Release Notes
Updates and announcements about our API and data signals.

Coverage of the `co2_moer` signal has expanded to 170 new regions, which brings our global MOER coverage to 342 grid regions total in 210 countries and territories. A new type of `co2_moer` model is used for these new grid regions, learn more about the new synthetic demand proxy regression model here. See our global coverage map here.
API accounts with global data access will automatically gain access to these new grid regions. If you’re having trouble accessing them, please contact support@wattime.org. If you don’t have a global license, but are interested, please contact us to discuss an upgrade.
API meta parameters:
model = 2024-08-15
type = synthetic_proxy
The proxy regression model used in ten grid regions has been updated. Affected regions are BRA, CHL, IND, KOR, MYS, NIC, PER, PHL, SGP, TUR. The update includes minor bug fixes, along with a retrain on newer data. [edit on 11/12/2024]: as of today, this model will be used by default when the optional model
parameter is not used.
API meta parameters:
model = 2024-10-10
type = proxy
From Aug 14 until resolution on Aug 20, the forecast data available from WattTime's API was published with lower confidence than usual. Many of the features that shape the forecast data were not included, and the forecast was created solely using long-term emissions modeling based on time-of-day. The recent and real-time grid operations data was not taken into account so the result was that each day had the same forecast as the prior day. This affected the forecast for all grid regions. A fix was deployed on Aug 20, which returned the forecasts to normal with full features and fidelity. We apologize for this temporary data issue. There is no action needed on your part to make sure you are getting the right data now. Please contact support@watttime.org if you have any questions.
WattTime has changed the HTTP response status code for missing, expired, or invalid authentication tokens in our APIs.
Issue | Old Status Code | New Status Code |
Token missing, expired, or invalid | 403 Forbidden | 401 Authorization Required |
Why might this matter? Some users may have a heuristic in their code that will re-authenticate after a token expires (reminder: tokens are valid for 30 minutes). If your code is designed to re-authenticate when you get an HTTP 403 response, but not if you get an HTTP 401, then you will need to update that heuristic accordingly so that it will properly re-authenticate when you get an HTTP 401.
Contact support@watttime.org if you have questions or concerns about this upcoming change.
WattTime published some erroneous values for CO2 AOER due to a change in the data reported by the US EIA. These erroneous values were backfilled with new data on Jan 29. If you store AOER data for future use, we recommend you re-pull AOER data for all 53 US regions (region list as csv download: My_access_list_aoer_US), for October through January. If you are using v3/historical, you can use the new `updated_since` parameter to pull just the data points that are new, i.e. 'updated_since': '2024-01-29T00:00:00+00:00' . Another option is to pull the entire months of October through January to replace all the data you previously pulled for these months. Please contact support@watttime.org if you would like support with this.
Coverage of the `co2_moer` signal has expanded to 12 new countries (21 new regions). These new regions are only available in API v3. A new type of `co2_moer` model is used for many of these new countries, learn more about that model type here. New countries: Mexico, Japan, South Korea, Brazil, India, Chile, Peru, Turkey, Malaysia, Nicaragua, Philippines, Singapore.
WattTime is excited to offer a new signal measuring the marginal damage to human health from electricity use. Read more about the health damage signal here. It is initially available in US grid regions only. Please contact us if you’d like to obtain access to this new signal.
Data model versioning in the new API uses dates instead of decimals. Each model will be labeled with a date string that roughly corresponds to its release date. Model dates can be unique to each combination of grid region and signal type. A full list of available model date versions can be obtained by using the /v3/my-access endpoint.
WattTime released API version 3 that provides expanded functionality including more intuitive and descriptive data delivery, signal information, and error handling. The old API (version 2) will continue to be supported until June 2024. A detailed transition guide explaining the differences between the old v2 API and the new v3 API can be found here.
Fixed bug that affected forecast requests that used local time for ‘starttime’ and ‘endtime’ parameters.
This `co2_moer` data model release improves our renewable curtailment modeling, and only applies where we model renewable curtailment. For ISOs where curtailment ground truth data is available, we train a supervised ML model to predict in real-time whether curtailment is occurring. We then apply a region-specific threshold to the relevant LMP prices as an additional filter in creating a curtailment probability value (LMP threshold used exclusively where ground truth is not available). This model version is not available in APIv2, it was only released in APIv3-beta (as meta=3.3), and will later be available in APIv3 (as `2023-03-01`).
We’ve improved our detection of marginality for certain fuel types, and we’ve also retrained our models on more recent data to reflect structural grid changes like plant retirements.
Standardized time-series frequency to 1-hour in all regions. Improved robustness to extended source data outages. Updated reference emissions factors to IEA 2019. Changed data source for CAISO from CAISO to IEA to ensure the calculation methodology is consistent in all regions.