Wind and solar energy obviously won’t work 24/7. One therefore needs efficient a

Question

Wind and solar energy obviously won’t work 24/7. One therefore needs efficient and large scale ways to store the energy. We want to estimate how to store the energy produced within 24 hours for the 5000MW power.
One way to store vast amounts of energy that can be later transferred back into electrical energy is to pump water uphill into a dam. Assume the water is elevated in average by 200 meters. When the water is released downhill through turbines to generate again electricity, assume one can get back 90% of the original energy used to pump the water uphill.

(i) What is the mass of the water needed to store the given energy?
(ii) Which area would this amount of water have in a lake of 100 meters depth? (iii) Discuss briefly what the advantages of this storage technique, i.e. pumping water uphill, is against other possible ways of storing energy, e.g. heating water, hydrogen electrolysis or charging batteries.

Explanation / Answer

MGH/t (j/s) = power (watt) [energy in the dam is stored in form of potential energy]

( M*9.8x200)/24*3600 =0.9x5x109

M = 198.36 x109 Kg

(ii) density = Mass / Volume

volume = area x height

198.36 x109 = 103x(Areax100)

Area =19836x104 m2   

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.