10 Things to Consider When Purchasing an Air Source Heat Pump (ASHP)
August 9, 2020
Air source heat pump technology rose in prominence in the 2010s in the UK, with the help of the Renewable Heat Incentive (RHI) – a subsidy paying for the low carbon heating generated to the improver, incentivising the take-up. Now in the 2020s the UK Government is looking to update the heating regulations to further accelerate the take-up of low carbon heating in exchange for the current gas boiler network.
Here we look at ten things to consider when deciding to purchase the air source heat pump for your home.
Installation cost consideration of Air Source Heat Pumps
Prior to installing what can ultimately be an expensive Air Source Heat Pump, ensure you have sufficiently insulated your house (see Solid or Cavity Wall Insulation, Loft Insulation, Floor Insulation), as otherwise the heat generated is not going to be efficiently used to heat your house. Insulation takes the heating demand down for your property, which allows ASHPs to be effective, given their low flow temperatures.
Buy certified MCS products and services
Only buy Air Source Heat Pumps certified under the Microgeneration Scheme or the MCS (make sure you check your supplier is signed up to the scheme), as this ensures the Air Source Heat Pump will be of suitable quality to fulfil your needs.
Offset cost of running Air Source Heat Pumps if possible
The Coefficient of Performance is a very important consideration
The Coefficient of Performance (CoP) is a measure of how efficient your heat pump is. For example if 1 unit of electrical energy is input into the Air Source Heat Pump, it should provide about 3.5 of useful heat energy (therefore it has a CoP of 3.5). The CoP varies between different Air Source Heat Pumps, so when buying a unit, remember the higher the CoP the better. The higher CoP Air Source Heat Pumps are usually more expensive (not always the case but check the manufacturer).
Air Source Heat Pumps perform poorly in low temperatures
Be aware that although Air Source Heat Pumps can still extract heat from the air in temperatures as low as -250c, the amount of heat they will provide at these temperatures will be much lower than if you live where there is an higher ambient temperature. So if you live somewhere that has a very cold ambient temperature, potentially look at other self generation energy solutions.
“Top-up” or secondary heating may need to be installed
The temperature of the water that an Air Source Heat Pump will produce is not as hot as a traditional boiler system, so you may need to consider secondary heating sources that act as a “top-up” heat form. Very popular is a log wood burning stove or an infrared heating panel.
Air Source Heat Pumps may irritate your neighbours
Air Source Heat Pumps produce noise, not a lot, but best to ensure it is not situated directly outside your bedroom or too close to the boundary of your next door neighbour. We filmed this short video clip on YouTube about Air Source Heat Pumps, therefore decide for yourself on the potential noise levels.
Always follow the latest planning guidelines prior to installation
In terms of planning permission, Air Source Heat Pumps are normally listed under permitted developments so no specific planning permission is actually required, however for this to be the case you do need to adhere to certain criteria of which the main one is related to neighbours and ensuring there is a suitable distance between your heat pump unit, and their house (please check with your installer / planning authority to make sure you adhere to building regulations).
Positioning of the system will drive its performance
You need to install your Air Source Heat Pump outside where there is a sufficient ambient air flow (we suggest doing so on ground level so it is easy to reach if it needs maintenance). Air Source Heat Pumps work by taking heat out of the air, so if you were to position it in an enclosed space, then it wouldn’t be effective.
Ensure you have a few quotes before you make a decision
As with all serious investments it is worth getting several quotes before investing in an Air Source Heat Pump. We also recommend speaking to other customers of your proposed installer, get their views and put your mind at rest when they tell you they have had a job installed to satisfactory standards.
If you are unsure about where to read up further about Air Source Heat Pumps because the whole thing sounds like a bit of a minefield, then we suggest going onto the MCS website and clicking on the section about manufacturers. It is worth speaking to a number of manufacturers so you get a feel for what the unique capabilities are of the systems you are looking to have installed in your property.
Introduction to Solar Thermal
What is solar thermal?
Solar thermal (also known as solar heating) harnesses the energy provided by the sun to provide thermal energy to heat water. The hot water produced by the solar heating can be used to supplement your domestic hot water (although the temperature might need to be topped up by a boiler), larger stores of water (like swimming pools), underfloor heating, and for space heating/cooling.
Unlike a solar photovoltaic cell array, which is designed to produce electricity, a solar heating system is designed simply to produce heat. A well-designed solar heating system will provide approximately 55% of your annual domestic hot water requirement. However, as it is reliant on the sun, your solar heating system will produce more heat in the summer months.
Types of solar thermal system
Solar heating systems all have a few components in common: a solar collector, insulated heat transport piping and heat storage. More complex systems also have electronic controls and freeze-prevention mechanisms (when situated in colder climates). There are three main types of solar collectors:
1. Flat panel solar collectors
These are the most common type of solar heating technology and consist of a box with a piece of glass on the top and a dark absorber plate on the bottom. Sunlight passes through the glazing on the top of the box, heating up the absorber plate and converting the solar energy into thermal energy. Copper pipes are attached on the top of the absorber plates, and the liquid flowing through these pipes absorbs the heat, which is then pumped away and stored until it is needed in the house.
2. Evacuated tube solar collectors
The evacuated tube systems tend to be more efficient, especially in cold or cloudy climates; however their advanced design makes them more expensive. These solar collectors consist of rows of parallel, transparent glass tubes. Each tube contains an absorber assembly and the entire tube is evacuated of any air (so it operates within a vacuum). The sunlight enters the glass tubes and hits the absorber assembly where it is absorbed. As this is operating within a vacuum, heat does not travel back from the absorber to the glass, so these are more efficient. A fluid transfers the heat from the absorber assembly through to the storage tank, where it can be used.
The two major advantages of evacuated tube collectors are that they can produce warmer water (so you will not need to supplement the temperature with a boiler) and they can also produce more hot water than flat-panelled solar collectors.
3. Plastic collectors
These are the cheapest type of solar collector and consist of black plastic pipe treated to withstand UV degradation. Hot water is simply pumped through the black plastic pipes, where it warms up (as the plastic absorbs the suns energy). Plastic collectors are most susceptible to ambient temperatures as there is no insulation in place, so if the outside temperature is cold, very little heat will be produced.
These are an ideal solution for swimming pools though, as they amplify the effects of the weather and its seasons. For example, most swimming pools are used in the summer, so installing plastic collectors will allow you to use the pool sooner in the year, and it will keep the temperature consistently higher.
Things to consider before installing a solar thermal heating system
As with solar photovoltaic cells, solar heating technologies require sunlight, so ideally you would install the technology on a south-facing roof that receives sunlight for most of the day to maximise the benefits. Likewise, the amount of heat you can produce is directly proportional to the amount of installed surface area you have; therefore if you only have a small roof, then this technology may not be appropriate.
In addition, you will produce more hot water in the summer, as the energy from the sun is more intense at this time, therefore you may well have to supplement the temperature of the water in the winter using a boiler. To boost the system, your boiler must be compatible with your solar heating system, but currently most combi or CHP boilers are not compatible. It is therefore very important that you check with your installer before undergoing any works.
If you live in much colder climates you may need to have some sort of antifreeze within your system (when water freezes it turns to ice it expands, potentially causing cracks in the pipes).
If you live in a listed building please note the restrictions. Like with many green technologies, it is worth contacting the local planning office to get permission to place the panels, to save yourself problems further down the line.
Installing solar thermal normally requires a new hot water tank
For many of us with old heat-only boilers, we have a hot water tank hidden away in the airing cupboard. Typically these hot water tanks are heated by a boiler and were purpose-built.
Since the introduction of the RHI, there has been a huge increase in the number of people installing solar thermal in their homes.
If you decide to install solar thermal in your home you will need a hot water tank to store the hot water produced from your collector – the problem though, is that you can’t plumb one of these systems into the older hot water tanks that are historically found with boilers.
Twin coil cylinders
The reason for this is that inside the hot water tank there needs to be a separate coil for each ‘hot water source’. In this case you would need a coil for the solar thermal and one for the hot water. Normally in a residential solar store (i.e. a hot water tank with a solar coil), the solar is connected to the lower coil and the boiler (or main heating source) is connected to the top coil.
Solar coils are much larger than traditional boiler coils because they need a far bigger surface area to transfer their heat into the water compared to a boiler. The reason is that the hot water travelling through the solar thermal coil is at a much lower temperature than the water travelling through a boiler coil.
As a guide, the surface area of a solar thermal coil needs to be in excess of 1.5m2, while a boiler coil can be as little as 0.6m2 – this increased surface area maximises the opportunity for heat transfer and is a must based on the lower water temperature flowing through the coil.
If you cast your mind back to your GCSE science, you will know that heat rises and therefore within a hot water tank, the water at the top of the tank is far warmer than the bottom of the tank.
In a solar thermal store, it is important that this temperature differential is maximised and this is achieved by making the hot water tank rather large and tall. So while the top of the tank could achieve temperatures of 600C plus, the water at the bottom of the tank might be as low as 150C degrees. What this means is that even if the solar thermal is only producing water to 200C degrees, it will still contribute to the hot water demand of the property.
Storing the hot water you produce on sunny days
Since the hot water tanks used for solar thermal systems tend to be big, they tend to be able to store far more hot water than is actually required by most families that install one of them. Since solar thermal is intermittent, (i.e. it produces much more hot water when the sun is shining), this oversized heat tank allows you to store the hot water; thereby taking advantage of favourable conditions a day or two later to help minimise the need to use the boiler.
Maximising return on your investment
The Renewable Heat Incentive (RHI) is now up and running, which works in a similar way to the Feed-in Tariff, rewarding you for any hot water you produce from renewable sources. You can find all the information you need about the RHI on our page here.
Solar water heating will provide hot water throughout the year, although less so in winter.
Once you have installed the equipment, it provides a free source of hot water.
All solar technologies are reliant on the sun shining; hot water will not be produced at night.
The maximum water temperature that can be achieved via solar heating is significantly lower than that achieved with gas or electricity-based water heaters.
The cost of installing a solar hot water system ranges from approximately £1,500 for a DIY system, to £2,000-£5,000 for a commercially installed system. These prices however, are dependent on the size of the system. The savings resulting from the installation will be approximately £50 – £90 per year.
Installing Solar Thermal
Interested in installing a solar thermal system at home? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local installer to help install a solar thermal system in your home, just fill in the form below and we will be in touch shortly!
The Domestic Renewable Heat Incentive – what is it?
The Renewable Heat Incentive (RHI) is a government scheme that pays people that produce their own heating and hot water using renewable energy sources such as heat pumps or solar thermal panels.
The scheme has been launched in an effort to help the UK government meet its legal commitment to ensure 15% of the UK’s energy comes from renewable energy sources by 2020.
This scheme has been up and running in the commercial sector since November 2011, however the domestic RHI scheme kicked off in April 2014 for households in the UK. The Renewable Heat Incentive works in a similar way to the Feed-in Tariff (which is for domestic renewable electricity production); households in this case being paid based on the amount of renewable heat they produce.
There are currently 4 technologies that are eligible for the domestic renewable heat incentive
Solar heating (also known as solar thermal – only flat plate and evacuated tube solar panels are eligible)
The payments will be made quarterly for seven years and should cover a significant proportion, if not all of the initial installation costs.
Domestic Renewable Heat Incentive tariffs
Each of the renewable technologies eligible for the renewable heat incentive have different RHI rates associated with them, mainly because the cost of installing the different technologies varies considerably and the RHI payments are designed to help cover some or all of the initial install cost.
On the whole, the RHI rates have increased very slightly in line with inflation except for biomass boilers and wood pellet stoves with back boilers which have dropped considerably – the rates below are correct as of September 2018. These can change from quarter to quarter, depending on how many people claim the payments. This is known as ‘digression’. You can find current rates here.
The payments are made on a quarterly basis and last for a total of 7 years. In addition, the tariff amounts are RPI index linked, so as inflation increases over time, the tariff rates above will increase with it. The RPI increases will be applied to the rates on 1st April each year.
RHI Payments will last a total of 7 years
Much like with the feed-in tariff, once you sign up to the RHI you will be locked in at the tariff rate that you initially get – so if you installed a Ground Source Heat Pump today you would get a payment of 20.46p per kWh of renewable heat you produced for the next 7 years (although it will increase with the the RPI each year).
Since there is a finite pot of money available for the RHI payments, it is likely the current tariffs will get smaller over time (again much like the solar feed-in tariff) therefore if you are considering installing a renewable heating technology it is worth moving quickly to ensure you get the highest payment rate!
The government do a quarterly review of the RHI scheme and adjust the tariff amounts in line with the total RHI budget so as to control the costs. Therefore if you install a renewable heating system you will get (and lock in) a better rate potentially than someone who installs a renewable heating measure 2 years down the line.
RHI payments are estimated based on heat demand rather than Metered
Tariff payments will be deemed rather than metered, which means they will estimate the heat demand of the property and base the RHI payment on that. This means that it is paramount to install a heating system that is correctly sized; because if you install a more expensive, oversized biomass boiler (that creates more than you require), you will be paid the same through the RHI and potentially won’t recoup the additional unnecessary investment.
Likewise, there are ways to maximise your RHI payments!
For biomass boilers and wood pellet stoves, the RHI payment can be fairly easily calculated based on the heat demand of the property. This heat demand figure can be found right at the bottom of the Energy Performance Certificate (EPC) expressed in kWhs – so it is simply a case of multiplying £0.0674 x this number, which will give you the total annual payment.
For solar thermal, the MCS approved installer calculates the RHI payment. They will deem a figure that is the estimated contribution of the solar thermal to the home’s hot water demand, but the calculation is based on occupancy – the more people that reside in the property, the higher the payment – worth bearing in mind when you are speaking to your installer / green deal assessor.
For heat pumps (both ASHP and GSHP) the heat demand figure from the EPC is combined with the heat pumps estimated efficiency to calculate the RHI. Remember not all the heat produced by heat pumps is renewable, therefore only the part that is will receive RHI support.
The technical term for the estimated efficiency is known as the Seasonal Performance Factor (SPF) – and this tends to be somewhere between 2.5 and 4 (this is also sometimes referred to as the Coefficient of Performance or CoP). So an SPF of 3 for example, means that for every one unit (kWh) of electricity used, 3 units (kWh) of useful heat will be produced.
Therefore the RHI for heat pumps is calculated using the 2 formulas below:
1. Eligible Heat Demand = Total Annual Energy Demand x (1 – 1 / SPF)
2. Annual RHI = Eligible Heat Demand x RHI Tariff
Example calculation for Air Source Heat Pumps:
For a home with a heat demand of 25,000kWh installing an air source heat pump with a SPF of 3.5 the annual RHI payment would be:
Then multiply by RHI tariff (10.49p / kWh) = £1,873.20 per year
Only heat pumps with an SPF of 2.5 or more are considered renewable under the EU Renewable Energy Directive and only those that are considered renewable will be eligible for the RHI.
How long will my renewable heating investment take to pay back?
This is a difficult one to answer to be honest because it is so dependent on your home’s individual heat demand.
In terms of investment, you can expect to pay about £8,000 for an air source heat pump, £20,000 for a ground source heat pump, £8,000 for a biomass boiler and £4,500 for solar thermal.
If you can get an accurate view of the heat demand (from the EPC) then you should be able to calculate the annual payment from the domestic RHI, which multiplied by 7, will give you to the total payments to expect over this period.
With the investment figure and the total lifetime RHI return (comparing renewable heating to the next best alternative), you should be able to get a rough feel of the payback.
Eligibility requirements for the Domestic Renewable Heat Incentive
Renewable heating systems don’t come cheap – the domestic RHI makes these systems more affordable by offering a financial incentive based on the amount of heat they produce. However, there are quite strict eligibility criteria, so it is worth ensuring that you adhere to the rules to make sure you are entitled to the payments.
Which technologies are eligible for the domestic RHI?
As previously mentioned, the renewable heat incentive is available on installations of any of the following technologies:
Air source heat pumps (limited currently to those that heat water)
Wood pellet stoves with back boilers
Ground source heat pumps (this term also covers water source heat pumps, which are considered GSHP by RHI guidelines)
Solar thermal (only flat plate and evacuated tube solar panels are eligible)
Download the full list of eligible installations here.
Who is eligible for the domestic RHI?
The scheme covers single domestic dwellings (as soon as the heating system is providing heat to more than one property, you would need to look at the non-domestic RHI). It is open to owner-occupiers, private landlords, registered providers of social housing, third party owners of heating system and self-builders.
Note to private and social landlords: you will need to agree with the tenants that an annual servicing visit will be required to ensure the system complies with the detail set of requirements and continues to be eligible for domestic RHI payments.
New builds are not eligible for the RHI – this means the renewable heating system was installed in the home before it was inhabited for the first time.
You heating system needs to be on the Government approved list
In order to ensure eligibility for the RHI, you must make sure the renewable heating system you get installed is listed on the Governments product eligibility list (PEL) – you can download this here.
MCS accreditation is a must!
To be eligible for the scheme, the installers must adhere to the European Standard EN 45011. The Microgeneration Certification Scheme (MCS) adheres to this standard, therefore as a rule of thumb you need to ensure that the team installing your renewable heating system are MCS accredited and the kit being installed is also MCS accredited.
Equivalent schemes to MCS do exist, but don’t simply take your installers word for it that they adhere to EN 45011 – check all the relevant paperwork before getting any work done.
Getting a Green Deal Assessment is no longer required!
In early 2016, the Government changed the elegibility requirements for the RHI and one of those changes involved scrapping the need for the Green Deal Report. The EPC is still a requirement though – this needs to be dated within the last 48 months – and will be used to calculate your RHI payments.
If your EPC recommends loft and cavity wall insulation it must be installed before you apply and you’ll then need to get a new EPC that no longer recommends these measures. The reason for this is that heat pumps and solar thermal tend to produce hot water at lower temperatures than traditional gas central heating systems. This means that radiators and underfloor heating will be operating at cooler temperatures compared to regular central heating systems, therefore it is very important the house is really well insulated prior to having them installed. The insulation process should bring the heating requirements of your home right down.
I have received other grants to pay for the technology. Do I still get the domestic RHI?
DECC confirmed in 2013 that any public funding paying for the domestic renewable heating installation would be deducted from RHI payments made. In addition, where an installation was not at least in part paid for by the owner, even where the installation was funded from a private source, that installation will not be eligible for the domestic RHI. An installation which has been part-funded by the owner will be eligible.
I have already installed my renewable heating system – Can I still claim the RHI?
You must apply to join the Domestic RHI within 12 months of the commissioning date of the renewable heating system. This can be found on the MCS certificate. The team that run the admin side of the RHI at DECC offer very little wriggle room here (99 times out of 100 – zero wiggle room!) so make sure you apply within the stipulated timeframes.
Technology Specific Eligibility Requirements
All heat pumps must have a Seasonal Performance Factor (SPF) greater than 2.5 to be eligible for the RHI. Heat pumps installed by legacy applicants will automatically be considered to have an SPF of 2.5, and will require a full assessment by an MCS installer to prove a higher SPF (which would lead to higher RHI payments – so may well be worth doing!)
If a heat pump is installed alongside another space heating system then a meter will need to be installed to gauge exactly how much heating is coming from the heat pump. RHI payments will be based on these meter readings rather than the estimated heat demand for the property.
Biomass boilers/wood pellet stove with back boiler
If a biomass boiler is installed alongside another space heating system then a meter will need to be installed to gauge exactly how much heating is coming from the biomass system. RHI payments will be based on these meter readings rather than the estimated heat demand for the property.
New installations of biomass boilers will need to meet strict air quality standards in relation to particulate matter and oxides of Nitrogen – as mentioned previously – legacy applications will not need to adhere to this.
If the air quality standards change in the future, you do not need to concern yourself with your installed boiler not meeting the standards.
To be eligible for the RHI, the fuel needs to be sourced from a supplier registered on the approved supplier list.
How do I apply for the domestic RHI?
The application process for the domestic Renewable heat Incentive is fairly simple, however numerous pieces of evidence (installation certificates, EPC, and photos for example) are required for the submission.
Since the RHI is funded out of a public kitty (through tax payers), it is important that the money being spent to subsidise the scheme is under the right level of scrutiny, hence the volume of evidence required.
Applying for the domestic RHI
Applications for the domestic RHI are made through the OFGEM website through the My RHI portal
However if you find the thought of carrying out this process a little too onerous, there are third party companies offering to complete this on your behalf, although obviously there is a charge for this service. The process genuinely is pretty easy though, so in our opinion certainly worth giving it a try yourself before getting this kind of company in!
The RHI is now closed to legacy applicants
If you are a new applicant (so the installation took place after the scheme launched), then you will be able to claim the RHI straight away.
Unfortunately the scheme has now closed to legacy applicants (i.e. those who installed their renewable heating system prior to the scheme going live in April 2014).
Can the set RHI levels be changed once I have applied?
The headline RHI tariff figures do change, like we have already seen for the biomass renewable heat payments, and as time goes on and the RHI budget gets used up, we expect further drops in the tariff to take place. The Government will look at the tariff levels every 3 months and adjust them accordingly – however if you are receiving the RHI – you have locked in to whichever rate was agreed at the beginning – this is the rate that you will receive for 7 years (although it will increase with RPI each year).
Is there anything else I need to know?
The government will run a “Metering and Monitoring Service Package”, which consumers can volunteer for. Data collected under this scheme will be shared by the Department of Energy & Climate Change (DECC) with the installer and consumer. Domestic RHI recipients who volunteer will receive £230 per year to have their heat pump installation monitored and £200 per year to have their biomass installation monitored.
Hybrid systems installed with a gas boiler or oil boiler will need to be metered, except solar thermal systems.
The system will need to be serviced annually in accordance with manufacturer’s instructions to ensure efficient running of the system.
Coefficient of Performance and Seasonal Performance Factor
February 28, 2014
When it comes to researching heat pumps, you will come across two terms constantly that you need to understand – Coefficient of Performance (often abbreviated to CoP) and Seasonal Performance Factor (abbreviated to SPF).
Understanding what these terms mean is absolutely key, since they reveal the efficiency of a heat pump. Obviously the more efficient the heat pump the better, since running costs will be lower, but also these values will have a direct impact on the amount you will receive via the renewable heat incentive!
The Coefficient of Performance of Heat Pumps
The Coefficient of Performance is a simple ratio of the heating provided by a heat pump to the electricity consumed.
In a heat pump, electricity is used to move heat from a cold reservoir to a hot reservoir in a very efficient way. How efficient? Where an electric heater converts 1kW of electricity into 1kW of heat, a heat pump converts that 1kW of electricity into 3 or 4 kW of heat.
It is easy to think that this is defying the laws of thermodynamics, but of course the heat from the pump is not being generated, it is simply being shipped from outside the property into the inside. The warmer the external heat source, the better, since there is less electricity required to get it up to a nice temperature.
The Coefficient of Performance therefore varies throughout the year – in the winter months, an air source heat pump will require more electricity to get the heat up to a comfortable temperature so the CoP will be relatively low (perhaps 2.5). In the summer the opposite is true; since the external temperature of the air is warm already, the heat pump doesn’t require much electricity to get the heat pump up to a nice temperature, so the CoP might be as high as 4 or more.
Now consider a Ground Source heat pump, this takes advantage of heat in the ground and uses a series of buried pipes to absorb the heat. Since the ground temperature has very little variation over the year, the CoP will likewise be relatively consistent.
Hopefully you can spot a problem with using CoP as the sole measure of heat pump efficiency – since there is massive seasonal variation we need a means of getting an average efficiency of the heat pump over a year, to be able to compare different heat pumps.
The Seasonal Performance Factor of Heat Pumps
As we have said, the temperature of the ground or air being used by the heat pump plays a key role in the system’s efficiency. The seasonal performance factor takes into account how well the pump works at both low and high temperatures, and is a far better reflector of how efficient your pump will be than the CoP.
It allows you to make calculations between different ground, air and even water source heat pumps, which is pretty fundamental since the variation in costs between the different units. For example we quote a guide price of £25,000 for a ground source heat pump, while an air source heat pump is far cheaper at just under £10,000. The SPF of a ground source heat pump could be as high as 4 over the year, while the SPF of an ASHP may be only just over the 2.5 mark. Depending on energy usage, this means that relatively quickly, opting for a GSHP could be a better decision based on energy savings.
Likewise, if you look at the calculation for the Renewable Heat Incentive – it takes into account the SPF, rewarding a heat pump that is more efficient through higher payments. You can see how to calculate the RHI here.
Good CoP, Bad CoP
As we have seen, the performance of a heat pump can vary wildly depending on a number of factors, but generally speaking ground source heat pumps can regularly be found on the market with a COP greater than 4. Air source heat pumps tend to be less efficient, and a COP over 3 is considered good. Comparing different air source heat pumps, it is worth bearing in mind that a heat pump with a higher CoP / SPF will cost more, and the same is true when comparing ground source heat pumps with one another.
The Domestic Renewable Heat Incentive Tariffs (finally) confirmed!
July 22, 2013
After much waiting and considerable government deliberation, the feed-in-tariffs for the Renewable Heat Incentive scheme has finally been announced. This means that generating energy using alternative renewable sources such as heat pumps and solar thermal will now get you money through a similar feed-in-tariff system to those already in place for wind and solar. The scheme launches next spring.
Greg Barker, Climate Change minister says, “Investing for the long term in new renewable heat technologies will mean cleaner energy and cheaper bills. So this package of measures is a big step forward in our drive to get innovative renewable heating kit in our homes.”
“The uptake of microgeneration technologies under the Feed-In Tariffs scheme has shown that renewable technologies can move from niche to mass market in just a few years, and with the support of the domestic RHI, I hope that renewable heating technologies will see such success.”
You can take advantage of the scheme if you have had any of the technologies installed since 15 July 2009. Those applying will also need to carry out a Green Deal assessment; which assesses a property’s energy efficiency and recommends suitable energy saving measures, the Department of Energy and Climate Change (DECC) says. In order to claim the incentive, householders must also ensure that their home has a minimum 250mm of loft insulation and cavity wall insulation if appropriate.
The Renewable Heat Incentive Tariffs
The generation tariffs for each technology are as follows:
Solar thermal (evacuated tube and flate plate) – at least 19.2p/kWh*
Ground source heat pump – 18.8p/kWh
Biomass boilers and biomass pellet stoves with a back boiler – 12.2p/kWh
Air source heat pumps (air-to-water) – 7.3p/kWh
This means that for every kilowatt hour of energy you produce using your renewable system, you will get a payment as above. Of course, these technologies do have high installation costs, but there is assistance available to help with this. Until next march you can take advantage of the Renewable Heat Premium Payment, which has been running for some time now, where you can get a lump of money towards the costs of installation, dependent upon the technology in question:
Ground source heat pumps – £2,300
Biomass boiler – £2,000
Air source heat pumps – £1,300
Solar thermal – £600
You can also get a Green Deal loan to help pay for the cost of these measures, for which you will require a Green Deal Assessment (as mentioned a prerequisite of the incentive anyway). Most of these technologies, just like solar PV already, offer a great way to move yourself away from dependence on the grid, and cut your fuel bills. The payback really could be worth it, so think about booking an assessment and getting yourself ready for the scheme when it starts.
Likely Returns to expect from the Renewable Heat Incentive
In terms of returns Steve Munday, MD of SMC solar ltd said “Running the numbers for an Air Source Heat Pump I can conclude that you will get around £8,000 back on a £9,000 investment (without considering fuel cost savings).Both these figures assume that a retro-fit to an existing radiator system does not require any upgrade. So the reality is that homeowners may need to budget a little extra for upgrading their radiator system. The amount of this will only become known after detailed room-by-room heat loss assessment.
Like with the Feed-in-tariffs to incentivise solar panels, the grants will be rapidly reduced over the ensuing years deliberately to incentivise and reward early investors.This really is a ‘no-brainer’ for anyone with a moderately old oil boiler. Even owners of gas systems are eligible although the fuel cost benefit will not be so pronounced until gas prices rise, as they inevitably will. ‘The early bird will catch the worm”
So there you have, act quickly to ensure you benefit from these generous tariff payments! If you want to learn more about the renewable heat incentive please visit our dedicated page here.
Microgeneration Certification Scheme (MCS)
What exactly is the Microgeneration Certification Scheme?
You will see across the site that we recommend installing microgeneration products that have the MCS stamp of approval. This is an eligibility requirement both for the Government Feed-in Tariff (FiTs) and the Renewable Heat Incentive (RHI – launching in Spring 2014), but what actually is it?
MCS stands for Microgeneration Certification Scheme and this is an internationally recognised quality assurance scheme fully supported by the Department of Energy and Climate Change. The MCS certifies products that produce electricity and heat from renewable resources.
It ensures that any microgeneration or renewable products you install (e.g. solar PV) have gone through a comprehensive assessment ensuring that they are built to a sufficient quality, they perform at an optimal level and they operate safely.
The MCS allows consumers to easily recognise good quality products and be sure that the performance promised by the manufacturer is what you might expect in reality.
MCS certifies electricity generating products up to 50 kW, CHP products up to 50kW and renewable heating products of up to 45kW.
MCS also covers Installers
Apart from using products that have the MCS stamp of approval, you also need to ensure that MCS approved installers have installed them. Making sure you use installers that are MCS qualified will help ensure you receive the money you are entitled to under the Feed-in Tarff, the Renewable Heat Premium Payment and any of the other renewable energy grants.
What Microgeneration products fall under the MCS?
The following renewable products fall under MCS quality assurance mechanism:
At present, the only other scheme that can be considered equivalent to the MCS is the CEN Solar Keymark Scheme, however this only covers solar heating collectors and it does not cover their installation (e.g. you will need to get the product installed by a MCS certified installer to ensure you are eligible for Government grants and subsidies).
How do I find an MCS accredited Installer
Before you begin your search to find an MCS accredited installer, make sure you understand everything you need to know about the renewable technology that you are trying to install. For ideas on renewable solutions please see our self generation section.
When you have acquired the knowledge in the technology, it is the right time to find an MCS approved supplier. If you go onto the Microgeneration Certification search functionality and find yourself 3 installers. It is important to get quotes so you get the best price for your work.
You will then get the products installed by the MCS approved installer. Once this is complete you should then receive your MCS approved certificate. If you click on the Feed-in Tariff page you will see what you need to do to start claiming your FiT payments.
Air source heat pumps convert heat energy from the air to provide heat and hot water for dwellings. They run on electricity, but are incredibly efficient (in some cases 300% or more), which means that for every one unit of electricity used, they produce 3 units of useful heat.
If you compare that to a brand new boiler which is 90% efficient (1 unit of gas produces 0.9 units of useful heat), you can quickly see why these systems are so popular. In fact, if you don’t have access to mains gas, heat pumps are definitely the way to go to fulfil your heating and hot water requirements – provided you have a well insulated home, which is discussed later.
Better still, if you decide to install an air source heat pump in your home, you can also benefit from the Renewable Heat Incentive, which pays you for each unit of hot water water you produce. In some cases, the funding will cover the cost of installing the heat pump, but it gets paid over 7 years on a quarterly basis, so you will still need to find the money upfront!
The air source heat pump needs to be located outside in the open air, and uses a fan to draw air into it. This air then flows over a heat exchanger, which contains a refrigerant liquid. An evaporator uses the latent heat from the air to heat the refrigerant liquid sufficiently until it boils and turns to a gas. This gas is then compressed by a compressor, which causes it to significantly increase in temperature. An additional heat exchanger removes the heat from the refrigerant (turning it back to a liquid), which can then be used as useful heat. There are two types of air source heat pump:
Air-to-water heat pumps
Air to water heat pumps are by far the most popular. These take heat from air outside the property and transfer this to water, which can be used for space heating or as hot water for washing within the house.
Air-to-air heat pumps
These remove latent heat from the air outside the property which is then simply fed into the home through fans. This type of heat pump cannot be used to produce hot water.
Since they include fans and compressors, air source heat pumps require electricity to operate, and bearing in mind the price of electricity is approximately 15p / kWh and gas is just 4p / kWh, on the face of it, you would expect heat pumps to be far more costly to run than gas boilers.
This is not the case though – since for every kW of electricity used to run them, they provide approximately 2.5-3.5kW of equivalent useful energy (depending on the model and the temperature of the external air). This makes running costs comparable to a traditional gas boiler.
The efficiency of air source heat pumps is measured by the Coefficient of Performance, which is simply how many units of useful energy produced from each unit of electricity are consumed to operate the system. For example, if at any moment the heat pump was producing 3kW of useful heat from each unit of electricity, the CoP would be 3.
The CoP varies throughout the year, with lower figures achieved during the colder months (meaning they are running less efficiently), since there is less ambient heat available to remove from the air. This makes comparing the efficiency of different heat pump systems very difficult, so we use what is known as the Seasonal Performance Factor to compare like for like performance of models. This is the annualised CoP, taking into account the different performance throughout the year.
Air source heat pumps don’t produce boiling water
The air source heat pump does not produce the sort of hot water temperature you would associate with a gas, LPG or oil-powered boiler. With a boiler, you would expect the hot water to be heated to about 850c, while a heat pump produces water to about 550c. Trying to increase the water temperature from a heat pump beyond this requires the compressor to work harder, meaning more electricity – this in turn reduces its efficiency or coefficient of performance.
As a result, it is very important to minimise heat loss from the property prior to installing a heat pump. This includes insulating the walls, loft and ideally the floor too. This means that even though the radiators won’t get as hot (using heat pumps), the house is still heated effectively and you are not straining the heat pump – which is expensive.
When installing a heat pump, you may be required to increase the size of some of the radiators in certain rooms too. This is simply because the heat demand will not be met with the existing-sized radiators. If this is the case, you can expect to pay about £200 – £300 for each radiator that needs to be replaced (providing the pipework running to the existing radiator can be reused).
Air source heat pumps and the Renewable Heat Incentive
Heat pumps are part of the Renewable Heat Incentive scheme recently launched by the Government. It means that, if you install a renewable heating technology, you can get paid for each unit of heat you generate. RHI payment rates depend on lots of things, but you can see detailed information here.
Occasionally, but not often, the RHI payments will be enough to cover the cost of the initial outlay of the air source heat pump. Air source heat pumps normally cost between £7,000 – £10,000.In a standard property you can expect to receive a total of about £2-5,000. RHI payments are paid quarterly over 7 years, so you will need to stump up the money up front.
Things to consider before investing in an air source heat pump
Placement of air source heat pump – An air source heat pump requires plenty of space, either to mount on an external wall or to be placed on the ground. The unit needs good air flow, and foreign objects such as boxes, containers etc need to be kept well away.
Cost of air source heat pump system vs system that is being replaced – Purchasing an air source heat pump on top of an existing heating system will prove to be an expensive option; therefore we recommend considering this when replacing an old electric or old oil-fuelled system. However an electric heater will convert 1kW of electrical energy to 1kW of heat energy and an air source heat pump will convert 1kW of electrical energy into 3.5kW (almost 4kW) of heat energy.
Insulation – The air source heat pump emits low temperatures but on a consistent basis. To maximise effectiveness, ensure that your home is suitably energy efficient by installing wall insulation (either cavity or solid wall) and draught proofing. These are low cost measures that will make a big difference to your utility bills, therefore it is worth investing in them prior to replacing your heating system with an air source heat pump.
Noise of air source heat pump – An air source heat pump does make some noise when operating, as both a fan and a compressor will be in motion. The noise is approximately 40-60 decibels (depending on the system) from a distance of one metre away. So please ensure if you invest in an air source heat pump, it is not placed directly outside your bedroom window!
We have filmed an air source heat pump in motion, (don’t say we don’t treat you) so you can see for yourself how they operate.
Efficiency of air source heat pumps – Despite air source heat pumps being able to operate at -250C, the efficiency decreases as the outside temperature drops; therefore if you live in a particularly cold place, you may well need to supplement the heat pump with an additional boiler to get the hot water you require. Try a CHP boiler if you can invest additional resources. The problem may be getting the two systems to work successfully in tandem; therefore a traditional boiler could be your only option.
Local authority regulation for air source heat pump installation
Generally there are fewer restrictions from local authorities in England and Scotland when looking to install an air source heat pump (noise being the main consideration), but please check with your council and installer before proceeding. In Wales and Northern Ireland, an air source heat pump installation requires planning permission.
As the heat pump provides the hot water for heating, there are large savings to be made on fuel bills – typically an air source heat pump can deliver up to 3.5kW of useful energy for every 1kW of energy needed to run it.
An air source heat pump can still take heat out of the air in temperatures as low as minus 20 degrees.
By installing an air source heat pump you can reduce your carbon emissions from your homes heating by 50%.
Air source heat pumps are potential income sources, if households qualify for the government Renewable Heat Incentive (RHI) scheme. The RHI is payable on an MCS ASHP installation, carried out by an MCS Accredited Installer and the payment is backdated to include any installation installed after 15th July 2009.
Air source heat pumps can be fairly noisy, approximately 40 – 65 decibels at a distance of 1m away (however this varies by manufacturer). Look at our video below for some first hand experience.
The equipment needs to sit outside the house, so may not be suitable if there is not sufficient space.
Air source heat pumps become less efficient at extracting heat from the air when the external temperature is low, so the amount of usable useful heat they produce is less.
An air source heat pump will cost from about £7,000 to install.
Installing heat pumps
Are you thinking about getting a heat pump? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local heat pump installer, just fill in the form below and we will be in touch shortly!
Ground source heat pumps use the earth as a heat source, taking advantage of the stable temperatures in the ground to provide heat and hot water for the home.
Ground source heat pumps are not a new concept and have been around since the 19th century. This technology became very popular in Sweden in the 1970s and since then units have been sold worldwide.
In the UK, there has been a sudden surge in demand in heat pumps since the launch of the Renewable Heat Incentive, which pays homeowners for each unit of hot water produced. Although rates are no longer as high as they were, they can still cover much of the initial install costs of the systems.
How do ground source heat pumps work?
A ground source heat pump system uses heat trapped beneath the ground and boosts it to a higher temperature using a heat pump. This heat is then used to provide home heating or hot water. The heat pump performs the same role as a boiler does in a central heating system, but uses ambient heat from the ground rather than burning fuel to generate heat.
Initially, a heat transfer liquid (normally glycol) is pumped through pipes buried deep in the ground. As the liquid travels through the pipework it absorbs ambient heat from the ground and warms up, before returning back to the ground source heat pump unit. Once it returns, a heat exchanger removes the heat from the liquid and it then continues to travel round and round the pipework in a continuous cycle.
The low-grade heat is transferred through the heat exchanger, then passes through a heat pump compressor which drives the temperature up to a level that is usable for heating and hot water.
How much pipework does a GSHP require?
The length of the ground loop depends on the size of your home and the amount of heat you need – longer loops can draw more heat from the ground, but need more space to be buried in.
The pipework can either be laid horizontally or vertically. If laid horizontally, the pipework tends to be buried in trenches 2-3m deep, spread over a huge surface area to ensure the heat transfer liquid has the opportunity to increase to a sufficient temperature. If the pipework is installed vertically, boreholes get drilled in to ground (at a cost of £6,000 – £8,000 for each borehole!). These need to be drilled by professionals and will regularly exceed 100m in depth to ensure that the heat transfer liquid again has the opportunity to absorb enough heat.
There are two types of ground source heat pump, and both have a few components in common – they consist of a ground heat exchanger, a heat pump and a heat distribution system (e.g. underfloor heating or radiators).
Closed loop ground source heat pump
The majority of ground source heat pumps installed today are closed loop heat pumps. As the name suggests, no outside liquid enters the loop of pipework at any point. In this set up, a sealed loop of high density polyethylene pipe is laid either vertically or horizontally in the ground. The heat transfer fluid is in a completely closed system travelling through the pipework and returning back to heat pump.
Open loop ground source heat pump
The open-loop ground source heat pump uses ground water to pump around the system; however the number of installations of this type are decreasing, mainly because you need a source of groundwater. Also an additional associated issue with the open loop ground source heat pump is that the quality of the groundwater can actually have a detrimental effect on the system.
Ground source heat pumps require electricity
The fact that ground source heat pumps run on electricity suggests that they are expensive to run (electricity is approximately 15p / kWh while gas is just 4p / kWh). However heat pumps are in fact incredibly efficient.
In fact, ground source heat pumps are even more efficient than air source heat pumps, converting each unit of electricity (required to run the pump and compressor) into 3.5 – 4.5 units of useful heat. Compare this to a brand new energy efficient boiler, which converts each unit of gas into just 0.9 units of useful heat.
The efficiency of air source heat pumps is measured by the Coefficient of Performance (CoP), which is simply how many units of useful energy are produced from each unit of electricity consumed to operate the system. With air source heat pumps, the coefficient of performance changes throughout the year. This is because since in the winter months, the unit needs to work harder (and hence uses more electricity) to drive the temperature up to an acceptable temperature.
For ground source heat pumps the coefficient of performance is relatively consistent – this means that even in the middle of winter, when hot water and heating demand are at a maximum, the GSHP should be running equally as efficiently as it does on a red hot summer’s day. This is because the temperature underneath the ground remains relatively constant all year round – and this is one of the key advantages of GSHPs over air source heat pumps.
Heat pumps do have some impact on the environment as they require electricity to run, but the heat they extract from the ground is constantly being renewed naturally, hence they are considered a renewable heating source.
Installing a ground source heat pump
The Energy Saving Trust (EST) recommends households considering a ground source heat pump to consult a Microgeneration Certification Scheme installer and only use a properly accredited professional to complete the work. During its trial, the EST found a variety of heat pumps incorrectly installed, which therefore didn’t perform as efficiently overall as they could have. It is essential to use an MCS-approved installer to qualify for the Renewable Heat Incentive.
It is important to shop around and we always recommend getting several quotes before choosing the best option for you. Studies have shown that most suppliers tend to exaggerate the savings in energy costs this system will produce.
Renewable Heat Incentive
Heat pumps are part of the Government Renewable Heat Incentive (RHI) scheme. It means that you can get paid for every unit of renewable heat you generate. You can get a significant chunk of the cost of installation back over 7 years of payments – not to mention the savings to be made from the heat pump itself. Read more on that here.
Ground source heat pumps can lower fuel bills, especially if you are currently using conventional electric heating (saving of £420), LPG or oil (saving of £50).
Ground source heat pumps are often classed as a ‘fit and forget’ technology because they need little maintenance, and no fuel deliveries are required, however they provide space heating and hot water 24/7.
Can reduce your carbon footprint: heat pumps can lower your home’s carbon emissions, depending on which fuel you are replacing.
Ground source heat pumps require a reasonable amount of land outside to lay the coils underground. If this is unavailable the technology will not be suitable for your home.
If you have a vertically submerged closed loop system and there is a leak, it can be difficult to gain access to.
Installing heat pumps
Are you thinking about getting a heat pump? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local heat pump installer, just fill in the form below and we will be in touch shortly!
What is Geothermal Power?
Geothermal power is utilising energy that comes in the form of heat from beneath the earth’s crust/ surface layer. Essentially this is utilising the same scientific principles as used in ground source heat pumps, but on an industrial scale. Geothermal power relies on large generators and infrastructure that can provide both heat and electricity to multiple dwellings and commercial properties.
Geothermal power is a renewable heat source that can provide energy for electricity production as well as heating for a number of applications and appliances. Currently in the UK there is one working geothermal power plant in Southampton, which is providing a local district heating solution rather than being used an electricity generating power plant.
Some areas of the world have much more geothermal activity (such as Iceland, West Coast of the US, Rotorua in New Zealand, etc.), and these are more obvious places to harness the earth’s geothermal power. However, if you dig deep enough, heat is available anywhere across the globe (including the UK) so we could definitely roll out this technology more, and build on expertise to harvest the heat in more effective ways.
The science behind geothermal power is relatively simple; heat is continuously flowing from the Earth’s core by conduction (travelling from hot to cold) to the surface and is therefore considered as renewable source as long as the Earth continues to have an active core. It is estimated that geothermal power could produce 44million MWs of power, so even if we could tap a very small percentage of this it would service most of our energy needs.
Geothermal Power for Electricity Generation
Utilising geothermal power requires accessing high temperature fluid that is heated deep underground. Historically this fluid has existed underground, formed by rainwater passing through cracks in the crust. The water is heated by hot rock underneath and compressed by pressure that maintain it its liquid form. The water potentially then finds a path through the Earth’s crust, and presents itself on the surface as hot water springs or geysers.
Nowadays, in addition to this naturally occurring phenomenon, we can also artificially mimic this by pumping cold surface water down into the earth’s crust, where it gets superheated and returns to the surface via circulation pumps. Existing Geothermal Power plants have either tapped into the naturally occurring process or mimicked this to produce the steam necessary to drive turbines to create electricity. As we can now have the technology to drill deeper than ever into the Earth’s crust, by utilising the man made process, we can implement geothermal power stations anywhere in the world.
Three common Geothermal Power generating systems
Dry Steam Geothermal Power
Dry steam geothermal power plants use geothermal steam directly to turn the electricity producing turbines. To have this structure in place requires steam directly travelling to the Earth’s surface, which is quite a rare phenomenon, so there are only few examples of this type of power station worldwide. The geothermal steam, which is superheated (above 1000C) is forced up through cracks in the ground under great pressure. The pressure of hot steam is driven through pipe shafts, which then rotate the turbines. The turbines drive a generator, which creates the electrical charge. Hot steam is then cooled in a cold heat exchanger and the cold water is then pumped back into the ground, which then kicks off this cycle again.
Flash System Geothermal Power
Flash steam geothermal power plants rely on highly pressurised, superheated water instead of steam. The highly pressurised liquid is pushed through a series of pressure tanks. In turn, these holding tanks reduce the pressure of the liquid, allowing it to turn into steam. This process is repeated several times in different depressurised chambers with the steam then collected and ’flashed’ through to drive a turbine generator system to create electricity. As with the dry steam geothermal power system, the excess hot liquid is cooled and / or condensed and then pumped back into the ground so the liquid is replenished.
Binary Cycle Geothermal Power
Binary cycle geothermal power plants use lower temperatures to produce energy and use technology much like that used in OTEC, using the heat gradient to turn a working fluid, such as ammonium and/ or propane into steam to drive the electro generating system. This type of system can be implemented using lower ground temperature as a working fluid has a lower boiling point than water. Once the working fluid passes through the turbine shafts, it is condensed back into the liquid and reused over and over again.
Geothermal Power for Heating
We have talked a lot about electricity generation in the above section, however geothermal power can also be used for heating solutions. Like ground source heat pump systems used in the home, a geothermal power system can be implemented as a district heating solution. In the UK, this would be optimal in areas that are not covered by the current gas grid. Using residual heat from the dry steam or flash system geothermal processes, local homes and businesses could be supplied with heat all year round.
The slight issue in the UK, is that the infrastructure requires investment by the generation companies to make this a feasible proposition, it would however allow them to supply both heat and power (CHP cogeneration) to consumers. These types of solutions are currently more common in Scandinavian countries, and therefore the UK is playing catch up as far as geothermal power goes.
Where is Geothermal Power now?
In the UK, there is enthusiasm about the prospects of geothermal power, but thus far DECC has not provided the additional support that the technology really needs to make a suitable foothold. Currently geothermal power qualifies for two Renewable Obligation Certificates (ROCs) per MWh of electricity generated, but the investment community believe this support should be closer to four ROCs, so that investment doesn’t go to other parts of Europe like Germany.
Geothermal power electricity is currently produced in 24 countries across the planet with the total combined installed capacity being approximately 10,715MW. The largest capacity is in the USA (3.1GW installed in 2010), however by 2015 this is expected to increase by 75%, taking installed capacity to 18.5GW. Geothermal power as a heating solution is much more widespread, and currently used in over 70 countries worldwide.
The largest geothermal power company in the world at present is the Calpine Corporation which taps geothermal electricity primarily in the geysers in California. The 19 geothermal power plants it has in this location provide 25% of the green energy to California. In the UK, the Eden Project in Cornwall was granted permission to build a hot dry rock geothermal power station in December 2010, which will power Eden and supply enough energy for 5000 additional houses in the surrounding area.
CHP cogeneration (combined heat and power for industry) follows the same processes and principles as micro CHP boilers, but on a grander scale. When a fossil fuel power station produces electricity, it also produces a lot of waste heat. In fact, 65% of the energy potential contained in the fuel turns to heat and only 35% is actually converted to electricity, which shows that there is a large efficiency gap. The heat produced is in the form of steam, which is used to drive the electricity-producing turbines. When you drive past a power station you will have probably have noticed the large cooling towers releasing this steam into the atmosphere, which highlights the wasted heat.
The unique point about CHP Cogeneration is that it captures this steam and reuses it for other purposes, such as providing heating for local districts or towns that are close to the plant. In other cases CHP cogeneration plants can fit in tandem with existing industrial processes; for example the production of sugar beet or providing steam to refineries.
Types of CHP cogeneration
As mentioned in the CHP boilers section, CHP cogeneration is underpinned by a number of different technological processes. The process that creates the energy required can either be a combustion process or a fuel cell chemical reaction. Both of these processes produce the heat and power to ensure they can be used for the purposes of CHP Cogeneration. A summary of the technological processes is in the sub-section below:
Combustion CHP Cogeneration
The structure of CHP cogeneration plants usually takes the form of an external combustion engine, which has been a technology widely used in steam engines. Many fuels can be utilised to produce the heat required including gas, coal, biomass, nuclear and geothermal. The fuel is combusted and this heats water, which is then forced into a pressurised boiler. This heat and pressure feeds the main engine or a turbine, which then rotates. The rotating motion then simply spins a large magnet (main engine) inside a coil of copper wire, known as the generator. This then completes the process of converting mechanical energy into electrical energy.
The difference with CHP cogeneration and other plants is what happens with the steam and heat generated from the boiler that then leaves the system. If the infrastructure is in place, this heat can be released out of this process and potentially pumped to a nearby facility for a different purpose altogether. Some of the secondary activities that heat can be utilised for are, district heating (as discussed above) and to drive newly built water desalination plants.
You can also have CHP cogeneration with power plants that are not primarily there to generate electricity but that are there to support additional industrial processes. For example, a bottoming cycle industrial plant produces high temperature heat for an industrial process such as glass furnacing or metal manufacturing. In addition, a waste heat recovery boiler recaptures waste heat from the manufacturing heating process. This waste heat is then used to produce steam that drives a steam turbine to produce electricity. Since fuel is burned first in the production process, no extra fuel is required to produce electricity. In the 1990s British Sugar built a state-of-the-art CHP plant, using excess heat and electricity to support some of its secondary processes – as well as providing district heating.
Fuel Cell CHP Cogeneration
An emerging CHP cogeneration technology is the fuel cell, where fuel, such as natural gas, is converted to electricity in a chemical reaction rather than a combustion process. Again, let’s talk a little bit first about this fascinating science. First requirement is to have solid oxide fuel cells (SOFC), which are allowed to operate at high temperatures. The fuel cells then on one side chemically interact with a fuel input (LPG, natural gas, hydrogen for example) and on the other side with air. This combined reaction – using an anode and a cathode – and is then able to produce electricity and heat (up to 1000 degrees centigrade).
The development of this technology for CHP cogeneration is ongoing, so that one day it can be used as a standard solution for both businesses and homes. Companies such as Mitsubishi Heavy Industries in Japan are looking at ways of introducing this process alongside conventional combustion processes. An example of how this is utilised could be when a company is enhancing existing gas plants with fuel cell technology, to make sure the levels of efficiency increase. As we have already mentioned, the electrochemical process from fuel cells produces heat, and this is then separately captured and used in a secondary process. For example the heat can be used to create steam, which can then feed a combustion system to create secondary electricity. Any excess heat can be recycled further and used to supply district heating or to enable further industrial processes to take place. These processes and recycling heat for multiple uses, increases plant efficiency, which ensures that as little heat as possible is wasted.
CHP cogeneration industry development
The principles of CHP cogeneration have been around since the 1960s in the UK. For example the Combined Heat and Power Association (CHPA) was set up in 1966 as the District Heating Authority to highlight benefits of district heating, but now it is there to highlight the benefits of taking an integrated approach to heat and power. Industrial and domestic CHP cogeneration generators of electricity can currently make use of the Renewable Obligation Certificates (ROCs) and Feed-in-Tariffs (FiTs) respectively. More on this in the section below, as well as an explanation of the Renewable Heat Incentive (RHI) in more detail.
In the UK, the Immingham CHP cogeneration plant (one of our featured case studies), has been in operation since 2004, producing 1.2GW of electricity, making it one of Europe’s largest CHP cogeneration plants. Some of its uses are as follows: providing steam and electricity to the Humber Refinery, steam to a neighbouring refinery, and power back into the grid.
Now a bit about our neighbours in Europe: CHP cogeneration is already used on a commercial scale in many Scandinavian countries, with 40% of Denmark’s total electricity capacity derived from this source, as is 30% of Finland’s. Germany on the other hand has also made its intentions clear in support of the technology. This signal was made clear since it decided to scale down and decommission the existing civil nuclear power plant project. However other parts of Europe like the UK have a lot of catching up to do to these countries.
Cogeneration CHP UK public policy
The DECC policy is to support measures such CHP cogeneration as well as solar commercial power plants, wind farms and nuclear power to ensure that by 2020 the UK is in a good position to meet its emission reduction targets. The main policy areas that cover CHP cogeneration are summarised below:
Renewable Obligation and Feed-in-Tariffs
ROCs are available to commercial electricity generators of CHP cogeneration, which are usually ones that are able to demonstrate the production of multiple MWh of electricity production (also considered a metric that symbolises the starting point for mass scale consumption). The level of support varies depending on the CHP cogeneration type. For example, if combusting waste CHP cogeneration, then level of support is 1 ROC per MWh. On the other hand, if you are using dedicated biomass fuel with CHP cogeneration, and can demonstrate sustainable fuel supply, then the entitlement increases to 2 ROCs per MWh.
FiTs on the other hand are an initiative to support micro generators of renewable electricity. If you are a small business or a community project (and this is your first time involvement in electricity generation), please note to satisfy the FiT criteria, you need to have a declared net capacity greater than 50kW and up to and including 5MW (2MW for micro cogeneration CHP). Income can be earned both from the generation tariff and the export tariff.
These two policy areas are great incentives if you are looking to invest in renewable CHP cogeneration projects or if you are looking to start up your own renewable CHP cogeneration plant.
Renewable Heat Incentive
The RHI is a payment subsidy (pence/kWh), for heat and hot water generated by households or businesses, using an eligible renewable technology, which includes CHP cogeneration.
In March 2012, the DECC set out a roadmap for district heating incentives. This has called on improvements to infrastructure around existing power plants and newly built ones to extract some of the excess heat and provide it for local homes and businesses. An apparent lack of investment in infrastructure is to blame for a lack of district heating incentives in this country. Everything in the UK is dug underground from electricity cables, telephony and natural gas distribution. District heating incentives for example would struggle to compete with existing infrastructure in large conurbations, but there appears to be an opportunity for connecting new out of town developments and/ or areas of the country which are currently off-grid.
Examples of some of the CHP cogeneration initiatives that could be implemented in the UK are as follows: heat from gas-fired CHP plants, biomass and biogas, heat pumps, energy-from-waste, solar thermal, excess heat from industrial processes and power stations. These processes are very common in Denmark, and as previously mentioned, are enablers used for helping the process of decarbonisation of the economy.
Installing Micro CHP
Interested in installing a micro CHP boiler? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local installer to help install micro CHP in your home, just fill in the form below and we will be in touch shortly!
Privacy & Cookies Policy
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.