Potential for generating electricty from waste heat using the termoelectric effect

A general article here...

http://www.physorg.com/news/2011-06-renaissance-year-technology-ease-21st.html

And a specific discovery of a metal that generates electricity direct from waste heat

http://www1.umn.edu/news/news-releases/2011/UR_CONTENT_343439.html

One of the challenges of urban design is now to find ways of cascading waste heat through the built environment, from one use to the next to minimise energy consumption.