Amazon is the world’s largest buyer of renewable energy. The company co-founded The Climate Pledge in 2019 and committed to achieving net-zero carbon emissions by 2040.

After originally targeting a 2030 goal to achieve 100 percent renewable energy - the company then brought this forward to 2025, before actually reaching that milestone earlier this year.

These are important and necessary goals. But while Amazon seems within touching distance of its sustainability targets, the final stretch might prove the most difficult to complete.

As the company cleans up its act, Amazon’s cloud unit is currently battling its hyperscale rivals for dominance of the AI space. Data center rack densities are rising quickly and there is a race to secure capacity, however green it may be.

Powering every data center

According to Amazon, 90 percent of the electricity consumed by the company in 2022 was attributable to renewable energy sources.

UPDATE: In the days between this piece being written, filed, and designed and then actually published in our August sustainability supplement, Amazon announced all of its operations are now offset with renewables. However, some critics have said the company is greenwashing its use of low-quality offsets. The company has still not reached its net-zero carbon target.

DCD's following conversation with AWS's Chris Walker was conducted prior to the company reaching its 100 percent renewable energy goal, some of the quotes reflect that.

Today, Amazon has investments in more than 240 utility-scale projects - including more than 170 solar projects and 60 wind farms globally.

Yet there is still work to do to bring down the carbon intensity of the energy it uses, and more so if the company continues to build out amid the current AI boom.

Some grids, such as Texas and Spain, are hosts to a huge number of utility-scale solar projects. Others are rich in wind farms. But some markets aren’t so clean. Poland, for example, has a heavily coal-dependent grid. As does South Africa.

The mechanisms for procuring renewable energy aren’t all equally accessible. Europe and the US are relatively mature in terms of Power Purchase Agreements (PPAs) and other arrangements, they are less common in markets across Africa, Asia, and Latin America.

Amazon might be one of the largest buyers of renewable energy in the world, but it's easy to add renewables to an already clean grid. Often the most impactful – and hardest – change can be made on the grids with the least amount of renewables already available.

DCD asked Chris Walker, director of sustainability at Amazon Web Services (AWS), if bringing renewable capacity onto those last few dirty grids will be the biggest barrier to meeting its targets.

“I'm not going to say it's easy,” he says. “I liken it to moving out of a house; we've moved the furniture, we've moved a lot of the big boulders, now we’re finding where we need to focus on the details.”

“While it may not be the easiest tranche to finish, I feel confident in the team that we'll be able to deliver on it. We're on track to hit it by next year, we have the right plans and the right pipeline in place to be able to meet our promise five years ahead of the original commitment.”

24/7 PPA matching and storage

The rise in generative AI – fuelled by energy-hungry Nvidia GPUs – is forcing a scramble to secure capacity wherever it is available in order to meet the expected demand.

AWS has long provided a number of GPU-powered instances – including those powered by the latest Blackwell processors from Nvidia – and offers access to its own Inferentia and Trainium chips.

And like other hyperscalers such as Microsoft and Google, Amazon is having to accelerate its data center build-out as demand for AI increases, raising further questions about whether the company can stick to its sustainability goals.

When asked if immediately available energy capacity from the utility or availability of renewable projects is a higher priority, Walker notes that availability is one of the “top tenets” of AWS.

“We first and foremost look for available utility capacity; We need the most consistent power that's available from utility,” he says. “From there on, we like to expand using the renewable portfolio and expand as we need to.”

When it comes to working with different partners in different markets, Walker says that while the company is “prescriptive” about where and how it signs up for deals, it's also flexible.

“It’s market-dependent more than anything. If we’re entering a new market, we might have a different approach in terms of partnering with larger utilities or the local companies,” he says. “In Virginia, for example, where we're scaling rapidly, there's different approaches on which companies we look to use rather than utility companies or vice versa. That flexibility is inherently built into our DNA and how we operate.”

While bringing new renewable capacity online is great for any grid, it’s also important to consider what happens when the sun doesn’t shine and the wind doesn’t blow.

When asked about 24/7 matching – and ensuring every electron going to a data center is offset by a renewable source at that moment – Walker says it's something the company is “continuing to work through.”

“We've had conversations at the policy level, we're having conversations around the GHG Protocol as well and how that fits into the strategy, but it's something that we're continuing to look at how that works for our industry and us specifically.”

To date, the company has invested in 10 solar energy projects paired with battery storage across California and Arizona, representing nearly 1.5GW of battery energy storage capacity.

Walker says the company will continue to invest in storage “where it works” for Amazon.

One power source the company doesn’t often talk about is natural gas. Lower carbon than coal, gas isn’t renewable or carbon-free, and Amazon has been making quiet efforts to use it in certain markets where energy capacity isn’t keeping up with data center demand.

The company recently dropped plans to tap into TC Energy’s Gas Transmission Northwest gas pipeline and temporarily power upcoming data centers in Boardman, Oregon, using gas-powered fuel cells from Bloom.

The company, which has been present in the area for more than a decade, planned to use around 24MW of capacity this way to overcome local transmission constraints.

While it is investing in the 90MW Leaning Juniper wind farm in Oregon, which is set to go live in 2025, Amazon’s presence is having a massive impact on the carbon footprint of the area.

Local utility the Umatilla Electric Cooperative has become one of the state’s largest polluting energy providers, despite only serving 16,000 people, because Amazon’s capacity demands are forcing it to procure fossil fuels.

Traditionally the utility has served customers via hydroelectricity, but Amazon’s power demands have forced it to buy energy – usually fossil fuels – on the open market.

In Ireland, again where transmission constraints are battling against data center growth demands, Amazon was one of several operators looking to rely on natural gas in order to continue growing.

What comes next: nuclear, geothermal, other?

While Amazon has hit its initial energy goals and continues to work towards its truly carbon-neutral goal, the challenge of how to maintain that consistently while still growing capacity is forcing the company to not just rely on wind and solar sources.

“Once we achieve that goal, we're looking at what's next beyond that?” Walker says. “As you look beyond just wind and solar, we need to look at what else is in our tool belt, especially looking further ahead to 2040 and how we're going to reach those ultimate goals, and carbon-free energy sources are the next evolution of that.”

When asked whether carbon-free energy to the company means nuclear, geothermal, or something else, Walker says the company is open.

“We're not limiting the options; we're looking beyond the traditional renewable sources and seeing what else there is. Carbon-free energy sources are going to be one of the tools that we're going to double down on and start looking at.”

Several hyperscalers are looking beyond the traditional wind and solar sources to keep up with demand.

Microsoft has signed several energy deals to procure nuclear energy from existing plants in North America, and recently announced plans for a geothermalpowered data center campus in Kenya as well as a geothermal PPA in New Zealand. Google has also invested in geothermal energy deals in Nevada.

Earlier this year, Amazon acquired energy firm Talen’s 48MW nuclear-powered data center in Salem Township, Pennsylvania. The company also secured a 10-year PPA to procure energy from the neighboring 2.5GW Susquehanna Steam Electric Station.

The company has since filed to develop a 15-building, 960MW campus across 1,600 acres.

When asked if AWS will look to acquire more data centers close to nuclear plants or merely sign more PPAs that involve nuclear power, Walker says the company is looking at “all of the above.”

“We haven't limited our options in terms of capacity. Depending on where we're building and at the rate we need to scale, [it's] certainly going to be part of the conversation.”

Longer term, fusion energy could perhaps power the company’s data centers. Microsoft and OpenAI have invested in Helion, which is promising to crack the elusive technology before 2030. Google has invested in Tae Technologies.

Amazon hasn’t made any public overtures to fusion energy, but its founder Jeff Bezos has previously invested in Canadian firm General Fusion.

Microsoft and Google recently partnered with steel producer Nucor to invest in early-stage new energy tech – including advanced nuclear, next-generation geothermal, clean hydrogen, and long-duration energy storage (LDES).

AWS on SMRs

Small modular reactors (SMRs) – small-scale nuclear reactors that can in theory be placed at power plants or on-site at data center campuses – are regularly being pitched as a new energy option for data center operators. Compared to traditional reactors, they can in theory offer capacity quickly and be built relatively cheaply.

Data center firms Equinix and Wyoming Hyperscale [since renamed Prometheus Hyperscale] have signed deals for SMR capacity with Oklo, while crypto mining firm Standard Power has said it will procure 2GW of SMR capacity from NuScale.

Like with ‘big nuclear,’ Walker says AWS is open to the concept of procuring energy from SMRs.

“We're always looking at and having conversations with partners,” he says, “whether it's governmental partners or utility partners in terms of what the options are. And SMRs fit into that portfolio.”

Deploying those nuclear reactors onsite at its data center campuses, however, isn’t on the company’s immediate roadmap.

“We haven't quite gotten as far as thinking how on-site fits into our portfolio yet,” says Walker. “I think a lot of the conversations that we're having all around the industry is what does that look like in practice?”

“At the end of the day, we are going to continue to be off-takers of energy, we're not looking to operate. We're not looking to develop and build nuclear sites, that's not in our wheelhouse.”

On other forms of on-site generation, the company seems equally nonplussed.

Rooftop solar isn’t uncommon at data center sites, but is rarely enough to cover the entire demand of a facility.

Amazon’s many renewable investments include a large number of rooftop solar deployments, especially at its distribution warehouses. But it seems to have little interest in on-site solar at its data centers.

Of the more than 200 on-site solar deployments the company has globally, most are around the 1-2MW mark, and the company has no such deployments in Virginia where it operates dozens of data centers.

“Never say never, but at this point, on-site renewable energy doesn't power a data center end-to-end,” Walker says. “But it’s important for a variety of reasons; it helps supplement that power that we use on-site, and it helps from a community engagement perspective to enhance the grid around the data centers.”

On-site or nearby hydro deployments for data centers are still niche, but could have some utility for data centers.

Of the 269 million kWh of energy used by Apple’s data center in Prineville, Oregon, two percent came from microhydro sources.

The company took over a micro-hydro deployment in the state in 2013, with the Earth By Design project built next to an irrigation canal. Apple said that it now has two such microhydro projects.

Likewise, Aruba’s facility outside Milan, Italy, is powered in part by several micro-hydro plants, totaling more than 10MW.

AWS doesn't currently have any micro-hydro sites, and Walker says any future investments would be entirely dependent on the site in question.

Carbon capture and removal

As well as greening the energy data centers rely on, data center companies are increasingly looking to remove and capture carbon emissions from the atmosphere.

Still a nascent industry, the methods to do this are varied – and there is little consensus on which are the most effective.

Microsoft, which has a goal to become carbon-negative and remove its historical emissions, has been the heaviest investor in carbon capture and removal.

As well as investing in various projects solo, Microsoft has joined Google and Meta in forming a carbon removal coalition to further the industry.

All three companies are also developing their own carbon removal technologies to green their data centers.

To date, Amazon has only publicly invested in direct air capture – a technology to literally suck carbon out of the atmosphere with fans.

Last year the company directly invested in CarbonCapture Inc., and purchased carbon removal credits from 1PointFive via its first commercial-scale DAC plant in Texas.

While shifting the company’s operations to renewable sources of power is a key goal of the company, Walker notes that efficiency – reducing the amount of energy facilities use and the emissions they create throughout their lifecycle – is just as important.

“The efficiency conversation is really becoming almost a parallel track,” he says. “Operating more efficiently, building more efficiently, applying advanced modeling techniques inside of our data centers.”

"AWS is looking at more around the embodied carbon in the steel and the concrete and how we apply that in building our data centers ongoing basis.

"Previously those were ad hoc conversations – we'd have to intercept designs or intercepted construction phases to get those materials put into practice. We've been successful in getting those materials put into the basis of design moving forward.”

“We're looking at more scaling back cooling, to allow our data centers to run more efficiently. Circular economy is becoming a huge piece to it; we're starting to feed some of those datasets into our hardware engineering team so they can start designing more for circularity at the beginning.”

“It's exciting seeing it not just in one area, we see it in almost all the phases of our data centers.”