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Turning food waste to energy using Anaerobic Digestion

Food waste is a global issue causing climate change.

Food waste is a global issue that has become a huge environmental issue over the last decade. In particular, food waste is a major source of methane (CH4) which is one of the most potent gases that is causing climate change. If food waste were a country, it would come in third after the United States and China in terms of impact on global warming. Hence, reducing food waste around the world would help curb emissions of planet-warming gases, lessening some of the impacts of climate change such as more extreme weather and rising seas.

Depending on how food waste is disposed of, it can cause negative environmental impacts. For instance, composting and landfilling are the most common methods of managing food waste, however, because of the growing population, future food waste management will be constrained by the scarcity of land and negative environmental impacts.

Landfills will be getting full, hence needing more land for food waste disposal while compositing has its own shortcomings since not all food waste can be composted. Compositing may cause health and safety concerns, especially if the basic rules of composting are not followed.

On the other hand, anaerobic digestion (biogas) is a technology that can help to reduce food waste while producing, heat, electricity, and bio-fertilizer.

As such, biogas has various useful uses or applications, for instance, it can be combusted directly in boilers to generate heat or combusted in internal or external combustion engines to produce electricity or used in combined heat and power (CHP) plants to produce heat and electricity.

Biogas can also be upgraded into bio-methane to be used as vehicle fuel in gas-powered vehicles. Biogas generator can also be used in the production of renewable energy to generate baseload energy for sustained energy use.

Anaerobic Digestion (AD) & food processing companies

The anaerobic digestion of food waste is a great method that can be used to treat waste whilst also producing energy in an efficient way and with very minimal environmental pollution.

Through a biological process, the organic carbon in food waste is converted to carbon dioxide and methane without the presence of oxygen.

The product which is biogas can be used as energy and is a mixture consisting of mainly carbon dioxide and methane with small amounts of other gases.

Feedstocks suitable for AD include a wide range of organic matter such as domestic and commercial food waste, municipal and industrial sewage, agricultural material and livestock manures that can be digested through AD. For example food waste in urban areas may include:

  1. Lipid wastes (fats, oils & greases)

  2. Simple carbohydrate wastes (bakery waste, brewery waste, & sugar-based solutions)

  3. Complex carbohydrate wastes (fruit & vegetable waste and organic fraction of municipal solid waste (MSW)

  4. Protein waste from dairy processing facilities

  5. Other waste from commercial and industrial facilities.

In the USA, AD is commonly used to treat wastewater and manure treatment, however, this technology is commercial and has been deployed in the US for over 30 years. Also, the benefits of AD are tremendous, including renewable energy generation, greenhouse gas emission reductions, reduced water pollution, and a potential revenue stream created from waste.

Kroger Case Study: Kroger Processes Food Waste for Energy

A few food-processing companies in America have benefited from AD technology to convert their food waste to energy.  The Kroger Co., Los Angeles, applied its first anaerobic conversion system in 2013 to process more than 55,000 tons of organic food waste into renewable energy annually and provide power for the over 650,000 square food distribution center. This system helps to divert food waste –about 150 tons per day from the landfill. This is about 500,000 miles of truck landfill trips reduced each year.

A second AD technology plant was implemented at Kroger’s K.B. Specialty Foods plant, in Greensburg, Ind., which has been a Zero Waste facility since 2014, diverting more than 90 percent of waste produced from landfills every year. This 2nd AD biogas generator is estimated at $9.5 million.

According to Kroger, the implementation of these biogas generators is in line with their corporate goal of attaining zero-waste manufacturing goals.

Financing of AD biogas technology.

The main barriers to entry of AD in the market have been the high capital costs and low biogas prices. However, despite these barriers, biogas has several potential utilization application options such as heat production, power production, or combined heat and power (CHP) as captured above.

Because of the high capital cost of AD biogas generators in the agro-industrial sector, nowadays some biogas technology providers have developed innovative financing solutions such as third-party financing to help farmers, food companies, landowners, etc find ways of minimizing food waste while promoting environmental sustainability.

In such financing models, for instance, farmers may not have to invest in the development of the AD plant but could benefit from the benefits of the AD biogas generator. The technology provider pays for everything, they do all the work such as feasibility studies and construction of the biogas generator, etc while the farmer may enjoy long-term attractive feedstock contracts, long-term site rental payments or they can benefit from digestate (bio-fertilizer) offered to them for free – an opportunity to significant artificial fertilizer savings.

Other financing options for AD biogas technology would include loans and cash options that an end-user that has a good feasibility study can benefit from project financing from biogas technology providers or even local financing institutions.

If you are interested in knowing more about agro-industrial biogas generator, going solar or energy efficiency, please contact us at

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