Back in May engineering.com posted a video titled “Electric or Hydraulic Drive for Better Hybrids“. In the post the author, James Anderton, explains hybrid systems as load leveling devices and goes on to ask the question, “Could a hydraulic system like Lightning Hybrids device work on light vehicles as well as trucks?” As you may know, in 2008 Lightning Hybrids started out to make a 100 MPG sports car, and our prototype is still in our facility, its sleek eye-catching design provides a great starting point for the history of our company.
Back when we first developed the hydraulic hybrid sports car, the automotive market was in great upheaval (think GM bankruptcy) and we found ourselves at a crossroads. We knew that if we could get the car to market we could certainly sell a 100 MPG sports sedan, however the cost of getting to market would be well over $2 million (Tesla found that number to be closer to $2 billion), mostly due to regulatory compliance and testing. While we never proved that the hydraulic hybrid sports car could get 100 MPG, we have proved that our hydraulic hybrid is right for trucks and buses in start-stop drive cycles.
Lightning Hybrids’ hydraulic hybrid technology is one of many approaches to lowering fossil fuel use and decreasing harmful emissions. As the engineering.com article points out, different technologies and fuel types will have various success rates in different vehicle types, drive cycles, and other variables.
Lightning Hybrids’ hydraulic system is designed for medium- and heavy-duty trucks, with a GVW from 10,000 to 35,000 pounds. For these large, heavy vehicles, hydraulic components work very well, delivering strong fuel savings, emissions reductions and brake component savings, as well as improved acceleration which is appreciated by the drivers.
Electric hybrids, either battery- or capacitor-based, are not successful in this vehicle weight range, primarily because electrical components do not have the high “power density” that hydraulics can provide. Power density is a measure of the rate at which energy can be absorbed into and delivered from a storage system, and therefore of how much of the vehicle’s motion energy can be captured during a braking event and deployed when accelerating the vehicle. A heavy vehicle decelerating has a lot of kinetic energy to shed in the space of a few seconds, and a hydraulic hybrid will capture more than 70 percent of that braking energy due to the simple mechanics of hydraulic energy storage which functions much as a spring does. Batteries can only capture 30 percent of the braking energy because of the it simply takes more time for the chemical reactions to occur. In order to achieve with batteries what a the hydraulic hybrid does with hydraulic accumulators, such a large number of batteries would be required that weight and cost would become prohibitive. Even with future improvements to battery and capacitor technologies, we do not foresee prices coming down to anything close to where our hydraulic solution is priced.
Conversely, as we consider cars and light trucks, we see the advantages of electric and battery hybrid technologies over the hydraulic hybrid. Many of our team members drive Prius and Volts and even a Tesla. We’re happy to focus our efforts on providing a system that helps heavy truck and bus fleets reduce their fuel consumption and lower emissions.