Performance solutions for performance applications

Flywheels for motorsport applications

Understanding that motorsports are a proving ground for advanced vehicle technologies, Blueprint Energy is committed to working with the industry to develop charge sustaining hybrids with a high degree of hybridization to improve performance.

Why charge sustaining hybrids in motorsports?

The opportunity for using hybrid architectures in motorsports is dependent on the type of racing. Formula 1 kinetic energy recovery systems (KERS) to date have been relatively mild (only 60 kW for 6.67 seconds, one use per lap) and therefore the fuel economy benefit has been minimal. Moreover, with no re-fueling requirement during the race, no competitive advantage arises from improved fuel economy. However for endurance and other forms of racing the improvement in fuel economy directly relates to fewer pit stops for re-fueling leading to more time on the track and therefore a significant competitive advantage.

The reduction in fuel consumption is proportional to the degree of hybridization of the vehicle.

Degree of hybridization (DOH) = ESS power / (ESS power + engine power)

Examples of DOH for existing motorsport vehicles include:

Vehicle specifications are sourced from a number of references and are approximate.

What is the impact of high DOH on passenger hybrid vehicles?

In our opinion, the high DOH sucesses earned in motorsports will be incorporated into passenger hybrid vehicle architectures. Independent of the motorsports world, this work has already begun with significant simulations and experimental work completed by the National Renewable Energy Laboratory (NREL).

The figure below shows the reduction in fuel consumption in comparison to stored energy for different degrees of hybridization on a stop and go city driving schedule (source J. Gonder et al., "Lower-Energy Requirements for Power-Assist HEV Energy Storage Systems—Analysis and Rationale," NREL, PR-540-47682, 2010).

NREL DOH simulation results

The NREL report gives the following conclusions:

• Fuel savings increase with higher DOH (engine downsizing)
• Fuel savings increase, but taper with larger energy window
• Significant benefit with energy window out to ˜50 Wh
• Additional benefit with energy window out to ˜150 Wh or so

Our own thoughts on strong hybrids

These high DOH or strong hybrid vehicles will consume less fuel than conventional or mild hybrid drives especially when driven under aggressive, real world conditions. Based on our research and experience we can draw a number of conclusions:

• Power not energy is the most critical variable in terms of high system returns
• Up to a 50% reduction in fuel consumption (doubling of vehicle range) is achievable with a high DOH system
• Battery solutions are energy biased and need to be oversized to meet optimal high power requirements
• There are no technical impediments to developing high DOH (strong hybrid) systems using flywheel ESS
• The ESS in a strong hybrid system requires high cycle tolerance and high conversion efficiency

A flywheel kinetic energy storage system is able to provide a high degree of hybridization without compromising vehicle performance