Hydro Electric Power
Hydro electricity systems are also known as hydropower stations, hydro systems and hydro electric energy systems. The term micro-hydro refers to hydropower systems that have a power rating of 100 kilo watts (kW) or less. A 100 kW system produces 100 standard units of electricity per hour.
If you are in the enviable position to have access to a source of running water and would like to generate your own sustainable energy, installing a hydro electric energy system could be an excellent option.
Hydropower is a mature technology that’s first recorded use was in Ancient Egypt over 2000 years ago in 250 BC. In 1882 hydro power was first used to generate electricity and since then it is a technology that has been greatly advanced.
Recent technological advances that have made turbine design much more cost effective, plus less stringent regulation for renewable energy sources, has led to a growing interest in micro-hydro in the UK.
How Hydro Power Works
Hydroelectric power systems make use of the force exerted by running water to turn turbines that generate electricity. The more water and the faster it flows the greater the amount of electricity that can be generated.
Hydropower can make use of the natural water flows found in rivers and streams. Even a small stream of water can be used to produce useful power.
Provided the micro-hydro installation is installed correctly it will have no negative effects on the local stream. Most systems will divert some of the available water so that it can be used by a turbine, after which the water is returned to the river or stream.
An easy way to generate hydro electricity is using the water from streams that flow down steep gradients. Using this method water is removed from the stream and dropped vertically down a pipe. The further the water drops the more energy it gains and the harder it will hit the turbine at the bottom. The force exerted by the water at the bottom of the ‘fall’ is absorbed by the turbine, and therefore causes it to spin. The turbine is connected to a generator and electricity is generated. After passing through the turbine the water will flow along a pipe or channel and re-enter the stream a little further downstream from where it was removed.
This is an excellent method of generating electricity because the fast water can be targeted onto the turbine, making good use of the energy and enabling the turbine to spin quickly. Electricity is best generated at 1,000 to 1,500 revolutions per minute.
Flowing water can have a strong current without having any fall due to:
Water that has a strong current can be used to generate electricity. Watermills can use the energy in the water to turn water wheels. Because the water wheels do not turn very quickly, gearing will be used to increase the revolutions before driving a generator.
Hydro turbines that can be placed directly into the water are available. They are made up of a unit that contain a generator and a propeller type device that is turned by the force of the water flowing through it. These turbines respond directly to the strength of the water current and are useful for producing low voltage (typically 12 volt) electricity, and are commonly used for trickle charging battery packs.
Is hydro power suitable for your home?
Micro-hydro can be one of the cheapest methods of generating your own supply of renewable electricity, but it is very site specific!
Firstly you will need to have a river or stream that has a fairly fast water flow, close to your home. The best sites for generating hydro electricity are on steep hills with a good supply of fast flowing water.
Old watermill sites can often be used and these have the advantage that most of the civil structures required may already be in place.
Water flows vary throughout the year and this needs to be considered. Some water flows may completely dry out in the summer months, so if being used to generate hydro electricity you will either:
Need to be connected to the national grid in order to buy electricity when you are not generating your own.
Require a generator, solar panels or a wind turbine to generate electricity when there isn’t enough water to do so.
In the past water was used extensively as an energy source to power machinery. It is estimated that there could be as many as 20,000 old water mill sites in the UK. Due to Government incentives for renewable energy it is now economically worthwhile to reactivate and develop many of these sites.
However, watermills are quite often situated where bodies of water are too slow moving to be suitable for the generation of electricity. Fast flowing water is much more suitable for generating electricity because it can be channelled to hit the turbine at high pressure. At some watermill sites it maybe possible to make use of gearing to increase the useable revolutions per minute that are produced.
Calculating how much electricity a source of water can generate [Expand This]
You can use the following method to calculate how much electricity a source of water can generate:
F x H x 10 = W
F = Flow of water in litres per second, or the amount of water you can use from the flow every second.
H= Height of the ‘Head’ in metres. The ‘Head’ is the drop that the water falls, measured from the surface of the water.
10 – is used to represent gravity
F x H x 10 is then divided by 2 to take account of inefficiencies and energy loss.
W= Represents the potential power generation in watts.
The calculation above illustrates that greater amounts of electricity can be generated the greater the water flow rate and the greater the ‘Head’.
Choosing a site to harness water energy [Expand This]
When choosing a site for a hydro-system the best place to harness the water energy is either where there is the greatest fall over the shortest route, or where the current is strongest. You will then need to ensure that a satisfactory amount of energy can be generated by your water source.
Environmental considerations [Expand This]
In most circumstances the larger the stream the great the amount of water that is available to generate electricity. However, not all the water can be diverted in order to generate electricity because water will need to remain flowing in all parts of the stream for environmental reasons.
Seasonal changes in water flow [Expand This]
Water flows vary throughout the year, some may even completely dry out in the summer months. Seasonal changes in water flow and the effect that this has on the amount of electricity that can be generated needs to be considered.
Suitable connection to the national grid [Expand This]
Electricity that is generated and not used by you can be sold to an electricity supplier. In order to sell excess electricity a suitable connection to the National Grid will be required.
Cost [Expand This]
The amount that it will cost to install a hydro system will depend on the size of the equipment and how much electricity it is capable of producing, plus the work required in preparing the sight so that the water power can be harnessed and the equipment installed.
You will need to obtain permission for your installation from the following
Local planning authorities [Expand This]
check to see which planning authority covers the area of your proposed installation. You will most probably require planning permission for the powerhouse and also for any pipework. Because hydro systems can be visually imposing and do create some noise you may have some resistance from neighbours.
Environment Agency [Expand This]
the Environment Agency is responsible for watercourses in the UK. They will want to know what effects the installation will have on the river ecology and also any flooding risks, so this will need to be assessed. It is very important that you obtain permission from them and an abstraction licence prior to installation.
Landowners permission [Expand This]
if you do not own all the land required to set up your installation you will need to obtain permission from the landowner or landowners.
Feed in Tariff
Receive payment for electricity that you generate [Expand This]
Under The feed in tariff scheme hydroelectric systems installed during 2010 and 2011 are able to receive payment for every kilowatt of electricity generated. To qualify the installation would have to be installed by a professional person who is accredited with the feed in tariff scheme. The scheme pays 19.9 pence for every kilowatt generated and a further three pence for every kilowatt that is sold back to the National Grid. Therefore you are not only producing renewable, carbon free electricity for yourself but also for others.
A 5 kW hydro system could generate its owner between £5,000 and £10,000 per year, on a scheme guaranteed for 20 years.
Hydro electricity is green – Hydro electricity is a totally renewable energy that does not release any CO2 or any other pollutants.
Cut or eliminate your electricity bills – Once you have paid for the hydroelectric system the electricity it generates is free.
Can be a cheaper alternative – For some remote properties installing a hydro electric plant can be a cheaper alternative to being connected to the national grid.
Can also provide free heating and hot water – Hydro electric systems are able to generate large amounts of electricity. They may generate more electricity than required to power lights and electrical appliances, and also be able to provide enough electricity for heating and hot water.
A constant water flow throughout the day and night – Having a constant flow 24 hours a day means that there is a reduced requirement for battery storage of electricity or connection to the national grid. This is particularly useful for properties in remote locations.
Season water flows tend to suite seasonal power requirements – During the winter months there is generally greater flow of water due to increased rain or snow fall. Therefore more electricity can be generated through the winter months, which is ideal because this is when there is a greater demand for electricity due to increased lighting and heating requirements.
Hydro systems can last a life time – Hydro systems are very reliable and robust. They are expected to have a working life expectancy of at least 25 years and many systems are expected to last for 50 years.
Low maintenance requirements – Hydro systems require very little maintenance and once installed are very cheap to maintain.
Can pay for themselves within 10 years – By selling the excess electricity generated through grid connection it is possible for most hydro systems to pay for themselves with 10 years.
Predictable energy outputs – The amount of electricity produced is very predictable. Water flows may fluctuate seasonally and with rainfall, but generally the electricity produced will be fairly constant.