Rethinking the European grid

For a number of years now, European research has been trying to overcome a major challenge: how to modernise distribution networks that are sometimes 50 years old by incorporating new production units that are dependent on the whims of the sun or wind.

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© Shutterstock
© Shutterstock
© Shutterstock
© Shutterstock
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The paradox of renewables

In response to climate change, recent years have brought a growth in renewable energies and with it the problem of incorporating them in the design of existing distribution networks. “This is in fact a problem that existed prior to the industrial revolution of the 19th century, when we relied on nature alone to supply our needs,” remarks Jacques Deuse, Technical Manager with the EU-DEEP (EUropean Distributed EnErgy Partnership) integrated research project on distribution networks. “With renewables, we are returning to the dependency on nature. Wind and sun in particular are not necessarily available when the consumer needs them. In our regions, for example, it is in winter that we need a lot of electricity but it is in winter that there is the least sun…” As it is not easy to store electricity, production must match consumption as closely as possible. This is why it is such a challenge for the network regulators to incorporate such a variable and unpredictable factor as electricity generated by solar and wind renewables.

While wind turbines generating flat out in high winds will create a production surplus if demand is insufficient, it is not possible to shut down production of traditional coal or gas plants as they take too long to start up again if the wind suddenly drops. They are rather switched to a low-generating regime, ready to fire up again when needed. But it is in this mode that power plants fuelled by hydrocarbons generally emit the most greenhouse gas per unit supplied. Thus the paradoxical situation whereby giving priority to wind-generated electricity can result in a more polluting production.

A radical rethink of distribution networks thus seems essential. As to the solution, this is what the dozens of scientists from research centres, universities and private and public companies working on the largely EUfinanced SmartGrids platform and EU-DEEP research project are seeking to come up with.

SmartGrids in the long term

Two key ideas underpin future distribution networks or electricity grids. The first is a better interconnection of existing networks to create a vast European grid. The bigger the network the greater the likelihood of being able to balance production and demand. If there is no wind to turn the turbines in Denmark, for example, the electricity shortage could be offset by solar-powered plants in Spain.

The other idea is to permit a two-way flow.

A myriad of small local networks powered by individual wind turbines or photovoltaic panels on the roofs of houses could ultimately be harnessed as part of the international grid.

When the mini-networks are not producing enough electricity for local consumption, the main grid could step in. If the opposite is the case, they could sell the surplus to the main grid. This design would ensure a two-way flow in which the consumer would to a degree be an active producer.

The SmartGrids researchers claim a number of advantages for their system. Renewable energies could easily be included in the mininetworks as well as the main grid, without posing any problems in terms of low voltage or intermittence. This would result in decreased CO2 emissions. Costs for the consumers would also fall as they would produce a part of their own electricity and could even sell any surplus.

EU-DEEP in the short term

Such infrastructure cannot be created overnight, however, and much remains to be done before being able to reap its full benefits on a large scale. It requires extremely high performance connection systems as well as highly developed logistics. As a result, it is a vision that is only feasible in the relatively long term. “On the other hand, the EU-DEEP project is deeply rooted in the here and now,” explains Jacques Deuse. “It is not a question of making a clean sweep and starting again from scratch.

We want to improve existing skills and infrastructures to meet the needs of today, tomorrow and the day after tomorrow. We are proposing a new design for distribution networks that permits a flexible integration of distributed electricity production into the grid. Within this system the consumer and the producer are solar-generated electricity.”

Matthieu Lethé


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Large-scale storage

While awaiting the large-scale implementation of new distribution networks, there remains the problem of the intermittent nature of the most renewable energies.

One solution would be to store surplus electricity production at times when consumption is low and then reinject it into the network at times of peak consumption. The problem with this is that electricity is very difficult to store in large quantities. But for several decades now there have existed vast reservoirs of electricity: Pumped Storage Plants. These consist of two successive dams, with a major level difference between the two. In Europe, the largest of these plants is situated in the French Alps, at the Grand’Maison Dam. At times of peak consumption, when production units – whether traditional or renewable – are unable to meet demand, the water held in the upper basin is released into the lower basin to generate electricity, like a traditional dam. On the other hand, when the electricity produced exceeds demand, the surplus is used to activate powerful pumps that transfer the water back to the upper basin.

Pumped Storage Plants have the advantage of excellent performance: just one-fifth of the energy is lost in the flows. The drawback is that they take up too much space and require a mountain site.


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