An often-overlooked renewable energy source within the domestic and SME market is hydro electricity. When we think of this form of energy, visions of massive concrete dams spanning wide rocky gorges often spring to mind. However, the small-scale systems that I want to look at here do not involve dams and can be built with minimum impact on the environment. I shall give a brief explanation of how hydroelectricity works and look at how it may be put to use in small-scale projects. While this article may only be aimed at the small minority of homes and businesses that are situated near a river, hydropower – as the world’s leading source of renewable energy – is an under-used source of clean energy and should not be ignored simply because it’s not available to everyone. It is also one of the most reliable and predictable; this is England don’t forget. It rains. A lot.
Hydro electricity production
Using water to power our technology is nothing new. The ancient Greeks used waterwheels to grind flour and watermills have been used right up through medieval times until steam power took over during the industrial revolution. Towards the end of the nineteenth century we began using water to create electricity, and now have massive hydroelectric projects such as the Three Gorges dam in China. Currently hydropower produces 20% of the world’s electricity and is responsible for over 90% of the world’s renewable energy [1].
To create electricity from water involves extracting the kinetic energy stored in the flowing water and converting it into electromagnetic energy. To do this is relatively simple; the water flows through a turbine, rotating it fast enough to produce an electric current, which we can then use to turn on our lights. There are various types of turbine, ranging from the Kaplan, which looks like vertically mounted ship’s propeller, to the Turgo, which looks like the front of a jet engine. All run on the same principle, nonetheless, using the weight and speed of the water to rotate them. The amount of energy available from the water is governed by two factors: the flow (the amount of water passing each second) and the head (the vertical fall of the water). A rule of thumb here is that to generate the same amount of electricity you will require either a low head with a high flow, or a high head with a low flow. Obviously the best system would have both of these, i.e. a large quantity of water flowing from a great height.
A hydro system can of course be used as an off grid power supply for remote areas, but more usually it will be attached to the grid so that there is aback up during dry spells. The advantage of a grid-connected system is that it can take advantage of the feed-in tariff [2]. This could see the system – depending on its size – earning about 20 pence per kWh it generates, plus 3 pence for every kWh that is not used and sold back to the grid. For a power source that could potentially be running all the time, that’s a fair amount of money and will certainly help to pay the installation costs.
Advantages of hydroelectric power
The most obvious advantage to using water as a power source is that you will always be happy when it rains – hooray! That aside, the other benefits include:
- It’s a free resource so once you’ve paid back the initial investment; you can enjoy clean, free energy.
- The maintenance costs are low because hydroelectric systems are very reliable.
- If you are using a FIT then all the time that the river is flowing, day or night you are producing electricity and thus making money. This is a notable advantage over solar power.
- The production of hydroelectricity creates no carbon emissions.
- For remote locations it can be a cheaper option that connecting to the national grid.
- Due to their high efficiency (over 80%), small-scale hydro systems are one of the cheapest forms of renewable energy per unit [3].
- Small-scale hydro projects are ‘run of river’ installations, meaning that they do not dam up any part of the watercourse.
The damage caused by large-scale hydroelectric projects
Just so that there’s no confusion with the hydroelectricity that I am describing here, I want to address the issue of environmental damage that can be caused by large-scale dam building. While hydroelectricity is a clean source of renewable energy, it is sometimes surrounded by conflict and contention because when a river is dammed the results can be harmful to the surrounding areas:
- When the reservoir is first constructed many communities can be displaced and watch their family homes disappear underwater. For example, the Aswan (Egypt) and Kariba Dams (Zambia) involved the relocation of 60,000 and 80,000 people respectively, while the Three Gorges dam submerged about 100 towns and displaced over a million people [4].
- When the area for the reservoir is flooded, the vegetation that is left to rot underwater produces large amounts of methane; a greenhouse gas about 20 times as potent as carbon dioxide.
- Further downstream the dam can radically affect the hydrological cycle and the water table, drying out areas that previously relied on the water and adversely affecting wildlife, vegetation and farming. If the amounts of water downstream are not affected, the dam can dramatically reduce the nutrients available that would have arrived with the naturally flowing floodwaters, again having huge implications for both human and non-humans.
The Three Gorges Dam, China.
Having said all of this, many other people benefit from the dams. Because of the building of embankments and barrages, these projects often provide flood control to previously flood-prone regions, helping to save lives and money. The reservoirs themselves can become areas for tourism, thus bringing additional income for local communities. It must also be noted that large-scale hydroelectricity is responsible for a very large percentage of the world’s renewable energy. The power supply is reliable, it does not consume any resources and the need to build fossil fuel or nuclear power stations is reduced.
Installing a micro hydro project
Obviously the first thing that you need to have is a supply of running water. This may be a waterway that runs through your property, or even that of a neighbour. A cooperative scheme involving a number of different properties could prove cost effective and also bring people together a community. One company that I found is willing to consider a joint venture with anyone who has the land (and water) available for the installation of a micro hydro system they will provide equipment consultation and investment for a share of the electricity generated [5]. Worth looking at if you’re sitting on the fence.
If you feel that you have the necessary amounts of water then you will need to contact a specialist installer – this is not a DIY job. These professionals will be able to give you the answers regarding the size of system you will need and will assist with the planning process (which can take up to 6 months) and the associated environmental impacts. To avoid unnecessary delays make sure you contact the relevant parties in good time: the installer, local planning authorities, the Environment Agency, etc.
If you have been put off installing a hydroelectric system because you are worried that it could have a negative impact ion the environment (killing fish, wildlife, etc.) then rest assured that, first of all, you won’t be allowed to install one if it is seen to be damaging, and second, there are ways and means to prevent environmental impacts. Remember also that hydroelectricity doesn’t actually take anything from the river itself, so the amount of water further downstream will not be affected.
The initial cost of a system can be quite high; for a 5kW installation suitable for an average home will be between £20,000 and £25,000 [6] but the quick payback times, especially if utilising a feed-in tariff, will offset this nicely, putting it on a par with any other renewable system.
In summary then…
Small-scale hydroelectric production would appear to be more accessible than at first I though it would be. Of course if you don’t have the water then forget it, but if you do then it would seem that installing hydropower is just as cheap and easy as many other forms of renewable energy production. If all of the planning and environmental concerns are handled correctly, then there’s no reason you shouldn’t start tapping into the free resource that’s running through your property. There’s nothing quite like the relaxing sound of fresh running water – if it’s also saving the planet and saving you money, even better.
References
[1] http://www.british-hydro.org/hydro_facts.html
[3] http://www.british-hydro.org/microsmall_hydro.html
[4] Boyle, G. (2004) Renewable Energy: Power for a Sustainable Future. Hydroelectricity. Open University. Milton Keynes.
[5] http://www.derwent-hydro.co.uk/joint_ventures_and_funding/index.html
[6] http://www.energysavingtrust.org.uk/Generate-your-own-energy/Hydroelectricity
