Elevator Energy Saving and Energy Recovery: Practical Supercapacitor Solution

In urban building energy consumption, elevators, as core vertical transportation equipment, account for 10% to 15% of total energy use. More than 90% of the downward potential energy and braking kinetic energy are wasted as heat for a long time, which not only increases building operation costs but also runs counter to the "dual carbon" goals. With core advantages such as millisecond-level response, high power density, long cycle life, and intrinsic safety, supercapacitors can achieve efficient recovery and reuse of elevator energy without complex modifications, making them a practical solution to the problem of high elevator energy consumption. Based on actual elevator operating conditions, this solution provides a implementable and highly adaptable supercapacitor-based elevator energy saving and recovery plan from aspects of scheme design, core configuration, implementation process, and energy-saving benefits. It is suitable for various new and old elevator renovation scenarios, balancing energy-saving effects and economic efficiency.

I. Core Positioning and Applicable Scenarios of the Solution

(1) Core Positioning

With the core logic of "energy recovery - efficient storage - on-demand release", this solution captures the regenerative energy generated during elevator descent and braking through a supercapacitor system. The stored energy is then used for power-consuming links such as elevator startup and acceleration to achieve "peak shaving and valley filling". At the same time, it optimizes elevator power supply stability and replaces traditional emergency power supplies, achieving the triple goals of "energy saving and consumption reduction + safety guarantee + cost saving". It does not change the original control logic of the elevator, and the non-intrusive modification makes it more practical.

(2) Applicable Scenarios

This solution is suitable for various passenger elevators and freight elevators, especially for the following high-energy-consumption and high-frequency start-stop scenarios, where the energy-saving effect is more prominent:

• High-rise buildings (10 floors and above): Elevators have long round-trip distances and large potential energy differences, generating a large amount of regenerative energy with significant energy-saving potential;

• High-frequency start-stop scenarios: Office buildings, shopping malls, hospitals, transportation hubs, etc., where elevators operate more than 1,000 times a day, with frequent braking and serious energy waste;

• Old elevator renovation: Energy-saving upgrading can be quickly achieved without large-scale modifications to existing equipment, solving problems such as high energy consumption and aging emergency power supplies of traditional elevators;

• Extreme environment scenarios: In extremely cold northern regions and high-temperature southern regions, supercapacitors can operate stably in a wide temperature range of -40℃ to 85℃ without additional temperature control equipment, with better adaptability than traditional energy storage media.

II. Core Principle of the Solution

During elevator operation, energy consumption is mainly concentrated in two stages: startup and acceleration (power consumption) and braking and descent (power generation). When the elevator carries people or goods upward, the traction motor outputs power to drive the car up, consuming grid electricity. When the elevator descends or brakes, the gravity of the car drives the traction motor to reverse, and the motor converts to a power generation state, producing a large amount of regenerative energy. In traditional elevators, this part of the energy is wasted as heat through braking resistors, which also increases the heat dissipation load of the machine room.

The supercapacitor solution achieves efficient energy utilization through a closed-loop design, with the core principle divided into three steps:

1. Energy Capture: When regenerative energy is generated during elevator descent and braking, the system quickly rectifies the AC power into DC power through a bidirectional DC/DC converter. Supercapacitors capture the energy at a millisecond-level response speed, with a recovery efficiency of over 95%, far exceeding the 30% recovery efficiency of traditional technologies;

2. Energy Storage: Supercapacitors adopt the principle of physical energy storage without chemical reactions, enabling rapid storage of short-term high-power electrical energy and avoiding energy loss. At the same time, they have the advantages of more than 100,000 charge-discharge cycles and a service life of 10-15 years, eliminating the need for frequent replacement;

3. Energy Release: When the elevator starts and accelerates, supercapacitors quickly release the stored energy to assist the traction motor operation, reducing grid electricity consumption. At the same time, they can stabilize the grid voltage fluctuation during elevator startup, avoid impacts on the grid and other electrical equipment, and optimize power supply stability.

III. Detailed Design of the Practical Supercapacitor Solution

(1) Selection of Core System Configuration

Combined with elevator parameters such as load capacity, speed, and operating frequency, suitable supercapacitor modules and auxiliary equipment are configured to ensure the solution is practical, efficient, and reliable. The selection of core configurations is as follows (adjustable according to actual operating conditions):

(2) System Installation and Commissioning Process

This solution adopts non-intrusive installation, which does not require modifications to the elevator's original control program and mechanical structure. The installation cycle is short and has little impact on the normal operation of the elevator. The specific process is as follows:

1. Preliminary Survey (1 day): On-site detection of elevator parameters such as rated power, load capacity, operating frequency, and machine room space, confirm the installation position of the supercapacitor module and auxiliary equipment, and formulate a personalized installation plan. Especially for old elevators, it is necessary to confirm the machine room load-bearing capacity and space adaptability;

2. Equipment Installation (1-2 days): Fix the supercapacitor module, bidirectional DC/DC converter, and protection module, connect the wiring kit, and connect the system to the DC bus bypass of the elevator inverter. Adopt a "non-intrusive" design that does not change the elevator's original operation logic to ensure safe and reliable installation. The "one device for multiple elevators" mode can be adopted to reduce renovation costs (a single device can cover 3-5 elevators);

3. System Commissioning (1 day): Start the energy management system, debug the charge-discharge parameters, simulate elevator operating conditions such as upward, downward, and braking, optimize the charge-discharge strategy to ensure that the regenerative energy recovery efficiency and energy release timing are accurately matched with the elevator operating conditions, and test the emergency power supply function at the same time;

4. Trial Operation and Acceptance (3-7 days): Put the system into trial operation, real-time monitor energy consumption data and charge-discharge status, troubleshoot potential faults, verify energy-saving effects and system stability, ensure that the energy-saving rate meets the standard and the emergency response is normal, and issue an acceptance report.

(3) Daily Operation and Maintenance Plan

The supercapacitor system has a simple structure and low maintenance costs, requiring no complex operation and maintenance. The key points of daily operation and maintenance are as follows, which can greatly reduce the overall operation and maintenance costs of the elevator:

• Regular Inspection (once a quarter): Check the appearance of the supercapacitor module and wiring terminals to confirm no looseness, corrosion, or overheating, and troubleshoot the operation status of the protection module and energy management system;

• Parameter Calibration (once every six months): Calibrate the charge-discharge voltage and current parameters through the energy management system, optimize the charge-discharge strategy to ensure the system is always in the best operating state and improve capacitor utilization;

• Fault Handling (real-time response): The system has a fault early warning function. If overvoltage, overcurrent, temperature abnormality, or other conditions occur, it will automatically cut off the power supply and issue an early warning. The operation and maintenance personnel will promptly troubleshoot the fault (such as loose wiring, module damage, etc.) and quickly restore operation;

• Lifespan Management: The service life of supercapacitors can reach 10-15 years, without frequent replacement. It is only necessary to test the capacitor capacity at the end of its service life (around 10 years) and replace the module as needed. Compared with traditional lead-acid emergency batteries (replaced every 3-5 years), it greatly reduces replacement costs and environmental pressure.

IV. Advantages and Energy-Saving Benefits of the Solution

(1) Core Advantages

• Significant Energy-Saving Effect: Recover elevator regenerative energy with a comprehensive energy-saving rate of 25%-45%. In high-frequency start-stop scenarios (such as office buildings and shopping malls), the energy-saving rate can exceed 40%. A single elevator can recover 4,000-12,000 kWh of electricity per year, equivalent to the annual electricity consumption of 10 households, far exceeding traditional energy feedback devices;

• Convenient Renovation and Controllable Cost: Non-intrusive installation, no need to modify the elevator's original structure and control program, installation cycle of 1-3 days, without affecting the normal use of the elevator. The initial investment can be recovered through energy-saving benefits within 2-5 years, with low later operation and maintenance costs. The "one device for multiple elevators" mode can further reduce renovation costs;

• Safe, Reliable, and Strongly Adaptable: Supercapacitors adopt physical energy storage, with no safety risks such as electrolyte leakage and thermal runaway, achieving intrinsic safety. They can adapt to a wide temperature range (-40℃~65℃) without additional temperature control equipment, suitable for various extreme environments and elevators of different brands and models, meeting the needs of both new and old elevator renovation. At the same time, they can replace traditional lead-acid emergency power supplies to achieve millisecond-level emergency leveling and improve elevator operation safety;

• Outstanding Additional Value: Stabilize grid voltage fluctuations during elevator startup, reduce impacts on the grid and other electrical equipment, and reduce additional energy consumption of the elevator control system. Reduce heat dissipation of braking resistors, lower the air conditioning load of the machine room, and indirectly achieve building energy saving. Some solutions can reserve photovoltaic access ports to realize "photovoltaic-storage-elevator" integrated operation in the future and improve the penetration rate of green electricity. At the same time, it can accurately measure energy-saving and carbon emission reduction to assist in carbon asset development and trading.

(2) Energy-Saving Benefit Calculation (Taking a 1.5-ton Office Building Elevator as an Example)

Taking a 1.5-ton office building elevator with 2,000 daily operations and an original daily power consumption of 120 kWh as an example, the energy-saving benefits after adopting this solution are as follows:

• Energy-Saving Rate: Calculated at 35%, the daily power saving is 42 kWh, and the annual power saving is 15,330 kWh;

• Cost Savings: Calculated at an industrial electricity price of 0.8 yuan/kWh, the annual electricity cost savings is 12,264 yuan. If the cost of emergency battery replacement is included (about 5,000 yuan can be saved every year), the annual comprehensive cost savings exceed 17,000 yuan;

• Carbon Emission Reduction: Each kWh of electricity corresponds to 0.785 kg of carbon dioxide emissions, reducing carbon dioxide emissions by about 12.03 tons per year, which is in line with the "dual carbon" goals. At the same time, a carbon footprint report can be generated to assist in carbon asset trading.

V. Notes for Solution Implementation

• Configuration Adaptation: According to actual elevator operating conditions such as load capacity, speed, and operating frequency, reasonably select supercapacitor modules and bidirectional DC/DC converters to avoid insufficient or redundant capacity, ensure energy-saving effects and system stability, and optimize configuration parameters through energy consumption calculation models;

• Installation Specifications: During installation, it is necessary to link with the elevator's original inverter and safety system to ensure standardized wiring and good grounding, avoid electromagnetic interference. Adopt "non-intrusive" installation without changing the elevator's original operation logic to ensure safe elevator operation. For old elevators, it is necessary to check the machine room load-bearing capacity and space adaptability in advance;

• Compliance Requirements: Follow national standards such as the "Interim Measures for the Administration of New Energy Storage Projects" and the "Code for Elevator Manufacture and Installation Safety", implement multiple safety protection measures to ensure compliant system operation. In some regions, energy-saving subsidies can be applied for to improve the economy of the solution;

• Scenario Adaptation: Prioritize the adoption of this solution for elevators with high-frequency start-stop and long travel, where the energy-saving effect is more significant. For elevators with low frequency and short travel, configuration parameters can be optimized according to actual energy consumption to reduce initial investment costs. For extreme environment scenarios, select high and low temperature resistant supercapacitor modules to ensure stable operation;

• Business Model Innovation: Combine the "insurance + technology + service" model to reduce promotion thresholds through insurance credit enhancement, achieve a win-win situation for owners, insurance companies, and technology enterprises, and promote large-scale implementation of the solution.

VI. Solution Summary

The supercapacitor-based elevator energy saving and energy recovery solution, focusing on practicality, efficiency, and low cost, achieves efficient recovery and reuse of elevator regenerative energy through non-intrusive modification. It not only solves the pain points of high energy consumption and serious energy waste of traditional elevators but also optimizes power supply stability and replaces traditional emergency power supplies, balancing energy-saving benefits, safety benefits, and economic benefits. This solution is suitable for various elevator scenarios, with convenient installation and simple operation and maintenance, requiring no complex technical investment and achieving quick results. It can not only help building operators reduce elevator operation costs but also assist in the realization of "dual carbon" goals, providing a replicable and promotable practical path for urban building energy-saving renovation.

With the continuous upgrading of supercapacitor technology and the optimization of AI energy management systems, "one device for multiple elevators" coordinated dispatching and "photovoltaic-storage-elevator" integrated operation can be further realized in the future. Combined with carbon asset development, elevators can be transformed from "energy hogs" to "low-carbon engines", injecting new momentum into the development of green buildings.