Energy harvesting that are able to operate in higher temperature gradients, and that can conduct electricity well without also conducting heat (something that was until recently thought impossible ), will result in increased efficiency. Future work in thermoelectrics could be to convert wasted heat, such as in automobile engine combustion, into electricity. This type of harvesting is based on the changing capacitance of vibration-dependent capacitors. Vibrations separate the plates of a charged variable capacitor, and mechanical energy is converted into electrical energy. Electrostatic energy harvesters need a polarization source to work and to convert mechanical energy from vibrations into electricity. The polarization
Energy policy of China has the goal of achieving an integrated nationwide grid in the period between 2015 and 2020. In 2015, China generated 73% of its electricity from coal-fired power stations, which has been dropping from a peak of 81% in 2007. China is the world's leading renewable energy producer, with an installed capacity of 152 GW. China has been investing heavily in the renewable energy field in recent years. In 2007, the total renewable energy investment was $12 billion USD, second only to Germany. In 2012, China invested $65.1 billion USD in clean energy (20% more than in 2011), fully 30% of