Introduction to modern hydro power

Modern micro hydro has a number of advantages over some other renewable energy technologies. It can work at higher efficiencies and is more predictable – we can predict the general rainfall pattern.

The power produced will vary gradually day to day, rather then minute to minute. It is long lasting and robust – systems are engineered to last 50 years or more and it is a technology which is more acceptable by people. In most cases it has very little impact on the landscape and environment.

What is hydro-electric power?

Electricity is produced when a flow of water is channelled through a turbine connected to an electricity generator. Two factors are important – the head or height the water falls and the amount of water. These will determine the amount of energy which can be produced.

Hydroelectric schemes can be divided into two broad categories: large scale – more than 5 MW and small scale – less than 5 MW. In the steep sided valleys of the South Pennine catchment area, most of the streams are low/med head, low flow and will deliver below 100 kW.

Hydro systems can either be connected to the main electricity grid or as stand-alone (off-grid) power systems. In a grid-connected system, any electricity generated but not used can be sold to electricity companies. In an off-grid system, the electricity can be stored in a battery bank. For either system, the source needs to be relatively close to where the power will be used, or to a suitable grid connection.

When planning a hydro system, there are a number of issues that need to be considered:

• Identify whether there is sufficient potential energy output to make the system viable.

• That the owners of the land – including any land necessary to develop and access it - have been consulted.

• That there is an access point to either the National Grid or building that can use the power.

Anybody thinking of developing a site should seek independent professional advice before committing significant financial resources to the design and construction of a scheme. An outline of the project lifecycle by Chris Brett of Inter Hydro Technology can be found here:

In total a scheme will comprise:

• An intake from the river, usually at a weir.

• A settling tank (or forebay' where any particles in the water are allowed to settle out. This usually has a rack of metal bars which filter out debris.

• A penstock, or pressure pipe, which takes the water from the settling tank to the turbine. Turbines convert the water pressure into mechanical power which is then used to drive a generator. These are housed, with the control equipment, in a suitable building.

• A tailrace which takes the water back to the river.

The electricity that is produced can either be fed directly into the grid, at a suitable point, or connected into a building that is close by the production site. For connecting to the grid it is necessary to talk to the Distribution Network Operator (a list can be found at the PV-UK website).

They will also provide an estimate of connection costs and the best location for feeding into their system.


Next: Feasibility studies


Power From the Landscape

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