This article explored the use of small scale anaerobic digestors (SSAD) on European farms. This topic was discussed due to the increase issue of climate change, it looked at SSAD as a more renewable energy production, more sustainable waste production solution and as a method of using methane. A SSAD combined heat and power (CHP) can have an electrical output of between >15 – <99kWe. Anaerobic digestion is the natural process which uses microorganisms to biodegrade materials over 4 continuous stages which include hydrolytic, fermentative, acetogenic and methanogenic in the absence of O2.
In return of this process biogas is produced which can be used to substitute natural gas and fossil fuels for a variety of applications. It typically has a composition of 50%-70% CH4, 30%-50% Co2 and other trace elements. For biogas to be injected into the grid it must be changed to biomethane which consist of >97% CH4 and up to standards which can vary depending on the site. There are many different options of SSAD plant designs but they must be chosen for each specific farm. They considerations that need to be looked at are feedstock availability, climate conditions and investment available.
“From 2011 to 2016, the installed electrical capacity of AD plants operating on agricultural substrates in Europe increased from 3408 MW to 6348 MW. Even with this rapid development, the potential biomass resources from the agricultural sector in Europe far exceeds what is currently utilised in AD processes.”
This quote is a little outdated but not much has changed in past years in relation to SSAD. It proves that there is a demand for this technology but there is a lack of knowledge surrounding it. Ireland has a very low uptake of SSAD although it has the ideal set up and landscape due to the many farms and land available. The increasing issue of climate change and the recent announcement of electricity shortage should increase the demand for these processes.
The main barriers and issues associated with SSAD is access to finance as there is little case studies done particularly in Ireland, therefore limited grants and schemes or investment available. Another limitation is the lack of technology and expertise in the area, this is a problem as there can be minor issues when starting a SSAD and quick efficient support would be needed on hand. Policy framework and support studied is the next issue as the studies and instability surrounding SSAD and research and is continuously being revised. The final barrier discussed was perception and public awareness. There is lack of public knowledge surrounding SSAD’s but if there was more research done and if the positives from the process were outlined this may be eliminated.
There is potential for more SSAD plants in Europe if more research and investment was available while also encouraging more grants and schemes to aid in the process.
Notes: Katie Noonan, MSc Agri-food Sustainability & Technology student, K.noonan3@nuigalway.ie
Source: (O’Connor, Ehimen et al. 2021)