The invisible power plant

“E ascolto dalla tua voce le ragioni invisibili di cui le città vivevano, e per cui forse, dopo morte, rivivranno”.

“Ogni città riceve la sua forma dal deserto a cui si oppone”.

(Italo Calvino, Le città invisibili)

In September we come back from the holidays — those who could take them — and we start filling the cities again. In the city we find the comforts of daily life, but also the frustrations and problems of metropolitan life.

In July we were talking about blackouts caused by intensive use of air conditioning, but now it's already the season of storms and cloudbursts, like the ones that hit Rome these past days.

Extreme rain, like the heat, is a tangible sign of the climate crisis, and it has direct effects on energy distribution.

In July hurricane Beryl — whose extremely rapid intensification was traced back to the effects of climate change — hit Texas and damaged the electricity grid, leaving Houston without power for a long time. Or rather, almost without power, because the news is that the microgrids enabled by prosumers supplied a good amount of energy to the city, managing to keep many essential services running.

And if it's true that stories like this are more and more frequent because of climate warming, and that the future will have cities as its setting — given that according to the UN by 2050 one person in three will live in a city of at least half a million inhabitants — then it's worth asking: how will we power our cities in the future? What possibilities do we have for answering the energy challenges that show up in cities in all their complexity?

The status quo

Historically cities were born close to essential natural resources, like water, fundamental for irrigation and trade. The first large human settlements developed where there was fertile land for agriculture, forests for timber, minerals for making tools and buildings. With the arrival of the industrial era the growth of cities expanded exponentially, and the link between settlement and natural resources was broken. Energy supply started to depend more and more on external sources, far from the urban centres, and it radically changed the relationship between cities and resources.

Cities give us the picture of how we've managed energy up to now: concentrating all of it in one point, and moving it outside inhabited places, or at least as far to the edges as possible.

All the energy we use in cities, in fact, comes from large plants placed outside the urban perimeter, from which the distribution network branches out. Plants of this kind have a heavy footprint and, when they're fuelled by fossil sources, they're also very polluting. On top of that, they make the city entirely dependent on a single supply channel.

To reduce the impact of energy generation, and limit exclusive dependence on single generation centres, we need to literally put energy back at the centre: bring it back to the centre of cities, to the places where we live, bringing generation and consumption closer together and making them interchangeable.

One technology that could help this movement towards the centre is solar. Solar isn't only clean, it has the advantage of being a modular technology: every single panel does the same thing, wherever it is, whether it's together with hundreds of others in a field, or alone on a roof in Brooklyn. This way solar generation can be broken up and spread out, separated from the large plant, and then recomposed by building networks.

Just like panels, the batteries that make energy storage possible have also become more accessible, and available for private and domestic installations. Thanks to these innovations the price of solar generation has fallen sharply in recent years, and its adoption is constantly rising.

Even so, individual private installations aren't enough to protect users from interruptions and faults. Reserves are limited and don't last long, they cover a reduced need.

The power of decentralisation shows itself when more and more people install home systems, and decide to connect to each other, sharing energy.

Together, many single panels can become a power plant.

Let's turn it over

A network of solar systems and batteries can become a genuine distributed power plant. How? Let's run a thought experiment.

Imagine the city of Future City, made up of three different neighbourhoods. The city is powered by one large plant, but in the three neighbourhoods there are different systems for producing and distributing energy.

First neighbourhood: the single plant. This area takes energy only from the large plant, sited outside the urban perimeter and coal-fired: it produces energy for the whole city and, through the distribution network, gets it to all consumers.
Second neighbourhood: the hybrid plant. Most of the energy comes from the large plant, but inside the neighbourhood several residents have installed private solar systems. The prosumers, however, are still few and isolated from each other.
Third neighbourhood: the invisible plant. The neighbourhood is dotted with solar systems installed by residents and companies, each with a storage battery. The systems are connected in a network, they share energy with each other and also feed it back into the main grid.

What happens in each of these three scenarios when an accident, a fault or an extreme weather event interrupts the distribution of energy coming from the large plant?

First neighbourhood: it's enough for the distribution from the plant to be interrupted at a single point to send the whole area into blackout, leaving every user without energy.
Second neighbourhood: here too most residents are left without energy: only those with batteries and solar systems manage to supply themselves, and for a limited time, tied to how long their own personal reserve lasts.
Third neighbourhood: there's power in every building, because everyone can draw on the batteries connected to the solar systems. The prosumers' independent systems have produced more energy than they need to keep their own buildings running, and so they can feed it into the main grid and supply energy to the two neighbourhoods left without electricity too. The network formed by connecting all the domestic and private systems becomes a genuine power plant, even if an invisible one.

An invisible plant of this kind, virtual and distributed, can supply energy not only in case of faults or accidents, but also in the moments when consumption peaks. In the time bands when energy demand is highest, in fact, the grid has to fall back on auxiliary plants, which are often inefficient and highly polluting.

There are, naturally, critical issues still being worked out before invisible plants can be built at scale. First of all, solar energy is, as is well known, tied to the intermittent presence of its source — sunlight — and doesn't run uninterrupted like a coal plant. Then there's a need to update and upgrade the infrastructure: to better integrate the contribution of renewable sources and support multidirectional distribution.

The spread of electric mobility could give a strong push in this direction: electric cars are batteries on four wheels, and when they don't use all the electricity they were charged with, they can give energy back to the grid. On top of that, the spread of charging stations will help innovate and strengthen existing infrastructure.

After all, smart grids and microgrids won't have to entirely replace the larger plants: they'll be able to work alongside them, to integrate with existing infrastructure. To take on and complete the energy transition we'll need every possible way of turning renewable sources into energy. And solar won't be the only resource to draw on.

Volta Energy exists precisely to get past the critical issues that slow down the creation of distributed, invisible plants: lowering the costs of installing systems, connecting prosumers and bringing them together in energy communities, dematerialising renewable generation plants so they become assets accessible from a distance too.

Think of a number

800

That's the GigaWatts of solar energy that could be added to the grid every year according to the projection of a Rocky Mountain Institute study, which analyses the growth trends of technologies supporting the energy transition. Similar growth trends apply to sales of electric vehicles and batteries, which together with the adoption of solar form a single, decisive ecosystem of innovation in the energy system.

I give you my word

UVAM

UVAMs (Mixed Enabled Virtual Units) are an intelligent system that helps balance the supply and demand of electricity. These systems group together different energy sources — solar systems, batteries, cogeneration plants — which can be managed together in a coordinated way. When there's a demand peak or a surplus of energy produced, UVAMs step in to keep the electrical system stable. This mechanism makes it possible to optimise the use of resources and reduce waste, helping to make the energy system more efficient and sustainable. Today in Italy there are over 220 UVAMs involving 1,072 domestic and industrial electricity users, with a combined capacity of around 1,280 MW — considerable, given that the most modern nuclear plants typically have a capacity between 600 MW and 1,600 MW.