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ortable gas and diesel generators help power many aspects of the global economy. Construction companies and the remote communities depend on gensets to provide heat and power in areas where connecting to the grid is not possible. They are also used to power outdoor events, concerts, military operations or provide a critical source of power in disaster areas. In the developing world, generators also help to overcome issues associated with unreliable, outdated and non-existent electricity grids. The vast majority of commerciallyavailable generators are designed to run on fossil fuels. However, a new equipment package could change that by allowing these gensets to be fueled with biomass-based syngas. Funding for the project was provided the the U.S. DOE National Energy Technology Laboratory. An ongoing project led by the University of Minnesota Morris and Californiabased All Power Labs LLC has resulted in a fully integrated solution that combines All Power Lab’s unique gasification system with a genset, a system housed in a single 20-foot shipping container. The result is the PowerTainer, a portable system that allows a diesel generator to run on more than 90 percent biomass syngas. Additional organizations participating in the project include Cummins Power
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Generation and the University of Minnesota Center for Diesel Research, and HGA Architects and Engineers. According to Jim Barbour, a staff scientist at UMM, Cummings provided the genset to the PowerTainer project, offered engineering consultation services, and participated with the integration of the genset with the gasification system. The Center for Diesel Research helped optimize the operation of the diesel engine on syngas.
Syngas Genset Technology The heart of the PowerTainer is a multi-staged biomass gasification system developed by All Power Labs. According to Jim Mason, company founder and director, the innovative system is a modified version of a fixed-bed, down-draft reactor. “We have separated the drying from the pyrolysis, and drive those off of waste heat from the engine,” he says. The multistate heat exchange system, Mason continues, functions to return all the waste heat flows from the gasifier and the engine to the appropriate process points within the reactor. “This is how we create temperature conditions that take care of the tar in the reactor,” he says. The tar treatment method is one element that makes the gasification system unique. Rather than dealing with tar removal downstream, an aspect of operation that
can complicate the system and also requires bulky equipment, the technology deals with tar in the gasification system itself. “We do that by the separation of different process stages within the reactor,” Mason says. The gasification system is overlaid with a highly effective automation system that works with maps of the reactor that specify where tar is and is not generated. The automation system can operate the reactor with a high degree of sophistication to control, within certain parameters, where gasification occurs. The automation system, combined with the heat-exchanger that pushes a large quantity of heat back into the system, allows for tar production to be minimized. The gaseous fuel that results is produced through an on-demand basis for the genset. The gasifier responds to the load variations of the engine, Mason says. The syngas produced by the gasifier is not very energy dense, which makes storing it inefficient. The syngas can fuel both spark-ignited engines and diesel engines. When the syngas is fed into a spark-ignited engine, it can replace 100 percent of the fossil fuel that would normally enter that system. When the syngas is fed into a diesel generator, such as the one contained within the PowerTainer, the producer gas must be mixed with a small injection of diesel fuel. Current