12-acres of Solar Panels in the Center of San Fransico

The city of San Francisco has begun harbouring its own solar energy from the heart of the city with a twelve-acre, 5 MW solar photovoltaic system on the surface of Sunset Reservoir. Once an empty void in the built up metropolis, this area now serves two purposes; as a source of water and energy. Each year it is expected to reduce carbon emissions by more than 109,000 metric tons, and will power more than 15,000 San Francisco homes.
Can other infrastructures like railway tracks offer similar opportunities?

Contributed by: Charlotte Keers

NEWater - Water Production in the the City of Singapore

NEWater is the brand name given to reclaimed water produced by Singapore's Public Utilities Board. More specifically, it is treated wastewater (sewage) that has been purified using dual-membrane (via microfiltration and reverse osmosis) and... read more

In Singapore they are not just cleaning sewage water, they are "producing" new water in the city (Singapore is all city), bottled and sold as drinking water..

They are not just "mitigating" problems of the water system, they are turning the system around.

Note that the bottled water is symbolic, it is not the driver, they are using it to visualize the fact that reclaimed water (reclaimed from sewage) is good to drink - more than ok, it is actually too pure for humans: we would need the minerals that dissolve in water as it filters through the soil and runs down the mountains; we need grittier water. 
It just proves the point that NEWater can be safely used in industry (generally the largest consumer of water) at a huge scale.

NEWater plants are designed so that they can be visited and become part of the culture and the urban landscape.