Unlike most of the billions of chargers sold every year and even universal adapters from brands such as iGo and Targus, GreenPlug power systems stop charging products when the batteries in their associated products reach full charge and includes a glowing status indicator like those in Apple's laptops. The solution relies on a chip and firmware called GreenTalk embedded into the device that communicates with the power supply.

Adding new chips to the cost-sensitive consumer electronics product can often spell bad news for a company with a hot new technology, and GreenPlug's solution would add significantly to a device's price. However, the company plans to seed high-volume consumer electronics companies with free chips to set its virtuous cycle in motion. Once there is a significant flow of GreenPlug-enabled devices in the market, accessory makers can begin offering AC adapters that work across a variety of devices from different manufacturers.

Power accessory makers such as Belkin, Kensington and Targus could offer a variety of multi-port power hubs, expanding the "universal" power supply market exponentially at retailers. There could even be enough critical mass for building charging hubs directly into lamps, desks, or even new houses.

So GreenPlug may be free to the likes of Sony, HP and Nokia. But why would they end years of selling scores of profitable replacement AC adapter models? There could certainly be an early mover advantage to the first manufacturers to offer an energy-monitoring solution and it's no coincidence that these three high-volume device companies have been loudly beating the green drum. GreenPlug notes that, while AC adapters bring in revenue, they are a major inventory management challenge. Sony alone maintains thousands of AC adapters for its products.

GreenPlug is also green in that it encourages reuse. There's no need to dispose of a GreenPlug AC adapter when you dispose of a product you use with it. In the long term and with a robust enough ecosystem, manufacturers could save money and reduce recall liability by not bundling AC adapters with their products. And manufacturers could still differentiate based on matching designs and other innovations. Acer, for example, could create a GreenPlug version of the brick for the Gateway One's AC adapter, which integrates USB host and Ethernet ports. Still, the manufacturer incentive is probably the weakest link in GreenPlug's chain.

The next Switched On will discuss some other challenges to GreenPlug and how the company plans to address them.