Water Purifier & Electric Generator

okay i make this post because i don't understand about some problem in this world which is i think is not really unsolved problem. so i think, analysis and try to solved it.
the problem i try to solved is this:

1. Lack of drinking water 

2. Lack of Electrical Energy

3. The land will overwhelm by the sea (which is due the global warming that melt the ice in north pole [frankly i lack data about this so i just put the general idea])

Okay about the first problem i had read some book to make drinking water out of seawater for survival. the main idea is just extract the salt concentration from it by boil it. so it's just like this:

liquid seawater - heated - water vapor - cooled - drinking water

below the image created using "paint" to tell the process

 

so because we will never lack of seawater (because will be recycled from the river or rain) we will never lack of drinking water.

Lack of electrical energy? as long we had a motion to spin the shaft we can extract electrical energy. if we don't have waterfall we can dam the water in certain height or connect them to the sea/river/ or any water source/ even the rain can be useful if contained in the dam than open the dam and let the gravity do the rest to spin the watermill (after gain the energy we can pump water that fall and hit the watermill and use the rest, if the energy to small by making why don't make it more in order to gain more.

the sea level will increase in the future? why not we make it our drinking water? why not use it as source of electricity generator? okay maybe it's hard to do that now, but as long as human can think is not impossible. Because all adversity in this world have an answer.

so this is my water purifier and electric generator design that solved all that problem, maybe i am to ideal and lack of other data or need other precaution because i just finish my engineer degree (lack of experience) but it can be solved with more research and discussion.
okay i sketch the design with pencil and colored it with crayon due to the laziness to do the CAD hahahaha.

any other advice or discussion to improve this will be helpful

the place ideal to use this maybe dutch ( because the land is under the sea level) or Middle East or Africa due to their lack of drinking water (who want to pay expensive water in developed country?)