Obstacles and Opportunities for the Take-up of Anaerobic Digesters on Small Farms in the US

Wilkerson, B., King’s College London and SuperSustain



Digester technology is scalable and can technically be used on farms of different sizes. Nevertheless, on-farm digesters are primarily being installed on large farms in countries such as the United States (US) despite the fact that there is great potential for digesters to be installed on small farms, and interest among those with different farm sizes. This study unravels the reasons why digesters are not being installed on US small farms and identifies opportunities to overcome these barriers.

Approximately 100 Midwestern US organic farmers have been surveyed and several interviewed. Organic farmers are studied as the organic literature suggests that these farmers would be more receptive to digester technology (compared to small farmers in general) due to their heightened awareness of environmental issues and reliance on a consumer base with environmental proclivities. The findings reveal interest in digester technology among 26% of the growers studied, and disinterest among 45%. The results expose technological, economic, political, and ideological obstacles surrounding the take-up of digesters on small farms. The research helps to identify the actions necessary for greater adoption to occur.

Keywords: Agriculture, Anaerobic Digester, Barriers, Biogas, Diffusion, Innovation Adoption, Organic Farmer, Scale.


Digester technology is supposedly scalable, meaning that it can be used on farms of different sizes (Welsh et al. 2010). As Gloy (2012) notes, “any size farm could technically install an AD [anaerobic digestion] system” (p. 245). Nevertheless, farm-based digesters are primarily being installed on large farms only. Small-scale digester systems are commercially available in the US (Lansing and Moss 2010), but the adoption rate has been low on small farms. This research therefore sets out to examine why there is a low adoption rate of digesters on small farms. For this study, small farms are classified as farms with less than 500 acres or ac (202 hectares or ha). According to the US Environmental Protection Agency or USEPA (2012a), 192 digesters are currently operating on livestock farms in the US. In 2011, on-farm digesters in the US generated 541 million kilowatt hours (kWh) of energy, which is equivalent to the supply of energy for 36,000 households over one year (USEPA 2011a). The rationale behind the adoption of digesters includes: reduction of odours, disposal of waste, creation of an alternative income for farmers (through the sale of electricity, carbon credits, and by-products of the process), plus the reduction of farm energy costs (Leuer et al. 2008). The technology helps reduce pathogens and the possibility of surface and groundwater contamination (USEPA 2004). Digesters cut emissions of methane, a highly potent GHG (greenhouse gas), as the process captures and reuses methane. Digesters also help decrease nitrous oxide emissions, which are over 200 times more potent than carbon dioxide (Paul 2008). This is significant as the agricultural sector is responsible for producing between 6-8 per cent of all GHGs in the US, with methane and nitrous oxide representing the primary gases (Johnson 2009).

Anaerobic digestion is the process by which biodegradable materials are broken down in the absence of oxygen. Digesters are being used on farms, among other places, around the world to convert organic matter (such as manure, crops and crop residues) into an energy resource called biogas. The main component of biogas is methane and it is considered to be ‘renewable energy’ by USEPA (2011b). Biogas can be utilised to generate heat, produce electricity, and even to power vehicles (by converting biogas to compressed natural gas). By-products of this process include fertilizer and manure fibre (used for livestock bedding), which can be sold by growers.

The research question will be explored through an examination of attitudes towards AD technology among organic farmers (mainly with small farms). Organic growers are specifically examined as one might expect them to be more sympathetic to the ‘alternative’ digester technology (USEPA 2012b) than small farmers in general due to their increased concerns about environmental issues (Sullivan et al. 1996; Mccann et al. 1997) and reliance on a customer base with similar environmental interests.

Contrary to what one might expect, organic growers have an even lower digester adoption rate in comparison to conventional producers. Only a handful of digesters have been installed on organic farms in the US (Gaura 2004; Chavez 2007; Wahl 2011; Johnson 2012; Spector 2012). In order to answer the research question, approximately 100 organic growers in nine Midwestern states (Colorado, Illinois, Indiana, Iowa, Michigan, Minnesota, Nebraska, South Dakota and Wisconsin) are surveyed. Several in-depth interviews are conducted with Midwestern organic growers that have installed, or plan to install, digesters on their small farms.

The adoption literature is drawn upon to examine and analyse the low take-up of digesters on small farms. As Rogers (1995) highlights, it is important to examine innovation diffusion when it is actually occurring. This will be done to better understand the current barriers to the adoption of the technology. The adoption/diffusion literature will be used as a theoretical lens to examine the drivers of adoption and rejection of agricultural innovations (particularly large and small innovations) by different farm sizes, and to provide insight into the innovation diffusion pathway.

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