DISTRICT HEATING PLANT SAVES MONEY AND CO2 WITH THERMAL DRONE SURVEY

These words are by Derek Leask, Executive Director of Shetland Heat Energy & Power Ltd. The district heating company provides heating and hot water to over 1200 homes and businesses – in a cool climate with an average high summer temperature of only 11.5°C.
He continues, “The resilience and longevity of the district heating pipe network in Lerwick were dramatically improved by achieving full visibility of our entire network. We are proud that we now save energy, CO2, and money at the same time.”

Published in Hot Cool, edition no. 4/2021 | ISSN 0904 9681 |

Thermal mapping reveals weaknesses

In January, Shetland Heat Energy & Power Ltd. used new technology to conduct a complete thermographic drone survey of their pipe network. The drone flew at night and used a thermal sensor to measure electromagnetic radiation at ground level. The resulting data were processed and analyzed to create an ortho map of the whole network. It reveals places where the ground temperature was higher than average.

Warm spots are shown as light dots on a purple map. Software specially developed in cooperation with district heating companies compares the map to the grid of pipes in the ground. This reveals irregularities like leaks, wet insulation, hot spots that need further investigations, or poorly insulated valves.

A few nights’ silent flying produced a precise map showing the entire network layout with every bit of defect pinpointed. From this, a priority list was compiled, and over 70 interventions were carried out as part of the summer maintenance and renovation campaign, dramatically improving the grid condition. Thanks to expertise from Danish Drone Systems, who developed the software, Shetland Heat Energy & Power Ltd. now has a thermal ortho map of the state of their pipes. It is precisely calculated from the temperatures measured around it.

“The thermal drone survey will be an integral part of our asset management program in the future,” says Derek Leask. He has already ordered another survey for 22 January.

Thousands of pounds saved on maintenance

Hot water savings are not the most significant financial gain from the survey. That comes from being able to spot minor issues before they become big problems. Replacing and re-sealing an area of wet insulation is much easier than repairing a leaking pipe and can be done during regular working hours.

“The thermal drone survey gives us an invaluable picture of the state of our 40-kilometer pipe network. We can see everywhere water has broken through the insulation, heats up, and affects the surroundings. This is normally shown in the soil or on the pavement. We can also detect any flaws that have led to little leaks in the welded pipe joints that can be addressed before becoming more serious. Although these are much less common, it is still crucial to find them.

Another major advantage is that we can then plan the renovation at a convenient time for customers and the community, which avoids unscheduled service interruption. The savings made by addressing a problem early and avoiding a single big breakdown (by performing just one planned intervention) covers the full costs of the survey,” explains Derek Leask.

He continues: “Also, it’s much cheaper for us to repair minor faults during normal working hours instead of having to call
out engineering contractors at 3 a.m. Plus, we avoid stopping the traffic during rush hours to mend a sudden breakdown.
The survey overview makes it possible to bundle all the repairs needed in one area, saving our asset management program
several thousand pounds. This is another way in which the survey pays for itself.”

The thermal drone survey is so precise it also revealed problems on Lerwick’s private estates. Therefore, Shetland Heat Energy & Power Ltd. was able to contact customers and warn them that a valve or a heat exchanger on their property seemed to be losing heat. A minor repair could probably result in a lower heating bill.

“Lerwick residents were initially a little worried about the drone flying over their houses in the dark. We explained that it did
not carry ordinary cameras but a thermal sensor; and that it only revealed problem spots where we all could save money.

They were also concerned that using drone-based thermography might mean the network was in poor condition. Our pipes
are 20 years old, and naturally, there is some degradation over time. However, the drone survey now gives us a new tool for tackling this issue, and I think the community is pleased we will be able to keep the network in good condition for years to come. I think they are now reassured by living in an area where the latest technology is used to reduce energy consumption and C02 emissions,” concludes Derek Leask.

Mentor scheme matchmaking

The relationship between Scottish Shetland Heat Energy Power Ltd. and Danish Drone Systems was established through
a mentoring scheme by Denmark’s leading district heating export organization, DBDH.

“We heard about pipe-monitoring issues in Shetland and arranged contact with a leading specialist in thermal drone inspections,” explains DBDH Business Development Manager Morten Jordt Duedahl. He adds: “This successful matchmaking achieved three things: we helped cut down on CO2 emissions, we supported exports by one of our members, and we improved district heating in a cold, wet area. As our mission is to promote district energy for sustainable city transformation, we are delighted with this outcome.”

Information for Lerwick residents

“Thermal drone surveys are a clear improvement on previous asset management tools. The drone flies at an altitude of 90 meters above ground, and quiet propellers ensure near silence. High-intensity anti-collision beacons mean you will see it more than you will hear it. It is equipped with numerous safety systems, including dual batteries and multiple sensors that feed real-time information back to the pilot. The whole operation has been entirely risk assessed to mitigate all hazards and safety risks. A crew of two operate the drone: the Remote Pilot has complete control of the aircraft and systems, and an observer monitors the drone’s flight path at all times in the air.

The thermal sensor on the drone does not take ordinary pictures; it measures 7.5 – 14 µm wavelength electromagnetic radiation. The software converts radiation intensity to a temperature reading, the temperature values are then assigned a color, and this is what generates the thermal image we can interpret.

The survey takes place at night and should require no more than two nights’ flying. Environmental conditions must be ideal to guarantee good results. The optimum situation is no rain or wet surfaces, low wind speeds, and low relative humidity. It can therefore be challenging to plan exactly when the survey will take place, but we provide continuous updates about planned and completed flights.”

Low carbon waste to energy heat

Shetland Heat Energy & Power Ltd. provides low carbon, waste to energy heat to Lerwick in the Shetland Islands, North of Scotland. The district heating company supplies hospitals, leisure centers, local government buildings, care homes, commercial entities, and more than a thousand domestic homes. https://sheap-Ltd.co.uk/

Over 400 leaks found… all over the world

Danish Drone Systems’ specialist technology delivers 100% thermal coverage and shows the complete picture of a district heating network. In contrast, traditional inspection methods (handheld or car-mounted infrared camera on the ground) only cover around 50-70%. As well as providing complete visibility of an entire network, the thermal drone survey also delivers greater precision. It pinpoints leaks and points of interest (including minor leaks on return pipes) within a meter.
Built on Danish high-tech know how, the company delivers thermal drone inspections of district heating networks worldwide.

It operates in every landscape and terrain – including inaccessible locations, often in collaboration with professional local drone pilots. The Shetland Island survey was carried out by local drone pilot Shetland Flyer Aerial Media, who delivered the thermal data to Denmark for processing and analysis.

To date, Drone Systems has successfully inspected over 16,000 kilometres (9,942 miles) of district heating network pipelines. During this work Drone Systems has identified and located more than 1,400 leaks, 4,800 emerging leaks, and 2,900 components (above 5 degrees in delta temperature), all with notable heat loss – damaging both the economy and the climate.