How much CO2 is saved by switching from helicopters to drones for power line inspections?

January 29, 2024
How much CO2 is saved by switching from helicopters to drones for power line inspections?
Max Hjalmarsson
Sales & Operations
How much CO2 is saved by switching from helicopters to drones for power line inspections?

For a utility with 22,000 km of overhead power lines that replace its helicopter-based inspections with drones, 258 tons of carbon emissions can be reduced every year, with the prerequisite that the drone pilot drives an electric car and charges it in Sweden.

power lines

Introduction


One benefit of using drones for the inspection of overhead power lines is the environmental gains, such as reduced noise and carbon emissions. At Airpelago, one common question from our customers’ is how much carbon emissions can be saved and how these can be calculated. In this article, we try to answer this question. Below, you find a series of assumptions and calculations on how much carbon dioxide emissions can be reduced by replacing helicopter-based inspection of power lines with drones. distribution networks, and we acknowledge that different inspection types, flight patterns, and characteristics exist for both helicopters and drones.

Part 1 – Carbon emissions from helicopter-based inspections


To calculate the emissions reduced with drone-based inspections, we first need to know how much emissions are generated by helicopter-based inspections.

Some of the most common helicopter models used for power line inspection are:

  • Robinson R44 - Although lighter than the models above, the R44 is often used for inspection missions due to its cost-effectiveness and ability to maneuver close to the lines. This popular and light helicopter, used for power line inspection and seating up to 4 people, consumes approximately 45-60 liters of gasoline per hour under normal flying conditions.
  • Airbus H125 (formerly Eurocopter AS350 B3) - This helicopter is famous for its versatility, reliability, and payload capacity. It also offers good maneuverability, which is necessary when flying near power lines. A larger helicopter like the Airbus H125 (formerly known as Eurocopter AS350), which seats 6 people, can consume between 150 and 190 liters of fuel per hour.
  • Bell 206 JetRanger - Another standard model for this purpose, the Bell 206, has been in production for a long time and is known for its reliability. Fuel consumption for a Bell 206 JetRanger varies depending on several factors, including load, altitude, weather conditions, and flying style. Generally, under normal conditions, it consumes between 85 to 100 liters of fuel per hour.

CO2 emissions from helicopters


The Bell 206 JetRanger is one of the most commonly used helicopter models for power line inspection in the Nordics. Therefore, we chose to base the following calculations on this model. It has an average fuel consumption of 92 liters of Jet A1 per hour.

To calculate the carbon dioxide emissions from the combustion of helicopter fuel, it's necessary to know the fuel's density and carbon dioxide coefficient. Jet fuel, commonly used in turbine helicopters, typically has a density of about 0.81 kg/L. The combustion of 1 kg of jet fuel (usually Jet A or Jet A-1) generates approximately 3.15 kg of CO₂.

These figures are approximate and may vary depending on the exact composition of the fuel and the combustion conditions. We also acknowledge the difference in fuel consumption and carbon emissions between helicopter models.

Using these figures, the CO₂ emissions can be calculated as:

  • 92 liter x 0,81 kg/L = 74,52 kg fuel
  • 74,52 kg fuel x 3,15 kg CO₂/kg fuel = 234,74 kg CO₂ / hour

Carbon emissions from helicopter

  • The Bell 206 JetRanger emits approximately 234.74 kg of CO₂ per hour.

Average flight speed of the helicopter


As a start, the helicopter must fly to the inspection area from where it is based. Once at an inspection area, the grid is not outlined in a perfectly long and continuous line but rather divided into several disconnected lines with multiple forks. The grid’s structure and how it is scattered through the landscape affects the overall inspection efficiency to a large extent.

Average flight speeds during various parts of the inspection are:

  • Establishment, where the speed is about 150 km/h
  • Transport between lines, where the speed is about 100 km/h
  • Inspection, which is the majority, where the speed varies between 40-100 km/h, depending on the type of inspection, terrain, weather, and grid structure.

Due to the nature of the network, a significant amount of time is spent on transportation between the disconnected power lines that are to be inspected. Overall, from when the helicopter take-off, day one to when it lands on the last day, the average effective speed over power lines, including the flight to and from the inspection area, is assumed to be 40 km/h.

Helicopter inspection efficiency

  • The average flight speed over a power line is 40km/h.
Inspection efficiency of the helicopter


The helicopter flies at an average speed of 40 km/h. Assume it must travel 2 km for every 1 km of power line it inspects due to the gaps between lines and the distribution grid's many forks and dead ends.

Emissions per inspected kilometer are calculated as:

  • 234.74 kg CO₂/hour / 40 km/h * 2 = 11.74 kg CO₂/km of power line

Conclusion: Carbon emissions for helicopter-based inspection of power line


Carbon emissions from helicopter-based power line inspection are estimated to be 11.74 kg CO₂/km of power line.

Part 2 – Carbon emissions from a passenger car during drone-based inspections


The drone pilot often uses a standard passenger car for transportation to, from, and within the inspection area of the grid. Therefore, the emissions produced when driving a car need to be calculated.

Passenger car fuel consumption per km

When gasoline is burned, approximately 2.31 kg of CO₂ is generated per liter (95 octane).

The fuel consumption for an average passenger car is 0.60 liters/km.

Passenger car carbon emissions per km

  • This results in carbon emissions of 1.386 kg CO₂/km for every distance driven by car.

Inspection efficiency and distance driven by car for every kilometer of power line inspected by drone


For drone-based inspections with standard off-the-shelf drones, the drone pilots must relocate several times each day. The inspection range varies with terrain, flight permit, type of inspection, the type of power line, grid construction, distribution throughout the terrain, and more. Based on our data from inspecting over 15´000 km of power lines, we have seen that this figure is close to 2 km by car for every 1 km of power line the drone pilot inspects.

CO2-equivalent emissions from an average passenger with a combustion engine are therefore calculated to be:

  • 1.386 kg CO₂/km by car * 2 km by car/km inspected line = 2.772 kg CO₂/km inspected line.


Conclusion 2: Carbon emissions for gasoline-powered passenger car


Emissions during drone inspection and gasoline-powered car: 2.772 kg CO₂/km inspected line.

Electric car

Carbon intensity of electricity in Sweden


The carbon intensity of electricity produced in Sweden is around 50 g CO₂/kWh.

Electric Car Energy Consumption

Typical energy consumption for modern electric cars ranges between 13 to 20 kWh/100 km, varying by model, driving conditions, etc.

The electric car consumes 15 kWh/100 km (on average) and is charged with electricity with a CO₂-intensity of 50 g CO₂/kWh. This gives us the CO₂ emissions as follows:

  • CO₂ emissions per 100 km = 15 kWh x 50 g CO₂/kWh = 750 g CO₂, and per km = 7.5 g CO₂/km.

Also, this car needs to travel 2 km for every 1 km of power line the drone pilots inspect (as per Assumption 5). This results in a total direct CO₂ emissions per inspected kilometer of line:

  • 2 * 7.5 g CO₂/km = 15.0 g CO₂/km.

Conclusion 3: Carbon emissions of drone-based inspection


Carbon emissions of drone-based inspection with an electric car charged in Sweden is 15.0 g CO₂ per inspected kilometer of power line.

Please note. Actual emissions may vary with factors like exact consumption of the car, charging infrastructure efficiency, and variations in electricity production CO₂ intensity. The initial CO₂ load from manufacturing should also be considered and spread over the car's lifespan. In this comparative example, the CO₂ load from manufacturing is neglected for both the passenger car and the helicopter.

Part 3 – Reduction of carbon emissions – Drone vs. Helicopter Comparison

Carbon emissions by inspection type
    • Helicopter-based inspection: 11.74 kg CO₂/km of line
    • Drone-based inspection with a gasoline car: 2.772 kg CO₂/km of line
    • Drone-based inspection with an electric car: 0.015 kg CO₂/km of line

    Helicopter vs. Drone with a gasoline car

    • Helicopter to drone (gasoline car): 8.96 kg CO₂/km of inspected line

    Reduction by alternative 2: Helicopter vs. drone with an electric car

    • Helicopter to drone (electric car): 11.73 kg CO₂/km of power line

    Reduction per 10,000 km of inspected power line

    • Helicopter to drone and a gasoline car: saves 89.6 tons CO₂ per 10’000 km of inspected line
    • Helicopter to drone and an electric car: saves 117.3 tons CO₂ per 10’000 km of inspected line

    For a network owner in Sweden, with a grid size of 22,000 km, the carbon emissions reduced by replacing helicopter-based inspections with drones is an astonishing 258 tons annually, given that the drone pilot uses an electric car.