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Always conduct a
borehole survey
Efficient aquifer thermal energy storage
requires a permeable sand layer so that the
groundwater can be pumped up without
difficulty. Less permeable layers can
have an enormous negative impact on
the efficiency of the system. Many ATES
designs are based on regional maps of the
subsurface. That represents a risk because
soil structures can vary depending on
the particular locality. A straightforward
borehole survey can provide clear
information about the local conditions
and maximise the effectiveness of an
ATES system. Borehole surveys measure
the electrical resistance of the soil over
depth. Electrical resistance in permeable
sand layers is much higher than in peat
and clay. The layer where permeability is
highest can be located without difficulty by
making a small investment, guaranteeing
the optimal efficiency of your ATES.
Make your ATES smart
Most ATES systems are quite stupid: the
temperature in the building determines
whether heat or cold from the subsurface
is needed. A smarter approach is possible.
Particularly on days when heating is
needed in the morning and cooling in
the afternoon. In these circumstances, it
costs less energy to store the heat or cold
above the ground for a while in a well-
insulated buffer tank. Extra temperature
measurements in the cold and warm stores
and in buffer tanks can be used in a smart,
automated control system. A system of
this kind can also retrieve information from
the Internet (such as current energy prices
or weather forecasts) and use it to control
the ATES in the best way. An appealing
extra: present the current saving calculated
by your smart ATES system in euros and
CO2 emissions on a screen at the entrance
to the building.
Store some extra heat or cold
Just imagine a very warm day. The ATES
system is pumping up groundwater with
a temperature of approximately 10oC
to cool your building. The groundwater
passes through the heat exchanger and
heats up to 20oC. The heated water
goes back into the ground and the heat
is stored for the winter. This is a missed
opportunity. Getting some extra heat into
Maximising the
returns from the
ATES system
Aquifer Thermal Energy Storage is a sustainable way of heating buildings
in the winter and cooling them in the summer. It also cuts costs
considerably. Heating bills can be reduced by up to 45 per cent and
savings on cooling can be as much as 85 per cent. So it is not surprising
that the number of ATES systems is rising rapidly, in the Netherlands and
in other countries. Even so, shortfalls in expertise mean that many ATES
systems are not performing as well as expected. Five tips for maximising
the returns from Aquifer Thermal Energy Storage
BY JOACHIM ROZEMEIJER