Over the past few weeks, I've had a number of meetings with engineers, executives and investors and such, and I keep coming away with the same conclusion.

The fastest-growing and arguably most attractive segment in alternative energy and energy efficiency lies in hardware, software and networking equipment. Yep, green IT. Part of the conclusion is a historical and personal bias: I wrote about semiconductors and PCs for eleven years. But I still think green IT is a sustainable trend. Here's why:

1. Looser-Than-Normal Wallets.

Data centers continue to inexorably absorb functions once handled in the real world--shopping, shipping, etc.--and now and videoconferencing has begun to displace travel.

As a result, data centers are necessarily becoming larger and more power-hungry. Subodh Bapat, Sun's former green guru, has estimated that by 2020 some data centers will consume 50 megawatts and take up 500,000 square feet. Data centers and desktops account for 40 percent of the power bills in the corporate world and can account for 70 percent to 80 percent of the bills in financial services companies, according to Fujitsu.

To keep a lid on their onerous utility budgets, data center owners have resorted to swapping out servers at a more rapid rate, investing in environmental monitoring systems like those from SynapSense and Power Assure, and reconfiguring air conditioners. In the near future, they may begin to start swapping out hard drive arrays for ones with flash memory and chips from companies like Sandforce. Others are building data centers in mines and bomb shelters and harvesting the waste heat.

In short, you have a central corporate function with a "needed now" budget item that comes with quantifiable benefits. Compare that to a solar array -- the lights won't go off tomorrow if the company doesn't buy one.

2. The Fear is Real.

Forget operating budgets for a moment. Power could soon become a life-or-death matter, according to Mike Dauber at Battery Ventures. (Battery invested in Smooth-Stone, which has created a low-powered ARM chip that will compete against Intel chips in servers.) Transistors replaced vacuum tubes, in part, because it would have been impossible to build and run large computers using millions of hot, delicate tubes.

Unless you build new data centers next to the Hoover Dam, it will be tough to physically tap the amount of power that will be required, says Dauber, unless you change the basic architecture.

Potentially, the need means that science projects like HP's memristors, phase-change memory, Microsoft's future predicting algorithms, probability processors and even non-Intel-based servers stand a decent chance of participating in trials at big data centers. Again, compare that to solar. Banks, utilities, installers and large buyers aren't showing a lot of interest in experimentation. (The picture shows Google's first storage device. They've graduated since then.)

3. Everything Dies a Quick Death.

A single piece of equipment might chug along for five years before giving up the ghost. Solar panels, power meters, LED bulbs, wind turbines, and air conditioners must last for decades. Live fast, die young, sell replacement parts. It's a great way to make a living.

4. Bread and Circuses.

Check out this screen from Qualcomm: it lasts five times as long on a single battery charge because it doesn't require an internal light source. Philips and E-Ink have similar energy-efficient color screens. You're selling energy consciousness and consumer lust at the same time.

5. The Trojan Horse Effect.

Is there any reason that the environmental control systems being deployed in data centers can't be used to control the air conditioners or lights in buildings and industrial sites as well? No. SynapSense, in fact, has already begun to talk about transforming its data center control technology into a building management system. Some other building management companies are getting their first contracts to help control energy in data centers, which are the highest-value real estate most companies own. The IT department, therefore, will become the early adopter and guinea pig for green building management.

6. Solar and Smart Grid Need It.

From a certain perspective, the smart grid isn't a revolutionary means for changing how the world consumes power. It is the land of misfit networking technologies.

ZigBee and Z-Wave struggled for years to find a home. Back in 2003, the most promising applications for these wireless protocols were home security systems and wireless keyboards. Then came the smart grid and home energy management. Suddenly companies began to talk about incorporating ZigBee into household appliances and utility meters.

LTE and WiMax? No one would have ever spent the hundreds of millions required for development on these if the estimated customer base consisted solely of the 3,100 North American utilities. The smart grid industry needs telecom to develop its components.

Solar manufacturers, meanwhile, are turning toward equipment from the hard drive industry to curb manufacturing prices and to embedded semiconductors to boost the efficiency of panels. To advance, solar will rely heavily on the work being done inadvertently on its behalf.  

7. Quantity is Quantity.

The underlying rule in corporate life is he who quantifies wins. The inherent nature of hardware and software means that the benefits are often relatively easy to measure. Hara has landed a large number of accounts -- Coke, Apple, News Corp. -- with its dashboard that meticulously measures consumption. In its new five-year plan for ecomagination, General Electric said it will emphasize improving existing technologies with hardware and software.

So what's the downside? IT equipment is actually somewhat efficient. Remember a few years ago when Google announced it would tackle the urgent problem of inefficiency in power supplies? The search giant unleashed a power supply (like the brick on your notebook) that was over 90 percent efficient. Power supply makers told me at the time that they were already in the 80-percent range.

Computers are really only a minor irritant in the grand diet of electrons. Data centers only account for close to 2 percent of electricity consumption. In commercial buildings, computers consume four percent of all energy used, according to the Buildings Energy Data Book from the Department of Energy. Refrigeration also consumes four percent, while lighting consumes 24 percent. You'd have to put six PCs on each desk to match lights. Even if you ran every PC in the world on The Clapper, the power saved would be tough to get excited about.

High efficiency, more profligate applications elsewhere: spending could easily flow into these other areas first, negating everything said above.

Utilities and state governments have not been as active in the rebate department as they could be. NetApp has built a state-of-the-art data center with funds from PG&E. Nonetheless, feed-in tariffs or monster-sized tax credits don't exist.

Nonetheless, think about the world of work. The CIO has gone from being a functionary to a strategic player. His or her budget might sink, but it rarely gets slashed.  Multibillion-dollar technology vendors continually concoct new devices for them.

Inside corporations, IT is the equivalent of the Department of Defense.