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Did you ever think trash could both produce power and generate revenue for your city? That is exactly what is happening in California. The city of San Jose decided to resolve a common problem by turning it into profit, creating the first large-scale facility of its kind. By recognizing that what is thrown away and causing pollution can actually be utilized to create a greener and brighter environment, Zero Waste Energy Development Co. (ZWEDC) formulated a plan to turn this realization into reality. Spurred by a California mandate to reduce landfill flows by 75 percent, the city of San Jose entered into a 15-year contract with the developer to reach economic development goals and reduce per capita energy use.

With each person averaging 4.5 pounds of trash per day, reducing landfill flows by 75 percent is no small feat. A majority of space taken up at landfills comprises organic waste such as food scraps and yard compost. These materials can take anywhere from five to 15 years to decompose on their own. Through the installation of a dry fermentation anaerobic digestion food-waste facility with technology from Lafayette, Calif.-based Zero Waste Energy, the process will only take 21 days and will allow the waste to contribute back to society through ways that are both environmentally and financially beneficial.

Instead of simply discarding trash, a combined heat and power (CHP) system fueled by biogas is able to produce power and heat at a rate of at least double the efficiency of the utility grid. Results include a reduction or elimination of money spent on electricity and heat, the ability to obtain revenue by selling electricity back to the power grid, and a substantial reduction in harmful emissions because the system is being used for heating and cooling. With all of these benefits, choosing to go with cogeneration technology has so far turned out to be a good decision.
 

Size selection

Determining the size of the cogeneration engine, or even the number of engines, is always based on the available gas volume and quality, and the amount of methane produced from the waste. St. Augustine, Fla.-based 2G Cenergy’s 2G biogas CHP systems are carefully sized based on the biogas production capacity of the digester facility.

These factors dictate the maximum electrical power generation capacity. This differs from natural gas installations where electrical requirements dictate the amount of gas that needs to be purchased. With biogas projects, the main focus is on disposing of the waste and converting organic feedstock into usable energy. The power and heat then generated can be used to reduce utility dependence or, as in the case of San Jose, sold back to the grid. This means the operator is able to reduce monthly energy costs while also creating a stream of revenue.

With San Jose’s yearly organic waste estimated at 270,000 tons, ZWEDC selected two 2G Cenergy’s avus 800 biogas CHP systems. These all-in-one modules are rated at 800 electrical kilowatts per hour (ekW/h) each and have an annual capacity of 13,300 megawatts per hour (MW/h) with a thermal output of 1,682 kilowatts (kW) per hour. Through the power generated by these modules, owner ZWEDC in San Jose is able to power his facilities while also producing enough energy to sell back to the utility power grid.

Incorporated in these modules are fully integrated MWM-brand core engines especially configured for 2G cogeneration technology, sophisticated heat extraction systems, thermal distribution and CHP controls. Gas treatment technology is also fully included. With everything together in one package, selecting 2G’s biogas cogeneration systems simplified the process.

Instead of the conventional design-build or site-build process, 2G customers decide for a 100-percent-modular “all-in-one” and “connection-ready” cogeneration system which can save on costs and reduce technical risk. The cogeneration process results in overall electrical and thermal efficiencies close to 90 percent, compared with most utility power plants operating in the 33 percent efficiency range. 2G’s systems are integrated packages, fully containerized and supplied as unique “all-in-one” and “connection-ready” energy conversion systems. Benefits over conventional gas engine gensets (often erroneously compared with CHP systems) include much higher overall efficiency, reliability, durability, extended life, fast installation and lower maintenance costs.

“The level of new high-tech biogas projects being developed in the U.S. shows that the technology is ready to catch up with other industrialized markets in Europe where biogas already plays an important role,” says Michael Turwitt, president and CEO of 2G Cenergy. “In late 2009 we started to introduce a well-proven biogas CHP technology that was new for the U.S. target audience.”

According to Turwitt, educating potential customers on the advantages continues to be an important factor in gaining more traction in the United States. “We noticed that many more biogas project developers see our technology as game-changing, helping to increase the overall project viability and economic factors,” he adds.

Ludger Holtkamp, COO of German-based parent company, 2G Energy AG says, “In the past there was the perception that biogas CHP systems had to be custom-built, using a basic gas generator set, and that individualistic, often makeshift solutions are the key to economic feasibility. Exactly the contrary was achieved by ending up with low efficiency designs that quickly failed, and resulted in very high maintenance cost.”

Holtkamp adds, “Today many more project developers understand that the key to success is to build biogas plants that are of modular design, consisting of highly reliable components and equipment that has been proven thousands of times in highly successful biogas plant installations.”
 

Deciding factors

2G’s output-optimized cogeneration CHP modules have been installed at more than 4,000 biogas plants around the world.

“This is the first large dry anaerobic biodigester plant in the United States, and the management of Zero Waste Energy, as well as the executives at ZWEDC, searched the market for the most reliable and proven biogas CHP cogeneration technology available,” says Turwitt. “They selected the 2G product, and we are pleased with this decision.”

He continues, “When you invest millions of dollars in a biogas production facility, you don’t want to take chances when it comes to converting valuable biogas into electrical and thermal energy. At the end of the day, every additional percent of increased efficiency makes a huge contribution to the overall project bottom line, resulting in more profitability and a much better economy for the system operator.”

With the innovative way the developers chose to both solve a problem and reap benefits, San Jose is definitely a cutting-edge waste-to-energy project. The results produced will pave the way for other waste management authorities to recognize the numerous benefits available in anaerobic digestion and modular biogas cogeneration.

The article was submitted by 2G Cenergy, St. Augustine, Fla. More information is available at www.2g-cenergy.com.