A Fourth ‘R’ ?
Reduce, Reuse, Recycle… Recover. As the population in large cities worldwide grows, waste management becomes an even bigger challenge. Recycling programs can divert large amounts of materials from landfills but some garbage still needs to be disposed of in landfills or Energy From Waste (EFW) sites. EFW facilities are capable of recovering energy from garbage that would otherwise be unused in landfills.
EFW and landfill gas capture systems operate on similar principles: produce steam to turn a turbine which generates electricity. The difference is the fuel used to produce the steam. Landfill gas based electricity generation relies on methane from the decomposition of organic material, while EFW facilities combust the solid waste. Both are good options as they prevent methane gas from escaping into the atmosphere. Methane has a global warming potential 72 times that of carbon dioxide. Both options sound good, so which is better? The better question is: ‘How much land and money do you have’?

In the World Bank, we recently did a report titled Bangladesh:
There is little empirical regularity that is as universal as the following: no matter what the path of economic development a country has followed, urbanization has been an inevitable consequence across the world. Already half the world’s population is urban. Currently,
Not so fast, argue equally many learned scholars! Didn’t Vernon Henderson, another acclaimed urban economist, report in the Journal of Economic Growth that higher levels of urbanization are not necessarily associated with higher rates of economic growth. And, hasn’t Africa been urbanizing rapidly over the past 15 years 

A helpful way for young math students to grasp the concept of exponential growth is to look at water lilies growing on a pond. They grow exponentially and double in area each day. If they will fully cover the pond by the 30th day, on what day is the lake half covered? The twenty-ninth day
For bees, bigger hives are better.
Tanzania has been growing steadily over the past ten years and 2012 was no different. The economy expanded by 6.9 percent, which is close to the historical average. A look at national accounts reveals that five sectors contributed to almost 60 per cent of Tanzania’s economic growth between 2008 and 2012:
The emergence of mega-regions, as metropolitan areas merge to form a system of cities, has demonstrably contributed to growth in the developed countries. With