Catalysts: The Next Energy Frontier

By: Subashini Thangadurai

14 | Calgary, Alberta

Terry and Sharon Allen Special Merit Award for Elementary

INTRODUCTION

The world’s demand for energy will increase by two or three times over the next 30 years, according to the University of Copenhagen [1]. This increase in energy demand can be associated with the expected increase in population, 7.7 billion today to 9.7 billion by 2050 [2]. Canada needs to be able to find a continuous sustainable option that is reliable to reduce harmful emissions that could result from an increase in energy demand. The production of greenhouse gases results from nonrenewable fossil fuel processes; hence the interest in reducing greenhouse gases by switching to more sustainable, renewable energy production. Green catalytic technologies allow renewable energy systems to be efficient, and permit its overall function and goal to reduce emissions. With climate change continuing to press on, renewable catalytic technology is something we should continue to innovate on.

Figure 1: Depicts catalyst reaction process that decreases activation energy. Adapted from ref. [3].

Types of Catalysts

A catalyst is a substance that increases the rate of a chemical reaction but does not undergo any permanent chemical change. A catalyst decreases activation energy, allowing chemical processes to occur more easily (Figure 1) [4]. There are many kinds of catalysts, which are defined both by what phase they are in and how their activity is governed. Heterogeneous catalysts exist in a different phase than the reactants. For example, the catalyst could be solid and the reactant a gas, such as in the process of fuel cells. The catalyst in a heterogeneous process can be separated and recovered more easily than a homogonous process, as the reactant is in a different phase. Homogeneous catalysts exist in the same phase as the reactants. Photocatalysts are catalysts that enhance a chemical reaction when activated by light, such as titanium dioxide. Electrocatalysts are a type of catalyst that specifically increases the rate of reaction on an electrode surface, such as in the process of electrolysis. Enzymes are biological catalysts that speed up chemical reactions biologically (in living organisms). Bifunctional catalysts are catalysts with two different catalytic sites; they can catalyze two different reactions.

Examples of specific catalysts that are important to sustainable design

An iron-based catalyst is used in the Haber process [5], which allows for the economically feasible production of ammonia and now accounts for the nitrogen-based fertilizer that continues to help feed up to half of the global population [6].

Platinum is a bifunctional catalyst, which is used in dehydrogenation processes. For example, the extraction of hydrogen from organic compounds (living thing) [5].

Hypothesis: How can we implement catalysts to design a sustainable community, supporting energy conservation?

DISCUSSION

A catalyst is something that speeds up the process of a reaction without getting consumed. It defines efficiency. Catalysts should be used more frequently in pollution reduction, materials savings, and to prevent energy loss [8], [9]. There is decade’s worth of research on these ideas, which could be implemented to a great extent in our communities. “If energy-saving catalytic processes get adopted widely. Energy use in 2050 can be reduced by 13 exajoules,” [7].

Figure 2: Depicts process of hydrogen reacting with oxygen creating electricity conversion through anode and cathode (and catalyst); with water and heat as byproducts [10].

HYDROGEN ECONOMY

Sir William Robert Grove invented the first fuel cell in 1839 [11]. As society continues to push forward with new and innovative technologies, cost is still limiting the movement towards sustainability. A fuel cell converts chemical energy into electricity (Figure 2). A catalyst (e.g. platinum) in a hydrogen fuel cell is the key tool to the release of protons and electrons to generate electric current [12]. The anode and cathode are both coated with a platinum catalyst, with an electrolyte in between. There is plenty of hydrogen on this planet to sustain a hydrogen powered community. To design an eco-friendly community, hydrogen needs to be created sustainably. Electrolysis can be used to create hydrogen, by separating water into hydrogen and oxygen. The electric current used to separate water can be provided by solar, wind, and other renewables. Catalysts are used to speed this process up, and much research is focused towards looking into electrocatalysts for electrolysis, such as noble-metal oxides [13].

HYDROGEN CREATION

One drawback to using electrolysis towards hydrogen generation is its lack of efficiency. For hydrogen creation, there is a 35% efficiency via electrolysis (renewable current), while batteries can achieve an energy production efficiency of up to 95% [14]. Wind energy is commonly used to perform electrolysis in places such as Europe, according to marketing director of Europe’s Panasonic Company [15]. If there is lots of wind, an excess amount of renewable energy is produced in the process of electrolysis. However, with the right timing, hydrogen produced could be used when there is no wind making it cost effective; utilizing the energy to balance energy shortage [15]. Therefore, there is a need for the implementation of practical choices of catalysts to increase the efficiency of green electrolysis [16], [14]. Effective catalysts to assist in electrolysis are metals such as ruthenium, iridium, and platinum. Though they are expensive these metals work well as catalysts due to their robust structure and have been tested in electrolysis environments. Catalysts used in electrolysis will provide an efficient solution, as designing green materials enhance the overall hydrogen generated.

Figure 3: Depiction of the conversion of carbon dioxide and renewably produced hydrogen to methane with the use of dual function material (DFM), which is the combination of an absorbent and catalysts [17].

INDUSTRIAL USE

Industries that produce oil, and other fossil fuel burning reliant systems, produce large amounts of flue gas (carbon dioxide). Therefore, as technologies become greener there is a focus on reducing the amount of greenhouse gasses created. 90% of chemical manufacturing companies use catalysts to increase efficiency processes [7]. However, the implementation of catalysts is often used to gain efficiency, rather than also increasing sustainability. The amount of energy used is increasing in industries, and, therefore, sustainable initiative needs to take place.

The process of using flue gas and renewably created hydrogen to create natural gas, and a byproduct of water, can be renewed once more for the process of electrolysis (to create hydrogen) (Figure 3) [18]. This is done using a heterogeneous catalyst, such as ruthenium, to speed up this process (in the DFM).

The process creates natural gas, while reducing carbon dioxide emission and minimizing the need to mine natural gas

Figure 4: This figure depicts the market for catalysts in the use of fertilizers which is increasing [19]

AGRICULTURE

Catalysts should be sustainably used in agricultural processes. Ammonia synthesis, used for fertilizer production, produces a large amount of carbon dioxide. 20 billion tons of greenhouse gas emissions comes from agriculture worldwide [20]. Production, transportation and utilization of fertilizers contribute to greenhouse gas emissions, including carbon dioxide and nitrogen. There is an increase in catalytic production and in supplier demand. If catalysts are used in fertilizers it will reduce the carbon footprint of this process and increase the efficiency of production. Ammonia is used for food production, fertilizers, and energy storage (Figure 4). Catalysts should be used to design a complete sustainable production line from the start to end to limit greenhouse gas emission from ammonia production.

HOUSING

Catalysts can be used in green fuel cell technology and development. The applications of fuel cells in housing are of importance to infrastructure development for a sustainable community design. According to Panasonic, a company dedicated to creating a hydrogen economy by 2024-2025, a family of four people using renewable hydrogen-based energy, rather than gas heating and electricity, would save 1.3 tons of fossil energy per year [15]. Thus, carbon emissions will be saved by using fuel cells instead of gas heating. Using a hydrogen economy is expensive, but using hydrogen alongside other renewables could provide a balance [15]. A hydrogen economy is expensive because of the expense of creating a fuel cell, which includes the cost of a catalyst (used in both hydrogen creation and fuel cell process) and overall materials. Despite the cost, carbon dioxide emissions from electricity and heat, which is gradually increasing in Canada, could be reduced by up to 20% (Figure 5).

VEHICLES

Hydrogen fuel cells are applicable in vehicles, stretching the limitations of transportation by providing carbon-free emissions [12]. In short, an electrochemical reaction generates electricity, which is made possible with the assistance of a catalyst, producing byproducts that are not greenhouse gases.

A Hyundai model, NEXO, was created in London. It is a fuel cell operated car that cleans the air as it moves, thus purifying the air. The capability of the car itself supports sustainable design. This design would be able to clean air almost as well as trees can. 10, 000 NEXOs can equate to reducing carbon as much as 60 000 trees [21], [22]. The energy cost of transport is enormous; it is why transport contributes to 30-40% of greenhouse gas emissions in the world. This technology, first shown in 2018, should be on roads by now, it is of urgent need. Fuel cell vehicles will help countries with air pollution, ‘cleaning the air as they go’.

SOLUTIONS

The world produces approximately 50 million tons of electronic waste (e-waste) according to a report written by United Nation agencies [23]. This e-waste has a value over $62.5 billion USD. With the world population projected to increase up to 9.7 billion people by 2050 [2], the amount of e-waste will increase as well. 20% of e-waste is recyclable, meaning that rare earth materials, including platinum, are being wasted. With technologies approving hydrogen economies, platinum supply has continued to slowly decrease from increased use. Cobalt used in phones is also being depleted from increase of use [24]. Cobalt is a catalyst important to desulfurization processes (removing sulphur from oil products) [25], and in other sustainable technologies such as in its usage as a cost-effective catalyst in hydrogen fuel cells [26].

If we were to recover catalysts from discarded electronic resources, such as phones, it would reduce the expense of generating new materials, and recycle materials for a sustainable community design. An example of this could be creating alloy catalysts (from a combination of metals) from recycled materials [27]. This is suggested and elaborated on in a recent article written by Wits University [28].

STATISTICS

Figure 5 shows the increase in greenhouse gas emissions in areas of energy, agriculture, transportation, and industry in the world over time. Graph (A) represents a rise of carbon dioxide emissions, primarily in the sector of electricity and heat production, from the year of 1960 to 2014. Graph (B) represents greenhouse gas emissions in the unit of tons, observing a rise in emissions per sector, sectors depicted are where sustainable catalyst applications should be encouraged. Graph (C) represents world carbon dioxide emissions from non-renewable forms of energy. This demonstrates the importance of using catalysts in green technologies to help combat the ever-rising greenhouse gas emissions our world continues to experience.

Figures 5: Depiction of carbon dioxide emissions by sector (A), greenhouse gas emissions by sector (B), and carbon dioxide emissions by fuel type (C) [29].

CONCLUSION

In conclusion, this research project advocates for innovations in fuel cell technology and the design systems using catalysis to focus on limiting the world’s greenhouse gas emissions. Using these technologies to a greater extent, Canada could decrease its energy consumption and emission numbers in transportation, agriculture, energy, and household heating. Therefore, the implementation of green-fuel catalysts can provide a more sustainable outlook. Catalysts depend on communities’ necessities, society’s safety, and cost. Though catalysts can be expensive, supporting a hydrogen-energy based economy could be a solution to this. Figuring out how to make these green energy changes is extremely important, with climate change and greenhouse gas emissions continuing to press on.

In the future, finding ways to diverse catalysts to help solve problems in communities that are different than the ones presented, and continuous research on how engineering a community will look differently in the years to come are of utmost importance.

The world is changing, due to climate change, energy, and environmental issues. The only way to overcome these challenges is to continue to imagine, dream, and take action. This project encourages the possibilities of sustainable energy design with the use of catalysts, which will make and create renewable energy processes possible.

ACKNOWLEDGEMENTS

Josephine Hill, University of Calgary, Calgary, Canada Robert J. Farrauto, Columbia University, New York, United States

REFERENCES

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About the author

SUBASHINI THANGADURAI

Subashini Thangadurai is a Grade 9 student attending Queen Elizabeth High School in Calgary, Alberta. She is interested in the area of climate change and environmental action, and has been a part of Alberta Youth Leaders for Environmental and Energy Education (AYLEEE) for the past year. She is involved in her school community and consistently looks for ways to implement sustainable change. She has been a dedicated science fair participant for the past three years, attending the regional fair twice, and participating in the Youth Science Canada (YSC) Online STEM Fair 2020 due to the cancellation of the regional fair. In her free time Subashini loves to read, spend time outdoors with family and friends, write in her journal, and play the ukulele. In the future, Subashini hopes to continue advocating for sustainability by becoming more politically involved in her community.