WWT April 2020: Improving Efficiency - Energy efficiency boost for geothermal heating solutions

As the cost of oil continues to rise and the drive to reduce carbon emissions intensifies, an increasing number of people and organisations in both the domestic and commercial markets are turning to geothermal solutions to make a difference to their heating bills.

Ground source heat pumps (GSHPs) can be used in a variety of settings, from a home environment through to commercial buildings, including factories, office complexes, hospital and schools.

In addition to reducing carbon emissions, they have very low running costs and a high resilience factor because – unlike other forms of renewable energy such as wind or solar – they do not suffer from intermittent supply.

And in very cold weather, when heating is most needed, a ground source heat pump has access to warmer temperatures from the ground than an air source heat pump has from ambient air.

John Findlay, founder of Carbon Zero Consulting and a council member of the The Ground Source Heat Pump Association (GSHPA), recognises that the higher initial outlay over more traditional solutions, such as a gas-fired boiler, is a factor that investors must assess, but says this is outweighed by the many advantages of a GSHP in the longer term, including:

• Lower heating costs compared to oil and direct electric heating, and comparable cost to mains gas
• A GSHP can also provide cooling, with no additional hardware and larger schemes are designed to store heat and/or cool in the ground to hugely increase seasonal efficiency
• Receipt of renewable heat incentive (RHI) payment. This remains open for new applications until April 2021.
• Greatly reduced carbon emissions from heating and cooling, see this shown real-time at https://gshp.org.uk/

He says: “The uptake of GSHPs has increased significantly in the last few years as biomass is no longer seen as a viable option for widespread installation. Similarly, GSHPs are powered by electricity with ever-reducing carbon-intensity.

“Carbon emissions from a GSHP are now similar to a gas CHP system, and so are becoming much more readily specified for larger buildings, especially where planners do not allow external plant.

“As a nation we have to turn to heat pumps as a major contributor to renewable heating to reach our net-zero carbon objectives. As part of this, the new government must quickly clarify the nature of support post-RHI, whether this is continued tariff support, or wholesale changes to building and planning regulations.”

One recent step forward which he believes could help boost the market is the launch of a new High Efficiency Submersible Borehole System (HES) from Franklin Electric. With a motor size of just 4”, it guarantees energy savings of up to 20%-30% above standard borehole motors.

Designed to fit within open loop ground source heat pump installations as well as in water abstraction from boreholes, its clever technology reduces the amount of parasitic energy required to run the pumping equipment.

Mike Deed, managing director of Franklin Electric’s strategic partner Geoquip Water Solutions, explains: “This is a gamechanger, especially in the geothermal and/or domestic markets where there may be smaller installations with lower flow levels.

“If you’ve invested in a geothermal heating system, then you will already be someone who cares about reducing energy usage. Being able to utilise a high efficiency system with a 4” synchronous submersible motor and a 4” submersible pump, rather than the less energy efficient asynchronous motors, ticks all the right boxes in moving to a more sustainable approach.” 

John concurs and says: “This is certainly a step in the right direction. It will make the process much faster and simpler and appeal to those who are keen to improve their energy efficiency and further reduce their heating and cooling bills in the longer term.”

Paul Harris, from H.D. Services, installers of Open-Loop Ground Source Heat Pumps, also believes the new High Efficiency Systems would add real value in efficiency terms.

“We have completed dozens of small domestic open-loop ground source heat pump installations throughout the south east since 2010,” he said. “Any one of these installations would benefit from these HES compared to the standard borehole pumping system they currently have.  Moving forward, we will be proposing the installation of HES for the water supply to our open-loop ground source heat pump systems, it is the equivalent of simply reducing the fuel delivery cost for the heat pump and therefore overall system efficiencies will be higher. For an Open-Loop GSHP where overall system efficiency is a factor, the HES is a 'no-brainer'.”  

Designed and manufactured by Franklin Electric under its E-tech brand, the HES comes complete with its own software programme, allowing customers to go online and see straight away what their payback period will be.

In another nod to renewable energy, solar versions are also available.

The only 4” submersible system of its kind on the market, the unit uses pre-written software and a synchronous submersible NEMA permanent magnet motor, an associated variable frequency drive and output filter to deliver greater efficiency with higher power density.

This sets it apart from current asynchronous technology as it means the windings are permanently magnitised, therefore using less energy when starting and running and, with less slip, it delivers both a smoother and faster solution.

Together, these combine to improve motor efficiency with significantly lower motor heat rise and promise a return on investment within two years.

Richard Knipe, Franklin Electric’s UK Sales Manager, said: “There is a lot of ongoing interest in the energy saving advantages of the HES and, even better, because the 4” motor has a smaller diameter, it is a more affordable option. That means a reduction in capital investment and a shorter payback time, so it’s a win-win solution.”

Monitoring and maintenance

Having invested in new equipment, both Deed and Knipe stress the need for regular monitoring.

Deed says: “The HES is creating a great deal of interest and is setting new standards in greener energy efficiency. Having made that initial decision however, the key to achieving this on an ongoing basis is efficient monitoring and regular maintenance. It is never enough to just fit and forget.

“Whether in a geothermal setting or a borehole, pumps, pipes and motors can all become contaminated with iron bacteria, iron oxide, manganese oxide and calcium carbonate deposits and this will lead to reduced flow and yield.”  

The best way to manage this problem is by installing bespoke remote monitoring and telemetry systems which will enable full remote access and round-the-clock checks. Once a problem is identified, the monitoring team can then decide on the best approach.

For example, if the pump is blocked then the yield will have dropped and information such as this is vital in forecasting the most appropriate course of action. Equally, if the well is drawing down more for the same flow rate, then the well inflows may be reducing, potentially as a result of residue or biofouling build up.

One solution is Geoquip’s range of BoreSaver products, approved by the NSF for the first time in the UK market. Easy to use, safe, and biodegradable, these can be used in situ, meaning there’s no need to dismantle and remove equipment except in extreme circumstances.

The addition of a marker into the formulation gives an instant all clear to demonstrate that any remaining chemical residue has been removed.

Deed says as well as solving the immediate problem, regular maintenance and checks will also extend the life of the pumping equipment and keep water flowing longer in future, increasing energy efficiency and continuing to earn against that return on investment.

For more information, visit www.geoquipwatersolutions.com or call 01473 462046.

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