Urban heat islands
in cities like Karlsruhe are influenced by factors, such as
population
density, surface sealing, vegetation, thermal radiation of buildings,
industry, and
transport. (Photo: KIT)
(December 20, 2015) KIT
Researchers Identify Underground Heat Islands from Surface Temperature and
Building Density – Publication in “Environmental Science & Technology”
Underground heat islands in cities have an enormous
geothermal potential. Warm groundwater can be used to produce sustainable
energy for heating and cooling. Researchers of Karlsruhe Institute of
Technology (KIT) have now developed a new method to find underground heat
islands: They estimate groundwater temperature from surface temperatures and
building densities measured by satellites. This is reported in the journal
“Environmental Science & Technology”.
In bigger cities, temperatures usually are far higher than
in the rural surroundings. These so-called urban heat islands result from
various factors, such as population density, surface sealing, thermal radiation
of buildings, industry, and transport as well as lacking vegetation. This
phenomenon affects the atmosphere, surface, and subsurface of modern cities.
Temperature anomalies may contribute to regional air
pollution and an increased mortality during hot spells in summer. Increased
groundwater temperatures influence underground ecosystems and may favor growth
of pathogens in groundwater. But underground heat islands also have high
potentials for energy supply and climate protection: Energy from
close-to-surface groundwater aquifers may be used for heating in winter and
cooling in summer with the help of geothermal or groundwater heat pumps. If
this geothermal potential would be used, part of the growing energy consumption
of cities might be covered. This would reduce emission of greenhouse gases and,
thus, counteract global warming.