Who would have thought you could patent slower, more expensive shipping? Amazon.com does. The online retail giant was just granted a patent for "Environmentally conscious electronic transactions." The patent envisions a system in which customers are given "a shipping option that might not be as fast, and might be more expensive, but that is more environmentally friendly in at least one way." It also suggests letting people buy carbon credits to offset the emissions generated by the packaging and shipping of their purchases.

The patent notes that "more attention is being focused on the environmental impact of the manufacture, purchase, and disposal of goods and services," and says some companies have responded by optimizing their routes and vehicles and using recyclable materials. But, the patent adds, e-commerce customers have "little control" over which environmentally friendly options they would prefer when ordering something online.

The answer, according to the patent, is to give customers a range of green shipping choices:

For example, an environmentally friendly option might use a smaller shipping company that takes advantage of hybrid or hydrogen-powered vehicles, or that places items onto vehicles with empty space that are already scheduled for a particular route. Another option might be one that always uses low-emission vehicles, but that may make several stops along the way and thus might take more time. Some companies might only transfer items at night, or avoid routes through major cities, such that traffic would be lighter and the effect on air quality will be lessened.

The patent also describes how people could choose to reduce the amount of packaging in their order, or combine multiple orders in one box. They might also select packaging materials made from specially designated tree farms (as opposed to natural forests) or manufactured in a solar or hydroelectric power facilities, according to the patent.

These shipping options could cost more, and entail a longer wait for a package, but presumably Amazon sees a potential market for this.

The patent also raises the possibility of Amazon selling carbon credits to customers to offset the environmental impacts of the shipping and packaging of their purchases:

Many companies offering such carbon credits perform activities that reduce the introduction of these emissions into the environment, and then apportion the costs over the amount of reduction. For example, a company might plant a certain number of trees, prevent a coal-burning plant from being built instead of a hydroelectric power plant, recover methane gas from a farm for use instead of fossil fuel, utilize carbon capturing chemicals, provide environmentally-friendly products to be used in place of highly-polluting products, or any of a number of other such activities.

It certainly would be fascinating to see Amazon apply its e-commerce model to the world of carbon credits.

The patent was originally filed in April 2009 and granted Oct. 12 of this year. It lists Eric Brandwine and Luis Cabrera as inventors.

Amazon has been making some moves in the green arena lately. The company launched a "frustration-free" packaging initiative last year — working with manufacturers to deliver toys, electronics and other products in recyclable cardboard boxes without all the plastic clamshells and twist ties.

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