Capturing CO2 in Metal Organic Webs

Smoke stacks with hexagon web over the emissions.

Clean technology will play a central role in Canada’s global position over the coming decades. The Federal Sustainable Development Strategy, published by the Government of Canada in 2019, is a far-reaching and ambitious plan to reduce environmental damage in virtually all aspects of economic development in the country. Covering sectors such as energy, infrastructure, food, and biodiversity, implementing the Strategy requires deep innovation. As a G7 member state with per capita greenhouse gas emissions in the top five on Earth, Canada’s ability to execute such a comprehensive plan will be the subject of domestic and international scrutiny. While our vast fossil fuel resources have quarterbacked the resource economy for decades and will remain indispensable as we transition to a sustainable future, securing a clean path forward will depend on innovation in how we generate and deploy energy.

In many cases, being able to meet our climate and other sustainability targets depends on technologies that do not yet exist. This is especially difficult to work with when devising policies to buoy those innovations such that they can make a meaningful impact. While our current arsenal of clean technologies ranges from oft-refined stalwarts like wind and solar energy to more nascent developments like carbon capture and storage (CCS), the long-term success of a technology often comes down to its economics. Previous attempts at implementing greener processes have faced challenges in deployment and ballooning costs, resulting in high household energy expenditures. Subsequent returns to the drawing board became tasks of overwhelming proportions.

“The materials are like a microscopic honeycomb with a massive surface area, which is great for safely storing a dangerous gas such as hydrogen.” — DR. YINING HUANG

Meanwhile, some of our ageing clean technologies are neither safe enough nor efficient enough to meet the demands of modern-day usage. For example, some of the enormous vehicles used in commercial mining are powered by hydrogen gas instead of diesel. The chemical reaction in a hydrogen fuel cell generates an electrical current that powers the vehicle while emitting only water as a waste product; the downside is that the extremely explosive gas must be stored in a tank on the vehicle, endangering the life of the driver and anyone else nearby. Likewise, coal plants cannot effectively reduce the large amounts of carbon dioxide (CO2) emitted from their smokestacks. The most widely employed method was first devised in the 1930s and uses a chemical reaction to trap the greenhouse gas but the high energy consumption and corrosive chemicals used make it a costly process. Unless more fundamental scientific achievements are made, to accelerate and ease the energy transition, Canada will find itself lagging in global environmental status.

Results

Enter Yining Huang and his research group in the Department of Chemistry at Western University, whose development and characterization of a class of advanced materials called metal organic frameworks (MOFs) has potential applications in clean energy solutions. Huang and his colleagues have been working towards developing MOFs capable of capturing CO2 out of a coal plant smokestack and storing hydrogen gas. “The materials are like a microscopic honeycomb with a massive surface area, which is great for safely storing a dangerous gas such as hydrogen.” explains Huang, “While hydrogen makes an attractive carbon-neutral fuel, people sometimes associate “hydrogen” with the Hindenburg disaster. Our research is to make sure that the world needed to learn the lesson only once.” Similarly complex, porous MOFs developed in part by Huang’s group can act as selective sieves, capable of scrubbing out CO2 from coal-fired power plant flue gases. Huang and his colleagues’ cutting-edge research in development and characterization of MOFs for green applications is a significant contribution to Canada’s technological battle against climate change.

At the molecular level, the MOF is like a Coz whose parts can easily be swapped out or modified by changing the component metals and organic molecules that link the metals. Because of their inherent versatility, MOFs have an astounding variety of applications, including harvesting water from the scant moisture in desert air, and controlling the accumulation of the gases that cause fruit to ripen while they are in storage and transit. The fundamental work conducted in the Huang lab to develop these materials can now be scaled up by engineering groups. While many of the applications of these novel materials have yet to be discovered, their extraordinary impact on health, the environment, and economics has already been demonstrated. Making these new technologies available at scale will lead to a safer, cheaper clean energy future for Canadians.