The Renewables Obligation (RO)
The Renewables Obligation is the main support mechanism for large-scale renewable energy projects across the UK. For smaller scale generators, the Feed-In-Tariff scheme has been the main source of support.
The RO first started in 2002 for England, Scotland, and Wales – closely followed by Northern Ireland in 2005. This scheme places an obligation on UK electricity suppliers to source an ever-increasing proportion of their electricity that they supply from renewable energy sources.
The scheme closed to all new generating capacity on the 31st of March 2017. Additionally to this there are also a number of early closures which are in force for specific technologies. Generators who are eligible can apply for a grace period can gain entry to the Renewables Obligation after these closures for a specified amount of time.
Renewables Obligation Certificates (ROCs)
The certificates issued to operators of accredited renewable generating stations for the renewable electricity they generate are called Renewables Obligation Certificates (ROCs). Operators are able to trade their certificated with other parties and are ultimately used by suppliers to demonstrate that they have met their obligations. ROCs are useful to suppliers who are incentivised to support the growth of renewable generation. The number of ROCs received for each MWh or electricity produced depends on the technology (wind, solar PV, anaerobic digestion, etc.) of the generation assets and when it was built. This process is called ROC banding and helps to promote newer technologies which will then receive more support with multiple ROCs per MWh.
Where suppliers do not present the minimum number of ROCs to meet their obligations in the reporting period (one year) they will be charged an equivalent amount to be paid into a buy-out fund. The administration cost of the scheme is then recovered from this fund and the rest distributed back to suppliers in proportion to the number of ROCs they produced in meeting their own obligations.
How many certificates have been issued for 2022?
| April | May | June | July | August | Total | |
| Hydro 20MW DNC or Less | 137,810 | 148,321 | 99,740 | 104,702 | 94,141 | 584,714 |
| Hydro 50kW DNC or less | 270 | 265 | 131 | 91 | 38 | 795 |
| Hydro Greater than 20 MW DNC | 7,348 | 0 | 12,648 | 4,459 | 2,043 | 26,498 |
| Micro Hydro | 3,777 | 4,264 | 2,651 | 2,697 | 2,170 | 15,559 |
How Does Hydro Power Work?
Hydro electric power is essentially a blanket term for any energy derived from flowing water, either from rivers or man-made installations. Man-made installations usually begin with high-level reservoirs, where water then flows down through a tunnel and away from a dam.
Within the flow of water are turbines, which are able to extract the kinetic energy and convert it into mechanical energy. This then spins turbines at a high speed, driving a generator that can convert mechanical energy into electrical energy we can use.
The amount of power generated largely depends on the flow and vertical distance that the water travels through (also known as the ‘head’).
What does DNC Mean?
In the table provided, all of the certificates are split by DNC figures.
This stands for Declared Net Capacity and is a measure of the contribution that the power station makes to the overall capacity of a distribution grid. This capacity is measured in MegaWatts (MW), or in megawatts electrical (MWe) for thermal power stations.
There is another expansion for this acronym in the UK, sometimes being referred to as Developed Net Capacity. Not to be confused, they mean the exact same thing.
For conventional power stations, the DNC rating is the maximum rated output minus the power consumed on-site. Sometimes this is called the ‘Switchyard’ output and takes absolutely no account of transmission losses in the grid (which in the case of remote hydro stations, can be quite considerable). Most power station ratings are DNC ratings rather than the capacity of the alternators.
For wind power stations, the situation is a little more complex. Here, the alternator of a wind turbine is usually specified to match the strongest wind in which the turbine is designed to operate in. This is due to most of the cost of a wind turbine coming from the rotor, tower, and bearings that support it rather than in the alternator. There is no economic sense in restricting the size of the alternator to anything less than the max that the rotor will deliver. This results in the wind turbine very rarely ever achieving its maximum rated output while operating, very different to how conventional power stations operate.
For conventional power stations, it is only regarded as available if the full power output is achievable. For wind power stations, no power at all may be available depending on wind speed. Even if a turbine is operating it may only be producing as little as 10% of its maximum rated capacity. A normal figure is around between a third and one half of the maximum rated capacity.
There are several recognised methods of allowing for this when quoting DNC figures for a wind farm, but none have achieved total general acceptance. The capacity quoted for a wind farm is normally a simple total of the maximum rated capacities of the turbines, coined as ‘peak capacity’. Many wind farm schemes also quote their expected and annual outputs in GWh to allow for more meaningful comparisons with other forms of generation.
Micro Hydro
There remains a strong focus on microgeneration and community schemes in the UK, with a lingering interest in redeveloping many disused watermill sites and small off-grid hydro projects. Micro hydro generation in the UK is still popular and looks set to remain so. This also includes pico, micro, and mini generators.
There are bountiful opportunities for sensitively sited micro hydro installation with up to 100kW installed capacity that can supply cheap, reliable generation with minimal visual and environmental impact.
Pico hydro is traditionally hydroelectric power generation of under 5kW, which is incredibly useful in small, remote communities that require only small amounts of energy to get by. Even smaller turbines of 200-300W may power an individual home with a drop of only a meter. Pico-hydro setups are typically run-of-stream which means that a reservoir of water is not created and only a small stream is common with pipes diverting some of the flow. This drops down a gradient and through a turbine before continuing back into the stream.
Flowing water has high potential energy as it flows downstream. Micro-hydro power stations convert the potential energy in small streams into kinetic energy via a turbine, driving a generator to produce electricity. The higher the drop and volume of water there is flowing through the turbine, the more electricity is able to be generated.
A steady and consistent stream of moving water has some incredible advantages over solar and wind generation systems. Hydro systems can run day and night in any weather as long as there is consistent flow of water through the turbine.
Niccolo Gas and Power
Unlike some suppliers, we actually want to talk to you.
If you are interested in our wide range of tailor-made product offerings then simply get in contact with us today. Or if you would like to find out more about anything discussed in this article, contact us directly or browse our website for ready-made solutions.
When you reach out to us, we will respond as soon as possible with our best prices – saving you money on your energy supply.
You can visit our website at https://niccolo.co.uk/contact-us
Or give us a call on 0131 610 8868
You can even email us directly at info@niccolo.co.uk
We look forward to hearing from you!