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Cities hold about half of the world’s population but account for 60 per cent of its energy use, according to the International Energy Agency, which is backed by developed country governments.
Many of the problems of urbanisation – local pollution, greenhouse gas emissions, provision of services and economic development – are linked to energy use.
In emerging economies, cities typically consume more commercially provided energy than rural areas. City dwellers are more likely to have access to electricity, to own energy-hungry consumer goods, and to work in places that need to be powered.
Rural areas typically use much more biomass such as wood and animal dung for cooking and heating, so their total energy consumption is often higher. But the demand for coal, gas and power is greatest in cities. In China, cities use twice as much commercial energy per capita as the countryside.
In developed economies, including the US and the EU, that pattern is reversed, and cities are typically the most energy-efficient places. In the US, people in rural areas use 12 per cent more energy per capita than city dwellers. Those in the suburbs use 20 per cent more.
Cities that address the challenges of energy provision can improve the lives of their residents and their prospects for economic development, as well as show the world ways to respond to energy shortages.
The entries for this category indicate that there is a demand for innovation that is economic and social, as well as technological. Often, the technology to make significant changes already exists, and the important part is finding ways for it to be deployed on a large enough scale to make a difference.
Proterra’s electric bus is an example of a technological innovation. With a completely new body and systems, and an innovative lithium titanate battery, the EcoRide has been out in front of the rest of the US bus industry.
Two other entries address the fact that poverty forces people to cook and heat their homes with coal, charcoal, wood and animal dung. Smoke and soot from those fuels are estimated to cause 2m deaths worldwide each year, mostly of women and children.
The Community Cooker from Kenya is a stove that burns waste at very high temperatures, above 800 degrees Celsius, to minimise noxious waste gases and ash. Reaching those temperatures was difficult, but the stove has been designed so that it can be built, maintained and repaired in the slums where it is being used.
The LPG project from India uses a very well-established technology, familiar from any backyard grill in the US, but with a new economic framework to increase access. One of the greatest obstacles to the use of liquefied petroleum gas by poor households in India is the upfront costs for a stove, a regulator, a gas cylinder and fuel. The LPG scheme takes regular contributions from members of a community and pools them to pay those costs for a few households every month. In the pilot project, all 60 households were connected over a period of five to six months.
Two influential cities, Tokyo and Houston, have taken very different approaches in their attempts to achieve greater energy efficiency and reduce greenhouse gas emissions.
Japan’s capital has introduced the world’s first city-level cap-and-trade programme for carbon dioxide emissions, requiring commercial and industrial buildings to make energy efficiency modifications or buy emissions permits.
The scheme, launched in 2010, is a culmination of Tokyo’s effort to improve energy efficiency, which it began in 2002.
In Houston, by contrast, the energy efficiency programme is voluntary. The mayor’s Green Office Challenge harnesses the competitive spirit of the city’s businesses to drive down their energy use, with recognition and the possibility of some small cash grants its only rewards.
One of the many concerns about worldwide urbanisation is that it will mean homogenisation – that economic development will mean standardised cities. While that may prove true eventually, the lesson of these awards is how diverse the challenges, as well as the solutions, still are.