By - Jim Vess

Google finds matching carbon-free energy to its data centers’ round-the-clock demand a challenge

Energize Weekly, October 17, 2018

Google has been the world’s biggest corporate purchaser of renewable energy, buying enough to cover all of its total global consumption. Now it wants to go further matching carbon-free energy to its demand for every hour of every day.

One of the biggest challenges of renewable generation is providing round-the-clock reliability, particularly for the two main sources, wind and solar. So, Google’s exercise is instructive.

In terms of sheer bulk, Google said it purchased more than seven billion kilowatt-hours of electricity in 2017—about as much as used in the state of Rhode Island—from wind and solar facilities built for the company.

That, however, wasn’t enough to meet the company’s 24-7 goal. “There is often not enough carbon-free energy available to match 100 percent of a data center’s hourly electric load in a given hour,” Google said in a report the company issued last week.

“There are several possible factors—related to Google or the grid—that can cause an hourly shortfall in carbon-free energy,” the report said. “On the Google side, factors may include a dearth of Google renewable PPAs [purchase power agreements] in the region; insufficient output from our existing renewable PPAs, due to low wind speeds or faint sunlight; or a lack of stored carbon-free energy to fill the gaps.”

 On the grid side, there still may be a mix of generation that is not carbon free, which could be the result of operating constraints limiting renewable resources, the report said.

Meeting the 24-7 goal in “all places at all times” requires different strategies than merely matching 100 percent of electricity demand. For example, in some regions, Google buys a surplus of electricity when solar or wind are plentiful. The company buys a larger amount of wind in the U.S. Midwest to offset a lack of renewable energy purchases in Asia.

Still, Google said there isn’t enough carbon-free energy to match the data center demands for every hour.

Analysis of the data centers’ clean energy performance around the world underscored the elements that are needed for Google to reach its goal.

The data center in Hamina, Finland, had a 97 percent record in matching demand and clean energy. Key features in getting to that level are a competitive regional Nordic energy market, multiple wind PPAs signed by Google in the region and a grid with other carbon-free generation, including nuclear, hydropower and biomass.

In Changhua County, Taiwan, however, only 20 percent of the Google data center’s demand was matched on an hourly basis with clean energy in 2017 as coal-fired and natural gas-fired generation dominated the state-run grid.

“After careful consideration and at the urging of Google and others, in January 2017 the Taiwanese legislature amended the country’s Electricity Act to open up the energy market, thereby enabling companies to directly purchase renewable energy,” the Google report said. “We are hopeful that this change will lead to new carbon-free power sources in Taiwan and be replicated elsewhere in Asia.”

Google’s Lenoir, North Carolina, data center was able to match demand and carbon-free generation 67 percent of the time with the aid of a solar purchase program the company developed with a local utility. The gap comes during nighttime demand when there are few carbon-free options, save a nuclear power plant.

In Iowa, Google depends upon wind farms to match its demand at its Council Bluff data center with carbon-free electricity 74 percent of the time. “The degree of matching can range significantly across different hours due to the variability of wind,” the Google report said. “During breezy periods, our Iowa wind farms can produce nearly three times as much power as our data center requires … On the other hand, there are days when the wind hardly blows at all; in those cases, the data center is scarcely matched with carbon-free power.”

Based on the experiences of its data centers, Google said that the insights it has drawn include the greater impact offered by a diversified carbon-free energy portfolio and the big contribution to meeting its goal provided by hydro and nuclear on some grids.

Among the initiatives Google said is needed to achieve a 24-7 match of demand and carbon-free electricity are:

  • Policy and market reforms to reduce the barriers to clean energy procurement
  • Development of emerging technologies such as energy storage, carbon capture and advanced nuclear
  • New energy contracting approaches emphasizing multiple generation sources and energy storage

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