Technical Summary: Study on Reducing Carbon Emissions in Household Cooling (Hainan, China)

1. Problem Statement

With rapid economic development, cooling energy consumption in China is rising exponentially, accounting for over 15% of total social electricity consumption and approximately 60% of summer peak loads. This surge drives significant carbon emissions, contributing to global warming. Hainan Province, located in China's tropical monsoon zone with long summers and high cooling demands, faces urgent pressure to control these emissions to meet national "double carbon" goals (carbon peaking and carbon neutrality). The study aims to identify effective pathways to reduce carbon emissions specifically from residential cooling energy consumption in this region.

2. Methodology

The research employs the LEAP (Long-range Energy Alternatives Planning) Model combined with scenario simulation analysis to project energy consumption and carbon emissions from 2021 to 2035. The study focuses on Hainan Province and utilizes the following data sources and parameters:

• Sampling Location: Hainan Province, characterized by a hot summer and warm winter climate, with an average cooling season of approximately 140 days and high daily cooling intensity.
• Population Projections: Based on the Hainan Province Population Development Plan (2030) and the 14th Five-Year Plan, the model assumes a permanent population of 13.03 million and an urbanization rate of 65% by 2035.
• Scenario Settings: Three primary dimensions were simulated:
  1. Energy Cleanliness: Projections of the electricity grid's carbon intensity, assuming a reduction from 381 g/kWh (2021) to 270 g/kWh (2035) through increased non-fossil energy (solar, wind, nuclear).
  2. Equipment Penetration: Forecasts for air conditioner and refrigerator ownership per 100 households, projecting AC ownership to rise from 170.1 (2021) to 356.1 (2035).
  3. Energy Efficiency: Two distinct scenarios were modeled:
     • Benchmark Scenario: Aligns with the national "Green and Efficient Refrigeration Action Plan" targets.
     • Ascension (Promotion) Scenario: Based on Hainan's specific low-carbon development requirements, assuming more aggressive market shifts toward higher energy efficiency grades (e.g., increasing the share of Grade 1 efficiency products).
• Calculation Framework: Carbon emissions ($C$) were calculated using the formula $C = Q \times EF$, where $Q$ is electricity consumption and $EF$ is the carbon emission factor per unit of electricity.

3. Key Contributions and Results

3.1 Impact of Energy Cleanliness

Simulations indicate that decoupling energy consumption from carbon emissions via a cleaner grid is highly effective.

• By 2035, under the energy cleanliness scenario, total residential carbon emissions in Hainan are projected to drop to 4.38 million tons (from 6.10 million tons in 2021).
• Specifically for cooling, emissions are projected to fall to 2.19 million tons by 2035, representing a total reduction of 6.95 million tons compared to 2021 levels, assuming consumption volume remains constant.

3.2 Impact of Energy Efficiency and Refrigerant Control

Improving the efficiency of cooling equipment and controlling refrigerant types offers significant reduction potential.

• Efficiency Gains: Under the "Ascension Scenario," residential cooling carbon emissions in 2035 are estimated to be 1.05 million tons lower than the baseline scenario. Over the 15-year period (2021–2035), this path could reduce cumulative emissions by 12.44 million tons.
• Refrigerant Control: Restricting high-GWP (Global Warming Potential) refrigerants (GWP > 150) is identified as a critical measure. Controlling refrigerant types is projected to reduce emissions by 16 million tons over 15 years.
• Combined Effect: The combination of energy efficiency improvements and refrigerant control is estimated to reduce CO2 emissions by a total of 22.3 million tons over the next 15 years.

3.3 Urban vs. Rural Disparities

The study highlights distinct consumption patterns:

• Urban Households: Characterized by high ownership of energy-intensive appliances (ACs and refrigerators), high energy consumption, and high carbon emissions.
• Rural Households: Exhibit lower ownership rates and lower overall consumption. However, due to limited purchasing power and lower acceptance of high-priced energy-saving products, the potential for reduction via efficiency upgrades is constrained compared to urban areas.

4. Proposed Low-Carbon Pathways

Based on the simulation results, the paper proposes two primary low-carbon pathways tailored to different household types:

For Urban Households

1. Clean Energy Adoption: Promote the use of clean energy from the grid and encourage the installation of household photovoltaic (PV) facilities to decouple cooling demand from fossil-fuel-based generation.
2. Efficiency Upgrades: Incentivize the purchase and use of high-efficiency air conditioners and refrigerators to reduce total energy consumption.

For Rural Households

1. Grid Cleanliness: Rely primarily on the decarbonization of the power grid and encourage rooftop PV installations to meet cooling needs with low-carbon electricity.
2. Targeted Efficiency: While efficiency upgrades are noted, the paper suggests they are less viable as a primary driver due to economic constraints; thus, the focus remains on source-side decarbonization (clean grid/PV).

5. Significance of the Study

The paper asserts that reducing carbon emissions from household cooling is critical for achieving China's carbon neutrality goals. The study demonstrates that:

• Dual-Path Strategy: A successful low-carbon transition requires a dual approach: source-side decarbonization (cleaning the energy supply) and demand-side management (improving equipment efficiency and refrigerant control).
• Contextual Specificity: Strategies must be differentiated between urban and rural populations due to disparities in appliance ownership, consumption intensity, and economic capacity.
• Policy Relevance: The findings support the implementation of the "Green and Efficient Refrigeration Action Plan" and provide a quantitative basis for Hainan's specific low-carbon development planning, showing that significant emission reductions are achievable through the combined application of clean energy transitions and efficiency standards.