Oct. 1 (Bloomberg) — Extracting energy from “processed
poo” to help power homes in the Birmingham area is what Severn
Trent Plc, Britain’s second-largest publicly traded water
company, is now doing to generate a cost-saving renewable gas.
The utility’s clients near the Minworth treatment plant are
able to cook food with “green gas” produced from their own
sewage after Severn Trent started injecting the bio-methane into
the gas grid last week. The gas becomes as clean, “exactly the
same,” after treatment as normal gas, the first time in the
U.K. a water company has delivered bio-methane to the grid.
Companies previously used it only on-site.
“Local domestic customers will be able to tap into the
energy contained within the biogas and bio-methane as it’s
injected into the grid,” Simon Farris, Severn Trent’s renewable
energy development manager, said Sept. 30 by phone.
The 8.4 million-pound ($13.6 million) facility treats
sewage from about 2.5 million people. This produces a sludge
that’s fed into systems that break it down into gas then washed,
compressed and tested for quality and odor to ensure it smells
like normal gas. After that it’s injected into the gas supply
network to power local homes.
“Although it’s a little unsavory, there’s lots and lots of
power locked in poo, and when that’s processed it’s perfect to
generate clean renewable green gas,” Farris said in a
statement.
‘Concrete Cows’
As part of the wastewater-treatment process, sewage sludge
is produced. This is fed to 16 anaerobic digesters at Minworth,
or “concrete cows which work like giant cow’s stomachs to
digest the waste material to produce energy in the form of
gas,” Severn Trent said. “Currently, we use 40 percent of this
energy to make electricity but more can be done.”
Under pressure from the U.K. water regulator Ofwat to keep
customer bills low, Severn Trent turned to “poo power” as part
of a series of measures to boost efficiencies and reduce
expenses. As energy is its second-highest operating cost, Farris
said, this enables the company to save as much as 1.7 million
pounds a year on its gas bill.
Ofwat published draft prices earlier this year that water
and sewage-treatment companies, including Severn Trent and
United Utilities Group Plc, can charge customers for the five-year period starting 2015. The proposals may see average bills
drop about 5 percent even after deducting inflation. Ofwat’s
expected to make a final decision on prices in December.
Severn Trent submitted a business plan to Ofwat that
proposed limiting household bills to 2020 to an equivalent of
1.2 percent below inflation a year, with a price freeze in 2015
and below-inflation rises the remaining four years.
Food Scraps
It’s not just human waste the utility is eyeing to help
deliver price cuts. It’s also turning to food scraps. The
company in June said it’s building a 13 million-pound facility
in central England that will turn food waste into energy and it
plans similar plants across the Severn Trent region.
Whether Severn Trent decides to roll out similar plants at
other treatment plants depends on the result of a government
consultation on subsidies, Farris said. The Department of Energy
and Climate Change is currently reviewing how much it pays
organizations that feed bio-methane into the grid. A date hasn’t
been set for a decision.
Without the subsidy, the technology isn’t yet economically
viable, Farris said. “It needs to have an incentive at this
stage. The hope is that over time the costs of this will come
down as the technology becomes more established.”
Severn Trent isn’t the only water utility experimenting
with poop. Thames Water Utilities Ltd. in 2010 started a 250
million-pound program to turn sludge to power across a number of
sewage-treatment works. And Wessex Water Services Ltd. has
produced biogas it used to power a Volkswagen Beetle car.
To contact the reporter on this story:
Louise Downing in London at
ldowning4@bloomberg.net
To contact the editors responsible for this story:
Reed Landberg at
landberg@bloomberg.net;
Randall Hackley at
rhackley@bloomberg.net
Randall Hackley