Hybrid Bulldozers?

While the most popular hybrids are currently small cars (for American tastes), the Volvo Group, makers of trucks, buses, construction equipment and other mostly diesel powered heavy equipment, is currently developing hybrid electric technology for heavy vehicles. We are all used to seeing dirty clouds of black smoke coming from a ground mover on a construction site, and technologies like this might reduce these significantly.
The Volvo Group sees opportunities to accelerate the development of a parallel hybrid system, especially for vehicles that accelerate and brake frequently. This is clearly a good match for construction machines, in addition to city buses and garbage trucks. While the technology might appear in trucks and buses fairly quickly, from a few months to a few years in trucks and buses, for construction equipment the commercial availability might have to wait a little longer. The hybrid system under development is comprised of a combined start motor, drive engine, generator, electronic control unit, batteries and diesel engine. The batteries are recharged by regenerative braking and directly by the diesel engine when possible. Wheel loaders, a particularly attractive application, might show fuel savings of up to 50%.

[Source: Equipment World]