"Green" means different things to different people. To a business traveler the lack of green used to mean your corporate budget is tight. But today's road warrior is dealing with another dimension in "green."

The challenge for road warriors and their corporate travel departments is figuring a way to strike a business travel balance between the "green" of economics and the "green" of the environment. Frankly, from where I sit, traveling green is not easy on either front.

One of the main reasons: There currently are no standards when it comes to green travel.

A hotel can say it's "green," but it is setting the criteria. The same holds true for other travel suppliers, including airlines. An airline or car rental company can adopt a carbon emissions program but that typically varies by supplier. There's no level playing field in the travel industry as to what's green and what isn't.'

Many suppliers are trying to do the right thing, but we are still in the early innings of the green travel revolution. It has yet to be established whether those suppliers' policies and action are relevant, consistent, and truly "green."

So where does that leave business travelers? How does a road warrior make smart "green" travel decisions? How do you tell a green airline, hotel, or car rental company from one that isn't?

Right now, unless you invest a lot more time than most business travelers can afford in studying the situation, you wouldn't be able to make a truly informed judgment. For now, the right choices are not crystal clear.

It's sort of like the process that happened in supermarkets, when food suppliers finally adopted unit pricing and you could actually tell what the actual costs were without lugging a portable calculator in your shopping cart.

The same thing needs to happen to travel. What business travelers need to see is a "green footprint" unit price.

A lot of companies would choose that smallest-footprint option -- if only they could tell which choice that was! As things stand now, a company that wants to go green would be hard-pressed to establish a clear corporate travel policy to achieve that goal. We are limited to making simple choices and relying on our common sense.

Sure, we know the green choice at O'Hare is to take the train instead of a cab. But companies could take one more step and ask if an employee really needs to take that trip at all. Could audio or video conferencing be an option? If so, the green benefits increase exponentially.

It is true that no phone call can replace the benefits of one-on-one meetings. But I think a lot of companies are becoming even more rigorous in examining who really needs to go on that business trip. And today's tough economy could actually drive that reality. The winner will be the environment, because less business travel generates less impact.

Meantime, the standardization shakeout will take time. That's because travel suppliers like the airlines are examining ways to go green that didn't make economic sense before. Now airlines are taxiing planes using just one engine. Other airlines are using new engine-washing technology to improve fuel mileage. Others are cutting down on on-board consumables. And without a doubt the new $15 per first-checked-bag will cause people to travel with less.

Yes, the economics of business travel and the imperatives of preserving the environment can coexist. In fact, they go hand in hand. As travel suppliers become more adept at providing standardized "green" information -- perhaps with an assist from an industry groups -- corporate travel departments and individual business travelers will have clearer choices.

Hopefully in the not-too-distant business travel future, the green choice will be the one that makes both economic and environmental common sense.