Cities are now home to more than half of the world’s population and account for almost two-thirds of global energy use and three quarters of energy-related carbon emissions. With about 20% of their energy supply currently from renewables, their potential for scaling up local renewable supplies is without doubt.
But a new study from the International Renewable Energy Agency (IRENA) makes clear there is no ‘one size fits all’ solution. It varies greatly depending on the city’s characteristics such as population density, growth prospects and energy demand patterns, which in turn vary on whether it is in a hot or cold climate.
City renewable energy use
The study analyses the energy use in 3,649 cities that together account for 60% of the global energy demand.
Energy use by application in different city types, 2014 (IRENA)
This shows that the average urban energy use in buildings and for transport ranges from about 5,000kWh to nearly 30,000kWh per capita, simply due to differences in climatic conditions, population density and each city’s level of establishment.
City renewable energy priorities
Given that buildings and transport are the two largest energy consumers in cities, these are identified as priority areas for action in order to scale up rapidly and substantially, along with a third – creating smart integrated urban energy systems, including smart grids. Renewable energy use in buildings encompasses heating, cooling, cooking and appliances. Sustainable options for transport include electric mobility, hydrogen and biofuels.
The study suggests that cities in emerging economies, which will account for the majority of global growth in energy use in the next decade, will be best positioned to deploy energy efficiency and renewable energy technologies in new buildings and can adopt more compact urbanisation models that ensure efficient and sustainable transportation. In urban and peri-urban areas, where extending energy access is a top priority, decentralised power generation and clean cooking solutions are crucial for sustainable development. There, renewable energy technologies can be deployed quickly, incrementally and cost-effectively.
Established cities, on the other hand, have lower building turnover rates and will largely rely on retrofits and technologies that can be added relatively easily to existing buildings, such as heat pumps and rooftop solar equipment.
Cities with high population density can benefit from renewable-powered electric public transit systems and cost-effective district heating and cooling systems. Low-density cities, with larger rooftop areas, could benefit from highly distributed renewable energy technologies such as rooftop PV and solar water heating and the growth of electric cars.
Renewable energy options for transport and in buildings in different city types (IRENA)
Advancing renewables in cities
What do these findings mean for cities? Transforming the urban energy system is not a question of simply replacing one form of energy with another, but of rethinking the entire energy system, the report states. This involves considering the main end users, including buildings, transport and industry. It requires designing smart, integrated urban energy systems that can manage variable power produced by solar panels and wind turbines, and that can take advantage of sector synergies where energy is produced and consumed. It also means taking all policy areas and governance levels into consideration.
Clearly also such planning should take place within the context of a smart city development plan. [Engerati-In Focus Smart & Sustainable Cities ]
Key players in city planning generally include mayors, city planners and municipal governments. With their experience and expertise utilities also should be a key party in planning future city energy systems. Their development also opens the way for the delivery of the new energy products and services, which will support the new energy system.