Although some energy sources are cleaner than others, all of them have an impact on the environment. With the increasing global temperature, using green technologies might not be enough to stop global warming because these technologies also emit greenhouse gases during component manufacturing and/or energy production.
Concerned with global warming and climate change, there are researchers focusing on technologies able to recycle carbon dioxide. These technologies include capturing CO2 from the environment and/or emission source and converting it into fuels and precursors for industrial processes.
Different types of hydrocarbons have been directly produced from CO2 through electrochemical reactions, including hydrocarbons with one carbon (C1: carbon monoxide, methane, formic acid), two carbons (C2: ethylene, ethanol, acetate), and with three carbons (C3: n-propanol). The type of hydrocarbon produced will depend on the catalyst used.
It is possible to produce more complex chemical compounds and higher hydrocarbons (C4+); however, this implies high energy costs. Currently, economic viability favors the synthesis of smaller building-block molecules, which later could be transformed into higher hydrocarbons.
Bushuyev et al.  divided some of the technologies aiming at CO2 recycling according to the following timeline for commercialization:
CO2 reduction by Electrocatalysis (conversion of CO2 into hydrocarbons using water, a flexible electricity source, and a catalyst), CO2 reduction by Photocatalysys (conversion of CO2 into hydrocarbons using water, direct solar energy, and a catalyst)
Biohybrid technology (combination of inorganic catalysts and enzymes that split water to generate H2, which will react with CO2 and produce hydrocarbons), Nanoporous Confinement (zeolites and metal-organic frameworks used as catalysts for reduction of CO2 into hydrocarbons)
Chain Insertion (CO2 directly used as a monomer for polymerization through chain insertion in the presence of a catalyst), Molecular Machines or nanomachines (artificial enzymes with dynamic components for the catalytic conversion of CO2 into hydrocarbons)
Academic researchers are not the only ones who are brainstorming solutions for global warming. The company, Climeworks is the first one to build a plant that captures atmospheric CO2. It uses a filter that chemically bonds to carbon dioxide. When the filter is saturated, it is heated to 100oC and CO2 is released and stored for later use. This allows the removal of 900 tonnes of atmospheric CO2 per year. The gas can be used by greenhouses, food and beverage companies, and energy, fuels and materials companies.
Climeworks envisions capturing 1% of global CO2 emissions by 2025 through the installation of approximately 750,000 shipping-size containers filled with CO2 filters, which is about 50,000 less containers than the number of shipping containers that pass through the Port of Shanghai every week (source: Joc.com).
As scientists continue to work on this field, it is only a matter of time before CO2 is captured and converted into hydrocarbons/precursors in the same plant it is emitted. These efforts may enable CO2 to be a solution to the energy crisis instead of an environmental problem. However, the wide adoption of those technologies needs to be done with caution, based on sound research, and considering all the possible consequences, so we do not follow a path that may lead us to another impasse.
BBC News Brasil, “A inovadora máquina que absorve CO2 da atmosfera e o transforma em um gás com valor econômico”, Nov. 17, 2017; Retrieved from: https://www.bbc.com/portuguese/geral-42024360 on Dec. 3, 2019
Bushuyev, O., Luna, P., Dinh, C., Tao, L., Genevieve, S., Lagemaat, J., Kelley, S., Sargent, E., “What Should We Make with CO2 and How Can We Make It?”, Joule 2, 825–832, May 16, 2018. Retrieved from https://www.cell.com/action/showPdf?pii=S2542-4351%2817%2930076-4 on Nov. 22, 2019
Climeworks website, https://www.climeworks.com/. Accessed on Dec. 5, 2019
Climeworks, “Capturing CO2 from air”, May 31, 2017; Retrieved from https://www.youtube.com/watch?v=63S0t4k_Glw on Dec. 5, 2019
Hood, G; “CU Has Developed A Tiny Muncher That Eats Carbon And Spits Out Bioplastic”, Jun. 15, 2019; Retrieved from: https://www.cpr.org/2019/06/15/cu-has-developed-a-tiny-muncher-that-eats-carbon-and-spits-out-bioplastic/ on Dec. 5, 2019
JOC; “Top 50 global port rankings 2018”, Aug. 9, 2019; Retrieved from: https://www.joc.com/port-news/top-50-global-port-rankings-2018_20190809.html on Dec. 6, 2019
The Week, “Capturing CO2 from air”, Jun. 19 2017; Retrieved from https://theweek.com/articles/705853/incredible-machine-suck-carbon-dioxide-atmosphere on Dec. 5, 2019
University of Toronto; “MSE PhD student proposes how we could use climate-warming CO2 for good”, 2018; Retrieved from: https://mse.utoronto.ca/news/mse-phd-student-proposes-how-we-could-use-climate-warming-co2-for-good/ on Nov. 22, 2019