This is a really interesting usage of blockchain technology to ensure you are really getting what you think you bought. Michael del Castillo writes on Forbes.com:

The fifth-largest oil and gas company in the world, valued at $262 billion, is investing an undisclosed amount in LO3, a New York startup using a modified version of the ethereum blockchain to make it easier for individuals to buy and sell locally produced energy using the existing network of power cables.

While the bitcoin blockchain lets users track the flow of value without the need of banks to audit the system, LO3’s platform, called Exergy, is designed to track the flow of energy as it is added to a shared, local energy network, giving the neighbors who purchase the energy absolute certainty it really came from a windmill, a solar panel or a gerbil running on a treadmill.