Due to increasing environmental pressures from lobby groups and the like, many have called into question the relevance of Formula 1 as an innovating force towards future technological advances (particularly those concerned with efficient cars). The FIA has been asked to consider how it can persuade the sport to move down a more environmentally friendly path. Therefore, in addition to the above changes outlined for the 2009 season, teams were invited to construct a KERS device, encompassing certain types of regenerative braking systems to be fitted to the cars in time for the 2009 season. The system aims to reduce the amount of kinetic energy converted to waste heat in braking, converting it instead to a useful form (such as electrical energy or energy in a flywheel) to be later fed back through the engine to create a power boost. However, unlike road car systems that automatically store and release energy, the energy is only released when the driver presses a button and is useful for up to 6.5 seconds, giving an additional and 400 kJ. It effectively mimics the 'push to pass' button from IndyCar and A1GP series. KERS was not seen in the 2010 championship – while it was not technically banned, the FOTA collectively agreed not to use it. It however made a return for the 2011 season, with all teams except HRT, Virgin and Lotus utilizing the device.