In the time before smart cities, electricity by and large was generated by burning fossil fuels in relatively remote locations before being transmitted via high-voltage power lines to population centres.

This will continue for at least some time to come, but new technology is starting to allow cities to generate electricity within their own limits from renewable sources. The potential benefits include reduced reliance on expensive electricity long distance electricity transmission, cheaper power, cleaner air and less climate change.

What are some of the most useful power technologies?

Many believe solar is going to become the dominant power generation technology globally sooner or later, and is certainly well suited to urban environments as it is more discreet than most other technologies. And of course, cities naturally house many suitable sites for hosting panels, namely roofs. In the future, virtually every surface of a building could function as a solar panel.

Wind is usually seen as less well suited to urban environments, but newer technologies might change that. Vertical-axis turbines can be easier to site in urban areas than the traditional, windmill-like horizontal-axis design. Low wind speeds and turbulence are common problems in urban areas, but the challenges are not insurmountable. Turbines can incorporate two rotors, one small and one large. The smaller one turns at lower wind speeds and in turn helps to turn the larger rotor which is attached to the generator. Urban environments can even present wind harvesting opportunities as tall buildings can create funnel effects, generating stronger winds.

Small scale anaerobic digestion – using microorganisms to break down food and other organic waste to produce biogas which is then burned to produce electricity – is an intriguing option. Two features of AD make it potentially very useful in cities – it deals with waste at the same time as producing energy, and the heat produced when the gas is burned is a useful resource for nearby homes and businesses.

A lot of renewable power, being weather dependent, is intermittently produced, so cities generating their own power will need smart features – systems that track power production and consumption, balancing them by storing energy for when it is needed and managing demand by offering consumers incentives to use more or less power to coincide with the peaks and troughs of the intermittent generation.

The key smart innovation is therefore the smart grid – a network of power cables souped-up with digital technology which can track the demand and control the sources feeding power into it, allowing the efficient matching of supply and demand.

A good example is the Pecan Street Project in Austin, Texas. This uses the 700-acre site of an old airport as a testing ground for smart energy management technologies, facilitated by a local smart grid. It has shown that by offering price incentives, electric vehicle owners can be encouraged to charge their vehicles when demand and prices are lowest. And if demand is high, those same electric vehicles could provide power back to the grid. This highlights the crucial role battery storage technology could soon play in urban energy supply.

How far off are we from 100% renewably powered cities? There are already 42 of them, according to the NGO Carbon Disclosure Project. Admittedly, these currently mostly rely on centralised generation outside city limits such as hydropower and biomass, but as distributed generation technologies evolve and become cheaper we are likely to see cities become their own power stations to a greater and greater extent, and they’ll need to become smarter and smarter as a result.

Incorporating these innovations into existing cities will raise legal questions around consents and licencing. Asset controllers will need agreements with property owners. It’s a developing field, and an exciting one. At Lewis Silkin we have the multi-disciplinary expertise needed to navigate all the issues.