Viridity Energy, the energy startup that is linking smart buildings, batteries, trains and other devices to the smart grid in an attempt to build “virtual power plants” for U.S. customers, has raised $15 million from a strategic Japanese conglomerate investor and big green investor Mitsui & Co. This trans-Pacific partnership has been seen as an opportunity to open up both markets.

In January 2011, the startup received a Series C round of investment at $14 million on top of a previous $10 million. The startup has also received other state grants and investments in millions of dollars to bring the total funding to about $40 million with early investors being Braemar Energy Ventures and Intel (News - Alert) Capital.  Mitsui has been offered a seat in the board and hopes to see its investment internalize its “Smart Green Information Technology” business line.

This line of business includes smart grid IT services, the development of renewable energy and carbon dioxide mitigation. Mitsui is particularly interested in Viridity’s V-Power platform and hopes to develop businesses based on that capability for both domestic and international markets that includes dynamic load management and energy storage integration for various industry sectors.

Viridity’s V-Power platform verifies load reduction and market demand response and grid power sales. According to Viridity, its software can also interface with building and energy management systems to help fine tune power loads to use less electricity when prices are high. So far, it is balancing and playing into power markets in Pennsylvania campus micro-grids and involved in several projects that link batteries to the grid to cushion customers during peak price times as well as a way to sell power back to the grid.

Mitsui, on the other, is working across the green industries spectrum investing in next-gen technologies. It has joined partners like Toshiba (News - Alert), Hitachi and Accenture to build Smart City Projects across Japan in the wake of the Fukushima disaster and the resulting nationwide nuclear power shutdown.

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