Diesel drain: Why tower cranes are burning through your budget

Andrew Deakin warms to a favourite subject: the needless waste of energy on most construction sites when it comes to powering tower cranes.

As technical director at Dumarey Green Power, a UK-based energy storage company that specialises in powering tower cranes, construction sites and others more efficiently, Deakin spends much of his time assessing alternatives to the status quo – and the trade-offs that rental buyers face.

Top of his list for inefficiency are the large diesel generators still used on the majority of construction projects.

“We don’t need that much energy to drive a crane,” Deakin said. “We should be able to do better than that.”

Severely overpowered

His central argument is that while tower cranes are essential to vertical construction, most are severely overpowered – and that misalignment is costing contractors and rental firms dearly in diesel consumption and CO₂ emissions.

Speaking at the 2025 International Tower Cranes (ITC) conference in Rome, Deakin presented operational data from a live site in London, where his company worked with Select Plant on powering Terex CTL 1600 luffing jib cranes.

Rated at 250 to 300 kilowatts, these large tower cranes appear to run constantly. But closer inspection told a different story: “Looking at the average power for the whole day, even though it’s a 300-kilowatt crane, that average is about 11 kilowatts,” he says. “We don’t need that much energy to drive the crane. It would be about 110 kilowatt-hours for the whole day.”

Despite the modest average load, many sites default to 650 kVA diesel generators to handle momentary power spikes and transients.

“That’s running at an average of about 2.1% of its peak power capability,” Deakin says. “These generators are massively oversized, but they must deal with the peaks and the high transients.”

Deakin explaining the energy flow in a Sankey diagram for diesel engine efficiency in a genset working at 40 per cent efficiency. Photo: Joe Mather/KHL

The result is a fuel bill wildly out of sync with actual energy needs. “We’re putting a massive generator on to deal with delivering a very small average power,” Deakin says.

This isn’t just a technical inefficiency. For rental firms footing the fuel bill, the costs quickly escalate. “A 500 kVA EU Stage III A generator powering a large tower crane uses 15 litres of diesel an hour on average, for 60 hours per week. That’s 45,000 litres of diesel a year, or €67,500 [US$77,406] at €1.50 [US$1.72] a litre, and 120 tonnes of CO₂.”

Yet the amount of useful energy produced is minuscule. Of the money spent on the fuel, just €4,500 (US$5,160) of it is turned into energy to drive the crane. The remainder, a staggering €63,000 (US$72,235), is wasted in heat.

Even diesel engines running under optimal conditions – at 40% efficiency – lose a significant share of energy through heat and mechanical loss. But under light loads, which are typical on crane sites, performance falls off a cliff. “If we look at the average demand of a tower crane, though, we’re down to 2.5 % load. It means we are running at about 5 to 10 % efficiency. It’s pretty poor. The question is what can we do about it?”

Worsening the issue

Tighter emissions standards under Stage V regulations can worsen the issue. “We’re down at 3 % efficiency and 97 % of the energy in the fuel is just being turned into waste heat. The conclusion is that with EU Stage Five we can make efficiency a lot worse.”

When available, Deakin is clear that mains electricity offers both the lowest emissions and the most attractive economics.

“We’re then not burning diesel and it should give off the least CO₂.” Grid emissions vary by country – from near zero in France to 662 grammes of CO₂ per kilowatt-hour in Poland – but all outperform diesel.

“It means if we take a large tower crane with an average power consumption of about 10 kilowatts, that is between zero and six kilogrammes of CO₂ per hour, produced in the powering of that crane, if it’s on the mains grid,” he calculates.

In locations where grid capacity is constrained, energy storage technologies can bridge the gap.

“We could replace the 500 kVA with a 200 kVA gen set plus a flywheel. That reduces our fuel consumption down to about seven litres an hour. Our brake power is still 10 kilowatts but we’ve pushed that efficiency curve up to 15 % efficient.”

Dr. Andrew Deakin giving his insight into the different technologies and challenges of more efficiently powering tower cranes. Photo: Joe Mather/KHL

Better still, combining a small generator with a full-sized battery or flywheel can unlock further gains, Deakin says.

“If we go to a full power device, for example, a battery energy storage system, or a very large flywheel, where the system is basically charging from the generator at high efficiency, then we could drop that to, for example, a 25 kVA generator and battery, that’s consuming less than three litres of diesel an hour.”

These hybrid setups offer resilience, too. “One is how quickly the battery responds because that battery has to protect the grid from the transients. We can’t put the full power onto the grid for short periods of time because it will just trip the grid breaker,” he says.

For those looking beyond diesel, a range of low-carbon alternatives is emerging – including hydrogenated vegetable oil (HVO), hydrogen fuel cells, hydrogen internal combustion (IC), and synthetic fuels. Deakin notes that Dumarey’s colleagues in Italy are already working with TecnoGen to develop a hydrogen IC generator with integrated flow.

But for now, these options remain limited in scope. “Today, around 99% of the hydrogen is still grey so that doesn’t help,” Deakin said. “If you’re burning HVO, it is things like palm oil in there that is less environmentally friendly than you might think it could be.” Costs, he adds, are also expected to remain high for the foreseeable future.

Hydrogen’s logistical footprint presents additional challenges. “Maybe you have one truck delivery of diesel to your site once a week, but that might be ten truckloads of hydrogen every week to be able to power those tower cranes.”