It’s a sustainable manure management process with major implications
for intensive livestock operations across the continent.
What’s believed to be the first biogas-power generating project of its
kind in North America, is expected to be turning dry Alberta feedlot
manure into electricity and a value-added soil amendment by late summer
2004.
The project known as IMUS – integrated manure utilization system - is
under construction this spring at Highland Feeders near Vegreville,
Alberta. The pilot plant will extract methane from raw manure to fuel
electrical generation that will produce one megawatt (one million watts)
of electricity.
The dry solid by-products of the process make an environmentally friendly
fertilizer, while the liquid component will be recycled as
irrigation-quality water.
The technology, which has been licensed to Highmark Renewables, a
wholly-owned subsidiary of Highland Feeders Limited, was developed by the
Alberta Research Council in a $7.9 million project funded by federal and
provincial governments, and industry investors. It has also been
established as a demonstration project under the federal Greenhouse Gas
Mitigation Program (GHGMP).
“The idea is to demonstrate the technology in this feedlot scale pilot
project and eventually market the technology nationally and
internationally,” says Mike Kotelko, president of Highmark Renewables.
First solid system
The concept is aimed at solving or reducing a number of the environmental
challenges associated with handling large volumes of feedlot manure. At
the same time, products produced through the process will provide
value-added revenue to not only cover the capital cost of the IMUS system,
but provide a revenue stream for the operators.
Similar biogas recovery and power generation systems have been developed
for liquid manure, but this is the first developed for solid manure
systems.
Raw feedlot manure is a valuable nutrient source, but it presents a range
of social and environmental challenges for feedlot operators. It produces
odour, improperly handled it releases greenhouse gases, proper application
is important to maintain ground and surface water quality, and manure is
expensive to haul.
The range of benefits from IMUS include:
- Reduced manure handling costs
- Protection of water resources
- Odour reduction
- Recycling of waste water
- Reduced energy costs
- Value-added revenue from the sale of energy and bio-based fertilizer
- Strengthening agriculture’s reputation of environmentally
sustainable resource management
The pilot project involves construction of a $6 million IMUS processing
plant on the edge of the Highland Feeders feedlot. Main components include
two 1,500 cubic metre capacity concrete tanks, which serve as anaerobic
digesters. The tanks are 15 metres in diameter and stand 11.2 metres high.
The tanks are capped with a heavy rubberized material.
Raw manure is placed in a hopper and fed into the digester tanks. Water is
added to create a manure slurry. “It is a continuous feed system,” says
Dr. Xiaomei Li, with the Alberta Research Council, the lead research
scientist on the IMUS project. “Fresh manure can be added on a daily basis
or as it is collected.” It takes about 14 days for manure to work its way
through the complete system.
Methane and carbon dioxide produced in the digester will be drawn off and
fed into a co-gen plant. The methane will be used to power a reciprocal
engine, which will generate electricity for their own needs, with surplus
power sold to the Alberta power grid. Any surplus gases will be eliminated
through a flare stack.
Once the gas has been removed, the slurry is fed into a solid/liquid
separator with the dry solids producing a nutrient rich fertilizer.
Nutrients will also be recovered from the liquid, leaving
irrigation-quality water that can be reused in the IMUS process.
“The whole process provides several benefits,” says Li. “The manure is
dealt with in an efficient and odourless process, and the technology
provides several value added products.” The pilot project is expected to
be fully operational by August.
Modular design
IMUS is designed as a modular system that can be expanded to meet
increased manure capacity simply by adding more components. Highmark’s
pilot project is geared for a 7,500 head feedlot, while a commercial IMUS
system is being targeted for a minimum 20,000 head-capacity feedlot. At
that scale, it is estimated the system can produce 13,200 metric tonnes of
bio-fertilizer annually with a value of $660,000 and 14,480 megawatts of
electricity worth $1.01 million.
The process will also offset greenhouse gas emissions. It’s estimated IMUS
technology will reduce the amount of carbon dioxide produced in land
application of manure by 36,000 metric tonnes annually. As a national
system is developed to reward producers for carbon reduction - often
referred to as carbon credits - this could be a bonus revenue source worth
an estimated $360,000 annually.
“The system provides a very environmentally safe and sustainable manure
management system,” says Li. “And looking at the big picture it addresses
some of the critical issues associated with our expanding livestock
industry. By reducing manure volumes it could reduce the land base
required for livestock operations, and by eliminating much of the manure
odour, it could reduce the minimum separation requirements between
intensive livestock operations and other land owners.” |
