What are the data for?

WattTime's core offering is our data on the marginal emissions rate of different power grids, in real time. We enable IoT companies to automatically reduce emissions from their products by shifting usage to the times that are less polluting. Our partners work with a wide range of flexible load types, from air conditioners and building chillers, to electric vehicles and battery storage.

This is a little bit similar to the concept of "demand response," but has greater environmental benefits. So, we call it "Environmental Demand Response" or EDR.

However, we've found that many others are interested in WattTime data too. We've also helped researchers analyze the power grid, educators teach about clean energy, and companies do their carbon accounting.

What data are available?

Most of the data is time-series oriented, kind of like a weather API—what's happening on the regional grid at a particular moment? In addition to metadata about data provenance, three kinds of data types are provided for each time series data point:

Generation mix
The power on the grid is generated from different fuel sources at different times; sometimes there's more coal, other times there's more wind. (We count wind and other renewables as types of fuels for ease of comparison.) The API provides the number of megawatts generated from each fuel.
Average carbon
Because the generation mix is constantly changing, the carbon impact of electricity use is constantly changing too. The API provides the total carbon emissions intensity in pounds of CO2 per megawatt-hour. These data are available to all users.
Marginal carbon
More important than the average carbon emissions is the marginal carbon emissions: this is the part of the carbon footprint that you can actually affect by using or conserving energy at a particular place and time, because it's the carbon emitted by the power plant that turns up or down a little bit in response to incremental changes in power demand. The API provides the marginal carbon emissions intensity in pounds of CO2 per megawatt-hour. These data are only available to Pro users and are subject to additional terms and conditions.
Tip: You can select specific date ranges by providing start and end time parameters to the datapoints or marginal endpoints.

And last but not least, there is metadata about each fuel type and its fuel-specific carbon emissions intensity.

What locations have data?

Geographically, the data are organized the same way the grid is: into "balancing authorities" that manage supply and demand for a given service area. The bigger balancing authorities, called Independent Services Operators and Regional Transmission Organizations (ISOs/RTOs), together cover about 2/3 of US electricity consumers.

The WattTime API provides marginal carbon emissions data for all balancing authorities in the lower 48 states of the US, and generation mix and average carbon emissions data for these ISOs/RTOs:

CAISO
California
BPA
Pacific Northwest
MISO
Upper Midwest
NYISO
New York
ERCOT
Texas
ISONE
New England
PJM
Mid-Atlantic
Tip: You can find out what balancing authority a user is in by providing geospatial parameters to the balancing_authorities endpoint.

Where do the data come from?

Power generation data are pulled straight from the ISOs in real time, as frequently as they release it: every 5 minutes in ISONE, MISO, NYISO, PJM, and BPA; every 10 minutes in CAISO; and every hour in ERCOT.

We combine this with CO2 emissions factors from the Energy Information Administration to calculate the average carbon emissions. In a few cases we have to use approximations if a region combines two fuel types. For example, BPA's data focuses primarily on its substantial renewable energy resources and doesn't distinguish between different types of thermal power plants.

The marginal carbon emissions are calculated using WattTime's proprietary algorithm, which matches real-time data about what's happening on the power grid (from balancing authorities and other sources) to historical data about the marginal carbon emissions in similar grid conditions (from the EPA). Learn more about WattTime's research here.

How can I use the API?

Get started by checking out the interactive documentation, the tutorials, and the user group. It's a standard RESTful JSON API, so you can make HTTP requests to API endpoints using any of your favorite tools, from iOS to d3.js to curl.

The API is completely free and open to anyone at the Visitor and Open levels, although access is rate-limited if you don't use an API token. API tokens are free and easy to get: just register for a user account. Data availability terms are subject to change without notice, although of course we'll do our best to keep the user group informed about any upcoming changes.