Our gross 2011 carbon footprint was 1,677,423 metric tons of CO2e (Scope 1: 29,563, Scope 2: 1,439,703, Scope 3: 208,157). After offsets, our net footprint was zero.
Per new industry guidance, we’re now deducting our green power purchases from our footprint, which accounts for the drop in emissions from 2011 to 2012. We also increased our renewable electricity purchases. We’re reporting our 2012 greenhouse gas emissions inventory both with and without green power purchase agreements.
Our net carbon emissions per million dollars in revenue is zero. Our gross carbon footprint per million dollars in revenue was 30.3 metric tons. This continues the downward trend of our footprint growing more slowly than our business. This trend occurs even when we do not deduct our green power purchase agreements. In other words, Google is getting less carbon intensive.
This calculation includes three components: renewable electricity native to the grid, renewable electricity from green power purchase agreements and renewable electricity from on-site facilities. To calculate renewable power from the grid, we multiplied the electricity consumption of our various offices and data centers around the world by the percentage of renewables in that location. For US locations (excluding those associated with green power purchase agreements), our grid renewables data are from the EPA’s eGRID. For non-US locations, our grid renewables data are from the International Energy Agency. For our green power purchase agreements, we assume they are 100% renewable. Similarly, we assume our on-site renewable power generation is 100% renewable. We sum these three totals and divide them by our total power consumption, including on-site renewables.
In 2012, Google’s long-term agreements for renewable power produced 727,732 MWh. These contracts covered 22% of our total electricity consumption. We also obtain green power from the grid and on-site renewables, making the total share of renewables in our mix over 34%. Note that our green power purchase agreements are separate from our renewable energy project investments, as discussed in the next question.
As of the end of 2012, our investments in renewable energy crossed $1 billion in total commitment. The total nameplate capacity of all our renewable energy project investments is over 2 GW. These projects are expected to generate over 5 billion kWh annually—far more electricity than we consume (although we don’t purchase or consume this electricity ourselves). To provide context, this electricity is equivalent to that consumed by approximately 500,000 homes. This assumes that the average home uses 11,319 kWh per year, which comes from the EPA’s GPE calculator. Here are a few other ways to view this power in everyday terms:
We have made additional investments in 2013, but the equivalencies above do not yet reflect them. Note that our renewable energy project investments are separate from our green power purchase agreements, as discussed in the previous question.
Data centers use energy to run the facility as well as to power the servers that do the work. Most data centers use almost as much non-computing or “overhead” energy (like cooling and power conversion) as they do to power their servers. At Google, we’ve reduced this overhead to only 11%. Additionally, we reduce the energy our servers use by designing our own servers, which we have optimized for the work they need to do. We’ve pulled out the components we don’t need, such as peripheral connectors and video cards. We've also efficiently redesigned the components we do need, like power supplies, voltage regulators modules and backup power systems. Combining our efficient servers and facilities, our data centers use 50% less energy than a typical data center.
We used an average commute distance for Googlers, the U.S. Department of Transportation's average fuel economy estimate of 23.5 miles per gallon and the U.S. Environmental Protection Agency’s estimated carbon content of 19.66 lbs CO2 per gallon of gasoline.
We estimate that Google uses the energy equivalent of driving one mile to serve an active user for one month. To calculate this we used the following assumptions:
To estimate the savings from Google Apps for Enterprise, we took our active users of this product and estimated the emissions before and after switching to Google Apps. We used the public Cloud Energy and Emissions Research Model developed by Lawrence Berkeley National Laboratory and Northwestern University. Except for the number of users, we used the same assumptions as those described in this paper.
We produce and track a small amount (less than 1% of our footprint) of biogenic emissions—emissions from biologically based sources like plants, animals or waste. These emissions are released via the landfill gas cogeneration facility we operate on our Mountain View campus and the biodiesel we use in our shuttles. Biogenic emissions are often excluded from an entity's compliance footprint (e.g. these California regulations) because they are part of the natural carbon cycle. The natural carbon cycle takes carbon out of the atmosphere on the front end (as opposed to using fossil fuels) and results in emissions that would have happened anyway. For example, the landfill gas we use to generate power would have otherwise been flared, resulting in the same emissions. Or it would have vented directly as methane which would have an even higher greenhouse gas impact. While we track our biogenic emissions, we do not include them in our footprint.
We’re reporting our carbon footprint separately from Motorola Mobility LLC because we operate the companies independently. Motorola Mobility’s carbon footprint, including its verification statement, is available here.