Steve Howard, a 49-year-old Brit, has devoted most of his career to fighting climate change. He spent seven years as CEO of the Climate Group, a global nonprofit whose goal is "a prosperous, low-carbon future for all." He sounds the part: "There is no peak sun, there is no peak wind," he declares. "We struck sun and we struck wind before we struck oil."

These days, Howard pursues his climate activism as chief sustainability officer of the IKEA Group, the world's largest furniture retailer. IKEA has invested $2 billion in wind and solar power to meet its goal of producing as much renewable energy as it consumes by 2020. "We clearly see them as our future sources of energy," he says.

IKEA is just one of dozens of big companies that are making significant investments in clean energy. In fact, a majority of Fortune 100 companies have invested in solar or wind power or have pledged to reduce their greenhouse gas emissions, or both, according to Power Forward 2014: Why the World's Largest Companies Are Investing in Renewable Energy, a report from the sustainability advocacy group Ceres. They are doing so because they believe it makes good business sense: The costs of solar and wind are falling, state and federal governments offer generous subsidies, and fossil fuel prices can be volatile. Some see green energy commitments as a way to burnish their reputations. Still others are responding to carbon regulation--Europe, California, nine northeastern states, and British Columbia all tax or cap greenhouse gas emissions, and some business leaders believe that many other governments will, and should, follow suit. Whatever the reasons, these companies are signaling that they accept the reality of climate change and proving that renewable energy is neither a job killer nor a drag on economic growth.

Last September, insurer Swiss Re, British telecommunications group BT, clothing giant H&M, food companies Mars and Nestle, and Dutch-based lighting, health care, and electronics firm Philips promised to switch to 100 percent renewable power by 2020 and launched an initiative to encourage other big companies to follow. That milestone has already been achieved by more than a dozen, including Kohl's, Whole Foods Market, Staples, TD Bank, Herman Miller, REI, and the Philadelphia Phillies, according to the EPA's 100% Green Power Users list. Other well-known companies--including Microsoft, Google, Apple, Starbucks, Lockheed Martin, Cisco, and Facebook--have not reached the 100 percent goal, but are nevertheless enormous consumers of green power.



The Walmart in Caguas, Puerto Rico is one of five Walmart facilities on the island equipped with solar panels. In addtion to Caguas, Walmart added solar to sites in Manati, Baymon and two in Ponce. | Photo Courtesy of Walmart

Controversial among this latter group is Walmart, the nation's fifth largest user of clean energy. The Arkansas-based retailer has installed 105 megawatts of solar photovoltaic power, mostly on the roofs of its stores and distribution centers. That gives the company more solar capacity than 35 states, according to Solar Means Business 2014, a report from the Solar Energy Industries Association. Given Walmart's focus on controlling costs, its rooftop arrays are compelling evidence that solar energy can compete with fossil fuels--at least in parts of the country with favorable policies. Elsewhere, however, Walmart gets nearly all its electricity--96 percent, according to critics, which include the Sierra Club--from utilities that burn coal and natural gas. Despite its large use of solar energy, Walmart's greenhouse gas emissions are actually rising.

The challenge for Walmart and other businesses that want to buy renewable energy is that solar and wind power are affordable and available in some states but expensive and hard to find in others. Weather conditions, state subsidies, and utility regulation all come into play. (More than two-thirds of U.S. solar generating capacity comes from solar-friendly California, Arizona, and New Jersey.) The Department of Energy conservatively ranks solar as more expensive than fossil fuels, and wind as more expensive than natural gas but less than coal or nuclear. Newer estimates from researchers at the investment banking firm Lazard all favor renewable power; they report that even without subsidies, "over the last five years, wind and solar PV [photovoltaic] have become increasingly cost-competitive with conventional generation technologies." What's more, corporate buyers say, the long-term costs of solar and wind power are predictable, unlike the constantly fluctuating prices of coal and natural gas. Once solar panels are installed or wind turbines are built, fuel costs are close to free.



Apple fuel cells: Photo taken on July 22, 2014 shows the methane gas fuel cells at Apple Data Center in Maiden, North Carolina, the United States. Running entirely on renewable energy, the Apple Data Center in Maiden, North Carolina, reduces energy consumption and greenhouse emission. | Photo by Xinhua/Eyevine/Redux

No industrial sector has been more committed to renewable energy than the technology industry. Tech firms tend to be nimble and future-oriented, and they compete aggressively for talent; young employees want to work for companies that contribute to solving big problems like climate change. Google, Apple, Microsoft, and Amazon have invested vast sums--a whopping $1.5 billion in Google's case--to develop renewable projects in the United States and around the world.

Apple has focused on its energy-hungry data centers, all of which are now powered by clean sources, including solar, wind, and geothermal. In Maiden, North Carolina, for example, Apple's data center is powered by a combination of two 20-megawatt solar arrays and fuel cells that run on biogas pumped in from a nearby landfill--this in a state where more than 90 percent of the electricity is generated by nuclear power and fossil fuels. Lisa Jackson, the former EPA head who now leads environmental initiatives at Apple, says on the company website: "Whenever you download a song, update an app, or ask Siri a question, the energy Apple uses is provided by nature."

Google's massive investments in renewable power include utility-scale solar photovoltaic and concentrated-solar power plants in California; wind farms in Iowa, Oregon, North Dakota, and Texas; residential rooftop solar across the United States; and solar projects in Germany and South Africa. The company views these investments as one way to deploy its vast hoard of cash--$60 billion at last count. Rick Needham, who directs the energy and sustainability team at Google, says that such clean energy investments help "diversify our cash, put it into businesses that can earn good returns and that aren't correlated to other investments."

Tech giant Microsoft has signed long-term agreements to buy electricity from wind farms currently under construction in Illinois and Texas, where the company operates data centers. In Cheyenne, Wyoming, Microsoft is building a data center that will be completely independent of the grid and run on energy generated from biogas, a byproduct of a nearby water treatment plant. The company helps fund its renewable energy projects by assessing an internal carbon fee on its business groups based on their output of carbon, primarily through electricity use and air travel.

Companies can take at least three approaches to support clean power. The first, and simplest, is to build, own, lease, or contract to buy electricity from solar panels, wind turbines, or biogas generators on their own sites, and then use the electricity to power their own facilities. Apple does this at its North Carolina data center and TD Bank at a branch in Fort Lauderdale, Florida, that is entirely powered by the 400 panels on its roof, on a drive-through canopy, and in an adjacent field, making it the first net-zero-energy bank in the country. The second approach is to invest in new, utility-scale wind and solar projects, no matter where they are located, as IKEA and Google have done. These projects deliver electricity into the grid, where it is mixed with electricity from other sources and sold by a utility. Finally, companies--including many atop the EPA 100% Green Power Users list--can opt for renewable energy certificates (RECs), which, some people would argue, are less effective at driving change.

RECs are cheap and easy to buy (you can order them online) but hard to explain. They are tradable commodities that represent green electricity's environmental qualities, not the power itself. You can't power a toaster with a REC, but you can use it to prove that--somewhere--you have created or purchased the renewable energy it takes to toast your bagel. Companies buy RECs to support renewable energy projects when green power isn't locally available, and they do provide a flow of income to the owners of wind turbines and solar panels, theoretically enabling them to build more. But RECs can be bought from projects that are years or even decades old; they don't necessarily bring new renewable energy projects to market.

Taken together, these varied corporate commitments should help drive the transition to a low-carbon economy, while also driving down the cost of wind and solar power because of their economies of scale. "If companies say they want renewable energy, people will line up to give it to them," says Andrew Winston, a consultant and author who is on the steering committee of RE100, a campaign to get big companies to go 100 percent renewable.

But don't expect corporations, by themselves, to buy enough clean energy to solve the climate crisis. Here's a rough but sobering gauge of corporate impact: The 1,300 companies and nonprofits that have joined the EPA's Green Power Partnership, a voluntary program to promote clean energy, collectively use 28 billion kilowatt-hours of green power annually. That sounds like a lot, and it is--but total U.S. electricity consumption is 3.832 trillion kWh.

This is why environmental groups, including the Sierra Club, say that government action is still essential to drive major change. That might involve aggressive clean energy mandates, utility reform to remove barriers to rooftop solar and energy storage, and, ideally, a price on carbon. To enact these changes, federal, state, and municipal politicians will need support from business. In California, a coalition of venture capital and technology companies helped defeat a 2010 referendum to repeal A.B. 32, the state's landmark global warming law. When Ohio governor John Kasich tried to roll back that state's clean energy mandate last year, he was opposed by not only environmental groups but also Anheuser-Busch, Honda, and the Ohio Manufacturers Association, whose members have invested in clean energy projects.

The current leadership in Congress, however, is not even ready to admit that climate change exists, let alone put a price on carbon. While the world waits, and warms, corporate America is increasingly stepping up on its own.