OT: others seem to be moving along and here we sit idle !!
December 14, 2015 Lisa McKenna
COME ON CIRQUE !!!! WTF IS GOING ON ?????
Big plans for biomass
Features - Technology Focus
Tennessee’s PHG Energy will employ its large-scale downdraft gasifier for two municipal projects in the state.
PHG Energy, headquartered in Nashville, Tennessee, is raising the stakes when it comes to gasification. The private company has installed 13 of its patented downdraft gasification units since 2010, and currently the company has two additional municipal waste-to-energy (WTE) projects in the design/build phase.
These latest projects represent a large-frame design of its gasification unit that the company says can more than quadruple the capacity of its standard gasification plants. The company also claims these new plants will be the world’s largest downdraft gasification units.
The municipal projects have occurred in Tennessee, one of the states that is benefitting from a series of federal grants designed to facilitate environmental mitigation. Besides the company’s three municipal projects, the company’s downdraft gasifiers have been used by industrial brick manufacturing companies to offset natural gas usage.
Recent projects
Much of PHG Energy’s (PHGE) project activity has happened in 2015. In late August the WTE technology company reported that it was selected to build a new biomass gasification plant for Sevier County Solid Waste in Pigeon Forge, Tennessee. And in June of 2015, the Tennessee Department of Environment and Conservation (TDEC) approved a $250,000 grant to the city of Lebanon, Tennessee, to construct a WTE facility to reduce landfilling and provide renewable electric power, using PHGE’s biomass gasification technology.
Ground was broken for the plant in November, and it is expected to be completed in mid-2016, at a total cost of $3.75 million.
A portion of the funds for the facilities have been awarded through the Clean Tennessee Energy Grant program, established by a federal court settlement from an enforcement action taken under the federal Clean Air Act. The action requires the Tennessee Valley Authority (TVA) to provide the state with $26.4 million to fund certain environmental mitigation projects over a five-year period.
The centerpiece of the upcoming installations will be PHGE’s downdraft gasifier, which uses gravity, high temperature and air flow to process biomass to produce synthesis gas.
In Lebanon, the feedstocks will comprise wood waste and dewatered sewage sludge, combined with shredded tires. In recent years and through other projects, PHGE found that the synthesis gas from its gasifier can be cost effectively used to produce electricity by feeding a standard heat exchanger (thermal oxidizer) to drive an oil heater which in turn runs a generator employing Organic Rankine Cycle (ORC) technology, creating electricity. Alternatively, the company says the syngas can be used like natural gas to power various types of steam generators in a more direct manner, or the gas can be directly combusted in kiln or other thermal operations.
The company first employed the ORC combination in 2013, when the city of Covington, Tennessee, began operating a new WTE plant using PHGE’s standard-size downdraft gasifier to process 12 tons per day of wood trimmings combined with dewatered sewage sludge. The resulting electricity from the process supplies half of the power needed to run the city’s wastewater treatment plant, while the other half powers the parasitic process, all while eliminating the city’s need to transport and landfill those biomass streams. That project, involving a 125-kilowatt system, is smaller than the Lebanon project.
The Lebanon facility will utilize a similar model in which its gasifier will produce syngas that is combusted in a thermal oxidizer to drive an oil heater, which in turn will drive an ORC electrical generator, providing parasitic power for the process and delivering up to 200 kilowatts of power for the operation of the wastewater treatment facility.
Nancy Cooper, business development analyst with PHG Energy, says the large-frame gasifier was designed to meet market demand.
“We had previously used up to six of our gasifiers in an array to achieve needed syngas production for brick kilns,” says Cooper. “Using a single large unit is more straightforward and economically practical.”
Gasifying biomass for odor control
In Nashville, Tennessee-based PHG Energy’s (PHGE) previously announced municipal projects, the company’s gasifiers are being used, or will be used to generate electricity. But for Sevier Solid Waste Inc. (SSWI), Pigeon Forge, Tennessee, PHGE Energy’s large frame gasifier will be used for a slightly different purpose.
The company announced in August that it had been selected to build the $2.25 million gasification plant for SSWI to process more than 30 tons per day of composted, mulch-like biomass material into thermal energy and produce a high-carbon biochar.
Nancy Cooper of PHGE says the biomass comes from the facility’s existing recovery and treatment process. SSWI operates a garbage composting plant that processes more than 100,000 tons of municipal solid waste (MSW) annually from the cities of Sevierville, Gatlinburg and Pigeon Forge and the Great Smokey Mountains National Park. Sixty percent of the processed MSW is made into compost.
The energy from the gasifier will be used in a thermal oxidizer to offer odor control at the MSW processing facility, allowing SSWI to defer other upgrades.
“This represents a significant savings from our current disposal and operating costs,” says Tom Leonard, director of SSWI.
The remaining biochar, representing 5 percent by weight of the processed biomass, will be sold as high-Btu fuel for a kiln operation in the region, PHGE says.
PHGE says it will provide the gasifier, thermal oxidizer and material handling equipment, and serve as general contractor for the facility, which will showcase the company’s second installation of its large-frame gasifier. ARiES Energy, a Knoxville, Tennessee-based energy consulting firm, recently acquired by PHGE, will serve as project developer.
The project represents PHGE’s 15th gasifier installation and is expected to be completed in mid-2016.
PHGE President Tom Stanzione says, “This is our second municipal project to receive approval this year and demonstrates the growing confidence in our technology. We have a strong research and development commitment to converting MSW to energy and reducing landfill usage, and this is another significant step in that process.”
Cooper further explains that in this case, power density is achieved less by the increase in size, than by the downdraft technology that provides more effective airflows through the biomass.
The company explains that by using gravity and other features, its process doesn’t require outside energy sources.Furthermore, the gasifier has no burning stage, and the thermo-chemical process takes place inside a sealed, “super-insulated” vessel.
“Our patented design employs unique interior shapes that create consistent thermal layers that allow for the molecular level breakdown of the biomass material,” Cooper says. According to the company, there is only one moving part inside the gasifier: the one that slowly shaves the biochar byproduct from the bottom of the process.
“We can convert about 95 percent of what comes into the gasifier to gas, and about 5 percent is left as a product called biochar,” says Cooper. This byproduct can be used as a fuel, like charcoal, and has industrial applications, such as carbon black. It also can be mixed with other nutrients to enhance soil amendments, PHGE says.
Cooper also says with this large-frame gasifier, the city of Lebanon will have the ability to customize the feedstock blends to accommodate shredded tires in addition to wood waste and dewatered sewage sludge from the nearby wastewater treatment facility, to be connected via conveyor.
“Wood waste is a common denominator in all our projects,” Cooper says, “and we also have utilized sludge and tires.” Cooper says while the tires have a very high Btu (British thermal unit) content, much like coal, PGHE’s process at the Lebanon facility calls for a blend of around 10 percent each tires and sludge and 80 percent wood, so there will not be a considerable difference in energy yield from previous projects, Cooper explains.
The tires will come from the county, which previously had to pay to have them hauled out of state to a shredding facility. As for the sludge component, Cooper says, it has been land-applied. In addition, Cooper points out that several local industries will be able to significantly reduce their wood waste to landfill, saving on disposal costs of around $70 per ton, by contracting with the city to accept these wastes. “The city has numerous commitments from both manufacturing and distribution companies,” Cooper adds.
When the plant begins operations, processed tonnages will be at about half of its 64-ton-per-day installed capacity.
“The extra capacity was built into the system to allow for added income as such biomass sources are identified,” Cooper explains. “The plant has a positive economic return at 32 tons, so the city will be seeking new sources of revenue, primarily from local industries who wish to pay smaller tipping fees and become more landfill-free.”
Siting the project at a wastewater treatment plant, as was done in Covington and is being done in Lebanon, enables the customer to use the electricity from the process at the facility or “behind the fence,” says Cooper, without involving grid or power distributors. She points out that it’s also beneficial not to have to transport the sludge biomass to an off-site facility.
A long-term solution
Cooper says the idea for the Lebanon project originated as the city sought long-term solutions to deal with these streams, and saw PHGE’s gasification technology as a “stage-one” plan.
“The city does not currently have a recycling program, so this is a big step into renewable energy,” she says.
The city has cited two primary reasons for selecting PHGE. One is the company’s track record of successful installations. In addition, the city has referred to the reputation and strength of PHGE’s owner, a Nashville family that also has owned and managed a regional Caterpillar dealership for 71 years.
One notable difference from the Covington facility, however, is that the Lebanon plant will not have feedstock processing equipment on-site. According to Cooper, a third-party company will be contracted to pick up and process the feedstock. Only processed materials will be delivered to the facility.
Cooper says the biomass and tires will be chipped into 2-inch pieces and screened so they are free of metals, glass and dirt.
Future project plans
Moving forward, Cooper says PHGE has many long-term visions for its gasification systems, one of which is to increasingly replace landfills with WTE technology. “There are many varieties of biomass we can now gasify, producing syngas and valuable biochar, thus trimming away at what is being dumped,” she says.
The next step, PHGE says, is to utilize the final product of existing material recovery facilities (MRFs) to produce energy. On that front, Cooper says the company has been successful in trials to convert refuse-derived fuel (RDF) pellets to energy.
“There are several projects in the development pipeline that will allow us to commercially deploy these systems,” she says.
