How to Choose a Power Supply Method for a Double Girder Rubber-Tired Crane (RTG)?

The core of choosing a power supply method for a double girder rubber-tired crane (RTG) is matching mobility, workload, cost, and environmental requirements. Mainstream solutions include: diesel generator sets, mains power conductor rails, lithium batteries, supercapacitors, and hybrid power. The following details the selection logic, comparison of various solutions, and selection steps.

I. Core Decision-Making Dimensions for Selection
First, clarify four key indicators, then select the corresponding solution:

Mobility: Is cross-regional operation, no fixed track, or frequent site relocation required?

Workload Intensity: Continuous operating time, lifting capacity, annual working hours?

Cost: Initial investment, energy consumption, maintenance, depreciation, subsidies?

Environmental Protection and Compliance: Noise, emissions, power grid conditions, policy requirements?

II. Comparison of Mainstream Power Supply Methods (Applicable to Double Girder Rubber-Tired Cranes)

1. Diesel Generator Set (Most Traditional and Universal)

Principle: Built-in diesel engine + generator, independent power supply for the entire machine.

Advantages: Highest mobility, no external power supply limitations, can operate in all or across different sites.

**Advantages:** Sufficient power, quick start-up, and strong continuous operation capability.

Low initial investment, mature system, and simple maintenance.

Disadvantages: High fuel consumption, high emissions and noise, significant environmental pressure.

High maintenance costs (oil, filters, overhauls).

High idling energy consumption and low efficiency.

Suitable scenarios: Port bulk cargo, storage yards, no power grid, high mobility, and low frequency operations.

2. **Maintenance-Powered Contact Line (RTG)**

Principle: A contact line is laid along a track, powered by a current collector, and driven purely by electricity.

Advantages: Zero emissions, low noise, and lowest energy cost (electricity price is much lower than fuel).

Simple maintenance, long lifespan, and low failure rate.

Suitable for high-frequency, continuous 24-hour operation.

Disadvantages: Poor mobility; can only operate along a fixed track and cannot be moved between sites.

High initial infrastructure costs (contact line, track, power supply cabinet).

Limited by power grid capacity and stability. Applicable Scenarios: Fixed storage yards, high-turnover container terminals, and areas with good power grid conditions.

3. Lithium-ion Battery Powered (Pure Electric RTG)

Principle: Powered by a large-capacity lithium-ion battery pack, with no external cables.

Advantages: Zero emissions, low noise, high mobility (similar to diesel).

Low energy consumption costs, fast charging, and high energy recovery efficiency.

Minimal maintenance (no engine, no sliding contact).

Disadvantages: High initial investment (battery + BMS + fast charging).

Limited range (4–12 hours), requiring centralized charging/battery swapping.

High requirements for battery life (5–8 years), low-temperature performance, and safety management.

Applicable Scenarios: High environmental protection requirements, areas with charging/battery swapping stations, and medium-to-high frequency operations.

4. Supercapacitor (Short Cycle, High Power)

Principle: Supercapacitor + auxiliary power supply, high peak power, and extremely fast charging and discharging.

Advantages: Millions of charge/discharge cycles, extremely long lifespan, and maintenance-free.

High energy recovery efficiency (recovery braking energy). Excellent low-temperature performance and high safety.

Disadvantages: Low energy density and short range (only 1–3 hours).

Requires fast charging/slide-on/diesel refueling.

High cost per unit power.

Suitable scenarios: Short cycles, frequent start-stop, and when used with slide-on/diesel hybrid systems.

5. Hybrid Power (Hybrid Electric/Lithium Battery + Diesel)

Principle: Diesel generator + lithium battery/supercapacitor, intelligent switching.

Advantages: Balances mobility and low energy consumption; can be used for short distances on pure electric power and long distances on diesel.

Fuel consumption reduced by 30%–50%, emissions and noise improved.

Flexible range, no range anxiety.

Disadvantages: Complex system, higher maintenance costs than pure electric/pure gasoline.

Initial investment higher than pure diesel.

Suitable scenarios: Balances mobility and environmental protection, medium to high frequency, and no fixed power grid.

III. Scheme Comparison Summary Table (Quick Selection)

IV. Selection Steps (Implementation Suggestions)

Define Working Condition Boundaries

Work Scope: Fixed Track / Full-Field Mobility / Cross-Field?

Annual Working Hours: <2000 (Low Frequency) / 2000–4000 (Medium Frequency)/> 4000 (High Frequency).

Lifting Capacity, Span, Lifting Height, Continuous Working Time.

Power Grid Conditions: Voltage, capacity, and whether capacity expansion is permitted.

Environmental Policies: Emissions, noise, and carbon emission requirements.

Prioritized Solution Matching:

Prioritizing Mobility: Diesel/Hybrid/Lithium Battery.

Prioritizing Low Cost + Continuous Operation: Mains Power Sliding Contact System.

Prioritizing Environmental Protection + Policy Subsidies: Lithium Battery/Hybrid.

Short Cycle + Energy Recovery: Supercapacitor + Sliding Contact System/Diesel.

Economic Calculation (Critical):

Live Cycle Cost (LCOE): Initial Investment + Energy Consumption + Maintenance + Depreciation + Subsidies.

Example:
Pure Diesel: Low initial investment, high annual energy consumption/maintenance.

Sliding Contact System: High initial investment, extremely low annual cost, payback period of 3-5 years.

Lithium Battery: High initial investment, low annual cost, payback period of 5-8 years, significant long-term advantages.

Technology and Safety Verification:

Lithium Battery: BMS, thermal management, fire protection, fast charging/battery swapping solutions.

Sliding contact: Current collector reliability, wind resistance, dustproofing, insulation.

Hybrid: Control system, switching logic, reliability.

V. Selection Conclusions and Recommendations

Fixed yard, high turnover, good power grid: Mains-powered sliding contact is the first choice, with the best long-term cost.

Fully mobile, no power grid, average environmental impact: Diesel generator is the safest choice.

High environmental requirements, charging facilities available, medium to high frequency: Lithium battery is the preferred choice, the trendsetter.

Balancing mobility and environmental protection, no fixed power grid: Hybrid power is the best balance.

Short cycle, frequent start-stop, energy recovery: Supercapacitor + auxiliary power supply.