Although not strictly renewable, heat can be extracted from aquifers and fed to district heating networks, as has been done in central Southampton. More generally, and without geographic constraints, use can be made of ground source heat pumps for heating buildings. By contrast, the prospects for the use of locally generated wave and tidal power directly in cites are limited, since the main wave resource is in remote areas offshore and few cites are on rivers with significant tidal ranges. However, in some locations it might be possible to use power from small onshore wave energy units or tidal stream generators in estuaries. So far, wind power has been seen as pretty much irrelevant in urban contexts.
Wind speeds are usually too low and finding acceptable sites almost impossible.
However, a colleague at the OU, Dr Derek Taylor, is developing a novel building integrated wind turbine system which fits into the roof space of a house, the Aeolian roof. This takes advantage of the fact that wind speeds can be increased by appropriately shaped roof designs. Assuming that noise and vibration problems can be avoided, we may yet see wind power make an urban contribution . Moreover, assuming continued improvements in the efficiency of energy use in buildings and elsewhere, and the integration of energy efficiency and energy conservation systems with advanced renewable technologies, such as renewably powered hydrogen fuel cell systems, then the urban renewables contribution could rise much higher. However, total urban self-sufficiency seems unlikely.