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Published on July 10th, 2019 | by Michael Barnard


What Is The Carbon Debt Of Cloud Computing?

July 10th, 2019 by  

The world of computing is more than not the world of Cloud computing these days. While online banking goes back to the bank’s data centers, they connect to the Cloud and the information transits the Cloud. The vast majority of data people consume online, from print to videos to music, is stored in the Cloud and accessible through websites maintained in various Cloud infrastructures. The apps on our phones talk to Cloud-hosted backends that provide us with all of the games and social media we can distract ourselves with.

This all begs the question: is that good or bad for the environment? Cloud data centers, wherever they are, all run on electricity. How the electricity is generated is the primary factor in whether they are more or less benign for all of the economic, education, social and entertainment values that they bring to us.

Microsoft Azure and Google Cloud are the best choices
if you are sourcing Cloud services today and environmental impact is an important concern.

And it’s pretty good. The best managed providers are much better than global averages for other industries. Given the economic value of the internet and the blossoming of innovation and entrepreneurialism, it’s worth pointing out that anything done in an automated fashion is almost by definition of lower environmental impact than anything done to the same extent but mechanically. That’s part of the major improvement in efficiency we’ve seen, with all of its pros and cons.

But determining how Cloud computing has impacts requires data, a methodology, and conclusions. We’ll need the electrical consumption of a large portion of the Cloud, broken down by major providers. We’ll need their current and future plans for sourcing electricity. And we’ll need some adjustments for specific cases and carbon debts for different forms of electricity.

This also assumes that the primary concern is global warming, which is also a good proxy for other fossil fuel pollution. However, it doesn’t take into account environmental challenges for computing unrelated to electricity.

Who are the biggies?

Source canalys from press material

Per canalys, over 50% of the Cloud is powered by three companies, Amazon, Microsoft, and Google, in that order. Their commitments and actions are the ones to assess, but Alibaba is worth looking at as well due to its high growth rate and positioning in the huge growth market of China.

How much electricity & related carbon is involved?

As of late 2017, US data centers — Cloud, co-located and private — consumed more than 90 TWh of electricity annually per a credible source for this assessment. Globally, the figure was 416 TWh. For context, total global consumption of electricity is in the 20,000 TWh range, so data centers are in the 2% of total global demand range and growing.

Carbon intensity of different forms of electrical generation matters. Low-carbon energy — wind, solar, hydro, nuclear — operates in a range clustered around 15 grams CO2e full-lifecycle per kWH. Average grids are operating in the range of 500 grams CO2e full-lifecycle per kWh due to prevalence of coal (1,000+ grams) and gas (500+ grams). For comparison, in 2013 the OECD was below that at around 432 grams, the USA was above at 512 grams and China and India were well above that, between 700 and 800 grams. All grids are seeing reduced CO2e per kWh since then due to the massive success of renewables, and China also saw substantial new nuclear and shutdown of the worst coal plants since then.

We’ll normalize this to TWh and metric tons CO2e full lifecycle for convenience of dealing with big numbers and use 15,000 metric tons CO2e per TWh for renewables and 500,000 metric tons CO2e per TWh for grid averages. We won’t try to deal with country variances for this assessment, as it’s coarse initially.

What are these vendors doing?

Amazon Web Services

commitment to 100% renewable energy. […] AWS exceeded 50% renewable energy usage for 2018.

That’s not great, but it’s better than a kick in the head with a frozen mukluk. A commitment without timeframe to 100% and a 50% achievement is okay.

What that means from an environmental perspective is that the data centers are mostly operating on forms of electricity with roughly 10 kg of full lifecycle CO2e emissions per MWh of electricity. Wind is a bit lower, solar a bit higher, and hydro varies substantially but is in the range.

A data point I was able to find quickly was a reference to Amazon data centers consuming almost 2% of US electricity. This, of course, also includes all of their own operations as well as operations for the cloud both for themselves and for others. Distribution centers are also major consumers of energy, and they have many office buildings.

Given market share, it’s quite possible that Amazon is in the range of consuming 2–4 TWh by itself in the USA, and 10–20 TWh globally. That suggests an annual global carbon debt for the Cloud portion in the range of 5,150,000 metric tons or 5 megatons of CO2e.

Microsoft Azure

We’ve been setting a price on carbon that is charged across the company since 2012. With the funds collected from this internal carbon tax, we have reduced energy consumption, increased our purchasing of clean energy, and invested in offset projects for the carbon we can’t reduce or replace. In 2017, Microsoft pledged to reduce its operational carbon emissions 75 percent by 2030 and is on target to achieve this goal.

This is a very positive statement. Unlike Amazon, Microsoft has a commitment to carbon neutrality as well as further emissions. For the sake of this comparison, we’ll consider offsets equivalent to renewables-only electricity.

Given market share, it’s quite possible that Azure is in the range of consuming 1–2 TWh by itself in the USA, and 5–10 TWh globally. That suggests an annual global carbon debt for Azure of around 150,000 metric tons of CO2e.

Google Cloud

Google matches 100% of the energy consumed by our global operations with renewable energy and maintains a commitment to carbon neutrality.

This is very good. Google ensures that it buys 100% of the energy that it consumes for its Cloud data centers from renewable energy sources. This doesn’t mean that the Cloud centers run only on renewable energy, but that Google ensures that demand is matched. This is completely reasonable given the way grids actually work and a global footprint. It sends a very strong market signal about the need for clean energy and minimizes environmental footprint of its Cloud.

Given market share and the absurd dominance of Google as a search engine, it’s quite possible that Google’s Cloud is in the same range of consumption as Amazon, 2–4 TWh by itself in the USA, and 10–20 TWh globally. That suggests an annual global carbon debt for Google Cloud of around 300,000 metric tons of CO2e.

Alibaba Cloud

Alibaba is an outlier in two different ways. The first is that its largest footprint is in China with China’s ~700 grams CO2e per kWh average. The second is that it doesn’t have a commitment to carbon neutral energy (that I was able to find in English-language sources), but is using high efficiency heatpumps with northern cold air and water-sourced cooling for its data centers where possible. The combination suggests an equivalence to a 10% mix for renewables and a 20% extra carbon debt for electricity than global average.

It has roughly a quarter of the marketshare of Azure, so we’ll use a 1:4 ratio for Azure numbers, suggesting a total consumption of 1–3 TWh of electricity. This suggests in the range of 1,600,000 metric tons of CO2e debt per year, or 1.6 megatons CO2e.

What does this turn into?

Chart: Mike Barnard

That’s a very wide range, and while necessarily imprecise in this analysis, it’s clear that Amazon is the largest source of carbon emissions from the Cloud globally, in part due to its dominance, but also because it’s just not as serious about sourcing carbon-neutral electricity as Google has been. Microsoft Azure, another of the big three outside of China, is lowest by a comfortable margin in part because it runs less of the world than Amazon or Google. Alibaba is growing rapidly as China virtualizes, and while China is rapidly expanding low-carbon electricity in the form of hydro, solar, wind and nuclear, it still has one of the highest carbon electricity supplies.

All of this will change over the next decade, of course. But if you are building a Cloud solution that needs to be green, then it’s obvious where to go today.

As always, if you see errors or have better sources, let me know. 
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About the Author

is Chief Strategist with TFIE Strategy Inc and co-founder of two current startups. He works with startups, existing businesses and investors to identify opportunities for significant bottom line growth and cost takeout in our rapidly transforming world. He is editor of The Future is Electric and designing for health. He regularly publishes analyses of low-carbon technology and policy in sites including Newsweek, Slate, Forbes, Huffington Post, Quartz, CleanTechnica and RenewEconomy, and his work is regularly included in textbooks. Third-party articles on his analyses and interviews have been published in dozens of news sites globally and have reached #1 on Reddit Science. He's available for consulting engagements, speaking engagements and Board positions.

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