Main results:
- Operating equipment with high inrush needs the optimal way
- Downsizing, and operating generators with maximum efficiency
- Saving diesel, cost, CO₂ and NOₓ
- Showing how our Energy Management System (EMS) enhances traditional solutions in a hybrid setup with flexible, adaptable options
DEALING WITH HIGH INRUSH CURRENTS
Careys needed a way to power tower cranes efficiently while reducing environmental impact. Sunbelt and Greener where able to provide the solution. Tower cranes have large energy requirements to cover the inrush currents needed for heavy lifts. The traditional approach is to provide a large diesel generator that can meet the maximum currents specified on the crane’s spec sheet. This leads to large generators on site burning thousands of litres of diesel each week and producing unnecessary CO₂ and NOₓ emissions.
Incorporating a Greener battery energy storage system (BESS) in a hybrid set-up with a generator enables downsizing of the generator, as the battery and generator together deal with high peak loads. Combining Greener’s 318 kVA / 422 kWh BESS with Sunbelt’s 300 kVA generator means the system can deliver a total load of 700 amps if required. This is the ideal set-up for tower cranes with high inrush current demands.
PROJECT RESULTS WITH CAREYS
Based on an 800 kVA comparison from December 2024 to July 2025, Careys achieved:
- Generator running hours saved: 5,052 hours
- Fuel savings: 126,961 litres
- CO₂ savings: 409 tonnes
- NOₓ savings: 1,903 kg
By working with Greener and Sunbelt Rentals, Careys showed how hybrid power solutions can meet high operational demands while delivering measurable environmental and cost savings.
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LETTING THE LOAD PROFILE DEFINE THE SOLUTION
Traditionally, a large generator is used to deal with the high peak loads of tower cranes. However, the average load of a tower crane throughout most of the day and night is low. This means large generators would be running at a low load 24/7, wasting fuel and creating unnecessary emissions.
Frequent underloading of diesel generators results in operational problems, increasing servicing needs and breakdowns. This is particularly problematic with Stage V generators, as underloading causes Diesel Particulate Filters to block.
In this hybrid set-up, Sunbelt Rentals’ 300 kVA generator is used to recharge Greener’s BESS. The battery’s Energy Management Software (EMS) calls for the generator when it reaches 35% state of charge. The EMS turns the generator on to recharge the battery at 80% of its maximum load and switches off once the battery is charged. This ensures the generator is operating at its most efficient and never idling.
BATTERIES ARE BEST FOR TRANSIENT LOAD PATTERNS
The transient load profile of tower cranes is ideal for delivery by batteries. Batteries can deliver high peak loads instantly through their inverters with no delay in power, unlike diesel generators. Generators operate best with an even load delivery, while tower cranes have very transient load patterns. When lifting, they have a very high peak load, but when idle, their energy demand is low. A battery in a hybrid set-up with a generator enables the ideal delivery of these transient workloads.
GREENER’S RAPID CHARGING SOLUTIONS LEAD THE WAY
The inverter power of our battery systems means it can be charged very fast, in this case at 400 amps maximum. This means the generator can charge the battery quickly and then return to silent running. This results in less diesel used, more silent hours, and reduced emissions. This is a great benefit for projects in residential areas and improves the working environment on site. Rapid charging sets Greener’s products apart from other solutions that charge slower and are less able to deal with transient load patterns.
