Hydro

Some developments will be lucky enough to have hydro potential onsite. Typically these will be on the sites of existing or old mills or weirs. At such sites careful consideration will have to be given to the head, the flow rate and the capital cost of the civil works which can sometimes be prohibitive. However, sites that can be developed into micro-hydro systems will benefit from a power output that matches the annual demand curve better than solar or wind, and a long-life technology if well maintained. Property developments typically are sited on flat ground - hence most hydro opportunities will be low-head hydro and run-of-the-river type systems.

Archimedean screw technology is currently a focus of attention because it achieves high efficiencies and has been known to work within heads of as low as 0.3 m, although 1.0 m would normally be the minimum - see the River Dart Country park link. Other low-head, high-flow technologies include syphonic head cross-flow systems such as that at Tellisford Mill in Somerset.

Abstraction or impoundment licences need to be obtained from the Environment Agency, and this will require environmental studies and design measures such as fish passes for anadromous (e.g. salmonids) and catadromous species (e.g. eels) and studies into what level of flow must be maintained within the depleted reach to maintain habitat quality.

Micro-hydro is a well developed technology internationally and resources are plentiful.