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| Titel |
Mitigation potential of horizontal ground coupled heat pumps for current and future climatic conditions: UK environmental modelling and monitoring studies |
| VerfasserIn |
Raquel García González, Anne Verhoef, Pier Luigi Vidale, Guohui Gan, Yupeng Wu, Andrew Hughes, Majdi Mansour, Eleanor Blyth, Jon Finch, Bruce Main |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250032955
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| Zusammenfassung |
| An increased uptake of alternative low or non-CO2 emitting energy sources is one of the key
priorities for policy makers to mitigate the effects of environmental change. Relatively little
work has been undertaken on the mitigation potential of Ground Coupled Heat Pumps
(GCHPs) despite the fact that a GCHP could significantly reduce CO2 emissions from
heating systems. It is predicted that under climate change the most probable scenario is for
UK temperatures to increase and for winter rainfall to become more abundant; the latter is
likely to cause a general rise in groundwater levels. Summer rainfall may reduce
considerably, while vegetation type and density may change. Furthermore, recent
studies underline the likelihood of an increase in the number of heat waves. Under
such a scenario, GCHPs will increasingly be used for cooling as well as heating.
These factors will affect long-term performance of horizontal GCHP systems and
hence their economic viability and mitigation potential during their life span (Â 50
years).
The seasonal temperature differences encountered in soil are harnessed by GCHPs to
provide heating in the winter and cooling in the summer. The performance of a GCHP system
will depend on technical factors (heat exchanger (HE) type, length, depth, and spacing of
pipes), but also it will be determined to a large extent by interactions between the
below-ground parts of the system and the environment (atmospheric conditions, vegetation
and soil characteristics). Depending on the balance between extraction and rejection of heat
from and to the ground, the soil temperature in the neighbourhood of the HE may fall or
rise.
The GROMIT project (GROund coupled heat pumps MITigation potential), funded by
the Natural Environment Research Council (UK), is a multi-disciplinary research project, in
collaboration with EarthEnergy Ltd., which aims to quantify the CO2 mitigation potential of
horizontal GCHPs. It considers changing environmental conditions and combines model
predictions of soil moisture content and soil temperature with measurements at different
GCHP locations over the UK. The combined effect of environment dynamics and horizontal
GCHP technical properties on long-term GCHP performance will be assessed using
a detailed land surface model (JULES: Joint UK Land Environment Simulator,
Meteorological Office, UK) with additional equations embedded describing the
interaction between GCHP heat exchangers and the surrounding soil. However, a
number of key soil physical processes are currently not incorporated in JULES, such
as groundwater flow, which, especially in lowland areas, can have an important
effect on the heat flow between soil and HE. Furthermore, the interaction between
HE and soil may also cause soil vapour and moisture fluxes. These will affect soil
thermal conductivity and hence heat flow between the HE and the surrounding soil,
which will in turn influence system performance. The project will address these
issues.
We propose to drive an improved version of JULES (with equations to simulate
GCHP exchange embedded), with long-term gridded (1 km) atmospheric, soil and
vegetation data (reflecting current and future environmental conditions) to reliably
assess the mitigation potential of GCHPs over the entire domain of the UK, where
uptake of GCHPs has been low traditionally. In this way we can identify areas that
are most suitable for the installation of GCHPs. Only then recommendations can
be made to local and regional governments, for example, on how to improve the
mitigation potential in less suitable areas by adjusting GCHP configurations or
design. |
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