Google (NASDAQ: GOOG) is a leader when it comes to being a "green" kind of company. It shuttles employees from the Bay Area to its Mountain View headquarters in biodiesel vans, has what is considered the be the largest solar array in corporate America and uses alternative energy in its operations, unlike most of the business world.

But what about all the actual electricity the company consumes? It has huge data centers all over the world that power its search and web product network, and these campuses consume gobs of electricity off the global grid. So, does Google purchase electricity for these data centers from electric cooperatives that generate all that juice with standard coal-fired electricity generation plants? Hard to tell, because the company won't say.

Computing giant Hewlett-Packard (NYSE: HPQ) said yesterday that it would soon be making a large investment in renewable energy to do its part in reducing greenhouse gas emissions from its operations. As part of the effort, the computer maker will install a solar array on the tops of buildings in its San Diego campus.

The array, once functional, will provide up to 1 megawatt of electricity to HP's operations in the San Diego area, which makes it one of the largest solar arrays in use by any company globally. SunPower will install the panels and will sell the electricity generated from them under an agreement with HP.

Google (NASDAQ: GOOG) currently is believed to operate the U.S. corporate world's largest solar array, which generates 1.6 megawatts of electricity. This HP initiative, though, is no slouch. The numbers: HP savings of $750,000 over 15 years along with offsetting 1 million pounds of carbon dioxide per year.

HP, which continues to have one quarter after another of impressive performance, now looks to join the elite corporate club of immense power misers as it fights off competitors to lead the computing industry in acknowledging environmental awareness. So far, both Google and HP are leading their respective industries while doing good for the environment at the same time. That's impressive.