Anaerobic Digestion

What is Anaerobic Digestion?

Anaerobic digestion is the breaking down of organic waste via microbes in the absence of oxygen. The anaerobic digestion process produces a number of products. After some refining these products most prominently include renewable natural gas (RNG), biogenic CO2, digestate fertilizers, and ammonium sulfate.

 More about the byproducts

  • Renewable natural gas is chemically the same as regular fossil sourced natural gas. The only difference comes from its source. Renewable natural gas comes from the anaerobic digestion of renewable resources. It also has a significantly lower greenhouse gas impact as it does not use sequestered carbon that fossil natural gas does.

  • Biogenic CO2, similar to RNG is chemically the same as regular CO2 except it comes from the natural carbon cycle. That is to say, it is not adding carbon to our environment. When for example, fossil natural gas is burned it is adding previously sequestered carbon to our environment by producing CO2 in the combustion process. Biogenic CO2 is made of completely captured carbon that was already in the atmosphere.

  • Digestate fertilizer encompasses two products. The first is a fiber based fertilizer that is low in nutrients but high in value. The fiber fertilizer has significant value in its use as a soil amendment. In products such as potting soil and peat moss substitutes.

  • Digestate fertilizer encompasses two products. The second is a granulized product made from the waste water of the anaerobic digester process. This product has similar nutrient values as many turf fertilizers though it has a higher concentration of micronutrients.

  • Ammonium sulfate for our process is made through the cleaning of the recycled water in our anaerobic digester systems. The water that is being recycled is very high in nitrogen. To remove this nitrogen it is removed from the water and reacted with sulfuric acid to create ammonium sulfate. We often call it sustainable due to the fact that traditional ammonia production is very high in carbon emissions. Our ammonium production has no carbon emissions at all.

What waste options do you have?

Dairy Manure

Dairy manure is an often chosen source as it produces a large amount of low carbon gas. Generally, dairy farms also benefit from large scale and easy conversion from current storage methods to anaerobic digestion. Storage of dairy manure currently creates a lot of carbon emissions that are avoided with anaerobic digestion.

Swine Waste

Swine waste is another common agricultural waste that is produced on large farms. It is a quality feedstock when it is not overly watered down which can be a common problem. Swine waste is generally processed in smaller, farm sized facilities as it is hard to transport swine waste efficiently. Swine waste projects would excel on larger swine farms.f

Food Waste

Food waste is a commonly talked about feedstock for new projects as food waste most often comes from humans. However, it has limitations in the collection, depackaging, and efficient processing of it. When done correctly food waste can make large amounts of high quality and valuable renewable natural gas.

Distillery Waste

Distillery waste is another very common feedstock for anaerobic digestion. Distillery waste is very high in fats that are ultimately what fuel the anaerobic digestion process. Because of this distillery waste makes a lot of gas very quickly. Distillery waste gas is not as valuable as traditional farm waste gases and does not avoid nearly the carbon emissions.

Poultry Waste

Poultry waste is unique in that their is only one project in the entire world that utilizes this waste. Poultry waste can be a very powerful feedstock if the anaerobic digester is designed correctly. Johnson Energy Solutions works in lock steps with its partners to design the first poultry only anaerobic digester in the United States. ffefefefefe

Manufacturing Waste

Manufacturing waste is a large source of possible feedstocks. Gas production can vary based on what organic matter is left over. The gas is also often less valuable as we are not avoiding carbon emissions. However, it is still a good feedstock option for some food and beverage manufacturing facilities.

Why choose poultry?

While Johnson Energy Solutions works on all types of anaerobic digestion projects, we currently focus on cutting edge poultry only anaerobic digester projects. These projects have a number of advantages. That include reliable feedstocks, high value gas, and significant gas production.

  • Poultry is the most commonly consumed meat in the United States. According to the USDA nearly 9 billion chickens were produced last year alone. Currently poultry only anaerobic digesters do not exist within the United States. Meaning, largely all of the waste created by those 9 billion chickens is available for digestion and energy creation.

  • Poultry litter when used as a fertilizer can produce large quantities of Nitrous Oxide, Carbon Dioxide, and Methane. These emissions come from both storage and application of the waste. When we instead choose to anaerobically digest the waste we avoid much of those emissions while creating energy and still are able to return the solid waste to farmers as a higher quality fertilizer.

  • Poultry litter in lab tests has proved to be an efficient feedstock at producing biogas. It is not exclusive to the lab either. Their has been one project that has successfully processed poultry litter only and many that have processed a combination of poultry litter and other feedstocks throughout the world.

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