Anaerobic digestion (AD) is well-known in the renewable energy field for turning organic waste into valuable biogas to provide green energy to homes and businesses. But its importance goes beyond just creating renewable energy.
AD has a crucial role in carbon capture and storage (CCS), which can help us not just to balance but actually reduce the amount of carbon dioxide in the atmosphere.
Looking at the carbon cycle and AD
It’s useful to consider how the carbon cycle is involved in bioenergy processes. Organic materials like agricultural waste, animal waste, or household organic waste capture carbon dioxide during their life.
Usually, when these materials decompose, this carbon dioxide would go back into the air, but through AD, we can control how much carbon is released back into the atmosphere. A significant amount of this carbon is converted into methane, the main component of biogas. When we use this methane for energy, we prevent it from entering the atmosphere, where it acts as a powerful greenhouse gas which is extremely damaging to the environment.
Capturing carbon after AD
After we produce biogas, a purification process happens to turn the biogas into biomethane, which is clean enough to be used as a fuel or be part of the natural gas network. During this process, carbon dioxide is also separated.
By adding carbon capture technologies to AD facilities, we can store this separated carbon dioxide. It can be permanently stored underground or used later in various industries, like pharmaceuticals, carbonated drinks, water treatment plants and food packaging.
Improving AD for better carbon storage
It’s important to note that not all AD processes are the same when it comes to capturing carbon.
Factors like the type of waste used, how the digester is designed, and what the biogas is used for can all affect how much carbon is captured and stored.
By carefully choosing these factors and using techniques like biochar production, which locks away carbon in a stable form, we can capture even more carbon from the process.
Reducing CH4 and CO2
AD’s potential for negative emissions comes from its ability to reduce both carbon dioxide and methane emissions.
By keeping organic waste out of landfills, where it would produce methane, we address the significant warming effects of methane, which are much greater than those of carbon dioxide.
When you combine this with carbon capture during biogas purification, you get a system that, when done right, can capture more greenhouse gases than it emits.
In conclusion: It’s time to use AD to its full potential
While AD’s role in producing renewable energy is well-understood, we also need to focus on its ability for carbon capture and storage.
As professionals in the renewable and bioenergy sectors, it’s our job to promote these technologies, encourage research to improve carbon capture in AD, and make these methods a standard part of energy and waste management strategies.
Doing this will help us turn back the clock on global carbon emissions and pave the way for a more sustainable future.
Image courtesy of Pentair: https://biogas.pentair.com/