for hardening concrete.

Carbon mineralization uses alkaline reactants to mineralize waste carbon dioxide. This mineralized carbon dioxide can produce inorganic materials, such as cements, aggregates, bicarbonates, and associated materials and chemicals. Carbonate materials can be effective long term storage options for carbon dioxide, especially in a built environment.

Sandia National Laboratories is using waste carbon dioxide used in place of steam for turbine-generate electricity has gained interested. In the process, the carbon dioxide is heated and pressurized into a supercritical fluid (meaning between a liquid and a gas) that can replace steam. The supercritical carbon dioxide transfers heat more efficiently and requires less energy to compress, resulting in more electricity production for the same amount of energy input.

Researchers at UNIST in South Korea and the Georgia Institute of Technology has developed technology using seawater and sodium hydroxide which captures carbon dioxide, and as the acidity increases, the number of protons increase and draw electrons to create electrical energy and hydrogen. The researchers think the technology could eventually be used to create batteries converting carbon dioxide into energy.

C2CNT, a finalist of the NRG COSIA Carbon X-PRIZE, has found a way to produce carbon nanotubes more cheaply than usual. The technology uses low-cost nickel and steel electrodes and low voltage current to create carbon nanotubes from flue gas that conduct electricity better than copper. These nanotubes can be used in steel, aluminum, textiles, ceramics, cements, electronics, packaging, manufacturing, and construction.

DyeCoo, a Dutch Company, has begun using waste carbon dioxide in their dyeing process. The technology pressurizes carbon dioxide so that it becomes supercritical and allows dye to readily dissolve, meaning the dyes need no chemical processing and can enter easily into fabrics. The process uses no chemicals or water, produces no wastewater, and requires no drying time. And 95 percent of the carbon dioxide used is recaptured and reused, meaning the system is a largely closed loop system and costs are reduced by 40 to 60 percent. The technology is used in Nike, Ikea, Adidas and Peak Performance products.

There are several challenges to carbon utilization technology and the adoption of the technology, including high capital and operating costs, low practical carbon reduction and sequestration capacities, ecological side effects, performance uncertainties, low technology readiness levels, a lack of enforced carbon regulations and a lack of feasible scale deployment. All carbon utilization sectors face challenges to commercialization in terms of technology, cost, or market acceptance. Three main underlying challenges are:

• Capturing carbon dioxide is a difficult and costly process, and it can only be performed on carbon-intensive industrial facilities, which rules out carbon dioxide emissions from transportation, farming, and housing.
• Industrial facilities that use carbon dioxide as a raw material must be located near the source of emissions or face transportation costs which reduce the effectiveness of carbon utilization.
• Carbon dioxide-based products must have existing commercial markets, but there are in general low value or niche markets which are high value but low volume.

Captured carbon dioxide as a raw material is technologically challenging. The capture of carbon dioxide is difficult, and to process and make the carbon dioxide feasible for use is more expensive than terrestrial and traditional carbon capture and mining efforts. The use of low-carbon materials, as well, such as those used in concrete and concrete aggregate, are not price competitive compared to traditional concrete and aggregate products. And for fuels, chemicals, and plastics, which can be put together due to the similarity of their production processes, is the technology and cost needed to operate at commercial scale.

A large challenge to the costs and difficulties for carbon utilization and its larger acceptance is the acceptance of carbon offsets and credits. The more popular version of this is reforestation projects, where company's can purchase these credits or offsets and are then enabled, in many jurisdictions, to label their products as "green" or "low-carbon".

Many of these challenges could be solved through support from governments. The support could come from government policy changes, financial enablement, research and development support, development of carbon dioxide transportation infrastructure, and a market preference for "green" or "low-carbon" labelling.