NOVELTY - The battery apparatus includes a mechanical battery (40) provided with a flywheel and further comprises of a chemical battery (42). The mechanical and chemical batteries are arranged in use to supply energy to a common load. The mechanical battery is arranged parallel with the chemical battery.    USE - Battery apparatus for an electrical machine of electric vehicle (claimed), such as a hybrid electric vehicle which is either a parallel hybrid electric vehicle or a plug-in hybrid electric vehicle (all claimed).    ADVANTAGE - The battery apparatus reliably harness the energy with exhaust gas and enable it to be stored for future use. An improved turbocharger efficiency is achieved after optimizing boost over a greater range of loads. The turbocharger and the flywheel are used in combination such that exhaust gas energy is intelligently captured and harnessed in order to assist running of the turbocharger to enable a more efficient operation of the turbocharger. Overall performance of the vehicle is improved by harnessing the otherwise waste energy since the flywheel is charged using driveline energy and exhaust gas or energy that would otherwise be wasted. The flywheel driven supercharger allows for downsizing of an engine since the engine power density during low exhaust mass flow events such as pull away is improved. The reduction in size reduces friction and pumping losses, improving its efficiency. Actively controlling the mass flow into the cylinder of an engine to optimum in all conditions allows the flywheel driven supercharger could to reduce up to a 30% reduction in fuel consumption for an engine even without downsizing. Downsizing the engine will therefore enhance this potential fuel consumption and also satisfy the growing consumer trend for achieving maximum performance from as small, compact and low cost an engine as possible.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a supplying method for energy to a system including a load.    DESCRIPTION OF DRAWING(S) - The drawing shows a layout for dual mode operation of the flywheel battery in parallel with a chemical battery.    Mechanical battery (40)    Chemical battery (42)    Power electronics (44)    Electric machine (46)    Hybrid driveline (48)