Frequently Asked Questions
Clear answers on planning, permits, construction and running a mini-hydro scheme.
Before you commit to a site
Most questions from new developers concern the first assessment of a river. The answers below explain what to measure and what to ask before any design work begins.
Power depends on two measurements: the head, which is the vertical drop between intake and turbine, and the flow, which is the volume of water available over the year. Multiply the two together, apply an efficiency factor for the turbine and generator, and you have an estimate. Flow should be measured across several seasons where possible, because a single dry week can give a misleading result.
Yes. Intake, penstock and tailrace routes often cross land owned by others, and rights to abstract water may be attached to the riverbank. Written agreements should cover access for construction, maintenance and eventual decommissioning, as well as any payment terms.
Timescales vary widely. Feasibility and surveys can take several months, while consents and grid connection often take longer than construction itself. Allow time for each stage and avoid fixing a commissioning date until the connection offer has been received.
Consents and engineering
Abstraction and impoundment licences are usually required before construction. Environmental bodies may also ask for fish passage, flow compensation and screening arrangements. Planning permission is needed for the powerhouse and any new access tracks.
Civil design should be carried out by a qualified engineer. The weir, intake and penstock must withstand floods, and the powerhouse must be protected from the water it houses.
Operation and maintenance
Once commissioned, a scheme needs regular inspection. The questions below cover the routine work and what to expect over the life of the equipment.
Screens must be cleaned during high flow, and debris records help predict when they need attention.
Turbine bearings, seals and runners should be inspected on a published schedule and after any abnormal event.
Routine work includes screen cleaning, lubrication of mechanical parts, checking control panels and reviewing generation output against expectations. Keep a log of each visit so that changes in performance can be traced to their cause.
It can, which is why screening, fish passage and minimum flow conditions are normally set by the regulator. Monitoring after commissioning confirms whether these measures work in practice and whether any adjustment is needed.
The main steps in order
Site assessment
Measure head and flow, and record the ownership and access position of the land.
Consents and design
Submit licence and planning applications, then develop the civil and electrical design.
Construction and commissioning
Build the intake, penstock and powerhouse, then test the turbine and grid connection.
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