WT: What is ‘the cloud’?

Marston: We’ve probably heard of the cloud and associate it with where all our photos, music, videos, and documents go.  This seemingly abstract location, however, is rooted in actual physical infrastructure.

The cloud is composed of multiple data centers distributed across multiple locations.  Each of these data centers has potentially thousands of servers to compute, store, and process data.

WT: How much energy do data servers consume?

Marston: In 2018, the global electricity demand of data centers was 205 TWh.  This represents about 1% of the total electricity demand.

The United States houses nearly 30% of data center servers, more than any other country.  In 2014, 1.8% of US electricity consumption was attributable to data centers, roughly equivalent to the electricity consumption of New Jersey.

Traditional data centers use between 15-100 times as much electricity as a similar size commercial building.  Much of this energy is not just to power the servers but to cool the facilities since these servers put off a tremendous amount of heat.

WT: What impacts do data center/server farms have on the environment and climate?

Marston: Approximately 0.5% of total US greenhouse gas emissions are attributed to data centers.  As we know, greenhouse gas emissions lead to climate change. 

Data centers use a lot of water.  US data centers directly and indirectly consume the equivalent of over 200,000 Olympic-sized swimming pools each year.  Roughly one-fifth of data centers get their water from water stressed watersheds.

While data centers use a lot of water, they still use far less water than is required to grow our food, for instance.  However, a data center’s water and energy demands can place a large burden on local infrastructure and can sometimes necessitate costly expansions of water and electricity infrastructure.

WT: Why are these stressed locations still hot spots?

Marston: Water availability and the environmental impact of a data center’s water consumption is not a key consideration when locating a data center.  Instead, things like proximity to clients, land costs, tax incentives, necessary infrastructure, energy availability, physical security, etc. are more likely to shape decisions on where data centers are placed. 

With much of the western US currently experiencing historic drought conditions, some data center operators are beginning to think more seriously about water requirements of their data centers, and the impact on the local environment and community, as well as how water shortages present a risk to their operations.

WT: If companies are attempting to prioritize their water consumption reduction, what sorts of things should they be considering and why?

Marston: Data centers use a tremendous amount of electricity, and in turn, electricity production often requires a tremendous amount of water. Locations where a greater fraction of electricity comes from power production that uses very little water –wind and solar—would in turn lower the data center's overall water footprint.

Companies should also consider the underlying water stress.  It is often better to use more water in a water abundant area, than less water in a severely water scarce area.

The environmental impacts of a data center’s water use during drought will be more pronounced due to reduced water supplies and an increase in water demand by other sectors.

The (A) water footprint, (B) WSF), and (C) carbon footprint of data centers can be reduced by placing them in subbasins with the smallest footprint (top quartile of all subbasins), as denoted by the shaded subbasins in each panel.  The bar graphs represent the percent reduction/increase of each environmental footprint within the shaded subbasins compared to the national average date center environmental footprint.  Hatched areas indicate subbasin that are among the most (top quartile) environmentally favourable locations for both water scarcity and GHG emissions. 

Water shortage may not only impact the water available to be used directly with a data center but will cause increasing brownouts/blackouts within the energy grid, posing additional risk to the industry.

WT: many companies site their servers at co-location facilities.  What questions should companies be asking to better understand the implications of their water consumption?

Marston: There are two primary concerns for data center clients when it comes to water.  First, companies are increasingly considering the environmental impacts of both their internal processes and the environmental implications of the companies that provide them with goods and/or services.  With respect to co-location facilities, clients should be asking:

• How much water is directly and indirectly being consumed per computing workload?
• Where is this water use occurring and what is the underlying water scarcity?
• How does the water footprint of the data center I’m utilizing compare against the industry average?

Second, companies may be concerned about how water shortage risks may impact the operation of the data center they are utilizing.

We are beginning to see more mandatory cuts to water use throughout the western US.  Companies should ask how likely these water use restrictions are to affect data center operation.  These risks appear minimal at the moment, but this could change quickly if water restrictions become more severe in the face of worsening water shortage.

Whether the company is concerned about environmental stewardship or operational risks, there needs to be greater transparency in data center operations and their impact on the environment.

WT: What steps can businesses take to reduce water consumption within the data center?

Marston: Use of economizers and advanced cooling systems (e.g., submerged cooling) can be potential solutions for reducing cooling water requirements.  However, we do not have any detailed analysis to compare the water footprint of different cooling systems.

WT: The water used for the energy powering a data center is part of the equation.  What sort of power has the least impact from a water perspective.

Marston: Solar and wind have the lowest water footprint compared to other methods of electricity generation.  These forms of energy also have the lowest carbon footprint as well.  However, data centers operate at all times –even when the wind isn’t blowing and at night – so wind and solar power may not be able to meet all a data center’s electricity requirements at this time.

WT: What are the solutions?

Marston: This is a system-level issue.  Many major companies are beginning to acknowledge this and are moving toward utilizing more clean energy sources.  Doing so will reduce both greenhouse gas emissions and water consumption.

When building new data centers, companies should also consider the environmental impact, not just economic considerations.  Our recent research shows that in doing so a company can significantly reduce the environmental footprint of their operations.

Climatic factors can make some areas more favorable due to lower ambient temperatures, thereby reducing cooling requirements.  Lower cooling requirements reduces both direct and indirect water consumption, as well as GHG emissions, associated with data center operation.

Since most data centers get their electricity demand from the grid, the composition of power plants supplying electricity to a data center plays a significant role in a data center’s environmental footprint.

For an industry that is centered on technological innovation, we show that real estate decisions may play a similar role as technological advances in reducing the environmental footprint of data centers.

WT: Data centers underpin our lives – all of us.  Do you have any advice for us?

Companies respond to their customer demands, so perhaps the most impactful thing an individual can do is to contact companies with large data centers, such as Amazon, Google, Facebook, and Netflix, and let them know your concerns.