Detailed layout of 100% producer gas engine based gasifier power plant installed in Orissa

TERI has been working on the development of power gasifiers for more than a decade, though the focus earlier was on dual-fuel diesel engine mode. A down draft throat-less gasifier supplies air and gas mixture to a diesel engine. This replaces upto 75-85% of diesel consumption. The raw producer gas obtained from gasifier is cooled down to ambient temperature to improve volumetric or breathing efficiency of the engine and cleaned to bring down tar and particulate content within the acceptable limit to minimize maintenance requirement.

Since 1998, TERI has started working on the small capacity (upto 20kWe) power generation systems with modified diesel engine capable of working on 100% producer gas for decentralized application in remote villages where even this 30% diesel might not be available. For achieving IC (Internal Combustion) engine operation on 100% producer gas, the diesel engine is modified—as use of SI (spark ignition)/petrol engine result in significant de-rating due to low compression ratios—by changing CI (compression ignition) to SI mode by replacing diesel injector with sparkplug. The specific wood consumption is about 1.0 kg/kWh for dual fuel systems and about 1.5 kg/kWh for 100% producer gas operation.

Under TERI-SDC partnership project, TERI is working on LIBERA (Livelihood Improvement through Biomass Energy in Rural Areas) programme. In its initial action research phase, TERI has been working on developing suitable package for small-decentralized power generation using biomass gasifier for providing access to electricity for achieving ultimate objective.

During 2002/03, TERI initially developed wood charcoal-based system of 10 kWe capacity through extensive laboratory trials at TERI’s Gual Pahari campus for its performance and long duration reliable trouble free operation. The effort had been on developing appropriate technological option suitable for remote location application. Hence, the focus was on simplicity in system operation and maintenance, using locally available consumable material. Simple pedal operated blower was used as a starting option to avoid the use of any conventional energy source, even for the first time.

Wood charcoal option was chosen for first time field operation to minimize maintenance requirement in the field. This was done to quicken the process of taking the system to the field for learnings on DDG (Decentralized Distribution Generation) and minimizing the risk of technology failure so as to gain confidence in the technology. Simple robust governing system was also evolved to take care of fluctuating loads, under field conditions, without needing to constantly adjust air-gas mixture valves to maintain engine rpm to maintain frequency.

Simple charcoal making system using updraft gasifier was also developed and demonstrated to obtain charcoal under field conditions.

Gasifier design has been improved—by supplying preheated air obtained using hot raw gas coming out of gasifier to gasifier at different locations—to minimize the tar content in raw gas, which in turn substantially reduces the load on the gas cleaning-cooling system.

Presently, work is underway for fine-tuning the producer gas cleaning-cooling system for wood gasifier system. This will be used for decentralized power generation for capacity up to 20 kWe and help in it's future large-scale promotion.