The Rural Voice, 2019-01, Page 30from the barn to the digester. It
automatically pumps fresh manure in
on a daily basis. After 20 days, the
manure is discharged into a large
lagoon at Harcolm Farms.
On the day of this interview, the
liquid manure was being pumped out
and spread by a custom manure
spreader. It’s a messy business to be
sure but a relief for Rob to get this
task underway in a wonky
crop/weather year.
Meanwhile, the biodigester keeps
working. A ladder tipped against the
reactor allows us to peek through a
circular glass window to see the
manure bubbling away. Biogas is
formed in the reactor through
anaerobic fermentation which
requires heat and stirring. The heat is
supplied from waste heat from the
engines. It’s run through water pipes
coiled at the bottom of the reactor. A
submersible mixer stirs the manure
for two minutes in a 15 minute cycle.
“Stirring is necessary because the
biological organisms that make the
gas are not motile,” says Rob.
The gas is purified and turned
into energy in the combustion engine.
The resulting energy is used on the
farm in the form of electricity and
heat.
“There is an elegant simplicity to
it. It’s a clean design,” says Rob.
Cost-wise, he estimated
payback in 10 years with the
following 10 years offering
significant energy savings and profit.
Payback comes in two forms:
hydro saved and hydro purchased.
Harcolm Farms executes two
contracts with Hydro One. The first
is a Net Meter contract that provides
a cost-avoidance savings of about 20
cents per kWh or $12,000 annually.
The second was a MicroFIT contract
where the farm ships surplus
electricity back into the grid at a
price of 25.9 cents per kWh or
$20,000 annually, reports the Bloom
Clean Technology Demonstrations
Project Case Study which Rob and
John are involved in.
The outlay, however, was
significant. John Hawkes, who is
marketing the biodigester with the
Martin Energy Group, believes
similar setups could cost in the range
of $350,000. However, being the first
of its kind in Ontario, and requiring
some barn modifications, the
Harcolm Farms biodigester came
close to half a million.
Since it was installed in March,
the digester has had very few
problems. Any issues have been able
to be resolved by phone in
conversation with Belgian
technicians. These were mainly
software issues.
All told, Rob thinks installing a
manure digester on farm is a no-
brainer. While saving on hydro
costs, he makes double-use of the
farm’s manure. He suggests that the
fertilizer value of the manure may
even increase after passing through
the digester since the organisms
already start the digestive process.
However, this is the first spread of
the manure which has passed through
the digester so there has been no
chance to monitor any yield
increases. Neither has Rob been able
to find anything other than anecdotal
evidence supporting this theory.
He has noticed the manure has a
different smell. When the digestate is
hot, “it has a bitter, rather than sweet
smell.” However, in terms of rating it
by “stink”, there is less odour than
raw manure, he believes.
Labour-wise, Rob says the
digester needs monitoring but it isn’t
26 The Rural Voice
Rob McInlay of Harcolm Farms
near Beachville peeks through
the window of the biodigester to
check on progress. Looking
inside, one can see manure
bubbling away as it is heated and
stirred to create methane gas
which is converted into electricity
to power the dairy farm. Rob,
along with his wife Rachel and
her parents, Dwight and Nancy
Hargraves, milk Holstein and
Jersey cows in a new, robotic,
freestall barn built in 2010. The
biodigester was added
in the fall of 2017.