Impact Bioenergy awarded patent for seasonal digester

Design includes below-ground wall system.

May 2, 2014
REW Staff

Seattle-based Impact Bioenergy has been awarded a patent for what the company describes as “a low-cost below-grade digester that operates on a one-year cycle for facilities like resorts, parks, islands, and farms with a seasonal waste pattern.” This technology enables seasonal facilities a way to generate energy from food scraps and organic waste. The alternative digester is quick to construct and contains both anaerobic biomethane production and aerobic feedstock finishing to convert food, paper, landscape material, and food production residuals into energy, heat, and compost, the company says. The system operates with a six-month loading and digestion cycle, followed by a four-month composting and unloading cycle.

The system is designed to generate 2.35 million British thermal units (Mmbtu) of energy and 8 cubic feet of finished compost per ton of waste input. If electricity is generated, this is equivalent to 227 kilowatt hours (kWh) per ton of waste input. The footprint of the totally enclosed, weatherproof system takes six square feet of ground space per ton of waste input. A standard system is designed for 2,600 tons of waste over six months (ideal for 20,000 – 40,000 people), generating 6.1 Mmbtu of biomethane and 22,000 cubic feet of finished compost. If electricity is produced this is equivalent to 590,000 kWh of power. The system is scalable down to 500 tons per cycle per module.

The unique aspects of the design include a rapidly-installed wall system that is below ground. This allows the proprietary floor, roof, and mechanical systems to operate with complete capture of methane and odor.

Impact Bioenergy has offices in British Columbia, Washington, and Oregon. It sells localized bioenergy technology, representing a paradigm shift in both waste management and renewable energy production. Impact says its systems eliminate the costs and environmental impacts associated with the disposal and hauling of organic wastes by converting them into heat, electricity, vehicle fuel, and soil amendments on-site at their point of generation. Impact’s bioenergy units are manufactured in the and are prefabricated for construction in under six months.

In addition to bioenergy products, Impact offers waste diversion and energy consulting services. Impact CEO Jan Allen states, “Impact’s technologies provide valuable tools for the environment that can eliminate waste hauling and fossil fuel energy dependency. We empower our customers to simultaneously do good for the planet and their bottom line.”