How is chemistry contributing to the fight against climate change?
What happens every time someone turns on the lights? The electricity turns on! The greenhouse gases which power this phenomenon aren’t visible and thus may not seem prominent in our daily lives, but our modern lifestyle is creating an ever-increasing amount of emissions. The United States Environmental Protection Agency, also known as the EPA, reports a shocking 90% increase in global emissions from 1970, with 78% of the pollutants created by fossil fuel combustion. Corresponding to the statistic, energy required for electricity and transport dominates the emissions by making up a whopping 73.2% of the total sum.
“As a student in high school, I worry about how life might change for those who are still in school, learning and preparing to be adults in the future,” says MVHS freshman Crystal Cheng, “I think climate change will change the way we will have to live our lives later on, and our lifestyles may be very different than what we are used to now.”
Despite these statistics providing Americans with the daunting fear of changing life as they know it, research for providing solutions to the emissions problem is on the rise. Javier Garcia Martinez, a professor of inorganic chemistry and a director of the Nanotechnology Laboratory at the University of Alicante, presents the latest invention to combat this issue, in which photovoltaic solar cells create energy to perform chemical reactions that turn carbon dioxide into usable chemicals. How do these chemical reactions happen, and to what extent will they help the everlasting fight against climate change?
How does it work?
There are four different types of approaches when it comes to converting carbon dioxide into other chemicals: bio-photosynthetic, photothermal, microbial-photoelectrochemical, and photovoltaic. Combinations of these types can also be utilized to decouple, or get rid of, several steps involved in each type and use more reactants in one device.
The process of turning carbon dioxide into other chemicals is “very similar to photosynthesis in plants,” says Dr. Joel Ager, an adjunct professor of the Materials Science and Engineering Department at UC Berkeley and a staff scientist at Lawrence Berkeley National Laboratory. “Water is oxidized into oxygen and the resultant electrons, boosted in energy by light, are used to convert CO2 to more reduced molecules—for example: ethanol, ethylene, as opposed to glucose made by the natural process.”
In order to operate these chemical reactions, electricity is required. While any energy source can power the machines, scientists discovered how to transform solar power to be as carbon neutral as possible. In addition, the machines themselves run continuously until the photocatalysts can no longer react. “Best demonstrations in the field thus far are a few 1000 hours of continuous operation,” Ager adds, indicating that the photocatalysts can last for multiple days at a time until they are replaced.
What Are The Benefits?
California recently announced its goal to reduce carbon emissions to the equivalent of 1990 levels by 2030, which also means reducing annual emissions from 14 tons to 10 tons per person. With this ambitious announcement comes drastic action required to meet this goal. The idea of getting rid of carbon emissions and using that to create sustainable materials has been widely sought after, with a variety of different labs working towards the same goal. One of the reasons behind why the invention is so sought-after is because the products of the reactions provide usable materials. For example, ethanol is an effective solvent in paint, lacquers, and varnish, and can also be used to create household cleaning products.
Despite the electricity requirements for the chemical reactions, utilizing solar energy decreases the amount of carbon being released, which means the machine requires a larger intake of carbon dioxide than it emits. Rachel Sheinberg, a current P.h.D student studying at the Institute of the Environment and Sustainability at the University of California, Los Angeles describes the effects of solar energy.
“The cool thing about solar panels compared to wind turbines and water is that there aren’t a lot of moving parts.” Sheinberg said. “For small solar for people’s individual roofs is easy to install, but a big solar plan, big dams, big wind turbines, require a lot of permits and that requires a lot of money.”
One of the greatest factors considered when implementing a zero-emission solution is the economic cost. Fortunately, photovoltaic solar costs are constantly declining, with power generation costs falling 82% between 2010 and 2019, according to the International Renewable Energy Efficiency. The organization also conveys that $23 billion will be saved annually if the cheapest 500 GW of existing coal were replaced with solar and wind sources, proving that renewable energy is becoming more economically sustainable as time passes. Additionally, even solar power is now cheaper than many other renewable energy sources. For example, the Vibrant Clean Energy dataset states that the majority of coal plants fall between $33 and $111 megawatt-hours while solar production costs $28 to $52.
Additionally, prior statistics only convey the pure cost of making electricity; they don’t include the costs involved with reversing the detrimental effects caused by carbon dioxide. Not only is investing in renewable energy expensive, the price increases as time passes. However, putting it off will create detrimental results in the long run. In 2012, the International Energy Agency estimated the cost for switching to low carbon energy was $36 trillion. However, the 2014 estimate was $8 trillion more expensive, amounting to $44 trillion. The Intergovernmental Panel on Climate Change, also known as the IPCC, reports that holding off on transitioning to carbon-friendly energy could increase costs by 40% if climate change is left untreated and the carbon emissions overpass 50% increase by 2030.
There is still much progress being made to improve the efficiency and safety of the new invention. The solar energy for powering the chemical reactions requires ultraviolet light. However, ultraviolet light is rare, making up only 5% of light, and it is also dangerous to humans due to an increased risk of skin cancer upon prolonged exposure. To fix this predicament, scientists are currently working to create catalysts that react to visible light, which is more abundant and relatively harmless for people as well.
Efficiency of the photocatalysts is also rapidly increasing over the years. A single silicon Photovoltaic cell can achieve a power conversion efficiency of 26.7%, with multijunction silicon cells being more than 47.1% efficient, while the prices for the cells continue to decrease. Although this may not seem like very high percentages, wind turbines are 30 to 45% efficient according to Good Energy (a British renewable electricity company), and coal has an average efficiency of 33%.
After the discovery of photoinduced reduction of carbon dioxide, the topic has been popular with many researchers, with the number of research papers published on the subject matter increasing by three-fold over the past six years. Big academic laboratories such as the Joint Center for Artificial Photosynthesis, the Sunrise consortium and the Max Planck Institute for Chemical Energy Conversion are all working towards solar chemical research to build on this recent discovery. As more research is built up over the years to improve efficiency, hopefully, they will be put into industrial use.