KNOWLEDGE DRIVES THE FORCE FOR CHANGE

Biogas is formed anytime organic waste decomposes. In the renewable energy industry, we build closed vessels called ‘anaerobic digesters’ to hold the organic waste as it decomposes. In this anaerobic environment, microscopic bacteria become very efficient at transforming carbon from a solid form, also known as organic waste, to a gas which is referred to as biogas. In essence, the bacteria are eating the waste, which is why these facilities are called ‘digesters’.

An anaerobic environment is an environment that lacks oxygen. This type of environment is essential in forming biogas because it allows for the growth and activity of anaerobic microorganisms, which break down organic matter in the absence of oxygen to produce biogas. Methanogenic bacteria are required to produce methane, and these bacteria only exist in anaerobic environments.

RNG stands for renewable natural gas. Raw biogas, as is produced in an anaerobic digester from organic waste, contains non-energy generating components. RNG is produced by cleaning these other components out of the raw biogas. RNG is an equivalent to fossil methane and can be used in the same way that conventional natural gas is used: in the natural gas pipeline or to fuel natural gas-powered vehicles. Additionally, like conventional natural gas, it is possible to compress and liquefy RNG for storage.

Biogas is the only renewable energy that targets organic waste derived from the production and consumption of food. It is part of a resource recovery ecosystem. Food production as an industry has a large carbon footprint, but anaerobic digestion is a beneficial reuse and recovery system that can be implemented at all stages of the value chain to recover waste generated by producers, consumers and everyone in between.

Biogas not only produces energy but can also improve soil health. Despite removing most carbon during anaerobic digestion, the leftover digestate still contains organic matter and nutrients that can nourish microorganisms. Land application of digestate reduces dependence on chemical fertilizers and decreases weed growth compared to non-digested manure. The Fitec Self-Cleaning Digester technology also filters out small plastic particles to prevent microplastic pollution.

Investing in a biogas facility can:

Diversify your farm revenue - Aside from generating income from energy generation, accepting off-farm wastes can also generate income from tipping fees.

Provide a responsible way to manage on-farm wastes such as manure - Placing this waste in the digester eliminates risks for water pollution.

Reduce your dependence on synthetic fertilizers - land-applying digestate leads to fewer weeds than raw manure application. Digestate is also more readily integrated into the soil microbiome than raw manure or synthetic fertilizers, improving crops more quickly and for less cost.

Generate carbon credits - Generating RNG or renewable electricity on your farm can allow your operation to be carbon negative, and to sell any extra carbon credits.

Landfills do capture some methane that is produced by waste, but the gas produced in a landfill contains a high percentage of other chemical compounds that are difficult and expensive to clean out or treat. This makes it challenging to produce a fuel that is of replacement quality for fossil natural gas. Additionally, the organic matter cannot be recovered from the landfill, whereas with anaerobic digestion, you can spread the digestate on farmland after methane production.

Contrastingly, compost facilities go through a process of aerobic decomposition, which produces heat and CO2, but not methane, and therefore, not biogas. Methane can only be produced in an anaerobic environment, which cannot be provided by compost facilities without the right equipment.

The minimum tonnage for a plant is 15,000 tonnes per year. This can sometimes be achieved by an individual producer but often requires different waste suppliers to come together to ensure the minimum tonnage can be achieved.

For a smaller project, the facility would require the amount of manure produced by at least 500 milking cows. A more secure and larger project could handle the manure capacity from 1000 milking cows. Co-digesting manure and food waste is another possibility, and can be accomplished with significantly less manure.

Any organic matter can go into an anaerobic digester, but the materials that ‘digest’ the best are ones with a faster rate of decomposition, and the ones that produce the most energy are the ones with large percentages of carbohydrates, fats and proteins. In other words, the more calorie-dense the waste, the more energy it contains.

Some of the more common feedstocks include:

• Manure

• Industrial, Commercial and Institutional (IC&I) food waste from grocery stores, hospitals, etc.

• Source Separated Organics (SSO) such as residential food waste diversion

• Fats, Oils and Greases (FOG) from restaurants and the food processing industry

• Slaughter-house wastes

Many municipalities use anaerobic digesters to treat their wastewater sludge, and many have been using the extra digestion capacity to co-digest food waste to maximize revenues and improve the return on investment for municipal infrastructure.

Fibrous materials like straw or leaf & yard waste take much longer to decompose and are better suited to composting applications. A Fitec Self-Cleaning Digester is great at separating this material out from more readily digestible materials.

While you can use leaf and yard waste in your digester, it produces extremely little biogas and is much better suited for composting. Using this waste for biogas does not provide a good return on investment since you would be occupying expensive volume in your digester that doesn’t generate a significant amount of energy.

Though we do have a database of values that can be used to create sample mass and energy balances, the best thing to do is to take a sample of your feedstock and have it analyzed at a laboratory to determine its energy content. Send us an email at hq@fitecbiogas.com to learn how to take a representative sample and get the name of a reputable laboratory in your area.

Biogas and digestate, or the digested feedstock, are fairly odorous. But that doesn’t mean that if you build a biogas plant that you will be a bad neighbour. All organics processing has bad smells, but good design and good operational practices make it manageable. Additionally, various studies have shown that digested organics (if properly digested) are less odorous than raw manure when spread on land. When spread on a field, the digestate smell stays within the confines of the area and does not spread in the same way manure might.

Absolutely! Operating an anaerobic digester can be challenging due to the complexity of the system, and there are not many people or companies in North America who have experience working with them. Fitec has experience working with many kinds of feedstock and many different facility designs. We have helped a number of clients fine-tune their non-Fitec operations in order to produce more energy. We will gladly have a conversation to learn more about your facility and to give you some ideas about how we can help.

The amount of work to operate a digester can vary. Though many of the individual tasks such as digester feeding are automated, there are still many components to the biogas production business that require some management:

• Feedstock contracts and deliveries

• Monitoring and maintaining mechanical equipment

• Monitoring the biological system to ensure consistent and continuous gas production

• End Storage monitoring and digestate application

It is safe to say that the equivalent of one full-time staff will be required to manage even a small digester operation. Other considerations include having enough staff for a rotation, or requiring more hours for a larger system.

The person operating a digester should be mechanically inclined and feel comfortable working with motors, plumbing, pumps and controls.