by Jim Moodie
EVANSVILLE—Lake Wolsey aquaculture operator Mike Meeker has already greened and diversified his industry by converting fish offal into a highly coveted form of compost, but he now wants to go a step farther and use that same waste product to create energy.
“I’ve been working with Brian Bell of the Ministry of Agriculture (Food and Rural Affairs) and Guelph University to see if I can take the fish waste, run it through an anaerobic digester, and use the methane gas to produce power,” said Mr. Meeker. “My goal is to make my farm a net-zero energy producer, but if I can produce more biogas than I use here, there would be green energy going back into the grid.”
Should Mr. Meeker proceed with his plan, he would become the first fish farmer in Canada to convert trout scraps into biogas. “It’s fairly common for dairy and chicken farms, but nobody is doing it with fish stuff right now,” he said.
That means there are very few models to go by. Mr. Meeker believes there are a couple of fish-farming operations in Europe pursuing a biogas sideline, and possibly one or two in the states, but for the most part he’s on his own in trying to figure out a workable system.
Not that this is really anything new. When he first developed his fish-based compost, nobody was really doing that either.
“Here we go again,” he chuckled. “There’s a lot of homework to do to make sure it’s viable, but everyone I talk to believes it will work.”
Before he springs on the pricey equipment to extract and store methane, however, Mr. Meeker wants to make sure there will be a big enough output of energy to justify the investment, as well as confirm that harnessing gas from the waste won’t affect its use as compost.
“I don’t think it will slow down the compost process at all,” he said. “It certainly won’t change the product, because we’re using the exact same material. So it will still be all-natural and non-toxic.”
The trick is to figure out the appropriate mix of offal and sawdust to put into the digester. “We’re already doing a study on this through a satellite campus of the University of Guelph,” said Mr. Meeker. “They’re taking the fish stuff, mixing it with sawdust, and testing it with systems to see what proportion works best.”
The next stage of the study will involve “running it through a bigger system, called a reactor, so we can get an actual estimate for gas production,” said Mr. Meeker.
As well, he wants to confirm that the chemical micronutrients in the compost won’t be altered after the waste is put through this gas-harvesting stage. “I don’t think there will be any difference, because it’s carbon that produces methane, and the (Guelph) professor told me there won’t be any change to the key components of the compost,” he said. “At the most, it might reduce the volume of the end material a little bit.”
A bio-digester essentially consists of a “sealed field container,” said Mr. Meeker. “It can be a concrete tank, with an inflatable membrane that expands as the gas is produced.” The gas collects as the organic material inside, deprived of oxygen, breaks down.
The air-like fluid is then filtered (to remove hydrogen sulfide, for instance) and pumped to a motor that has been modified to run on methane, which in turn generates electricity.
“There is a safety aspect when you’re dealing with methane, because it is combustible, but it won’t just blow up because of a leak,” said Mr. Meeker. “You want to keep open flames away from it and you’re not going to have guys smoking around the tank.”
He expects there won’t be much of a hazard, as his plan “is not to store very much anyway,” he said. “If I figure the system out right and have the right size of generator for what I produce, I would basically be burning it as I produce it.”
The fish farmer recently attended a two-day conference in southwestern Ontario that drew together dozens of experts in the field of biogas as well as representatives of all the major companies that produce equipment for the harvest of this resource.
While Mr. Meeker found the experience a bit overwhelming—”it was hard to take in every session, because there was so much going on”—he did manage to connect with an Alberta-based firm called Highmark Renewables that he expects will be the company he engages for his own project.
“I wanted a system designed by a Canadian company, and I found one, so hopefully I’ll be working with them,” he said, adding that he plans to make a trip out to Alberta in the next while “to see some of the systems they’ve set up out there.” Some of these “have been on line for six or seven years,” he noted, so it will be useful to tour those sites and assess how a similar setup might work at his Lake Wolsey property.
He additionally hopes to visit “a few in the Guelph area that are about the size I want to be,” he said. And the professor who is conducting tests on his behalf wants him to tour a couple of biogas operations outside of Ottawa.
None of these, he noted, are “using fish,” but it will be instructive nonetheless to see a few farm-based gas plants in operation.
While methane power would be a first for both Mr. Meeker and the aquaculture sector in general, it wouldn’t be the fish farmer’s first experience with alternative energy. While living in a remote area of BC, he and his wife powered their off-the-grid home with a wind turbine they erected themselves.
“I’ve always been interested in being energy self-sufficient, and I like the idea of reusing waste,” he said. “What’s really exciting about this to me is that you can reuse the waste in three ways instead of just one.”
Apart from turning the fish offal into eco-friendly compost, and eventually into methane gas, Mr. Meeker is also finding uses for the effluent that is produced as the waste gets processed.
“When you mix fish and sawdust, the moisture level is too high for the compost to cook properly, so you basically end up with a liquid waste,” he explained. “But this stuff is high in dissolved nitrogen and it’s in huge demand by gardeners and golf courses.”
The effluent can also be used to grow a type of red algae, said Mr. Meeker, which would be an extra bonus, as this plant could be incorporated in fish food to help produce the pink tint that wild stocks get from dining on crustaceans like shrimp.
At present, many fish farmers “add a pigment to the feed that makes the flesh of the fish redder,” he explained. This is purely for aesthetic reasons, as there’s no nutritional benefit to the colouring, but studies have shown that “70 percent of consumers still want the red, even though it’s unnecessary,” said Mr. Meeker.
For fish farmers, that bit of pink pigment is quite costly, “because it adds 15 percent to the cost of production,” he noted. And there’s also a bit of controversy over this additive, as aquaculture critics like David Suzuki “have convinced some people that it’s a harmful, chemical dye, even though it isn’t,” said Mr. Meeker.
Culturing a red-tinged aquatic plant from the effluent accomplishes two things at once, in his view: not only does it provide an extra use for this waste product, but it offers “a cheaper and more natural” way to provide that pink hue that consumers covet in the fillets they see on fish counters.
Mr. Meeker’s interest in biogas follows the same logic. Since he’s already making compost out of fish detritus, why not also capture the methane that is in this material, since it’s there for the taking but currently going to waste?
“The whole (compost) system was set up at first so that we wouldn’t produce methane, hydrogen sulfide or ammonia, because you are just venting it to the atmosphere,” he said. “Now, the idea is to do the exact opposite, and capture those gases instead of venting them.”
While it may be a few months yet before Mr. Meeker has a bio-digester set up on his property and a system for converting the gas into electricity, he’s very keen and virtually committed to going this route.
“The beauty of it to me is that once we figure out the best digester and combination of fish and sawdust, the incoming substrate will be consistent,” he said. “In the city, the stuff comes in from landfills, and it’s all different materials, and it’s the same with restaurants, where you get all these different fats, oils and greases.”
Mr. Meeker is confident that his waste material will be both an effective and reliable source for bio-energy, so now it’s just a matter of figuring out what system to implement and how big he should go in terms of gas production.
“I want to look at the numbers to see what kind of scale we can do,” he said. “Maybe I will set up one digester, which at the very least would make me a net-zero farm for energy. But if it makes the kind of gas that I believe it could, we could duplicate that system, and sell the hydro back to Hydro.”
