WattTime Grid Carbon Intensity API
WattTime grid carbon intensity REST API for energy management systems, software companies, and sustainability teams to access real-time and forecasted marginal carbon emissions rates for US and international electricity grids — enabling automated clean energy shifting, carbon accounting, and emissions reduction through time-based and location-based grid carbon data. Enables AI agents to manage real-time marginal emissions for clean energy dispatch automation, handle grid region lookup for location-based carbon data automation, access emissions forecast for predictive clean energy scheduling automation, retrieve historical emissions for carbon accounting automation, manage MOER (Marginal Operating Emission Rate) for grid emissions factor automation, handle clean energy signal for automated load shifting automation, access regional grid data for multi-region carbon comparison automation, retrieve carbon accounting report for Scope 2 emissions automation, manage automated demand response for clean electricity optimization automation, and integrate WattTime with building management, EV charging, and industrial load management for end-to-end grid carbon optimization automation.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Grid emissions data. GDPR. Token auth. US. Grid carbon intensity data.
⚡ Reliability
Best When
A software company, building management system, or sustainability team wanting AI agents to optimize electrical consumption timing based on real-time and forecasted grid carbon intensity through WattTime's marginal emissions data.
Avoid When
GRID REGION LOOKUP REQUIRED: WattTime data is organized by grid balancing authority region (BA); automated coordinate-to-region mapping assumption creates missing region discovery step; automated must call region lookup API with lat/lon before requesting emissions data. MOER vs AER DISTINCTION: WattTime provides both MOER (marginal emissions — impact of changing load) and AER (average emissions — for general accounting); automated single emissions metric assumption creates wrong methodology choice for specific use case; automated must use MOER for demand flexibility and AER for carbon accounting. FREE TIER IS CURRENT DATA ONLY: WattTime free tier provides only real-time data; automated historical data access on free tier creates access_denied; automated historical or forecast data requires paid subscription. GEOGRAPHIC COVERAGE IS INCOMPLETE: WattTime has excellent US coverage but incomplete global coverage; automated worldwide grid coverage assumption creates unavailable_region for many non-US grids; automated should verify region availability before committing to international deployments.
Use Cases
- • Shifting flexible electrical loads to cleaner grid periods for corporate sustainability automation agents
- • Accessing real-time grid carbon intensity for data center clean energy scheduling automation agents
- • Generating Scope 2 market-based carbon accounting reports for ESG reporting automation agents
- • Optimizing EV charging timing based on grid emissions forecast for fleet management automation agents
Not For
- • Solar or renewable asset generation data (WattTime is grid consumption carbon data, not generation monitoring)
- • Utility billing or electricity pricing (WattTime provides carbon data only, not tariff data)
- • Real-time grid control (WattTime is informational carbon signal, not operational grid SCADA)
Interface
Authentication
WattTime uses username/password to obtain token for API authentication. REST API with JSON. Oakland, CA HQ. Founded 2014 as nonprofit. Acquired by RMI (Rocky Mountain Institute) 2021. Products: Real-time MOER, MOER forecast, historical emissions, region lookup, carbon accounting. SDKs: None public. US coverage comprehensive (all NERC regions); limited global coverage. Free tier available. Partners: Google, Microsoft, Apple for carbon-aware computing. GDPR compliant.
Pricing
Oakland CA. RMI nonprofit subsidiary. Free tier for real-time US data. Commercial for forecast/historical. Climate mission.
Agent Metadata
Known Gotchas
- ⚠ TOKEN-BASED AUTH FROM USERNAME/PASSWORD: WattTime authentication requires username+password POST to get Bearer token; automated static API key header assumption creates 401; automated must POST to /login with credentials to get token, then use Bearer token for API calls
- ⚠ REGION LOOKUP REQUIRED BEFORE DATA: WattTime grid regions are balancing authority codes (e.g., CAISO_NP15, MISO); automated lat/lon-to-emissions direct call creates missing BA region; automated must call /ba-from-loc endpoint with coordinates to get correct BA before data queries
- ⚠ MOER VS AER FOR DIFFERENT USE CASES: WattTime MOER (marginal) is for load flexibility optimization; AER (average) is for Scope 2 carbon accounting; automated using MOER for carbon accounting creates methodologically incorrect emissions inventory; automated must choose correct metric per use case
- ⚠ FREE TIER IS REAL-TIME ONLY: WattTime free tier restricts access to real-time current data only; automated historical data request on free account creates access_denied; automated historical analysis or forecast access requires commercial license
- ⚠ 5-MINUTE DATA UPDATES: WattTime MOER data updates every 5 minutes; automated sub-5-minute polling creates redundant API calls; automated should poll at 5-minute intervals maximum for optimal efficiency
Alternatives
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Scores are editorial opinions as of 2026-03-07.