Sure ! add me <| sep |> you can get paint for mac by applying it liberally to the front end until you get a nice , smooth coat and finish <| sep |> uck will beat anyday serbian units . <| sep |> I live in an arid area where a drought has made water supplies low . To get enough water to store enough energy for a city ' s energy consumption during the night will require more pipes from an already depleting , far away , natural water source . Digging 2 big holes , buying enough water and land in a population dense area , and preventing evaporation in an arid environment are major problems too . And a huge problem that would affect any reservoir that is completely closed system is growth of algae , mosquitoes , or other potential contaminants you wouldn ' t want to run through your pumps . Unless massive containers can be built , which is another engineering problem . Although I do not know the exact costs , I would assume the reason gravitational potential energy is not used as a storage device is because of cost and size . That ' s why molten salt power generators exist . They are conveniently small and can be adjusted to match energy consumption of the surrounding area . This is also why I wish nuclear were more accepted by the American public . The ability to generate energy at any time of the day erases the biggest problem of renewables energy storage .