The potential of applying ground source heat technology to extract heat generated within landfills in order to use it for various industrial applications was recently studied at a landfill in the United Kingdom.
This technique could be significant for a process such as handling leachate – the liquid material caused by percolation of rainwater into a waste mass – by raising the temperature of leachate prior to its biological treatment.
New requirements involving carbon reduction in the UK are causing waste management companies to look at how they can be less reliant on fossil fuels. Since leachate must be treated, a waste operator may be able to avoid using a costly fossil fuel like liquid petroleum gas by turning to an alternative heat source.
Golder did the conceptual design for a trial closed loop horizontal heat exchanger and the associated pipework that was installed in a leachate extraction trench. The heat exchangers were placed about 4-5 metres (~ 16 feet) below ground level and in direct contact with waste and leachate, but below capping and restoration layers. The closed loop ensures there are no contamination issues.
We performed a thermal response test that was conducted over a 49-hour period to determine the increase in heat energy output from the ground collector.
This warmer liquid could provide heating for the leachate treatment plant at the landfill site since it requires heating during the winter months to establish optimal conditions for treatment. The test showed that there was significant heat energy available, which may be sufficient to provide direct heating without an additional heat pump.