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Securing Your Energy Future

Producing Renewable Energy through CHP and Anaerobic Digestion

Did you know that for every 100 units of energy used to create electricity at a power plant, only 30 to 35 percent actually reaches the buyer? The rest is lost in transmission and distribution. As an industrial manufacturer trying to maintain cost-conscious operations, these losses present a real challenge when considering the global rise in electricity costs and decline in conventional fuel supplies.

Having reliable energy can mean the difference between getting your product to market and having to shut down your facility’s production line. As a facility owner and operator, you should consider onsite energy management or distributed generation—through combined heat and power (CHP) or anaerobic digestion—to manage energy purchasing costs, avoid costly disruptions and increase efficiency and sustainability.

Combined Heat and Power

Tom Drake Viewpoint: Securing Your Energy FutureZoom in on the benefits provided by these two onsite energy options.

CHP for distributed generation using natural gas power systems provides an option for owners interested in offsetting utility costs by generating electricity and beneficial heat onsite. These “behind the meter” units are efficient, transferring between 80 and 90 percent of the energy they consume into useful electricity and thermal energy that can be used on site—a significant improvement over power purchased through utility transmission and distribution lines. Instead of releasing the heat they create into the atmosphere, CHP systems recover it as hot water or steam for use in the facility. In applications where chilled water is required, these thermal BTUs (or British thermal units) can be fed into chillers to support refrigeration or air conditioning needs. Properly designed CHP systems can support a facility’s existing emergency generator, ensuring continuous operation during outages. This added power security makes CHP attractive for many types of facilities. In addition, the cost-per-kilowatt generated with CHP is much more reasonable for smaller- and medium-sized manufacturers to implement than solar or wind renewables, allowing them to meet sustainability goals without breaking the bank.

If contemplating a CHP project, first consider your daily energy needs—electricity and thermal. How many hot and cold BTUs do your processes require? Second, how much money do you spend on energy today and do you expect that total to rise significantly? Third, are you willing to take a long view on energy management for your entire facility? While payback for a cogeneration project may take between 4.5 and 8 years, the energy efficiency, security and sustainability benefits cannot be understated.

Anaerobic Digestion

For owners and operators whose process waste streams are high in organic material, anaerobic digestion can produce clean power in place of traditional fossil fuels. Anaerobic digestion is a biological process that uses bacteria (in the absence of oxygen) to break down organics in liquid or slurry form. As the organics are broken down, biogas is released. This gas, which consists of approximately 60 percent methane and 40 percent carbon dioxide, can be recovered, treated and used onsite. The digesters also enable better water treatment, producing high-quality effluent that is low in odor and rich in nutrients. Anaerobic digesters have been around for a while, particularly in the food and beverage market; however, until recently, their financial potential has been overlooked.

Like with CHP, the energy produced by anaerobic digestion—the biogas—can be sold to the electric grid or used behind the meter at facilities that use lots of power. There are plenty of beneficial uses for the biogas within the facility as well: heating onsite digesters and buildings; fueling vehicles, boilers or kilns; generating heat or steam; and, offsetting fossil fuel purchases and use. Solids removed from wastewater by anaerobic digestion can also be sold as animal bedding, soil amendments and fertilizer, creating multiple revenue streams for facilities from material they are “throwing away.” Not only would diverting this wasted energy to anaerobic digesters create financial opportunities, but it would also allow energy-intensive facilities to decrease their greenhouse gas emissions, accomplish sustainability objectives and improve their market position by touting their commitment to green production to consumers.

Thinking that anaerobic digestion may be appropriate for your facility? Ask yourself the following questions. First, how much waste do you produce daily and how much does it cost to dispose that material via landfill or other means? Second, do you have to treat your wastewater prior to discharging it? Third, do you have continuous energy needs—electric and thermal? A properly designed anaerobic digestion system can be a valuable tool to facility managers planning for long-term certainty on waste handling and energy costs.

As the cost of energy rises and business are driven to streamline production costs, onsite power generation—whether through CHP or anaerobic digestion—offers owners and operators a path to improve energy use and management, reduce utility costs and create new revenue streams.

Tom DrakeTom Drake is a gas-to-power client service leader with the Louis Perry Group, a CDM Smith Company. Tom has 17 years of experience in the power generation and manufacturing industries. He has worked with municipal, industrial and agribusiness customers to deliver CHP systems running on biogas and natural gas in both the United States and Mexico.