Six Ways We Can Meet Net Zero Targets By The End Of The Century
Since the industrial revolution, humans have emitted more than two thousand gigatons of carbon dioxide into the atmosphere. That is the weight of more than four hundred billion African elephants, five and half million Empire State buildings, or three hundred and fourty seven great pyramids. These thickening blanket of heat trapping greenhouse gases has a tremendous effect on the climate and the world we live in. It is important to understand some of the ways scientists are actively trying to remove carbon dioxide from the air.
While the extension of renewable energy and more efficient energy systems is expected to cut global emissions to more than half by the end of the century, most estimates show the need to remove about a billion metric tonnes of carbon dioxide annually by mid century to keep the climate in check. While carbon removal may come in many ways — ranging from simple to complex technologies — we are going to look at six ways scientists are trying to pull greenhouse gases out of the atmosphere.
1. Forest
This is the simplest and oldest method available to us. Trees are probably the most common carbon sink. By the way, a carbon sink is a forest, ocean or other natural environment viewed in terms of its ability to absorb carbon dioxide from the atmosphere. Forest absorb over 15% of the carbon dioxide generated by burning fossil fuels which is about 15 million metric tonnes of emissions per annum. Trees use photosynthesis to remove carbon dioxide naturally. They convert it to wood and food. Trees also absorb and store carbon dioxide in the soil. Therefore, expanding and managing existing forest is crucial. Every acre of land or soil of temperate forest can sequestrate about 3 metric tonnes of carbon dioxide per annum. This approach is relatively inexpensive and yield cleaner air and water. However, reforestation and forest expansion is a potential threat to food security as the land used for crop cultivation could shrink. This dynamics makes sequestrating and managing existing forest especially challenging.
2. Farm
Similar to trees, soils naturally store carbon. Loamy soil contains four times more carbon than the total stored in all living organisms. There a more than 2 billion acres of farmland in the United States. That is the size of Texax and California combined. Agricultural soils are running a big carbon deficit due to their intensive use. Because of how much farmland there is, even small improvements in farming practices that increase the carbon pull in farms will hugely be impactful. Building soil carbon is moreso beneficial to farmers and ranchers since it increases soil health and crop yield. By planting cover crops, the ground remain covered when field would otherwise be bare during off seasons to extend photosynthesis throughout the year. Using compose can improve yields while storing complex carbon context in the soil. Scientists are even working to breed crops with deeper roots making them more resistant to drought while depositing more carbon into the soil.
3. Bio-Energy and Carbon Capture Storage (BECCS)
BECCS is another way to use photosynthesis to combat climate change but is far more complicated than planting trees or managing soils and it doesn’t always work for the climate if it not done right. BECCS is the process of extracting bioenergy from biomass while concurrently capturing and storing the carbon. As trees are planted and grown, carbon dioxide is pulled out of air through photosynthesis. The trees will then be cut down and processed to extract biofuels. The biofuel produced is separated from carbon waste and used as fuels for cars and planes. The advantage is that biofuels emits negligible amount of carbon dioxide which is environmentally friendly. The carbon that is left behind is then stored underground or mixed with products like concrete. As of 2019, five facilities around the world are actively using BECCS technology and are capturing approximately 1.5 million tonnes of carbon dioxide annually. While the technology is extremely expensive, research have shown that similar methods could increase energy generation and carbon dioxide removal by more than fifty times relative to modern BECCS systems. Therefore the technology does show promise.
4. Direct Air Capture (DAC)
This is what most people think of when talking about removing carbon dioxide from air. Direct Air Capture (DAC) is the process of chemically scrubbing carbon dioxide directly from the ambient air and either storing it underground or using it in consumer products. DACs are sited closer to power plants or industrial facilities where concentration of atmospheric carbon dioxide is high. It is relatively straightforward to measure and account for the climate benefits of DAC and its potential to scale is enormous. However the technology remain costly and energy intensive. Technology cost is expected to decline through learning and development. Also, energy from renewable sources is expected to provide cheap alternative for DAC technology. DAC has the potential of capturing billions of tonnes of emissions annually.
5. Seawater Capture
Oceans are the largest carbon sink on earth and has a great potential for emission reduction. When seawater absorb carbon dioxide in large amounts. it becomes acidic thereby destroying coral leafs and other delicate seawater bodies. By reducing reducing the concentration of carbon dioxide in seawater, the seawater can then draw more carbon dioxide from the air to regain balance. This method has the potential to capture carbon dioxide from air in great amount. As promising as it sounds, it comes with its challenges as carbon dioxide present in seawater can not be moved to any processing facility due to its heaviness, even though it is easier to process carbon dioxide present in seawater than in air. The United States Navy has already developed a prototype seawater capture device. This technology converts captured seawater carbon dioxide to fuel which allows vessels to feed their own fuel from the sea. This technology balances emissions and its future application can form long term application and storage of carbon dioxide.
6. Enhanced Weathering
Some minerals naturally react with carbon dioxide turning it from gaseous to solid form. It is a typically slow process hence scientists are figuring how to speed up the process. This could mean pumping mineral water from underground deposits to the surface where minerals can react with the air.
All this technologies have to grapple with how cost effective and easy to scale they are. The final answer probably would not be be just one of them but a combination of them working together.
Author
Gubihama Joel is a climate change scientist on a mission to decarbonize traditional carbon intensive industries in order to meet the net zero emission target by end of the century. For more details visit www.energetycs.com or www.gubijoel.com
