1. Storage of renewable energy (a) A typical roof-top solar panel on a residential home in the American Southwest produces 3.5kW. How many cellphone type Li-ion batteries are required to store one hour's worth of power? Assume that each battery operates at a constant voltage of 3.7V and has a capacity of 1000mAh. (b) Calculate the volumetric and gravimetric energy densities of the Li-ion batteries described in part a). Suppose each battery weighs 85g(3oz) and has dimensions 5cm0.5cm3cm. (c) A few years ago, windfarms in Germany were generating so much electricity, such that in some areas, the government had to pay renewable energy companies to switch off their turbines to stop congesting the power grid. "In 2015, northern Germany produced 4,100 GWh in excess energy* that could not be stored or transported to industries in the south. This excess energy is reported to be enough electricity to supply 1.2 million households for a year." (Source: The Guardian ) How many cell-phone type Li-ion batteries with the same characteristics as in (a) and (b) are required to store the excess energy generated by these windfarms? Assume that a building with height 8ft tall and a square footprint is built to store these batteries, and that the volume of the batteries = the volume of the building. What are the dimensions of the building required to hold these batteries