America's 'greenest' big companies and institutions

Isaac Brekken | For The Washington Post | Getty Images

Whether it's carbon neutral office blocks, automated lighting systems or a commitment to plant thousands of trees, governments and businesses all over the world are always keen to trumpet their green credentials.

In 2001, the United States Environmental Protection Agency (EPA) established the Green Power Partnership as "a voluntary program that encourages organizations to use green power as a way to reduce the environmental impacts associated with conventional electricity use."

Here, CNBC.com takes a look at the Green Power Partnership's National Top Partner Rankings, which detail and rank the green energy use of the scheme's partners.

By Anmar Frangoul, special to CNBC.com, on Wednesday March 4, 2015.

10: Unilever
Oscar Siagan | Getty Images AsiaPac | Getty Images

Annual green power usage: 515 million kWh

Consumer goods giant Unilever makes the top 10 of the Green Power Partnership's National Top 100. According to Unilever USA, by 2020 the business will, "more than double our use of renewable energy to 40 percent of our total energy requirement" when it comes to manufacturing processes.

Furthermore, Unilever says it slashed CO2 emissions between 2008 and 2013 by 833,000 tons— "a reduction of 32 percent per ton of production."

9: Starbucks Company-Owned Stores
Jason Alden | Bloomberg | Getty Images

Annual green power usage: 583 million kWh

Operating over 20,000 coffee shops in more than 60 countries around the world, coffee giant Starbucks has made concerted efforts to mitigate its environmental footprint.

The company has set itself the goal of cutting water consumption in its stores by 25 percent by 2015, cutting energy usage by 25 percent and covering, "100 percent of our electricity consumption with renewable energy by 2015."

In 2013, 65 percent of new Starbucks stores were "built to achieve LEED (Leadership in Energy & Environmental Design) certification"—a green-building accreditation program.

8: US Department of Energy
Ethan Miller | Getty Images

Annual green power usage: 595 million kWh

According to the EPA, 12 percent of the U.S. Department of Energy's electricity use comes from green sources such as wind, solar and biomass. In 2014, both the vast Ivanpah solar plant (pictured) and Petra Nova, a carbon-capture project, "were made possible by Energy Department funding."

7: City of Houston, Texas
Scott Halleran | Getty Images

Annual green power usage: 623 million kWh

More than 2 million people live and work in Houston, Texas, and authorities there are making a concerted effort to go green.

In 2013, the City of Houston announced that it would purchase more than 140 MW of renewable energy power for two years, adding that, "the City's purchase of green power will account for half of its annual electricity demand."

Speaking at the time, Annise Parker, Mayor of Houston, said, "Houston is already known as the energy capital of the world, but we are committed to becoming the alternative energy capital of the world as well."

6: Apple
Noah Berger | Bloomberg | Getty Images

Annual green power usage: 626 million kWh

The company behind the iMac, iPod and iPhone states on its website that it believes, "climate change is real. And that it's a real problem."

In light of this, Apple is taking steps to limit its own impact on the environment. Its data center in Maiden, North Carolina, for example, has earned Leadership in Energy & Environmental Design—or LEED—Platinum status from the U.S. Green Building Council. The center is able to generate renewable energy using solar arrays and biogas fuel cells.

Over 140 Apple stores in the U.S. were powered by renewable energy in 2014, according to the tech giant. The new Apple headquarters in Cupertino, California, will be 100 percent run on renewable energy and have over 300 charging points for electric vehicles.

5: Wal-Mart Stores, Inc.
Patrick T. Fallon | Bloomberg | Getty Images

Annual green power usage: 651 million kWh

Retail giant Wal-Mart has a presence in 27 countries and employs more than 2 million people globally.

According to the company's website, it has set itself three ambitious sustainability goals: To have a 100 percent renewable energy supply; to generate zero waste; and to "sell products that sustain people and the environment."

Wal-Mart recently completed the installation of its 250th solar energy system. The company says that these systems provide between "15 to 30 percent of a store's electricity needs."

4: Google Inc.
Tony Avelar | Bloomberg | Getty Images

Annual green power usage: 737 million kWh

Search giant Google has been a carbon-neutral company since 2007 and claims that its data centers—which feature a range of green tech including smart temperature controls— "use 50 percent less energy than the typical data center."

Other initiatives include 1.9 MW of solar panels at the company's head office in Mountain View, California; a shuttle program that has taken the equivalent of 5,700 cars off the road; and what the company describes as "agreements to fund over $1.5 billion in clean energy wind and solar projects."

3: Kohl's Department Stores
Robert Nickelsberg/ | Getty | Getty Images

Annual green power usage: 1.5 billion kWh

Wisconsin-based Kohl's operates department stores across the United States. The business is described by the EPA as having, "embarked on a committed, integrated approach to environmental stewardship in all facets of its business endeavours."

According to Kohl's website, the company has 160 locations that use solar power, while as of October 2014, 81 Kohl's stores had charge stations for electric vehicles. In addition, 433 Kohl's buildings are LEED certified.

2: Microsoft
Mike Kane | Bloomberg | Getty Images

Annual green power usage: 2.5 billion kWh

The EPA states that Redmond, Washington-based Microsoft has met its goal of, "reducing carbon emissions by at least 30 percent per unit of revenue below the company's 2007 baseline."

As part of its commitment to sustainability, Microsoft has reported that it has entered into a "power purchase agreement" with a wind project of 110 megawatts.

1: Intel
Justin Sullivan | Getty Images

Annual green power usage: 3.1 billion kWh

Famous for its computer chips, Intel has also won a host of awards for its use of green power sources.

According to the EPA's website, "Intel purchases more than 3.1 billion kilowatt-hours a year of renewable energy certificates, generated from wind, solar, geothermal, low impact hydro, and biomass sources, all third-party certified."

Marty Sedler, Intel's director of global utilities and infrastructure, is quoted on the EPA's website as saying, "Our renewable purchase is just one part of a multi-faceted approach to protect the environment, and one that we hope spurs additional development and demand for renewable energy."