A recent survey of Wisconsin’s biogas industry — which includes 172 anaerobic digesters —highlights challenges and solutions needed to advance biogas facility development.
Wisconsin boasts one of the highest number of anaerobic digester (AD) systems in the United States, with 172 digesters covering a variety of sectors, sizes, operational approaches, and system applications. A recent survey conducted by the Wisconsin State Energy Office (SEO) provides a comprehensive assessment of the Wisconsin biogas industry. Altogether, these facilities produce millions of Btus in heat energy, generate 140 MW of electrical capacity and offset thousands of gallons of diesel fuel per year.
But the survey went further than simply identifying the current output of Wisconsin’s biogas systems, striving to answer critical questions about the development of the state’s anaerobic digester industry, such as what are the primary operational challenges, what are the key financial barriers to project development, and where are the opportunities for greater progress.
Biogas Industry Challenges
The survey responses outlined four primary challenges to system operation and development of the biogas industry as a whole:
- Cost-effective and safe operation of electricity generators, which is particularly important as power generation has been relied upon for a primary source of project revenue.
- Intersector collaboration and information sharing has been lacking, leading to conflicts over organic waste resources and appropriate project siting.
- Generating revenue for a biogas project has recently become more challenging, which has led many in the industry to assess possibilities to generate revenue outside of power generation, such as renewable natural gas and compressed natural gas (CNG).
- Establishing effective system operation and maintenance procedures, which are particularly challenging for agricultural systems.
Still other challenges exist, such as environmental regulatory compliance, establishing fair tipping fees, and unavailable capital for project financing. However, these are intimately connected to the four primary challenges outlined above and may be addressed in concert.
The failure of AD system design to protect electrical generation equipment quickly rose to the top of the list, with survey participants pointing to ineffective or absent biogas cleaning mechanisms to extract impurities that can harm the generator equipment. This presents tough questions about how system developers and builders design these often very complex projects, but also allows for establishment of novel alliances in system design going forward.
Intersector Collaboration And Information Sharing
Those surveyed further identified lacking collaboration between the four main biogas industry sectors (farms, wastewater treatment plants, landfills, and industrial facilities) which, they asserted, inhibits information sharing that could allow the industry to, for example, better utilize available feedstock and collaborate to resolve operation and maintenance concerns. This evoked intriguing discussions about information sharing methods that Wisconsin’s biogas industry can utilize to resolve these difficulties in order to maintain its leadership status in the United States.
The ability of AD systems to generate revenue was a close third in the industry challenges expressed in the survey. In the past, electrical power generation was a very popular way for AD projects to generate revenue in Wisconsin. This strategy relied heavily on the state’s renewable portfolio standard, which required all Wisconsin electric providers to provide their retail electricity customers with 10 percent of electricity generated from renewable resources by 2015. This resulted in favorable power purchase agreements (PPAs) for biogas facilities. Since the major investor-owned utilities (IOUs) in the state met this standard in 2013, utilities have not been offering increased tariffs for renewable generation for quite some time.
System Operation And Maintenance
Not only does AD system operation and maintenance require revenue, it also requires specialty training and knowledge. As such, system operation and maintenance has proven to be a large challenge in and of itself. Operators are often consumed by other tasks either on the farm or at the factory and are unable to dedicate the required time and resources to properly maintain and operate the equipment. In some cases, as noted, systems lack the necessary biogas cleaning components to enable safe operation of the generators, leading to heavy maintenance requirements and sometimes a dramatic reduction in the operational life of the equipment.
Solutions And Opportunities
Put together, these challenges present opportunities that could streamline the industry and diversify how biogas facilities are built and operated. While each potential solution could go a long way to improve certain aspects of an AD system, the challenges they address are complex and require equally complex strategies to overcome them.
Several potential solutions to generator concerns were forthcoming from survey respondents, including a requirement to allocate equal capital expense for biogas scrubbing as for electricity generation and contracting with an outside operator to conduct operation and regular maintenance of the generator equipment. The discussion about biogas scrubbing equipment also highlighted the importance of incorporating one or more techniques that were effective in removing specific contaminants and polishing the biogas to ensure safe combustion in a generator.
Several farm operations also detailed the advantages of outside contracting for operation and maintenance of the AD system (in addition to the generator). Dedicated, highly-trained operators could service the system while the farmer or the plant manager attends to his or her daily responsibilities and could justify a more aggressive maintenance schedule for key system components, including generators. These dedicated contractors could also be shared between several facilities thus reducing costs for individual system owners.
Read the full article in BioCycle Magazine