Nexterra hedges its bets on fledgling syngas
Renewable biomass may be the least familiar renewable energy source, but at least one company is confident gasification of bio-scrap is set to take-off, despite its relative newness.
Nexterra, a Vancouver-based developer of biomass gasification energy systems, is set to open a $27 million combined heat and power co-generation plant at the University of British Columbia (UBC). The university will use one of Nexterra’s bio-gasification and synthetic gas (syngas) conditioning systems to power a General Electric (GE) Jenbacher engine, which generates up to two megawatts of electricity and heat using locally sourced “wood residuals.”
The project is being funded with more than $20 million in federal and provincial incentives from the likes of Natural Resources Canada, the BC Bioenergy Network, the Innovative Clean Energy Fund and Sustainable Development Technology Canada.
Another $350,000 comes from FPInnovations, which is partnering with paper-producer Domtar on a $36 million demonstration plant in Quebec to produce a biomass-strengthening agent called nanocrystaline cellulose.
Nexterra’s system is a North American first and the company expects it to reduce the university’s greenhouse gas (GHG) emissions by 4,500 tonnes a year – the equivalent of taking 1,100 cars off the road. It will also reduce the university’s reliance on natural gas by 12%.
“One of the major benefits, compared to conventional biomass applications, is the higher efficiencies it achieves,” says Darcy Quinn, Nexterra’s director of business development. “It uses much less water because it’s not steam-based, which is becoming increasingly important in a number of jurisdictions.”
The closed-loop gas filterization process at UBC uses wood for fuel, and was developed over four years of intense R&D at Nexterra’s home base in Vancouver.
“The heat is actually recaptured and recirculated back into the process,” explains Quinn.
But the syngas must first make a bit of a journey.
To achieve desired capacities, the project needs 12,500 bone-dry tonnes a year of waste wood, tree bark, wood chips and construction debris.
The “wet” wood material goes into a dryer to achieve a moisture content of 25% for the proper melt. Residue is then sent to a storage facility until it’s needed and then conveyed to the gasifier for partial oxidization. Pyrolosis and gasification occur at between 815 to 982 degrees C (1,500 to 1,800 degrees F). The syngas is then sent through a conditioning system where thermal cracking removes tars as it breaks the gas molecules down into shorter chains, before they go through another set of filters. Next stop is the Jenbacher internal combustion engine that powers the generator and keeps the university’s lights on.
“Thermal-cracking is crucial to this project,” says Quinn. “Without it, tars within the gas molecules would essentially turn into glue and ruin the engine, which would shut things down pretty quickly.”
Handling the heat
The system also includes a thermal application, which produces up to 9,600 lb. of steam per hour to power the school’s HVAC system. Syngas is fed into an oxidizer, where it combusts. The resulting flue gas is diverted through an electrostatic precipitator filtration system that cleans out almost all particulate matter. The syngas then proceeds to a boiler that produces steam – enough to power 25% of the university’s heat.
UBC is looking at a potentially massive payoff by having the facility on site because it gives the school the ability to micro-manage its power consumption, says Brent Sauder, director strategic partnerships.