energy costs / electricity demand / grid ancillary services / petroleum energy / system management / transport energy supply base / electric car / renewable energy supply / electricity / Variable and cost-reflective electricity pricing / energy efficiency / renewable energy / smart recharging infrastructure / energy system / energy network / lower-value stationary utility energy storage applications / retail price / smarter network / supply electricity / non-petroleum energy sources / car manufacturers / energy intensive appliances / ancillary services / contingent services / excess renewable energy / energy opportunities / renewable energy target / grid-connected energy storage / electricity networks / energy / /