Water Use
Supporting Guidance (WAT-SG-62)
Groundwater Abstractions - Geothermal
Energy
Version: v4.0
Released: Aug 2014
Copyright and Legal Information
Copyright© 2014 Scottish Environment Protection Agency (SEPA).
All rights reserved. No part of this document may be reproduced in any form or in any
means, electronic or mechanical, including (but not limited to) photocopying, recording or by
any information storage and retrieval systems, without the express permission in writing of
SEPA.
Disclaimer
Whilst every effort has been made to ensure the accuracy of this document, SEPA cannot
accept and hereby expressly excludes all or any liability and gives no warranty, covenant or
undertaking (whether express or implied) in respect of the fitness for purpose of, or any
error, omission or discrepancy in, this document and reliance on contents hereof is entirely
at the user’s own risk.
Registered Trademarks
All registered trademarks used in this document are used for reference purpose only.
Other brand and product names maybe registered trademarks or trademarks of their
respective holders.
Update Summary
Version
v1.0
Description
First issue for Water Use reference using approved content from
the following documents:
WAT RM XX Abstraction Geothermal Energy following WPRSG
100210
v2.0
Reviewed and updated to reflect CAR 2011.
v3.0
Updated to specify that boreholes >200m depth escalated (from
GBR) to complex licence from 1 April 2013.
v4.0
Replace outdated 2009 standards with Standards Directions 2014
Notes
References: Linked references to other documents have been disabled in this web version
of the document. See the References section for details of all referenced documents.
Printing the Document: This document is uncontrolled if printed and is only intended to be
viewed online.
If you do need to print the document, the best results are achieved using Booklet printing or
else double-sided, Duplex (2-on-1) A4 printing (both four pages per A4 sheet).
Always refer to the online document for accurate and up-to-date information.
2 of 14
Uncontrolled if printed
v4.0 Aug 2014
Table of Contents
1. Introduction..........................................................................................................4
2. Types of Geothermal Systems ............................................................................5
2.1
Introduction ...............................................................................................5
2.2
Closed Loop Geothermal Systems ...........................................................5
2.3
Open Loop Groundwater Systems............................................................6
3. Regulatory Control ..............................................................................................7
3.1
Introduction ...............................................................................................7
3.2
Closed Loop Systems ...............................................................................7
3.3
Open Loop Systems .................................................................................8
3.4
Interpretation of GBR 17 ...........................................................................9
Annex A – Potential Environmental Impacts from Geothermal Systems ...............10
References ............................................................................................................13
v4.0 Aug 2014
Uncontrolled if printed
3 of 14
1. Introduction
Energy from the water environment is increasingly being used for heating or
cooling. This heat can be utilised via open loop systems, where water is
abstracted and discharged back to the either surface water or groundwater,
or closed loop systems where no abstraction or discharge takes place.
This document provides guidance on the regulation of open and closed loop
geothermal systems in relation to impacts on the water environment.
Geothermal energy is broadly defined as energy from the interior of the earth
used for heating or cooling.
Thermal energy from other water sources e.g. water in lochs or the sea, is
not covered in this guidance. However, where there is no abstraction of water
or discharge of substances liable to cause pollution (e.g. antifreeze) into the
water environment as a result of the activity e.g. in a closed loop system,
then SEPA will not require these to be registered or licensed under CAR
unless the boreholes are drilled to or below a depth of 200m from 1 April
2013. Information on the regulation of open loop heating/cooling systems in
surface waters can be found in WAT-RM-05: Regulation of Trade Effluent
Discharges to Surface Waters and WAT-RM-01: Regulation of Abstractions
and Impoundments.
4 of 14
Uncontrolled if printed
v4.0 Aug 2014
2. Types of Geothermal Systems
2.1 Introduction
There are two main types of geothermal systems, closed loop systems and
open loop systems. There are environmental impacts in terms of heat
addition or loss to groundwater from both systems although there is greater
potential for pollution to the water environment and disruption to flow in the
water environment from open loop systems. This is because water from open
loop systems is removed, potentially changing its chemical composition, and
the water may then be discharged in a location different to that from which it
was abstracted.
2.2 Closed Loop Geothermal Systems
Closed loop groundwater geothermal systems work by circulating a fluid
around a closed system with one part of the circuit in groundwater and one
part connected to a heat pump in the building to be heated or cooled
(Figure 1). The fluid in the system uses groundwater as a heat source or a
heat sink. There are no abstractions from or discharges to the water
environment from this type of system. The introduction of heat into the water
environment is a controlled activity, but SEPA will generally not require
authorisation under CAR for the ongoing operation of closed loop geothermal
systems, including those where there is an introduction of heat, as the
impacts on groundwater are likely to be negligible. However, where a
borehole is to be drilled to or below a depth of 200m from 1 April 2013 a
complex licence application will be required.
Figure 1 A Closed Loop System1
1&2
Geothermal (Ground-Source) Heat Pumps A World Overview, J. Lund, B. Sanner, L. Rybach,
R. Curtis, G. Hellström, GHC Bulletin, September 2004
v4.0 Aug 2014
Uncontrolled if printed
5 of 14
Supporting Guidance (WAT-SG-62)
2.3 Open Loop Groundwater Systems
In open loop systems groundwater is abstracted, used as a heat source or
sink in a heat pump, and then returned to the water environment (Figure 2).
Figure 2 An Open Loop System2
1&2
Geothermal (Ground-Source) Heat Pumps A World Overview, J. Lund, B. Sanner, L. Rybach,
R. Curtis, G. Hellström, GHC Bulletin, September 2004
6 of 14
Uncontrolled if printed
v4.0 Aug 2014
3. Regulatory Control
3.1 Introduction
Abstractions (including borehole construction) from and discharges to the
water environment are controlled activities as described by the Water
Environment and Water Services (Scotland) Act 2003, regulated through The
Water Environment (Controlled Activities)(Scotland) Regulations 2011
(‘CAR’) and described further in Controlled Activities Regulations: A Practical
Guide. Geothermal systems may involve both activities or neither.
The introduction of heat into the water environment is included in “pollution”
as defined in the Water Environment and Water Services (Scotland) Act
2003.
Table 1 summarises the regulatory control for closed and open loop
geothermal systems.
Table 1
Regulatory Control for Geothermal Systems
Closed
Loop
Open Loop
Return of Water to Same
Geological Formation and
No Alteration to Chemical
Composition of the
Abstracted Water
Return to a Different
Geological Formation or there
is an Alteration to the Chemical
Composition of the Abstracted
Water
Abstraction
3
<10 m /d
Abstraction
3
≥10 m /d
Borehole
Construction
GBR 3(a)*
GBR 3(e)*
GBR 3(b)*
GBR 3*/
Registration/
licence*
Abstraction
N/A
GBR 17
GBR 2
Registration/
licence
Discharge
N/A
GBR 17
Registration/
licence
Registration/
licence
* Note that for boreholes drilled to or below a depth of 200m from 1 April 2013 a complex licence
will be required.
3.2 Closed Loop Systems
Where a borehole is drilled as part of a closed loop system the construction
of the borehole is controlled by GBR 3(a). To comply with the GBR and
prevent pollution, unacceptable mixing of water between layered aquifer
systems or loss of water from artesian aquifers the borehole should be
grouted throughout its length. Efficient heat exchange can be achieved by the
use of thermally transmissive grout. This does not apply where the borehole
is drilled to or below a depth of 200m from 1 April 2013 as a complex licence
will be required. WAT-RM-11 provides further details.
v4.0 Aug 2014
Uncontrolled if printed
7 of 14
Supporting Guidance (WAT-SG-62)
There are no abstractions and discharges from closed loop systems. The
introduction of heat into the water environment is a controlled activity, but
SEPA will generally not require authorisation under CAR for the ongoing
operation of closed loop geothermal systems, including those where there is
an introduction of heat, as the impacts on groundwater are likely to be
negligible.
3.3 Open Loop Systems
These systems abstract groundwater and discharge the water back into the
environment. For regulatory purposes, open loop systems may be subdivided
into those where the water is returned to either:
the same geological formation from which it was abstracted and the
chemical composition is not altered, or
another part of the water environment, e.g. surface water or a different
geological formation or the chemical composition of the returning water
has been altered.
Return of Water to Same Geological Formation and No Alteration
to Chemical Composition of the Abstracted Water
If an Open Loop system returns water to the same geological formation from
which it was abstracted and the chemical composition has not been altered,
the construction of the borehole (unless it is >200m in depth), the abstraction
and subsequent return are all covered by GBR 3 and 17.
Return to a Different Geological Formation or there is an
Alteration to the Chemical Composition of the Abstracted Water
If an Open Loop system returns water to a different geological formation or
another part of the water environment such as a surface water body, or the
chemical composition of the abstracted water has been altered, by for
example addition of chemicals from a cooling process, then the abstraction
and discharge can not be authorised by GBR 17.
In these cases:
The abstraction of <10 m3/day (including the drilling) can be authorised by
GBR2 and 3 (unless the borehole is >200m in depth);
Any abstraction of ≥10 m3/day can be considered for authorisation by
either Registration or Licence depending on the volume abstracted. The
construction of the borehole can be authorised by GBR 3 if less than
200m deep and no more than 150 m3/yr is abstracted for the purpose of
testing. An application to SEPA is required to construct the borehole
should this be exceeded. Refer to WAT-RM-11: Licensing Groundwater
Abstractions including Dewatering for information on licensing
groundwater abstractions;
8 of 14
Uncontrolled if printed
v4.0 Aug 2014
Regulatory Control
An application to SEPA for a CAR authorisation for the discharge
(Registration or Licence depending on volume) will be needed which
should be assessed in line with WAT-RM-05: Regulation of Trade Effluent
Discharges to Surface Waters or WAT-RM-06: Regulation of Trade
Effluent Discharges to Groundwater. Best practice would be to avoid the
addition of any substances (including chemicals) to the abstracted water;
Where either the discharge or abstraction (including borehole
construction) is at licence level, then both activities should be included on
one licence.
3.4 Interpretation of GBR 17
GBR 17 allows for the ‘abstraction and subsequent return of groundwater for
the purpose of extracting geothermal energy from the abstracted water’.
SEPA considers that:
A map showing the location of the abstraction and discharge and borehole
logs should be kept by the owner/operator to demonstrate compliance
with Rule (a).
any volume of water may be abstracted but the volume of water
abstracted and not returned must not exceed 10m3 per day;
Rule (c) means that nothing can be added to or removed from the
abstracted water which would alter the chemical composition.
Drilling of the borehole is covered by GBR3 provided the rules are complied
with and the borehole is <200m deep (from 1 April 2013.
v4.0 Aug 2014
Uncontrolled if printed
9 of 14
Annex A – Potential Environmental Impacts from
Geothermal Systems
A1. Introduction
This annex provides some information on how to consider the environmental
impacts of geothermal energy systems in order to prevent pollution of the
water environment and operate an effective system. This assessment is not a
requirement of the GBR but details some of the things that the operator may
wish to consider in order to aid compliance with the GBR and operate an
effective geothermal system. It also provides some information on the
environmental impacts of these systems which will help in assessment of any
registration or licence application by SEPA.
Systems that remove heat from groundwater can give rise to sub-zero
groundwater temperatures, those that add heat can give rise to groundwater
temperatures in excess of 20°C. In either case such temperatures may
adversely affect sensitive groundwater dependent ecosystems or other water
users.
A2. Feedback Impacts on the System
In addition to the immediate risk of pollution, poorly designed systems can
result in thermal breakthrough. When this happens the returned heat affects
the heat in the groundwater so that the groundwater is at a different
temperature to natural groundwater.
Where a ground source heat pump system is used for both heating and
cooling and uses approximately the same quantities of energy for each, i.e. it
is a balanced system, temperature equilibrium of the groundwater is quickly
established close to the pre-existing groundwater temperature and thermal
breakthrough or significant adverse environmental effects are unlikely.
Where the system is unbalanced, i.e. there is a difference in energy used for
heating and cooling, or the system only heats or cools, groundwater will
gradually become warmer or colder in the vicinity of the introduction. This can
lead to a positive feedback loop resulting in larger volumes of groundwater
being affected with an increased risk of pollution and a reduction to the
efficiency of the heat pump, increasing the running costs. It may be several
years, if ever, before temperature equilibrium is established and may result in
the system becoming unsustainable. Figure 3 illustrates what can happen.
A number of software packages, e.g. SHEMAT, FEFLOW, are available for
assessing the sustainability of a scheme, i.e. assessing whether thermal
breakthrough occurs, and if so whether this will lead to an unacceptable
reduction in efficiency of the heat pump or have a significant effect on other
parts of the water environment or on other water users.
The risk of thermal breakthrough can be avoided by adequate separation of
abstraction and introduction locations.
10 of 14
Uncontrolled if printed
v4.0 Aug 2014
Annex A – Potential Environmental Impacts from Geothermal Systems
Figure 3 Thermal Breakthrough
A3. Impacts on Surface Waters and Other Receptors
Where a temperature increase or chemical composition of the discharge may
impact upon a surface water body either directly, as a result of a discharge
from an open loop system, or indirectly, as a result of groundwater-surface
water interaction, the discharge must not cause a significant adverse impact
on surface water. Information on thermal surface water status boundaries is
set out in the Standards Directions 2014. WAT-SG-85: Application of
Standards to Thermal Discharges also provides further details.
The impact on other receptors such as wetlands and abstractions also needs
to be taken into account. Where an abstraction is impacted, the use made of
the abstracted water will be a key factor when deciding what temperature
increase or decrease or chemical change is acceptable.
A4. Assessment
Prior to the installation of a geothermal system an assessment of the
potential impact of the discharge should be undertaken by the operator or
their agent. This should include:
The temperature and chemical composition of the discharge in relation to
the receiving water and where relevant an examination of the possibility
that there may be interaction between the discharge and the geological
formation;
v4.0 Aug 2014
Uncontrolled if printed
11 of 14
Supporting Guidance (WAT-SG-62)
The location of the discharge (groundwater/surface water, direct/indirect
to groundwater, depth);
Proximity to receptors (surface waters, wetlands, other water users);
Assessment of the risk of thermal breakthrough (taking into account
cumulative impacts from nearby schemes), significant changes to
hydraulic regime (for example the potential for groundwater damming if
ice forms where heat is being removed) or interference with other water
users; and
Assessment of the risk of pollution (heat or substance). Consideration
should be given to the fact that warming of groundwater can have a
significant impact on contamination issues e.g. enhancing the mobility of
non aqueous phase liquids.
Where this assessment indicates that the system will not fall within the scope
of the relevant GBR or may have an impact upon the receiving water then
pre-application discussion with the local SEPA office is essential. Only after
discussions regarding the different options and potential impacts should a
decision be made regarding formal application for authorisation.
When in doubt about the viability or impact of a system contact SEPA.
12 of 14
Uncontrolled if printed
v4.0 Aug 2014
References
NOTE: Linked references to other documents have been disabled in this web
version of the document.
See the Water >Guidance pages of the SEPA website for Guidance and other
documentation (www.sepa.org.uk/water/water_regulation/guidance.aspx).
All references to external documents are listed on this page along with an indicative URL to
help locate the document. The full path is not provided as SEPA can not guarantee its future
location.
Key References
WAT-RM-01: Regulation of Abstractions and Impoundments
WAT-RM-05: Regulation of Trade Effluent Discharges to Surface Waters
WAT-RM-06: Regulation of Trade Effluent Discharges to Groundwater
WAT-RM-11: Licensing Groundwater Abstractions including Dewatering
WAT-SG-85: Application of Standards to Thermal Discharges
Other References
Controlled Activities Regulations: A Practical Guide
(http://www.sepa.org.uk/water/water_publications.aspx)
Geothermal (Ground-Source) Heat Pumps A World Overview, J. Lund, B.
Sanner, L. Rybach, R. Curtis, G. Hellström, GHC Bulletin, September
2004
Standards Directions 2014
• The Scotland River Basin District (Surface Water Typology,
Environmental Standards, Condition Limits and Groundwater
Threshold Values) Directions 2014
• The Solway Tweed River Basin District (Surface Water Typology,
Environmental Standards, Condition Limits and Groundwater
Threshold Values) (Scotland) Directions 2014
NOTE: This link provides access to the documents via a managed SEPA intranet
page.The full set of Standards Directions for each river basin district in Scotland can also
be found via the Publications page of the Scottish Government website
(www.scotland.gov.uk/Publications/)
Water Environment (Controlled Activities)(Scotland) Regulations 2011
(http://www.sepa.org.uk/water/water_regulation.aspx)
Water Environment and Water Services (Scotland) Act 2003 (as
amended) NetRegs (http://www.netregs.org.uk )
v4.0 Aug 2014
Uncontrolled if printed
13 of 14
Supporting Guidance (WAT-SG-62)
- End of Document -
14 of 14
Uncontrolled if printed
v4.0 Aug 2014