New York consumes too much energy, London and Paris use relatively fewer resources and Tokyo conserves water well, according to a new study on "megacity metabolism," as reported by ScienceDaily.
As the world's first comprehensive survey of resources used and removed in each of the world's 27 largest metropolitan areas, the findings could point the way toward strategies to make cities more sustainable.
To examine how resources pass through the world's largest cities, engineers at the University of Toronto led an international team of researchers to study such issues as burning natural gas for heating, using electricity for public transit or disposing of solid waste and wastewater.
Today's megacities hold only 6.7 percent of the world's population, but consume 9.3 percent of global electricity and produce 12.6 percent of global waste, the study finds. Megacities are defined as metropolitan areas with populations greater than 10 million — which continue to grow in size and economic importance.
But some cities are more environmentally offending than others. New York, for example, has 12 million fewer people than Tokyo, but uses more energy in total — the equivalent of one oil supertanker every 1.5 days. Some of these differences can be explained by geography — colder megacities such as Moscow and New York use more fuel for heating.
Economic activity also is a factor — wealthier people consume and waste more. The average New Yorker uses 24 times as much energy as a citizen of Kolkata, and produces over 15 times as much solid waste.
However, Tokyo's efficient design and large network of public transit reduces its environmental impact, and shows that smart urban policies can reduce resource use, even in the face of rising GDP and increasing populations, Science Daily reports.
In the study, the researchers shared several successful policies:
Moscow has built the largest district heating system in the world, providing combined heat and power to buildings housing 12 million people; this being more efficient that using separate systems for each building.
Seoul has developed a system for reclaiming used wastewater for secondary uses such as flushing toilets, increasing the overall efficiency of water use.
London has been subject to rising electricity costs and taxes on the disposal of solid waste. It is the only megacity for which per capita electricity use is going down even as GDP increases.
Globally, megacities are experiencing an explosion in population, but are growing even faster in terms of energy use and GDP. With many of these megacities sprouting up in the developing world in countries such as China, the mix of more people and more consumption per capita is putting a big strain on the planet's resources.
But the study suggests that, as megacities proliferate, smart policy decisions can make a difference in reducing overall resource use.
This could contribute to further sustainable economic growth — smart city technology revenue will grow from $8.8 billion annually worldwide in 2014 to $27.5 billion in 2023, as cities around the world adopt smart city technology to meet sustainability goals, boost local economies and improve services, according to a 2014 report by Navigant Research.
By 2025, cities around the world will invest $64 billion in light-emitting diode (LED) and “smart” streetlights, according to a separate recent study by Northeast Group. With these infrastructure projects, cities across the world modernize their streetlights with more efficient LED lights. They also are deploying sensors, communications and analytics software throughout their street lighting infrastructure to become "smarter."