Energy, the agent of change for cities in the 21st century
The city, as a great guzzler of energy produced outside its borders, is committed to an energy transition that will allow for its decarbonisation. The first pillar is to move the mobility model towards a system of shared electric vehicles. However, buildings’ energy consumption must also be changed and gas must be relegated to a secondary role as a heat supplier. The solutions include the large-scale installation of photovoltaics on roofs and, in particular, aerothermal systems, which would be conceivable with economy of scale proposals such as citizen energy communities (CECs), an entity already covered in a European directive.
City and energy. It has been a binomial of two factors that, for as long as we can remember, have never gone hand in hand. Cities have always been holes that guzzled the energy produced elsewhere. From the grain brought from Egypt to ancient Rome, to industrial London, which consumed coal extracted from mines all over England and generated serious air quality problems in the 19th century, to modern cities that consume energy brought in from all over the world to run heating systems and ensure mobility. Cities, synonymous with civilisation and culture, are also the manifestation of the separation between the biosphere and humankind, with their capacity to gobble up natural resources. The question we must ask ourselves is whether the city could become a physical space for reconnecting with nature. Beyond the need to create space for recreation and the introduction of biodiversity, might it be able to run on the generation of its own energy?
In the 20th century, the energy transition was not part of the municipal agenda, because it was not a challenge that could be met. Resources, thinking and proposals were available for educational and cultural policies, and the urban planning model was thought out and rethought. But now they must also have an energy transition strategy, since the climate scenario demands it (cities generate 70% of greenhouse gas (GHG) emissions), and, for the first time, they can supply themselves with a significant proportion of the energy they consume. Not entirely and not at all times, but a significant proportion of it.
The first point to keep in mind is that mobility consumes a large amount of energy and generates most of the emissions produced in the city. According to the study The Future of Sustainable Cities: Urban Energy Transition to 2030, published by Deloitte in March 2019, in a Mediterranean city like Barcelona, 62% of GHGs come from mobility, while mobility accounts for 40% of energy consumption and the residential sector is responsible for 60%.
The conclusion is quite obvious: decarbonising the city calls for a courageous strategy aimed at traffic calming, greening the urban landscape and, at the same time, coming up with proposals for city access that allow for sustainable entry and exit. These measures must be accompanied by a proposal that can bring about the necessary change in culture with regard to the use of private vehicles. Throughout the 20th century, Western societies have associated so-called freedom with car ownership. These vehicles, which are used only 2% of the time, take up 70% of public space. But the reality is that the inhabitants of big cities do not need a car for their day-to-day lives, but only for certain times.
A proposal needs to be widely implemented to move from a culture of ownership to one of service, in which private vehicles are used as a means of transport that is returned once the need is met. This model would undoubtedly imply more intensive vehicle use and less occupation of public space, and should be linked to a system of shared electric mobility. The fight for superblocks and for a change in the city model is, above all, a cultural battle; to bring it to fruition, improving the streets and neighbourhoods concerned is crucial. It must be backed by a proposal to move from the culture of vehicle ownership to one of vehicle service.
Retrofitting roofs with photovoltaic panels
The other major issue is buildings’ energy consumption. Cities need electricity, which until now has been brought in from elsewhere, and gas to heat homes and run industries. This source accounts for more than one third of energy consumption in the residential sector, which makes it clear that consumption needs to be reduced and that we need to move towards an electrification landscape that eliminates gas from homes. Today, greater efficiency comes from options such as hot and cold air pumps and aerothermal energy. In turn, in the climate change scenario, thermal comfort will increasingly be aimed at coping with heat waves, with a greater need to provide cooling, and to improve insulation to deal with high temperatures.
But the question we must ask ourselves is whether our cities can move from a scenario of absolute energy dependence to one that sees a large-scale roll-out of renewables. It is in this context that we must say that we need to bring about a change in the appearance of roofs and some public spaces. Today, the cheapest kWh comes from renewable sources and, particularly, from photovoltaic energy. The relevant regulatory framework (RD 244/2019) allowed for shared self-consumption through a low- or medium-voltage grid, within a radius of 500 metres between the installation and the consumption points. The Council of Ministers later extended it to 1,000 metres and last November Minister Teresa Ribera announced that it would be extended to two kilometres. This brings it closer to more advanced regulations, such as that of Portugal, where shared self-consumption may have a radius of two kilometres for low-voltage lines, four kilometres for medium-voltage lines and up to twenty kilometres for very high voltage lines.
The regulatory framework should make us commit to mobilising all suitable roofs, especially high-volume roofs, to achieve maximum production during daylight hours.
This shared self-consumption means that there are either no or fewer charges and tariffs to pay. But what it does mean is that the more energy supplied locally, the less losses there are in electricity distribution. The regulatory framework is important, because this scenario should make us commit us to mobilising all suitable roofs, especially large-volume roofs, to achieve maximum production during daylight hours. Today, thinking of self-consumption as an individual exercise results in a situation where only those with the best roofs (usually the upper classes) can deploy the energy they need. It is therefore the responsibility of the citizenry as a whole to install photovoltaic panels on the city’s roofs on a wide scale, starting with public roofs, continuing with public spaces where it can be produced and also provide shade, and ending with roofs in the industrial and logistics sector. Distance is important, as in broad radii it would allow interaction between the city and industrial and logistics areas. The latter, with higher consumption from Monday to Friday, are extremely complementary to residential areas, which have higher consumption at weekends.
The installation of photovoltaics also has another determining factor: energy education. In other words, greater awareness of the cost of producing a kWh. Digitalisation and shifting consumption towards self-consumption production hours will introduce us to a culture where the best kWh is the one that is not consumed, and the next best kWh is the one that comes from renewable sources, thus paving the way for the electrification of what consumes the most energy in a household: the climate.
The city must harness its renewable energy potential to the full, but a territorial pact is also required. It is materially impossible for the metropolis to become self-sufficient.
This large-scale roll-out of renewables in the city is also important to be able to make a territorial pact. The transition to a model based on renewables has the advantage of greater energy sovereignty, but what does their roll-out represent in practice? In Catalonia, 63% of the population lives in 7% of the territory. And, beyond the need to reduce consumption, it is materially impossible for this metropolis to become self-sufficient. To make this pact possible, the metropolis must harness its renewable energy potential to the full while, in parallel, a proposal for territorial deployment is put forward.
Other transition tools
Finally, it is also worth considering the figures that could play a leading role in this transition in the city. The European directive on the internal electricity market proposed the creation of a new energy agent, citizen energy communities (CECs), which would be made up of citizens, local bodies and SMEs, and in which large companies could participate provided that they do not have effective control over them. The profits should be passed on to the members and to the territory where they are deployed. It is no coincidence that the directive and the entity are so innovative. There has been a realisation that, to play a leading role in the energy transition, an element of trust between consumers and energy, which has been fundamentally shattered in recent years, must be restored.
CCEs could be the tool on which cities’ energy transition is built; the clear advantage enjoyed by this entity is that all the roles in the energy sector have been assigned to it: generation, commercialisation, aggregation, and it could even be involved in distribution. In this context, the shared self-consumption of the energy community is much more than that: if we really want it to play a decisive role in the energy transition scenario, we need these communities to be sizeable and strong, not small “phalansteries” that interact with a small group of conscientious citizens, but that take on the scale of a neighbourhood, district or city.
Mediterranean cities face the challenge of relegating gas to a secondary role as a household heat supplier.
It is on the agenda of these communities that a real breakthrough in the energy transition of cities should be made. Without a doubt, the widespread installation of photovoltaics on urban rooftops is necessary, but not just that. Today, Mediterranean cities face the challenge of relegating gas to a secondary role as a household heat supplier. In addition, to achieve the mass deployment of aerothermal energy, we need economy of scale proposals that bring about lower prices and, at the same time, assume the scale of neighbourhood communities. This measure is not only significant in terms of decarbonising and lowering energy bills, but it is also particularly important in terms of turning the periods of local photovoltaic production into the thermal inertia of heating or cooling. Metropolitan energy communities are the ideal instrument to play a leading role in the territorial pact, where an aggregate purchase of renewable energy, especially wind energy, will have to be made in order to provide renewable electricity outside of daylight hours.
- Fraternidad y ecologíaJoan Herrera. Los Libros de la Catarata, 2019
- Cuánta desigualdad puede soportar la democraciaJoan Herrera. RBA Libros, 2014
- Economia i ecologia: propostes per sortir de la crisiJoan Herrera. Columna CAT, 2010
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