PREVER: waste as energy

Producing energy from waste: at a time when energy issues and environmental concerns are becoming increasingly acute, the approach of IMT Atlantique's PREVER (1) platform is quite attractive. "We are working to offer innovative solutions to industrialists to recover their waste," says Khaled Loubar, the head of the platform and a researche-lecturer in the Energy Systems and Environment Department (DSEE).

Inaugurated in 2014 and located on the Nantes campus, PREVER works on all types of waste: residues from the food industry and agriculture, floating wood (about 100,000 tons per year land on French coasts) or wood soiled by pollution, leftover plastic and composite materials, sludge from wastewater treatment plants and packaging waste. For each of them, the approach consists, first of all, of "characterizing" it, so that it can then be treated in an appropriate way - combustion, gasification, pyrolysis, solvolysis (2) or other means- to convert it into energy. This can be electrical, thermal or co-generation. Finally, the energy performance of the "alternative" fuels obtained in this way is evaluated under different conditions of use, as is their environmental impact.

For each type of waste, a specific "treatment"

"As a general rule, we propose to set up pre-industrial pilot projects," explains Khaled Loubar. With a dozen researchers and as many doctoral students, the platform has powerful equipment: press, mill, pyrolysis and gasification furnaces, gas turbine, biomass boiler, co-generation equipment, etc., and all grouped into three distinct areas: a hall housing various reactors for converting residues, a set of test cells for internal combustion engines (diesel or gasoline), and a complete laboratory to perform physicochemical analysis of alternative fuels.

For used tires, for example, the platform has tested pyrolysis, a thermal degradation process at high temperatures and without oxygen. "We then obtain three elements: a gas, an oil and carbon black, which is used in particular by the tire industry," explains Khaled Loubar. This work has led to the writing of several theses.
Wet waste is subjected to high pressure and high temperature, a treatment that produces an oil. The team is also studying the recovery of plastic waste - only 30% is currently recycled in Europe. "The first results in the laboratory are promising," he says.
As for the engine test bench, it can be used to compare the performance of an "alternative" fuel with that of a traditional fuel, using a series of sensors. It can also be used to take various measurements depending on the conditions of use: injection can be shifted, different settings can be changed, and in some cases, particle emissions can be greatly reduced. The PREVER team has even tested mixtures in which hydrogen replaces diesel fuel (up to 80%).

Production, but also storage of energy

Another aspect of the platform's activity is energy storage. This is done using a chemical process that produces gas (hydrogen or methane), or by gas compression.
These different projects, generally spread over two or three years, are of interest to a number of industrialists, who thus have at their disposal, right next to the institution's laboratories, demonstrators providing a solution to their problem. The PREVER team has therefore forged links with a dozen companies such as TotalEnergies, Véolia and Séché, which finance the studies carried out on their behalf. The platform is working continuously on about ten projects, with regular partners. It also receives funding from the French National Research Association (ANR).
All of this work can lead to the writing of theses, but also to the creation of companies. Two doctoral students have created a start-up with a demonstrator dedicated to gasification. Another start-up is working on a methanization process.

For its part, Athena, a start-up that emerged from IMT Atlantique's incubator, is dedicated to producing hydrogen from waste products, mostly of agri-food origin (dairy, cookie production, shrimp cooking water, rendering blood, etc.). Located right next to the PREVER team, it produces samples in the form of bottles of various sizes, and is working on the development of a reactor for quantities of around one cubic meter, intended for tests with a view to growing to industrial scale and it hopes to produce 40 tons of hydrogen per year by 2025, not to mention the steps involved in cleaning and purifying the hydrogen before use.

Thereafter, the PREVER team hopes to continue to grow. In particular, it plans to further professionalize its operations - introducing cost accounting, improving the costing of its services, etc. - especially in order to participate in European research projects. Another objective is to recruit new staff in order to strengthen its links with industry. Finally, the team would like to welcome more students and involve them in its approach. "Those who come to visit our premises, for example during practical work, are generally very motivated by the production and use of biofuels," observes Khaled Loubar. As we can see, there is no shortage of projects for PREVER. All of this reinforces IMT Atlantique's already strong position in  energy transition.

(1) Platform for Research and Study on the Energetic Valorization of Residues.
(2) Reaction of a compound with a solvent, which dissolves it in whole or in part.