Paris is showing the way to a much more sustainable future with iinnovative, practical solutions to growing food in the city, managing its water resources sustainably for the public good, and developing more localized energy generation.

The French capital hosts Nature Urbaine, Europe’s largest urban rooftop farm, on the roof of Pavilion 6 of Paris Expo Porte de Versailles. It has been producing more than 10 tons of fruit and vegetables each season since spring 2020, and last year, was recognized as the world’s first urban farm to net offset carbon. Its computer-controlled hydroponic and aeroponic systems use 80% less water and produce 62% fewer CO2 emissions than a conventional farm for the same yield. 

Its produce helps supply an on-site restaurant and is sold to residents and surrounding businesses such as hotels. The rooftop also hosts tours and events, helping make the project financially viable.

NU-Paris also rents 156 urban vegetable gardens in “Parisian squares” on a yearly basis for city residents. Tenants have daily access to their garden every day of the year and to collective facilities (relaxation area, sink, compost, equipment, handling of green waste).They get a welcome growing kit, and expert advice from Nature Urbaine gardeners twice a week in season to help choose preferred seeds, plants and growing equipment.

Agripolis, which built Nature Urbaine, also runs five other urban farms in the city, on the roofs of hotels, a municipal swimming pool and a water purification station.  A mushroom farm in a former parking lot distributes its produce within a 15 kilometer radius and a 7,000 square-meter farm whose greenhouse is heated by 300 servers from a data center below it. There are honey-producing beehives on the roof of the Paris National Opera.

The Les Parisculteurs project, launched in 2016, has added more than 50 urban farming projects to the city, increasing its overall farming land from 11 hectares in 2014 to 30 hectares currently. The long-term target is 100 hectares.

The rationale? “Hosting agricultural projects on roofs, walls, ground and basement spaces contributes to the construction of a sustainable and resilient urban model: short production, processing and distribution circuits; strengthening of social bonds; awareness of responsible eating; strengthening an edible plant landscape in the city; ecological rainwater management; circular valorization of organic waste; development of biodiversity; fight against heat islands; thermal comfort of buildings.” A toolbox helps proposed projects know the rules for urban farming.

“If we consider that one needs on average 50 m2  of market garden to feed one person, it would be necessary to cultivate 11,000 hectares to guaranty the self-sufficiency in fruit and vegetables of the population of Paris and 5,000 hectares more for non-resident workers, that is 1.5 times the surface area of Paris,” says the Paris Urbanism Agency (APUR) . | This doesn’t include the 29.3 million visitors to Paris each year. However this population (32.6 million) represents a very large consumer potential of fresh products. Here lies the urban agriculture challenge: to produce, supply networks and distribute. “

“Urban agriculture is not a total solution to feed an entire city,” Pascal Hardy, founder of Agripolis, who estimates city farms could supply 5% to 10% of demand in Paris, told Bloomberg. “But if we can integrate food production, it could have a significant impact.”

By the end of the year, authorities will publish a renewed plan for the Paris Green Belt, a 350-kilometer loop circling the city created in 1983 to protect natural and agricultural spaces from urban sprawl.

Water

“Water is such an important resource,” says Dan Lert,  deputy mayor of Paris in charge of the ecological transition and the climate, water and energy plans. “But the unprecedented climate change in Paris and France means it’s the end of the abundance of water. So we have to do everything we can to use this resource as best we can.”

In 2009, Paris nationalized its public water management system, classifying water as a common  good instead of a profitable commodity, and guaranteeing low prices for users. “We needed to have a democratic control of water,” says Lert, who is also currently president of Eau de Paris, an innovative and sustainable public service mode.. “This allows us to have a long-term vision and we can reinvest everything back into the service, unlike the profit-making private sector.”

In the last 15 years, the city has cut water-related greenhouse gas emissions by 25%, and water use itself has fallen by 10% over the past decade.

A key strategy is preventing pollution rather than having polluters-pay after the fact. For example, authorities are working with farmers in the Greater Paris region to encourage organic farming and limit use of fertilizers and pesticides. Lert is campaigning with mayors across France to introduce a nationwide ban on pesticides or nitrates in water areas.

Another strategy is to target and fix leaks by using 3,000 acoustic devices and educating the public about the cost and impact of leaks. Last year, it saved a million cubic meters of water from being wasted.

Regenerating the network of public fountains is cutting use of plastic bottles, as well as making water freely available around the city. A set of 73 “refreshing” fountains, some of which provide cooling mist in the summer, will supplement the 1,200 water points in streets, squares, gardens and woods. The city treats drinking water using low-pressure reverse osmosis, which produces lower emissions than other methods.

In 1900, during the first edition of the Olympic Games in Paris, swimming events took place in the Seine. The 2024 Olympiad served as a lever and catalyst for improving the entire ecosystem of the river, including new wastewater treatment plants and construction of a stormwater basin to prevent wastewater from overflowing. Athletes will inaugurate swimming in the Seine as part of the Olympics in 2024, and in 2025, that will be open to residents. Around 20 potential sites in 16 municipalities in the Greater Paris Metropolis, bordered either by the Seine or the Marne, have been identified as future bathing sites. 

In June, the city inaugurated Orly 2, a €45 million, low-carbon drinking water plant that produces 300,000 cubic meters of water a day, enough for 650,000 Parisians.

Energy

As part of its goal to reduce local emissions by 100% by 2050, Paris is looking at the idea of combining rooftop photovoltaics with electric vehicles as a scalably strategy for providing clean, cost-effective, and dependable electricity – the SolarEV City Concept.

Researchers from the Tohoku University in Kyoto have proposed the idea, which would combine the use of solar panels on rooftops with electric vehicles in the city. The, EVs would reduce the carbon footprint significantly by decreasing emissions from gasoline and diesel and has the potential to store surplus electricity generated by solar panels.

Upon analyzing the surrounding Parisian region, which is characterized by numerous low-rise buildings, the researchers uncovered that by equipping 71% of the rooftops with solar panels, it could meet a considerable 78% of the total electricity demand for the year 2019. “Our study not only highlights the carbon reduction potential of implementing a SolarEV City in Paris and the Ile-de-France, but it shows the need to consider regional variations,” said Takuro Kobashi, associate professor and co-leader of the research.

Sources:

Can a City Feed Itself? Bloomberg, Jul. 7, 2023

Paris is undergoing a water revolution. Reasons to be Cheerful, Sep. 7, 2023

Eau de water website

The SolarEV City Concept: key to net zero emissions by 2050. Interesting Engineering, Sep. 15, 2023