According to a UN estimate cities are using 75% of the global primary energy and are responsible for 70% of CO2 emissions.
In a way cities are a way to get a more efficient use of resources, energy included. Studies have shown that the higher a city density the less energy consumption pro capita.
However, a city is an ensamble of buildings, roads, vehicles, factories, shops, … citizens and more. Each of these components uses energy. For heating and for cooling, for moving atoms and for moving bits around, for illumination and for manufacturing…
Making an energy balance sheet is complex, finding the relationship among its different component a challenge. And yet, this is the first step to get a better “energy infrastructure”. Some of the energy use is under private control, other under biz control and other under Municipality control. Trimming private energy use has been done by enforcing rules (in Italy homes can be heated up to 22°C but there is no enforced rule for cooling them -even though cooling is more energy hungry than heating), by levying taxes on energy and by raising awareness. Modern technologies would let us work in this latter direction much more efficiently than in the past. I’ll look into that when discussing the awareness infrastructure.
There are technologies than are more energy efficient than others and new deployments should take this into account. Also, replacing technologies with more effective ones can make sense from an environmental point of view and the challenge is to find economic sustainability. An example is illumination.
Illumination plays a significant role in cities budget, reaching 40% of a Municipality electricity expenditure.
Notably, illumination tended to be much better in larger cities than in smaller ones. Over the last decade, though, illumination has become more evenly spread. In France the number of hours “illuminated” per year was 4,000 in large cities but only 1,000 in villages and small cities. Nowadays it is 4,000 hours everywhere with a pro capite consumption of 91kWh per year (it was 70 in 1990). This represent the output of two 1GW nuclear plant for France.
In the past the energy focus for cities was on power consumption. In the last decade power production has become something to address as well. New technologies for power production are being studied and brought to industrial maturity. It is no longer just photovoltaic panels on buildings roofs. Building paintings, windows, even smart bricks can double up as power generators.
Along with it the evolution towards smart grids that can balance the loads with production making power distribution more efficient. An effective distribution network llike the one in the US is wasting some 5% of the generated power. Other Countries are wasting more.
The rise of electrical vehicles will bring along the problem of disseminating power charging stations and upgrade the grid to support them. In the long term, some studies have pointed out, vehicles batteries connected to the grid can play the role of grid accumulators acting like energy buffers between production and consumption. The technology Vehicle to Grid is still in its infancy (there are so few electrical cars today…) but it is something a Municipality should get involved into, since it requires a blending of regulations, logistics and infrastructures evolution that can only be implemented by a public institutions.