What are water source heat pumps?

Water source heat pumps work on a similar principle to both air source and ground source heat pumps. Instead of taking advantage of the heat in the air or the ground, they take advantage of the relatively consistent temperatures found in a body of water.

A series of flexible pipework is submerged in a body of water, such as a lake, river or stream. A heat pump pushes working fluid through the network of piping, and this fluid absorbs the heat from the surrounding water as it goes.

This working fluid is then compressed by an electric compressor, in a similar fashion to the other types of heat pump, which raises the temperature. A heat exchanger can then be used to remove the heat entirely from this working fluid, providing you with hot water that can be used for space heating (in radiators or under floor heating). It can even be plumbed into your hot water system, where a boiler can just provide the small amount of additional heat needed to bring it up to the required temperature, so it can be used for showers and baths.

Once the heat has been removed from the working fluid via the heat exchanger, it is once again pumped back through the pipework, thereby completing a continuous cycle.

The benefits of a water source heat pump

The heat transfer rate from water is higher from the ground, making them more effective than ground source heat pumps. In addition, if using a water source heat pump with a moving body of water, the heat is constantly being replaced, as new warmer water replaces the cooler water that has had its heat extracted by the working fluid.

For every 1kW of energy required to run a water source heat pump, 4-5kW of equivalent heat energy is produced which can be used to warm your home. This makes the technology more efficient than both air and ground source heat pumps.

The supply of hot water is also pretty much constant, despite being cooler in the winter; the body of water will still possess sufficient heat to enable the water source heat pump to operate in the winter. An issue only arises if the body of water completely freezes.

Unlike ground source heat pumps, where bore holes or trenches need to be dug on your plot for the piping, the pipework for a water source heat pump is relatively simple to install; it simply needs to be situated within a body of water, which should have little impact on your plot of land.

Benefits

• Installing a water source heat pump is relatively easy if there is a body of water available on your property.
• Water source heat pumps have a higher Coefficient of Performance than ground source and air source heat pumps: so for every unit of electricity used to operate them, they can produce more hot water.
• There is little visual impact on the property, since all the pipework in the water source heat pump system is submerged within the body of water.

Limitations

• A water source heat pump is reliant on there being a body of water at your property.

Cost

• Anywhere around £10k

What is biomass energy?

Biomass is biological material derived from living – or recently living – organisms. In the context of biomass energy, this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material. The carbon used to construct biomass is absorbed from the atmosphere as carbon dioxide (CO2) by plant life, using energy from the sun. Plants may subsequently be eaten by animals and thus converted into animal biomass, but the primary absorption is performed by plants. This is however the basis of biomass energy, which in essence is the capture of the sun’s energy that is stored in living organisms.h

Fossil fuels on the other hand offer high energy density, but making use of that energy involves burning the fuel, with the oxidation of the carbon to carbon dioxide and burning the hydrogen to produce water (vapour). Unless these emissions are captured and stored (see CCS), then these combustion products are usually released into the atmosphere, returning carbon sequestered millions of years ago and thus contributing to increased atmospheric concentrations.

How is biomass energy different to fossil fuel energy?

The vital difference between biomass and fossil fuels is one of time scale. Biomass takes carbon out of the atmosphere while it is growing, and returns it back to the atmosphere as it is burned. If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. Forms of replenishment are as follows: (1) woodland or arboriculture management or (2) coppicing or (3) as part of a continuous programme of replanting with any new growth taking up CO₂ from the atmosphere. This maintains a closed carbon cycle with no net increase in atmospheric CO₂ levels, which means the release into the atmosphere by combustion is absorbed by new growth.

Biomass energy for your business

The main difference between biomass boilers and fossil fuel-fired systems is that biomass energy systems are larger. The heating system itself works in a very similar way to a conventional system. A biomass energy system typically consists of the following: a boiler, control system, mechanical system (pipes, valves, flues etc.), infrastructure to receive and store fuel and infrastructure to transfer it to the main boiler unit.

Heat energy

Biomass energy is extracted using biomass fuel, which is burnt in a combustion chamber and the heat is then used to heat water. This hot water then heats the building through a normal hot water heating system. Steam can also be used in industrial processes where appropriate, and hot air is sometimes used for space heating. However unlike electricity generation, which is subsidised by the ROCs, the Renewable Heat Incentive (RHI) is not yet in place to help subsidise district renewable heating solutions.

Electricity

For generating electricity, the steam produced can be used to power turbines, which then runs an electric generator and creates power. As biomass energy is part of the renewable fuel grouping for electricity generation, users can now also benefit from Renewables Obligation Certificates (ROCs), which are received at a prescribed level for every MWh of power generated.

Biomass energy plants can vary from being small, manually-fed systems with basic controls, to fully automatic systems with advanced controls and remote monitoring. You should always consider fuel availability and consistency, as well as storage and handling, during the design, implementation and operation stages. Of all possible renewable heating solutions, biomass energy has the potential to deliver some of the most significant and cost-effective carbon savings, particularly for commercial and industrial applications. In addition to carbon savings, biomass energy also offers significant benefits for users, including operational fuel cost savings and reduced fuel price volatility.

A biomass energy plant in a small town or village for example can stimulate local economic activity by creating fuel supply chains and making good use of resources that would otherwise be treated as waste and sent to landfill.

ROCs for biomass energy electricity generation

As mentioned in the previous section if you have a biomass energy system, then depending on the power output, the system can be eligible for ROCs if the plant generates electricity. The precise number of ROCs depends upon the biomass generation type. According to the Department for Energy and Climate Change (DECC), if the electricity generated is partly from fossil fuel and partly from biomass, then it is entitled to 0.5 ROCs per MWh. Dedicated biomass generation is applicable for 1.5 ROCs per MWh. The use of energy crops mixed with fossil fuel or CHP (cogeneration) process entitles the generator from 1 ROC to 2 ROCs depending on the mixture. Pure energy crop electricity entitles the generator to 2 ROCs per MWh.

How suitable is biomass energy for my business?

• Do you have any planning exclusions, e.g. vehicle movements, visual intrusion, noise restrictions or limitations on chimney heights?
• Is there enough space for lorries to regularly deliver the fuel?
• Do you have sufficient space for the larger boiler and a fuel store?
• Do you have the capital to invest in such a system? Biomass energy solutions tend to have higher capital costs than fossil fuel-fired systems, but can attract financial support schemes.

Sourcing fuel for biomass energy

The three most common types of commercially available biomass fuels are wood-based (logs, woodchips and pellets). However, other fuels such as straw are also used as part of the biomass energy grouping.

Biomass energy fuel supply needs to be sustainable in principle, so that the renewable credentials are maximised. You should diversify the scope by purchasing biomass fuel from many suppliers, and you can make long-term agreements to secure a fixed price into the future. If you can source the fuel locally then you will also have more control over the security of your supply.  This will also increase your on-site storage giving you that buffer against short-term supply problems.

It is common practice to undersize the biomass boiler and to include a thermal store (large hot water tank). This helps to smooth the heat demand profile and ensures that the biomass boiler runs for long hours at high load. An auxiliary fossil fuel fired boiler is then used to cope with peak loads. This multi-fuel strategy gives greater security against fuel problems too, but is not as good for the environment.

Industry policy trends for Biomass Energy

The take up of biomass energy in electricity generation in the UK, and its long-term outlook, is mixed. For example, companies like Drax Power and E.ON have moved away from their initial enthusiasm for expansion, which has been due to uncertainties, driven by the outcome of the Renewables Obligation (RO) review. However, the government has signalled on more than one occasion that the banding will expand, so as to further support CHP initiatives. For this reason the industry is waiting for more details to emerge on the Renewable Heat Incentive – due to launch later in 2012 / early 2013.

Benefits

• Return on your investment in three years if the biomass replaces electric, fuel oil or LPG.
• Net carbon emissions per kilowatt hour (kWh) are much lower than energy sources from fossil fuels. E.g. The carbon emissions for woodchip are 10-23kg of CO2 per megawatt hour (MWh), compared to 263-302kgCO2/MWh for natural gas.
• Biomass systems are relatively easy to convert to other fuels and offer greater flexibility for an uncertain energy future.
• In some regions biomass are considered waste products; burning them for energy can reduce disposal costs and free up landfill sites.

Limitations

• Biomass plant will typically cost two to five times as much as an equivalently sized fossil fuel system.
• The payback won’t be quite as fast if you’re replacing natural gas.
• Larger size boiler and the storage and handling equipment needed.
• Burning biomass usually takes more operator attention then burning conventional fuels.
• In contrast to other fuels, biomass fuel is variable in quality. It may require more vigilance and effort from the owner to ensure the desired fuel quality.

What is the RHI Scheme?

On 20^th September 2012, Greg Barker MP, Minister of State for the Department of Energy and Climate Change, released the first consultation on the proposals for the domestic renewable heat incentive (RHI) scheme. This document can be found on the DECC website.

Just under half the energy consumed today is used for hot water and space heating but only a tiny proportion of this comes from renewable sources. In an effort to meet the UK’s ambitious carbon reduction targets, the government is proposing to subsidise heat producing renewable technologies.

Similar to the feed-in tariff, which provides the consumer with a monetary payment for every kWh of electricity produced, the RHI scheme pays the individual for every kWh of hot water they produce.

Who is Eligible for the RHI scheme?

There are 3 key eligibility requirements for the RHI scheme.

1. Types of Green Technology – Under the current consultation, only 4 technologies are currently included (although others are under consideration):

• Air source Heat Pumps
• Biomass Boilers
• Ground Source Heat Pumps
• Solar Thermal

2. Date of Installation – To be eligible for the payment, the technology has to have been installed after 15^th July 2009 and needs to be MCS certified.

3. Green Deal Energy Efficiency – Homeowners will also have needed to install all of the energy efficiency measures which got ‘green ticks’ on the green deal assessment. Insulation is by far the most cost effective efficiency measure to install in the home, since it dramatically lowers the amount of energy required to heat it.

Tariff Details

The proposed payment terms for the RHI is 7 years, which is designed to pay for 20 years of heat generation and takes into account the additional capital cost of the renewable heat installation (over and above replacing a like-for-like fossil fuel equivalent). In addition, the tariff is also designed to provide a level of compensation for the installation of the renewable technology (such as additional building costs). And finally, it also provides some reimbursement for the 7.5% cost of financing a loan to pay for the initial installation.

Almost guaranteed to change as the result during the Consultation, these are the current details of the tariff due for each of the 4 technologies:

Biomass                                            5.2 – 8.7p / kWh

Air Source Heat Pump                      6.9 – 11.5p / kWh

Ground Source Heat Pump             12.5 – 17.3p / kWh

Solar Thermal                                   17.3p / kWh

The differences in subsidy payments between the technologies take into account factors like differing energy efficiencies, upfront technology costs and the technology lifetimes.

Final Thoughts on the Initial Consultation

Overall, we think the government have got the initial consultation about right. And we are delighted that Greg Barker and his team recognise that going green is not simply about sourcing electricity from emission free-technologies.

Paul Thompson, the Head of Policy at the Renewable Energy Association said ‘Renewable heat is the sleeping giant of UK renewable energy policy’ and with heat accounting for almost 40% of the UK’s energy usage, you can see why. If we were to source all of our heat from renewables, it would really help the UK stick to its 2020 carbon emission reduction targets.

It is a shame that some techs have missed the cut and have been excluded from the scheme (CHP boilers for example), since this would have dramatically boosted uptake and therefore energy savings.

For more information on the initial consultation please visit this link, which will direct you to the DECC website, where you can read the document in full.

If you have any queries please don’t hesitate to get in touch at james.alcock@thegreenage.co.uk

Have a great weekend!