It turns out that burning coal still provides a major source of electricity generation in ohio. coal yields about 30 gigajoules (gj = 109 j) of electricity per metric ton (1000 kg). assuming that the coal plant is 30% efficient (i. e. the plant captures 30% of the energy converted by burning coal), how much total coal has to be burned to keep the led from question 1 lighted for the week? how does that compare to the coal required to light the incandescent bulb for the same period?