Managing Risks to Reap Rewards
With interest in clean, renewable energy on the rise, the biogas market is poised for a period of strong growth in the coming years. According to a 2012 Pike Research report, global revenue is projected to double from $17.2 billion in 2011 to $33.1 billion by 2022. But as new production comes on line, owners and operators should take into consideration not just the opportunity, but the risks as well.
Biogas is produced by anaerobic digestion, or the decomposition of organic waste in an oxygen-starved environment. It is typically composed of about 50 percent methane and must be upgraded or purified for transportation fuel applications. The process begins in an anaerobic digester, which is a controlled environment where bacteria work to break down the organic waste (also called feedstock), and turn it into biogas and an organic fertilizer byproduct. Biogas recovery systems, meanwhile, help to reduce methane emissions by capturing the methane that otherwise would have been released into the atmosphere and converting it into energy.
Biogas facilities, however, present a number of potential risks for property damage as well as risks to the health and safety of workers and visitors. In 2012, for instance, a digester used to produce biogas at an Oregon dairy farm caught fire, resulting in an estimated $250,000 in damage.
By taking steps to properly construct and maintain biogas facilities, owners and operators can not only increase the reliability of the facility, they can also greatly reduce the risk of loss and injury.
A Growing Market
The biogas market may be a small part of the overall bioenergy sector, but it is expected to grow quickly. In its Biogas Opportunities Roadmap released last August, the U.S. government discussed its efforts to increase the use of biogas and reduce methane emissions. As part of its biogas efforts, the government plans to use existing programs as a vehicle to enhance the utilization of biogas systems, leveraging over $10 million in research funding to enhance the economic viability and benefits of biogas systems. The government also will review opportunities to overcome barriers toward achieving a robust biogas industry. In addition, a Biogas Opportunities Roadmap Working Group will collaborate with industry professionals to publish a progress report in August 2015.
More than 191 biogas sites are already operating on farms and about 1,500 more are at wastewater treatment plants, according to the American Biogas Council. With the proper support, more than 11,000 additional biogas systems could be deployed, according to the Roadmap.
Potential Biogas Risks
Unlike other types of renewable energy, such as wind and solar, biogas facilities generate flammable gas and use a controlled environment as part of the production process. These factors increase the potential for property damage resulting from accidents, fires and explosions and threaten the health and safety of workers and visitors. For example, digester equipment and surrounding property could be damaged if the controlled environment explodes. Similarly, workers or independent contractors may be injured when working in confined spaces or from contact with toxic gasses or oxygen deprivation. Without proper PPE (personal protective equipment) requirements and safe work practices, these same workers could also be exposed to pathogens that could cause illness and latent diseases.
Biogas facilities should be designed and constructed with both safety and production capabilities in mind. These facilities should have a robust confined-space entry program, even for small, farm-based biogas facilities. The facilities must also have the proper controls to ensure flammable gases are properly managed
Equipment should be properly maintained and well protected. A predictive and preventative maintenance program should be implemented for all equipment, especially for equipment critical to the plant's operation. Critical, hard-to-replace spare parts should be kept on hand so that any problem can be resolved quickly without significant downtime. The equipment should be frequently inspected and cleaned as necessary.
Even when maintenance best practices are followed, gas leaks that could lead to fires and explosions remain a real possibility. To identify problems quickly, methane detectors should be installed, along with smoke and heat detection systems with callout alarms to provide early warning. Fire suppression systems also should be installed in critical areas of the facility.
To limit the potential for damage, owners and operators should consider segregating critical assets, such as the engines used in biogas systems, so that they are not all located in one room. By segregating assets, it may be possible to limit losses in the event of an engine fire. Equipment also should have an automatic shut-off in case of emergency and should not have an automatic restart feature.
The buildup of too much pressure, or conversely a vacuum condition within the bioreactor, is another concern for owners/operators to consider. Digesters should have a minimum of two pressure release devices to prevent either an explosion or implosion of the tank and these devices should be manufactured and certified according to a recognized national standard. The relief device set points should be within the designed pressure rates of the associated tanks. In addition, digesters should have a flare system to burn off excess gas.
The benefits of biogas systems are clear. A viable biogas industry can help boost the economy and provide a reliable source of renewable energy while reducing greenhouse gas emissions, according to the Roadmap. However, biogas production is not without risk. But those risks can be managed with the proper planning and maintenance.
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