What is the Future of Small-Scale Anaerobic Digestion?

By | 2019-07-12

Although anaerobic digestion of small amount of organic waste was considered unprofitable a few years ago, it is growing today with a new model of biogas production: small-scale digestion (or micro-scale digestion). By the end of 2016, 130 micro-scale digestion facilities were in operation in Europe. Smaller, less expensive, easily self-sufficient, these production units attract farmers, but also investors in eco-neighborhoods, wishing to develop new sources of clean energy.

There are over 20,000 full-scale AD systems in the world and over 1,000 new projects per year. However, the valorisation process for organic waste can still be optimized. One way to do so is to use small-scale digestion. Today’s trends: modular approaches (e.g. in containers), mobile units and “plug and play”.


What is micro-scale digestion?

Micro-scale digestion involves the production of biogas, but on a small scale within farms or small communities. The small-scale digestion production units are below 80 kW. Most agricultural units have a power capacity between 100 and 300 kW, while some industrial units exceed 1,000 kWe. A small-scale digestion project is carried out starting from 100 dairy cows or 200 cows or between 200 to 5000 tons of organic waste per year. ”The interest for small-scale digestion is not to have to invest in large facilities,” explains François Xavier Dumur, Nov & atech Project Manager. ”Micro-scale digestion allows the autonomy of the system by supplying the digester with the farm products.”


Small-Scale On-Farm Digestion

The development of micro-scale digestion on-farm units emerged after 2010. Agriculture is truly well fit to be juxtaposed with anaerobic digestion for many reasons. It helps farmers: 

  • produce their own power and heat, and therefore save money;
  • reduce greenhouse gases related to livestock manure and energy consumption;
  • reduce the strong odors associated with the use of untreated manure as fertilizer;
  • minimize the need to transport the organic inputs for treatment to the proximity of on-site facilities;
  • benefit from the advantages of digestate: more liquid material and therefore easier to spread, fewer weeds and mineralized nitrogen, etc.

In France, this energy alternative is becoming very successful, particularly in Brittany, where a dozen projects are planned. For farmers, small-scale digestion is a good way to diversify their activity at a reasonable cost. 

Small-scale digestion in numbers table


Until recently, the costs of a biogas plant were hampering farmers in opting for micro-scale digestion. However, since December 13, 2016, in France, a decree fixes the new rules for the electricity feed-in tariffs generated from biogas, which has helped reassure potential investors.

Farmers now benefit from a resale tariff of 0.175 € / kWh. They are also entitled to a premium of 0.05 € / kWh if they transform more than 60% of the residues of their activity. Starting at € 220,000, a farmer can now install a 22 kW power station on his farm. The Government also decided in February 2016 to extend the duration of electricity purchase contracts produced by methanation from 15 to 20 years. This action will help them achieve the objectives of the Energy Transition Law.

Similarly, the Energy Transition Law requires the generalization of waste sorting at the source to all stakeholders by 2025. This obligation will also promote waste recovery solutions such as small-scale digestion.

Until now, the laws and regulations adopted mainly favor installation with a power of several Kw supplied by multiple sources of inputs, according to Énergies & Environnement. Positive fact: according to this website, some of the big players in the Small-Scale digesters sector have a return on investment time of less than 10 years!

Nevertheless, other obstacles remain: regulations that are not adapted to small-scale digestion, the complexity of the authorization request, the evaluation of the environmental performance still to be carried out, etc.

Small-Scale Digestion in Cities

In France, one of the challenges in the years to come will be to develop small-scale digestion in cities. Several companies have created small-scale digesters and stations for the treatment of organic waste adapted to urban spaces.

 HomeBiogas, located and manufactured in Israel, has developed an anaerobic digester specifically designed for domestic use, in which food waste is converted into biogas and fertilizer. Six liters of food waste per day is needed to feed it. The biogas produced can thus be used for cooking, heating and even lighting.

HomeBiogas systems have already been installed in several eco-districts in Great Britain and close to 1,000 family sized Biogas systems have been deployed to over 90 countries since 2015. The new model, HomeBiogas 2.0, offers a larger micro-scale of Biogas production- it can digest up to 36 Liters of animal manure and/or up to 12 Liters of kitchen waste.

However, a legal framework should be applied in order to develop micro-small digestion in cities. The legal framework must allow small-scale digestion in urban space, although the development of renewable energies is still defended by the French government.

A Few Small-Scale Digestion Projects

Funded by the European Union under the Intelligent Energy Europe Program, the project BioEnergy Farm 2 aims to open the market for micro-scale digestion. The project was carried out by a quite large consortium, representing 7 European countries.

The project objective is to assist 700 farmers in checking the feasibility of their project by doing business plans. The project has played an important role in producing and sharing knowledge about all aspects regarding small scale digestion. Bioenergy Farm also presents a report on the whole market for the various small-scale digestion technologies and assesses the development potential of 13 European countries.

HoSt launched a few years ago the Microferm. It was designed for agriculturalists who want to process manure on a small scale, and to convert it to sustainable energy. Depending on the size of the company, the farm can produce between 60 and 150 kWe green energy. Apart from the production of electricity and heat, the formed biogas can also be upgraded to natural gas quality and be supplied to the natural gas grid. Furthermore, in 2019, HoSt was building his first MicroFerm+ agricultural biogas-to-biomethane plant in France, at a cattle farm.

Methania is a Tunisian company that specializes in developing solutions for biogas, cogeneration and energy. She combines her knowledge of the most advanced technologies with her expertise in engineering and project management to provide reliable and high-quality solutions for your project. Its Jallagaz process helps farmers to valorize cows, goats and sheeps manure, crop waste and others type of waste that have a dry matte higher than 25%, through their small-scale dry digestion system.

In Canada, CCI Bioenergy offer a small-scale digestion system specific for food waste and act as a onsite solution for the valorisation of organic waste. CCI Bioenergy is a Canadian company that is considered to be a pioneer in North America in the development of organics processing solutions using anaerobic digestion.

Biolectric developed a standard technology for small scale digestion to transform liquid manure into odor-reduced, nutrient-reduced, biologically active fertilizer. Bioelectric’s technologies are adapted for a 100-cows dairy. Their solutions can also work with duck or pork manures. More than 200 Biolectric installations are currently operating in Europe.

Here are some small scale digestion unit producers in France: BIO4GAZVALOGREENAGRIKOMPARKOLIAEVALORKUB ProcessENERPRO.

A Handbook to Help You Develop Your Small-Scale Digestion Project

Published by Bioenergy Farmthe handbook  « Implementation Guide for Small-Scale Biogas Plants  » accompanies you in your microscale digestion unit project. Different topics are discussed:

– What steps should I follow to achieve my project?
– What technology should be chosen and what size adapted to my operation?
– What legislation applies to my project and what assistance can I get?
– What financial assistance can I get for my project?
– How can I ensure that the project is profitable?
– Etc.

The right supplier at the right time

BiogasWorld will be pleased to help you to achieve your small-scale anaerobic digestion project. We have a large network in the industry. We can help you find the right suppliers at the right time to facilitate the development of your project.

Do you hesitate to contact us at info@biogasworld.com or to schedule a meeting with us.