Carbon intensity is a measure of greenhouse gas emissions per unit of output, usually expressed as kg CO₂e per kWh of electricity. In EV charging, carbon intensity shows how “clean” the delivered charging energy is and is used to compare sites, time periods, and energy sourcing strategies.
What Is Carbon Intensity?
Carbon intensity is an emissions ratio:
– Carbon intensity = CO₂e emissions ÷ energy delivered (kWh)
For EV charging, it is most commonly reported as:
– kg CO₂e per kWh delivered to EVs
– g CO₂e per kWh (same metric, smaller unit)
Carbon intensity can be calculated:
– Per charging session
– Per site (monthly/annual average)
– Per network (country or region)
– Per time window (hourly or peak/off-peak)
Why Carbon Intensity Matters in EV Charging
Total emissions alone can be misleading because they scale with usage. Carbon intensity matters because it:
– Enables fair comparison across sites with different utilization levels
– Shows the impact of electricity sourcing (grid mix vs renewable procurement)
– Supports ESG reporting and tender scoring with clear, comparable KPIs
– Identifies where operational changes (scheduling, load shifting) reduce emissions
– Helps fleets and property owners report emissions per kWh and per vehicle
– Supports carbon dashboards and automated reporting for customers
Lower carbon intensity generally means charging is powered by cleaner electricity.
What Determines Carbon Intensity for Charging
Key drivers include:
– Grid emission factor at the location (country/region mix)
– Time of charging (hourly grid mix can vary; peak periods may be more carbon intensive)
– Renewable procurement approach (market-based instruments like Guarantees of Origin (GO))
– On-site generation (solar canopy, PV) and behind-the-meter storage (BESS) operation
– Losses and overhead (charger efficiency, standby consumption, site auxiliaries)
– Allocation method if reporting includes shared overhead emissions
How Carbon Intensity Is Calculated in Practice
A typical calculation includes:
– Metered kWh delivered from chargers or billing-grade metering
– Emission factors for electricity (location-based and/or market-based)
– Optional inclusion of charger losses and site overhead (defined boundary)
– CO₂e results divided by the kWh delivered
For consistency, organizations often report both:
– Location-based carbon intensity (grid average)
– Market-based carbon intensity (based on procurement contracts and instruments)
Typical Use Cases
– Fleet reporting: kg CO₂e per kWh and per vehicle group
– Business parks allocating emissions intensity to tenants
– Public charging networks comparing carbon intensity by region
– Tender submissions showing low-carbon operation strategy
– Optimization projects scheduling charging to lower-carbon hours
– Carbon dashboards displaying trends and progress vs targets
Key Benefits of Using Carbon Intensity
– Comparable KPI across sites, customers, and time periods
– Clear evidence of improvements from renewable sourcing and operational optimization
– Better decision-making for charging schedules and energy management
– Supports “greener charging” customer reporting when properly documented
– Enables benchmarking and continuous improvement
Limitations to Consider
– Results depend on methodology and boundary definition (losses included or not)
– Emission factors vary by source and can change annually
– Hourly intensity requires high-quality time-stamped energy data
– Market-based reporting requires strong governance to avoid double counting
– Low carbon intensity does not automatically mean low total emissions if usage grows significantly
Related Glossary Terms
Carbon Footprint
Carbon Accounting
Carbon Footprint Reporting
CO₂e
Emission Factors
Guarantees of Origin (GO)
Load Shifting
Behind-the-Meter Storage
Billing-Grade Metering
Carbon Dashboards