INTRODUCTION
As the world grapples with the urgent need to address climate change, efforts to combat greenhouse gas emissions have intensified. While carbon dioxide remains the primary target for removal via carbon sequestration, attention has now turned towards addressing other greenhouse gases such as methane (which is more potent).
Through principles similar to those found in carbon sequestration methods, endeavors to remove methane from the atmosphere are gaining traction. These efforts present promising avenues for mitigating climate change by reducing overall greenhouse gas concentrations in the atmosphere.
Carbon removal and methane capture or removal endeavors are under scrutiny to ascertain their effectiveness and overall benefit in mitigating the impacts of greenhouse gas emissions. While skeptics question the feasibility and cost-effectiveness of such approaches, ongoing research and practical implementations reveal promising outcomes.
A recent research by Abernethy et al. underscores the potential of methane removal in cleaning the air and cooling the planet, thus complementing efforts to reduce carbon dioxide emissions and meet climate goals (Abernethy et al., Methane removal and the proportional reductions in surface temperature and ozone, 2021).
The recent surge of initiatives in Africa highlights the continent's commitment to addressing climate change through carbon sequestration and methane removal. From reforestation projects to renewable energy initiatives, these endeavors demonstrate Africa's proactive stance in tackling climate change.
WHAT IS CARBON SEQUESTRATION
Carbon sequestration is the capturing of carbon dioxide from the air and directing it somewhere else. For example, directing it to plants, oceans, and ground/soil.
Carbon dioxide (CO2), a greenhouse gas and a big air pollutant, is released into the atmosphere through natural and human activities. People and animals exhale carbon dioxide everyday and that's considered a natural source. But the carbon dioxide that comes from the burning of fossil fuels (natural gas, oil, and coal) is carbon from human activities (“How does carbon get into the atmosphere?”, USGS). Because of this air pollution problem, carbon sequestration is used as one strategy to clean up the air.
A 2022 report by The Congressional Research Services (CRS), on Carbon Capture and Sequestration (CCS) in the United States, provides insights into carbon capture and storage processes. It covers topics such as CO2 capture, transport, injection, and sequestration.
CARBON SEQUESTRATION METHODS: HOW IT’S DONE
Carbon sequestration can happen naturally. For example, plants use the pores in the leaves to absorb carbon dioxide from the air. But, because of the dire situation we are facing, people believe that artificial measures would make the process quicker. Thus, a lot of carbon dioxide can be removed from the air faster.
Artificial carbon capture/ sequestration includes capturing CO2 from the air. In this case, companies use fans to inject the collected CO2 deep into the ocean or ground. One research agenda paper looked at things like planting more trees, storing carbon in soil, sucking it straight from the air, and adding iron to the ocean to help plants absorb more CO2 (ocean iron fertilization). They tried to figure out if they can remove about 10 billion tons of CO2 every year, which is a quarter of what people put into the air (Jackson et al., Atmospheric methane removal: a research agenda, 2021).
Natural Carbon Sequestration Methods / Natural Sink
1| Plants (Land and Water Plants)
Plants use the pores in the leaves to absorb carbon dioxide from the air. The carbon is then stored in the body of the plant, including roots and leaves. Through photosynthesis, the carbon becomes oxygen, which is then released into the air. This is the good air we breathe (“Biomass explained”, U.S Energy Information Administration, updated June 8, 2021).
Oceans naturally sequester carbon dioxide through water plants. These water plants absorb CO2 during the photosynthesis process. When the plants die, they sink to the bottom of the ocean and release carbon through decomposition.
2| Peat Bogs
Peat bogs store high numbers of carbon. This is because peat bogs lack oxygen and this slows down decomposition of plants. A peat bog is a wetland that has moss growing on the soft and spongy ground. These bogs have no air flowing due to heavily compacted moss. The moss can be turned to fuel or soil food.
3| Animals
Animals consume plants and transfer the carbon in the plants to the soil. The transfer of carbon happens when animals discharge solid matter (pass stool), when they die, and when they decompose.
Artificial Carbon Sequestration Methods
1| Planting Trees
Plant trees that grow fast and live for many years. These trees keep trapping carbon for a long time without releasing carbon back in the air through decomposition. For example, the baobab tree, found in Africa, can live for thousands of years. Constantly sucking CO2 from the air.
2| Managing or Stopping Forest Fires and Managing Wetlands and Grasslands
Bury dead trees deep in the ground so the carbon dioxide is trapped there. This stops decomposing trees from producing carbon in the air.
3| Feeding Ocean Plant with Nutrients
Feed ocean plants with nutrients that are artificial. For example, if you inject iron filings into ocean plants, there is high carbon absorption through photosynthesis.
4| Changing Cropping Patterns
Using cover crops, crop rotation, no tilling farming, and compost/manure are important farming practices. These methods capture carbon dioxide from the air and transfer it to plants and soil. Also, the less heavy fueled powered machinery is used, the less carbon is released into the air.
5| Injecting Carbon Dioxide Into the Ocean
Carbon dioxide can be injected into the oceans, in very deep areas. The gas dissolves (liquefy) or solidifies because of high pressure. Pipelines can be used to inject liquefied carbon deep in different places.
6| Injecting Carbon Dioxide into Old Oil Fields
Countries like the United States inject a lot of CO2 annually into underground reservoirs to enhance oil and gas recovery. While most CO2 comes from natural sources, using CO2 from factories could be financially beneficial. Some research suggests that employing CO2 captured from industrial sources for enhanced oil recovery (EOR) can result in crude oil with a lower overall greenhouse gas emissions intensity compared to oil produced without EOR or oil produced using naturally occurring CO2.
Most CO2 projects in the U.S. are on land, particularly in western Texas. Additionally, CO2 can be stored underground in depleted oil and gas reservoirs for long-term sequestration, although this doesn't generate revenue like increasing oil and gas production does (CRS report on Carbon Capture and Sequestration (CCS) in the United States, 2021).
7| Injecting Carbon Dioxide into the Ground
This process involves capturing carbon from the air and injecting it to the ground. In their 2022 paper ‘Carbon Capture and Sequestration (CCS) in the United States’, The Congressional Research Services (CRS) states that the Carbon Capture and Sequestration (CCS) system has three main parts:
- Catching and sorting CO2 from other gases
- Squishing and moving the caught CO2 to where it's stored
- Squirting the CO2 into underground rock layers
Climeworks, a company in Iceland, focuses on large-scale sequestration. Carbon dioxide is captured into collective containers through fans. Then it is sent inside the facility rooms for processing and mixing with water. After that, the mixture is injected into the ground where it stays for more than 1000 years.
One facility has the capacity to capture over 4,000 tons a year. This however, is not enough to eliminate the carbon problem fast enough. This is because, about 4 billion tons of carbon dioxide is released in the air every year, much of it from fossil fuels. Climeworks goal is that by 2030, it should be able to capture over 1 million tons of CO2 annually (Time, Climeworks Raises $650 Million to Scale Up Carbon Capture Technology, April 2022).
In Texas, USA, the Stratos project endeavors to eliminate 500,000 tons of carbon dioxide (CO₂) from the atmosphere every year upon reaching full operational capacity by 2025.
LIMITATIONS OF ARTIFICIAL CARBON SEQUESTRATION METHODS
As good and welcoming artificial carbon sequestration is, there are problems and concerns:
- Using sequestration plants is an expensive way to remove carbon. Thus it might not be a magic bullet to eliminating the carbon problem. A 2022 report by The Congressional Research Services (CRS), on Carbon Capture and Sequestration (CCS) in the United States stated that catching carbon is very hard and expensive. Some equipment parts for this, such gears, are costly to build and need a lot of energy to run.
- Carbon sequestration power plants require a lot of electricity to operate, as stated above. Most of these power plants use fossil fuels to operate. Fossil fuels are the biggest carbon producer and the heart of the global warming problem. Also, if power plants are using a lot of energy to catch and squeeze CO2, it means there's less electricity to sell to customers. CRS pointed out that this loss of energy, sometimes called the energy penalty or the extra load, can be about 20% of what a power plant can produce.
- If we focus on this artificial way to remove carbon, we might lose track of the ultimate goal or solution—using cleaner renewable energy.
- If injected into the ocean in high volumes, the carbon dioxide might turn acidic and endanger aquatic life.
- Burying dead trees deep in the ground will allow the carbon to be released and trapped in the ground rather than the air. However, this is a cumbersome task, it requires a lot of effort to bury every fallen tree.
- The effort is to only remove carbon dioxide, leaving other gases in the air, like methane, which is more potent.
HOW METHANE GAS CAN BE REMOVED FROM THE AIR
Methane capture from the air hasn't been studied as much until recently. Researchers look into using things like special light-activated materials, certain metals, living organisms, and spraying iron-salt mixtures into the air.
Researchers still need to continue assessing cost, how well it can work, if it can be done on a big scale, how much energy is used, and any bad side effects. They also talk about ways to naturally break down methane in soil and using certain filters to trap methane. They suggest using iron-salt mixtures to help the lower part of the atmosphere soak up more methane (Jackson et al., Atmospheric methane removal: a research agenda, 2021).
A paper led by Stanford University, ‘Methane removal and atmospheric restoration’ that was published in Nature Sustainability in 2019, talks about the process of removing methane from the atmosphere.
The process involves replacing methane with carbon dioxide. It aims to offset the impact of methane, a potent greenhouse gas, by converting it into a less potent form (CO2) that has a longer atmospheric lifetime. Even though methane has a shorter atmospheric lifetime, it contributes significantly to global warming.
This would represent a substantial overall advantage for the climate. The idea of replacing methane gas with CO2 seems counterintuitive, but the authors of the paper emphasized that if optimized, this technology has the potential to restore atmospheric methane and other gas concentrations to pre-industrial levels.
People make 60 percent of the methane in the air, which is now two and a half times higher than before the factories/industrial era. The paper stated that even though there's more carbon dioxide in the air overall, methane heats up the climate way more, about 84 times stronger in the first 20 years after it's let out.
Scientists say we could get methane levels back to where they were before factories/industry era by getting rid of about 3.2 billion tons of it from the air and turning it into carbon dioxide. This would be like offsetting a few months of pollution from factories worldwide.
Some sources of methane, like from cows, are really hard or expensive to remove. So, another idea is to balance out these emissions by removing methane from the air, so it doesn't add to warming up the earth. Methane is difficult to remove from the air because there's not much of it there. But scientists say a special material called zeolite could act like a sponge to soak up methane. Zeolite has tiny holes and a big surface area, and it can hold onto copper and iron, which helps grab methane and other gases.
To do this, they imagine a huge machine with electric fans blowing air through chambers or reactors filled with powdered zeolite and other stuff to catch methane. Then, they could heat up the trapped methane to make carbon dioxide and let it out.
The researchers said that zeolite setup could work for other greenhouse gases too, making them less harmful to the environment (Stanford University, ‘Methane removal and atmospheric restoration’, Nature Sustainability, 2019).
ARE CARBON SEQUESTRATION AND METHANE REMOVAL WORTH IT?
Is carbon sequestration beneficial?
Some people may ask this question. The Massachusetts Institute of Technology (MIT), in their white paper, discussed the reasons why CO2 should be sequestered.
MIT discussed the future of fossil fuels and the problems caused by these gases in relation to climate change. They focused on CO2 and its role in trapping heat in the atmosphere, which leads to global warming.
To deal with this, MIT talks about how more effective technologies are needed to address climate change issues because many countries are not meeting their goals to reduce emissions. The white paper talks about different strategies to reduce CO2 emissions, like using energy more efficiently, planting trees, and using renewable energy sources. However, these strategies might not be enough in the long run, so the white paper suggests also implementing technologies like capturing and storing CO2 underground.
These technologies could provide long-term solutions to reduce greenhouse gas emissions while still using fossil fuels. The white paper also suggests that these technologies could be alternatives if other non-fossil energy sources like solar or nuclear power don't become widely used.
Through ongoing research, these technologies hold the promise of offering an affordable solution to mitigate greenhouse gas emissions, aligning with policies focused on limiting these emissions and ultimately stabilizing their concentrations in the atmosphere.
In a 2021 research by Buylova et al, it was discussed how certain methods of removing carbon from the atmosphere might impact our ability to meet climate goals. Right now (in the year 2021), forestation and storing carbon in soil seem more feasible than other technologies like Direct Air Carbon Capture and Storage (DACCS) and Bioenergy with Carbon Capture and Storage (BECCS), which are still expensive.
However, there are challenges to carbon removal via reforestation, like trees growing slowly, forests getting damaged by fires or storms, and limited space for planting trees. As for technological solutions, there are concerns about safety, effectiveness, and high costs (Buylova et al., Cancel (Out) Emissions? The Envisaged Role of Carbon Dioxide Removal Technologies in Long-Term National Climate Strategies, July 2, 2021).
Is methane removal beneficial?
Researchers want to understand not only the environmental benefits of methane capture or removal from the air or landfills, but also its costs and practicality compared to other ways of reducing greenhouse gases. Getting rid of methane is important, but it won't solve the whole problem of climate change. We still need to reduce carbon dioxide emissions. However, if we can figure out how to remove methane from the air on a large scale, it could help slow down global warming, especially in the short term (Jackson et al., Atmospheric methane removal: a research agenda, 2021).
Research into the effects of getting rid of methane from the atmosphere is ongoing. Scientists are trying to figure out if technologies to remove methane, a potent greenhouse gas, can be practical on a large scale. They also want to understand how removing methane could impact the climate and air quality. This involves looking at complex interactions between methane and other factors like climate change, ozone levels, and the earth's natural systems.
So far, scientists have used simplified models to study these interactions, but now they're using more detailed models that simulate how different parts of the earth system interact. They're also comparing different scenarios to see how methane removal could affect things like temperature, air quality, and even crop yields.
One big idea is to compare different models and scenarios to see which methane removal methods might work best and have the most positive impact on the environment. Researchers are also looking at how methane removal could interact with other ways of fighting climate change, like reducing carbon dioxide emissions.
METHANE REMOVAL AND CARBON SEQUESTRATION IN AFRICA
Africa Climate Week
In September, 2023, in Nairobi, Kenya, the Africa Climate Change Fund (ACCF) brought together important partners in order to talk about how to reduce methane emissions in Africa and how different regions are paying for the process.
The coordinator of the ACCF, talked about how the fund helps African countries deal with climate change. She mentioned they've already funded many projects and are planning more. She also asked for more donations to help fund these important efforts.
Countries like the United States give grant opportunities to assist countries carry out methane removal activities. The United Nations Environment Programme (UNEP) is also helping some countries make plans to reduce methane (as of September 7, 2023). It was also suggested at the meetings that nonprofits could also assist countries financially to carry out methane reduction measures.
Key players that were in attendance at the Africa Climate Week 2023 were Clean Air Taskforce, Climate and Clean Air Coalition (CCAC), Global Methane Hub (GMH), and the Nigerian government.
The African Development Bank’s representative stressed how important it is to reduce methane emissions because it affects air quality and people’s health. It was said that the bank is committed to helping reduce methane emissions by securing funding from donors.
Overall, the meeting helped everyone understand what needs to be done to reduce methane emissions in Africa through methane capture/removal and how they can work together to make it happen (Africa Climate Week 2023: ACCF convenes partners to discuss efforts to abate methane emissions in Africa, November 20, 2023)
African Countries Taking Steps to Reducing Carbon Through Reforestation and Renewable Energy
The Democratic Republic of the Congo (DRC), Niger, Mozambique, are some of the African countries that use reforestation as a weapon to reduce carbon dioxide from the air. This is one way that countries around the world, including African countries, are sequestering carbon cheaply. Niger, for example, aims to rehabilitate 15,000 hectares of forest by 2030.
These countries, and Tunisia, are also focusing on renewable energy (through solar, wind, and hydroelectric energy) with the goal of improving living conditions and expanding electricity access.
Sustainable agriculture practices like rainwater harvesting and methane recovery, to reduce greenhouse gas emissions are focused in Mozambique (UNCC, Four African Countries Ramp Up Ambition for Transition to a Low-Carbon Future, July 25, 2023)
Adaptation and Mitigation
A 2022 article by Baninla et al., ‘An overview of climate change adaptation and mitigation research in Africa’, examines climate change research in Africa, focusing on adaptation and mitigation efforts. Researchers looked into how climate change affects ecosystems and services, like in Tanzania and Kenya, where forests have been declining. They also studied things like groundwater systems and carbon storage in the soil.
Countries across Africa have different costs for carbon sequestration, with Nigeria and Mali being lower compared to places like Botswana and Congo DRC (Adetoye et al., Forest carbon sequestration supply function for African countries: An econometric modelling approach, 2018). Policies regarding reducing deforestation and degradation were explored, but it was noticed that just paying people doesn't always motivate them to participate.
Much of the focus has been on forestry and carbon absorption as a way to mitigate climate change. Research showed forests have been absorbing atmospheric methane for a while, even back then in 1992.
CONCLUSION
In conclusion, the quest for carbon sequestration and methane removal emerges as crucial strategies in the global fight against climate change. While advancements in technology and research offer promising solutions, challenges and limitations underscore the complexity of these endeavors.
However, initiatives such as those witnessed in Africa, coupled with international collaborations and innovative approaches, provide hope for a sustainable future. As we navigate the complexities of climate change mitigation, it is important to recognize the importance of continued research, policy interventions, and collective action.