A change in the mix reduces energy consumption by 50 per cent
The Danish water sector accounts for 2.4 per cent of the
country's total energy consumption and 65 per cent of that is
consumed in wastewater treatment alone. Not surprisingly energy
efficiency has become a top priority for the Danish Water and
Wastewater Association (DANVA). DANVA has committed itself to
reducing the national water sector's energy consumption by 25 per
cent by the end of 2013.
This has inspired the Drøsbro wastewater plant to pursue an
on-going and in-depth investigation into how it can save
"We are always seeking new ways to lower our energy consumption.
Energy is a big expense and as a public institution we are under
constant pressure from local authorities to lower our operating
costs and our impact on the environment", says Kurt Poulsen,
Production Manager at Drøsbro.
Good for the environment - and budget
Recently Kurt headed a project in cooperation with Grundfos that
significantly lowered energy consumption. Wastewater entering the
plant at Drøsbro goes through a series of processes to extract the
clean water. Mixers are used to move the water between the various
tanks, using ten per cent of the plant's total energy consumption
in the process.
Grundfos investigated the energy-saving potential in replacing
the mixers in two of the tanks with Grundfos flowmakers. The
analysis and test demonstrated that replacement would reduce the
tanks' energy consumption by 50 per cent with a payback time of
four years. It also showed that an overall replacement would equate
to a reduction in C02 emissions by around 11,200
Hopes for the future
DANVA is currently evaluating its 25 per cent energy reduction
goal, with results like the ones achieved at Drøsbro furnishing
high hope for the upcoming results.
"The results from Drøsbro prove that our goal of a 25 per cent
energy reduction by 2013 is not only an ambitious but also a
realistic one. As we have seen with other cases it really pays off
to take a close look at the processes as the potential savings are
often bigger than first anticipated,"adds Helle Katrine Andersen,
Head of Water at DANVA.