We are all hindered by unintended consequences, Sweden one might argue a global leader for harvesting leftover heat was hamstrung by the law which prevented other suppliers accessing the district heating grid, but that changed when a law was passed last year that allows outside suppliers to deliver heat through the district heating grid. Now the town of Kiruna in northern Sweden can use waste heat from their local industry to cheaply heat homes, a neat solution when the mercury hits -30 Deg C in winter. Details are scarce in the Guardian article  however using waste heat whether from industry or power generation is cost-effective when the distance (where increasing distance equates causing increasing heat loss) between the source and end-user is not great.
Less commonly known is that waste heat can be used in the tropics to drive air conditioning, necessary in large parts of Asia. Low grade heat energy is often dumped into rivers or the sea, instead it can be used to change the concentration of liquid salt, e.g. lithium bromide, creating cold water for comfort cooling.
Handling food waste is a global problem, but is all food waste equal? There is waste from dining generated in homes, restaurants, and Dai Pai Dong’s, and there is food waste from markets, wet markets, and supermarkets, the latter being merely past its sell by date. HKSAR Government intends to create four food waste to energy plants, but no mention of their location and tragically RTHK’s report confirms our fears, about 3,000 tonnes are dumped into landfill every day! That is 1,095,000 tonnes per year.
However, collection, handling, shipping it across the territory, and bulk storage in central facilities is the worst possible solution in my view. To tackle local problems we need local education and local solutions, shipping it “way” will only perpetuate the most common reaction NIBMY.
Eco-District or community scale solutions demonstrate locally there is no distant landfill to handle the waste, you use it, you see it, you handle the waste. Therefore encouraging participation in the solutions, today’s over emphasis towards Green/Smart cities overlooks an important aspect, the human scale. The biggest challenge for eco-districts will be success, where the WTE (waste to energy) plant and equipment is designed for the worst case scenario, and the neighbours begin to understand that their waste creates a local waste problem, over time the total volume of waste will shrink, leaving oversized equipment in its wake. We need District, not City scale solutions.