Did you know that on any given day, the 240 million U.S. vehicles on American roads waste more than 10 million megawatt-hours of energy? That’s roughly twice the amount of energy that was generated daily by coal plants, as recently as 2008.
A significant amount of this energy can be harnessed through a variety of techniques and that is exactly what Vecarius intends to do.
Vecarius, which stands for Vehicle Energy Capture and Recycling Initiative – U.S., is a group of MIT-trained scientists and engineers. Its primary focus is on energy harvesting through waste heat recovery. Automobiles are based on a very inefficient design that loses 75% of the energy content of the fuel as heat, in the process of moving the vehicles and its contents down the road.
Unlike some hybrid cars, which recover waste heat that is generated in braking and uses it to recharge the battery, Vecarius continuously recovers heat from the engine and uses it to help power some of the on-board electronics. Of course, there is no reason why you couldn’t do both. People don’t realize that the onboard electronics in a typical modern vehicle use between 3-10kW, an amount comparable to or greater than what a typical home might use. Using waste heat to drive these electrical loads, instead of driving them from the engine through the alternator, can result in a fuel efficiency improvement in the range of 8-15%
Given that this technology is new and hasn’t come down the cost curve yet, it would take a typical commuter more than five years for this level of efficiency to pay for itself with gas at $3 per gallon. That is why Vecarius is focusing its efforts on service and delivery vehicles which easily spend upwards of $10k per year. These applications will see a 2-3 year payback today, even at current gas prices. Of course, as prices creep up, which, I think we can all be sure they will, and as the cost of their systems come down, it would not be at all surprising to see this kind of technology showing up in cars as early as 2015, especially as automakers struggle to meet the new CAFE standards.
Most vehicle waste heat recovery systems that are currently being developed utilize a thermoelectric converter to create electricity, as the name implies, directly from heat. These devices depend on a unique property of certain materials which result in the Seeback effect, discovered in 1821, where the application of heat produces an electric current. The devices have no moving parts. You could think of them as similar to photovoltaic cells, except that they respond to heat rather then light.
An effective waste recovery system requires three elements: 1) a thermoelectric material package, 2) an electric power management system, which directs the electricity injected into the vehicle’s electrical system to the place where it will do the most good at any given time, and 3) a thermal management system, which is essentially a sophisticated heat exchanger.
While other companies are racing to develop the most effective thermoelectric material package, according to CEO William Sanchez, Vecarius distinguishes itself primarily through its power management system. Depending on the specific conditions at any given moment, their system will either directly power certain electronic devices in voltage mode, or alternatively, it will boost the alternator in current mode. The power management system will make this determination depending on which results in a higher overall efficiency for the vehicle.
Vehicles with waste heat recovery were first demonstrated using thermoelectrics by VW (photo) and BMW in 2008.
Of course, the idea of waste heat recovery is not a new one. That is the core principle behind the cogeneration movement that is sweeping through the power industry. It’s a smart idea whose time has come and it should be used everywhere that makes sense.
RP Siegel, PE is the co-author of the sustainability thriller Vapor Trails.
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