Army scientists improve garbage-to-energy prototype device
December 5, 2012
- "It's really geared for where there's a concentration of people and there's a need to get rid of garbage and make energy," -- Dr. James Valdes
ABERDEEN PROVING GROUND, Md. (Dec. 5, 2012) -- The year was 2008 and the on-going war in Iraq was a dangerous landscape for Soldiers on the ground, especially convoys traveling to and from base camps.
Roadside bombs and enemy ambushes were frequent occurrences for U.S. Armed Forces transporting fuel, a risk that may be reduced if camps are equipped with a Tactical Garbage to Energy Refinery prototype.
"If you're a forward-operating base, you don't want a local contractor coming in to haul your garbage out because you don't know if they're good guys or bad guys," said Dr. James Valdes, a senior technologist at the U.S. Army Edgewood Chemical Biological Center. "You also don't want to be hauling fuel in because those convoys are targets and risk the lives of Soldiers and contractors."
For 90 days, Camp Victory in Baghdad was home to the first two TGER prototypes, a deployable machine tactically designed to convert military field waste into immediate usable energy for forward operating bases. The biorefinery system is a trailer-mounted hybrid technology that can support a 550-person unit that generates about 2,500 pounds of trash per day, and converts roughly a ton of that garbage--paper, plastic, packaging and food waste---into electricity via a standard 60-kilowatt diesel generator.
"We picked a forward operating base in Iraq because we wanted to really stress the system. All other energy systems had been tested in laboratories or under ideal conditions and temperature climates. What we really wanted to do was stress it with heat, sand and real world trash in a low infrastructure environment," Valdes said. "You know that old Chinese saying, 'Be careful what you wish for, you might get it'? Well, we got it," We learned an awful lot over there about what works, what doesn't work and what'll break."
As ECBC project director for TGER, Valdes is responsible for leading a team that has successfully implemented the necessary re-engineering of the new prototype, TGER 2.0. Among them is an automated interface that uses a touch-screen panel, which makes it easier for workers to input information and monitor every part of the machine, from oxygen levels in the gasifier-to-ethanol production and power output. What used to take three technicians to operate the machine now takes two people: one person to feed the garbage and another person to monitor the progress. But Valdes hopes that as the prototypes advance, TGER could eventually be used by one technician or Soldier.
One of ECBC's most valuable lessons learned while the TGER was deployed in Iraq was the realization that the downdraft gasifier had a tendency to get clogged if there was too much plastic in the fuel pellets. Additionally, a large percentage of the synthetic gas was inert and could not be used as viable fuel. To fix the problem, Valdes' team developed a horizontal gasifier with an auger device that rotates the trash, eliminating the mechanical step of pelletizing the trash.
The TGER 2.0 prototype also enables steam to be injected into the gasifier, which allows a larger conversion of output gas to become energetic. According to Valdes, the old system produced 155 BTUs (British Thermal Unit)/cubic foot of gas, whereas the new TGER 2.0 prototype produces 550, more than tripling the amount of usable energy.
Also, TGER 2.0 is environmentally friendly with its zero-carbon footprint.
"We think of garbage in terms of volume, not weight. There are things that take up a lot of space in landfills but they don't weigh much, like Styrofoam. TGER reduces the volume of waste in 30 to one ratio. If you start off with 30 cubic yards of trash, you end up with one cubic yard of ash, and that ash has been tested by the Environmental Protection Agency. They call it a benign soil additive. You could actually throw it on your roses," Valdes said.
The advanced prototype was shipped back to the manufacturer for modifications after undergoing a final field trial on Sept. 20 here, where the green technology was tested to see how long it could run at the highest levels of garbage input before breaking down. Within two hours of powering on, TGER 2.0 can make synthetic gas that enables a generator to be run on about ¾ power. Within 12 hours, alcohol is produced and blended with the synthetic gas to run on full power at a steady state if the machine is continually fed.
One of the innovations Valdes said he would like to capitalize on is recapturing the excess heat that the machine produces with a heat exchanger that can apply the energy to field sanitation and heating water. The new TGER prototype could also be transitioned into the commercial sector, Valdes said.
"Longer term, we will be talking to project managers about transitioning it but we'll also be talking to some companies that do things like support oil and gas operations in places such as Mongolia and parts of the world that are difficult to have camps in," Valdes said.
Oil and mining operations, camp sites, hospitals, mess halls and even post-natural disaster events like Hurricane Katrina are just a few of the places the green technology could prove beneficial. ECBC and contracting firm SAIC recently entered into a cooperative research and development agreement--an agreement between a government agency and a private company--to speed the commercialization of the technology.
"It's really geared for where there's a concentration of people and there's a need to get rid of garbage and make energy. If an oil exploration company is out in Mongolia, they've got a lot of people there. Those camps can be as big as 10,000 people," he said.
"TGER is geared toward a smaller base camp but industrial operations start off small and build up. They still have to get rid of garbage and they have to somehow get energy in. So what they're looking for is ways to get rid of the trash and generate power. If you think about it, there are far more commercial opportunities for TGER than there are Army applications."
ECBC and defense contractor SAIC are also working with the TGER Technologies, Inc., Defense Life Sciences LLC and Purdue University.