‘Micro hydro’– Frequently Asked Questions
The answers in this document are designed to give a concise understanding, for the layman, of the process of installing a hydro system. More technical information can be found on the TGV Hydro website and on links via our website.
Please note that we use the short form ‘Micro Hydro’ or ‘Hydro’ to mean a small sized (less than 50kW) hydro electricity installation throughout these FAQs.
What is Hydro?
Hydro is the name that most people use when talking about generating electricity by using water power. There are various methods of production, but here we are discussing mainly the use of small, steep, streams to drive a turbine and generator. For more information on how hydro works see the TGV Hydro website at http://www.tgvhydro.co.uk
What do I do first?
Contact TGV Hydro to get a Viability Report, a short, desk based study of the stream which you believe might be OK for a hydro. We do not charge for single site Viability Reports.
I’ve checked out my stream, what next?
A full feasibility report is the next stage. This will go into the details of the flow of your stream and give you a clearer, but not guaranteed, idea of the potential output and income available from it.
I have a big river on my land but not much drop in height – can I have a hydro?
All falling water will be able to produce some electricity. We at TGV Hydro specialise in high-head hydro. ‘Head’ is the height difference between the start of a scheme (intake) and the end of a scheme (turbine house). We consider high-head to be where there is at least 20m (and preferably over 30m) of head. If this type of head cannot be achieved on your land then you could consider going into partnership with adjacent landowners to achieve the head. There are other options for streams with a lower head and we recommend you contact the British Hydropower Association (http://www.british-hydro.org) who have details of installers of low head systems
How much will it cost?
Every micro-hydro system is unique, depending on the water flow, the complexity of the weir structure, the size and length of pipe, the detail of the turbine house, the size of the turbine and its electric control equipment and a number of other factors. The Feasibility Study will give you the best idea of what your system will cost, how quickly it could pay back and the potential saving on greenhouse emissions.
Is the Feasibility Study expensive?
Costs for Feasibility Studies range from around £500 to £1,000 for a simple stream to around £5000 for an area study to £2,000 depending on the scale and complexity of the system, which looks at options over, say, a large estate or Local Authority area. But for farmers and smallholders and community groups we offer a discount price from £500 to £1,000.
Are there any Government grants to help with the cost?
No. The Feed-In Tariff (see below) is the alternative to up-front grants and is payable in arrears according to your output generation levels. For community groups there is sometimes support available for the costs of Feasibility Studies and the cost of obtaining permissions. However for private individuals, if you own a property in Powys, there is a small interest free loan scheme now available. Details from email@example.com
I like the look of the figures, what now?
The next step is the Design and Permissions stage, where TGV Hydro will produce detailed drawings and all the paperwork required for obtaining the necessary licences, permissions and agreements.
What permissions do I need?
In most cases there are three main areas of permission required.
The first is Planning Permission from your Local Authority.
The second consists of three separate watercourse related licences from the Environment Agency (if you live in Wales it is now Natural Resources Wales (NRW)). These licences are:
a) Abstraction: details the amount of water you are allowed to take out of the watercourse.
b) Impoundment: details the type of structure you are allowed to build in/across the water course.
c) Flood Defence: confirms that the works adequately deal with any potential increase in flooding risks of the surrounding area.
The third is permission is from the local National Grid’s District Network Operator (DNO). This agreement will give you permission to connect your hydroelectric scheme to the National Grid and export electricity. It will also determine the work that the DNO need to do to the overhead wires and local transformer.
Why do I need these licences if I’m only “borrowing” the water, not removing it?
Good question! Unfortunately that is just the way it is. It helps to ensure that the stretch of stream between the intake and the turbine maintain sufficient flow to protect plants and wildlife. The percentage of the water in your stream that you will be allowed to use will be determined at this time; there will always need to be a residual flow to protect the environment, you will never be able to take all of the water. Without the licences you will not be able to receive the Feed-in Tariff.
When can I start digging?
Once the site is going to become subject to a planning application no works relating to the construction on the system should be undertaken until planning permission is granted. If you do so this may impact on your planning application
How long does this take?
It is sensible to allow the best part of a year to obtaining all the necessary permissions as some surveys (e.g. fish, crayfish etc.) can only be undertaken at certain times of the year.
Planning Permission will normally take a maximum of a couple of months unless there are any special conditions which need to be looked at.
The three NRW licences take somewhat longer and include a pre-application stage to ensure that the scheme is likely to be OK before committing too many resources to the full application.
The time to process the DNO application and agreement varies throughout the country and would be between a number of weeks or a number of months. Any works that maybe required will usually have a lead in time of three or four months.
Is that all?
Yes, at this stage it is possible to begin construction. Registering for Feed-In Tariff and electricity exporting tariff cannot be completed until construction is finished.
What are Feed-In Tariffs?
The Feed-In Tariff (FIT) is a Government payment for producing renewable energy and is directly related to the amount of energy (in kilowatt hours) your system produces. The amounts payable for different types of technology and for different levels of output are published annually by OFGEM and can be accessed via the TGV Hydro website Links and Resources page. Just because it is called Feed-In doesn’t mean that you only get paid for what is exported to the National Grid, you can use the electricity in your own home and still get paid the FIT. Any electricity you do not use will be exported to the National Grid (see below).
Off-grid hydroelectric schemes will get paid the FIT for all generated electricity, but of course no Export payment.
What about exporting surplus to the grid?
As your system will be a part of the National Grid – a mini Power Station – whatever generated electricity you don’t use in your home or business will automatically feed into the National Grid.
Depending on the size of your system some companies will require for a separate export meter to determine how much you will be paid, others will simply allow a percentage of your output and pay up to that irrespective of the actual export level. The Government allow 75% of production to be counted as export for small systems under 30kW. Currently the minimum export tariff is 4.5 pence per unit.
How do I get these payments?
You will need to register your scheme with OFGEM, this can take some time, but all payments are backdated to the date of commissioning. Once registered you can complete an export agreement with your electric supplier. You then submit your total generation (and if applicable) your export readings figures quarterly to your chosen electricity supplier (e.g. SSE) and they will pay both FIT and Export to you.
I heard FIT rates were cut is it still worth doing?
The 2012 FIT review left hydro unchanged. The entry rate available for new schemes will go down by 5% a year starting April 2014, but remember your FIT rate also rises with RPI every year. It is anticipated that the export rate will also rise beyond the rate of RPI so that any reduction in your FIT starting rate may be offset by an increase in export rate.
Regardless of the changes in FIT rates your scheme would still contribute towards an overall reduction in greenhouse gas emissions.
Can I incorporate common land into my scheme in Wales ?
Yes you can utilise an area of common land, but you will need S38 consent – TGV Hydro can arrange this for you. It is possible that you will have to make a payment to the Commoners Association for the use of the land.
Can I develop a scheme with my neighbour(s) and earn FIT
Yes, a scheme can be on a number of separate landowners’ property. There are many ways of setting up the agreement between all the parties, from leasing all the land to a separate company that will run and administer the scheme to a simple rental agreement between parties.
TGV Hydro has set up a number of such schemes and can help you with this.
Will my electricity meter run backwards?
If you have an older style meter this may well happen. It will be your responsibility to tell your electric company that this is happening and they will arrange to come and have the meter changed.
Will I be able to keep my appliances running even during a general power cut? Sadly no, unless you invest in additional back-up battery capacity (see below).
As your hydro is part of the National Grid it is a legal requirement that it must stop producing at exactly the same time as the rest of the Grid. This is to protect the public and power workers from unexpected electricity on fallen or damaged cables. The DNO will not sign the connection agreement until they are sure that the appropriate protection is in place.
If your property regularly experiences prolonged power cuts then it would be possible to establish a back-up battery powered electricity systems but this must operate independently of your household wiring so as to ensure that no power is fed into the National Grid. This back-up arrangement can be established by any household and is not reliant on having a renewable energy source.
Will the generator be noisy?
No, from the outside of a turbine house hydroelectric turbines and generators are fairly quiet (especially in comparison to the flowing stream next to them). If your turbine house is somewhere that is particularly noise sensitive, then additional sound insulation may be added to the turbine house.
Will I have to upgrade the nearby electricity transformer?
That depends on the output of your system and the capacity of the adjacent transformer. This will be covered in the Feasibility Report and fully costed at that stage.
Can I build my own micro-hydro?
In principle yes, but in practice the complexities of both the intake design and construction and the technicalities of the turbine and controller units mean that only the pipeline (penstock, in industry jargon) and turbine house are viable for most competent landowners to complete themselves. Landowners with higher levels of construction skills may be able to undertake more. TGV Hydro however recommends a complete construction package to ensure that all parts of the system are compatible, but will always be willing to discuss the nature of the work and potential cost savings if the client wishes to build elements of the works that suit their skill levels.
We would always recommend that the turbine and turbine controller and all electrical work is only carried out by those with the relevant experience and qualifications to carry out such work.
Does building the system cause much mess and damage?
All works are carried out with the aim of creating as little mess and damage as possible; the Planning Permission will include a methodology statement that complies with planning rules to minimise any disturbance to wildlife and the environment. Laying the pipeline will probably incur some digging and the turbine house, if not in an existing building, may require foundations to be excavated.
What comes first in the construction?
That depends of many factors, including access, the weather and availability of components.
Does the installer have to be certified, as they do for PV panels?
At present there is no Government certification scheme for micro hydro in the way that PV and wind power installers must be certified to MCS. This is due to the unique status of each and every micro-hydro as opposed to the ‘off the shelf’ aspects of, particularly, PV generation. However each micro-hydro undergoes a check by OFGEM before FIT can be claimed (see above) and the local power distributor (the DNO) will have to ‘sign off’ the system for electrical safety as well (see above).
What does the intake look like?
Most often it’s a small dam, usually concrete, with a small stainless steel or concrete box in front of it, called a forebay tank. The top of the dam wall will have a couple of weir sections. One to allow water to bypass the scheme and stay in the watercourse, and the other will direct the water into your hydro system.
This tank has a stainless steel mesh lid which allows the water through, but stops leaves, twigs, frogs and the like from getting into the penstock. The penstock pipe is secured into the front of the tank.
In most cases there will also need to be a fish pass incorporated into the intake to allow any resident or migratory fish to circumvent the intake dam. This is usually made of concrete or stone and will be an integral part of the intake. The actual design will be determined at Design and Permission stage and be part of the Impoundment licence.
Can I take all the water in my stream?
No. The exact amount will be determined by the Abstraction licence and the intake design will be such as to ensure the correct proportions flow past the intake to maintain the stream.
Will the pipeline be visible?
Where possible the pipeline will be buried and so out of site, but there may be times where the land is too tricky to work and then it will be routed on the surface. All efforts will be made to ensure that it is not unsightly.
What is the turbine house like?
It can be anything from a small garden shed to a stone or brick built construction or it can be fitted into the corner of an existing building. This will be determined at the early stages of design and will be controlled by the Planning Permission rules.
What goes into the turbine house?
Inside the turbine house you will find the turbine itself (which you will find is actually quite small in most cases), the electricity generator, a series of automatic or manual valves and the grid controller unit.
What does the generator look like?
Basically it’s an electric motor, but instead of electricity powering it to do a job in the workshop or home, the water-powered turbine wheel is driving it to produce electricity. An electric motor in reverse, in other words.
What are the valves?
The valves control the flow of water to the turbine, ensuring that the pressure is maintained to drive it at the optimum speed for the amount of water available. Generally there will be one or more spear valves, which are constantly variable nozzles controlling the amount of water in the jet that hits the turbine. In addition there may be one or more butterfly valves which will be either Open or Closed and only function once the spear valve is at full capacity. Normally these will be automatically controlled.
Is the controller complicated?
Inside, unless you are an electronic or computer engineer, it looks very complicated, but the controls, which most users will only ever need to see, are very simple and require very little input from the user. However it is the key piece of equipment in turning water into useable electricity.
I’ve seen photos of turbine houses with electric heaters on the wall. Does the turbine house have to be kept at a constant temperature?
No, the heaters are used to ensure a controlled shut down of the system in the event of a power cut on the Grid. They allow the energy still being produced as the valves close down to be safely ‘bled off’ protecting both the Grid and your generator. Commonly these are known as ‘Dump loads”.
How do I get the electricity into my house?
TGV Hydro will ensure that all the connections from the turbine to your property are correctly arranged and covered with the appropriate safety devices.
How does the system know to use ‘my electricity’ rather than the Grid power?
This is not a perfect analogy but Voltage is a bit like pressure in a water pipe. Your hydro electricity will push with a bit more voltage than the grid so when the hydro scheme is working it will push out the hydroelectricity into the national grid rather than the other way.
Is there an ongoing need for maintenance?
Most components do not require any ongoing/regular maintenance, apart from cleaning the mesh on the intake from time to time. Some parts of the system do benefit from annual checks and there may be elements of the control systems which may require replacing after a few years. TGV Hydro can draw up a maintenance plan and schedule to ensure the continued ‘health’ of your system.