Some figures on the biogas?

[moinsdewatt]

The Rezé wastewater treatment plant becomes the first in Loire-Atlantique to produce green gas

BY FRÉDÉRIC DOUARDJUNE 25, 2021

While the city of Rezé near Nantes already has two beautiful biomass boilers, of 7,5 and 13 MW, since June 2021, the La Petite-Californie wastewater treatment plant, also located in Rezé, produces biomethane. This 100% renewable gas is produced by anaerobic digestion of sludge from wastewater treatment. Nearly 50% of local production is reserved for Nantes Métropole's own needs. This is the first time in Loire-Atlantique that a wastewater treatment plant has been connected to the gas distribution network to supply it with renewable energy. With this project, the metropolis is keeping its commitments in terms of greenhouse gas reduction. Its objectives: to achieve carbon neutrality and 100% renewable energies by 2050.

“We are convinced that the energy transition cannot be decreed, it is planned with voluntarism. With this virtuous and local production of 100% renewable biomethane, Nantes Métropole is proving that the energy transition irrigates all public policies, here, that of water and sanitation, waste, mobility ... Very concretely, this are public buildings and no less than 350 vehicles that will be supplied with this locally produced green gas ”declared Johanna Rolland, President of Nantes Métropole.

“The green gas produced by the La Petite Californie wastewater treatment plant fully participates in the emergence of a territorial circular economy where our wastewater becomes agronomic and energy resources” said Christelle Rougebief, Director of Customers Territories GRDF Midwest.

A new valuation of biogas into green gas
After ten months of work, the La Petite-Californie wastewater treatment plant, operated by Epuréo of the Suez group, is equipped with a purification system for the biogas produced by the anaerobic digestion unit. This system replaces a biogas cogeneration installation dating from 2011.

The new installation will produce 10,7 GWh of gas per year, or the equivalent of the consumption of 2140 homes.

The process is simple: the sludge is introduced into a methanizer in which the bacteria present transform the organic matter into biogas, with the absence of air. Once purified, odorized and then checked by GRDF, the biogas takes the name of biomethane. The latter can then be injected into the natural gas distribution network. Heating, cooking, hot water production, fuel, these uses are strictly identical to those of natural gas but here 100% renewable and local. This € 2,8 million investment will pay off in just four years.

https://www.bioenergie-promotion.fr/901 ... -gaz-vert/

[izentrop]

Pierre Aurousseau, Jean-Pierre Jouany, Gérard Fonty, Daniel Chateigner, four scientists react to a recent article published on Web-agri on the impact of digestate in the soil. https://www.web-agri.fr/tribunes/articl ... sur-le-sol

Excellent article, but experts who react very late.

Methanizers need dedicated cultures, Cive https://www.arvalis-infos.fr/une-interc ... cle.html#3 which need to be fertilized to produce enough and to be harvested before the end of the growing cycle, because the digester does not accept woody-type organic carbon.

Standard digestate is a horror for soils:
- The labile carbon extracted to make methane is also the life energy of the soil ... It is therefore lacking.

anaerobic digestion and spreading of digestates will add its contribution to all the mechanisms which have already contributed for several decades to the decrease in the rate of organic matter in soils.
Plant growth can therefore ultimately be negatively impacted by the use of digestates. Ms. Houot had nevertheless mentioned it during her hearing in the Senate and the reference author taken from the Web-agri article (Thomsen 2013) also specified it. As we can see, and some biogas farmers are already pointing out, the imbalance introduced can only lead to fear of obtaining unstructured and infertile soils over the medium to long term. »

- Too much ammonia, which is lost by evaporation, kills earthworms and bees.

The volatilization of ammonia gas when spreading is responsible for olfactory genes given the irritant, hygroscopic and toxic nature of ammonia (INRS: H331 - Toxic by inhalation). She is also responsible for the mortality of bees in the vicinity of spraying and surface rise and mortality of earthworms.

[sicetaitsimple]

To follow up on the exchanges on page 13 relating to the regulations on methanation inputs, a new decree has just been released:

It distinguishes the "main cultures" (whereas before we spoke of "food culture" or "energy culture", with several possible definitions of a "main culture", and the "intermediate cultures" which are normally cultivated between two "main crops" (with some exceptions such as permanent grassland).

The maximum value for using a "main crop" in a methanizer is set at 15% of the annual tonnage treated.

For more info: https://www.legifrance.gouv.fr/jorf/id/ ... 0046144291

[izentrop]

The maximum value for using a "main crop" in a methanizer is set at 15% of the annual tonnage treated.
For more info: https://www.legifrance.gouv.fr/jorf/id/ ... 0046144291

As a result, they will have to increase the distances to be traveled to supply the digesters, which is going in the wrong direction: increased consumption of fossil fuels.

The important thing would be to take advantage of this to increase the storage of carbon in the soil and it seems that this is quite possible by increasing the production of plants with high biomass and in soil conservation agriculture.

Anaerobic digestion is compatible with human-sized farms”, explains Bertrand Guérin, farmer and member of the AAMF, who does not understand the scientists who talk about soil impoverishment. The opposite of his observation on the ground!

For Konrad Schreiber, former project manager at IAD, there is a risk of soil impoverishment if we continue with "classic" agricultural practices, but anaerobic digestion can on the contrary be an opportunity for virtuous agriculture if the on the contrary, so-called “soil conservation” farming practices are applied, as we have seen on the farms that use them. With a livestock/crop mix, no tillage, agronomic rotation of crops and permanent plant cover, “we have the keys to maintaining rich soils while producing energy. The secret is to increase plant production and make bacteria and fungi work”. For Konrad Schreiber, however, there is a risk: “With the FNSEA, agriculture is going into the wall, because the agronomic bases are false.

https://www.innovation24.news/2022/03/2 ... ur-au-sol/

With a strong use of CIVE, more energetic than catch crops, an important point which also goes in the wrong direction: the life of the soil lacking carbon, will draw on its stock. Where the 15%?

• Short carbon chains

“An essential point was not mentioned by Sabine Houot, that concerning the labile material of methanization inputs, material fermentable by anaerobic bacteria, which is not found in the solid digestate. The latter, serving as energy, food, to a large part of the soil biosphere, left with the biogas, in the form of methane (CH4) and carbon dioxide (CO2). The corollary of obtaining solid digestate to “feed” part of the soil biosphere is therefore the deprivation of food for the other part. The absence of labile carbon in the digestates is detrimental to development and activity. of the soil microbial biosphere (this is “soil carbon hunger”). This point is important for maintaining soil life in the medium and long term. It is also important for the root use of soil nutrients by plants. This imbalance can lead to fears of obtaining unstructured and infertile soils in the medium or long term. »

[sicetaitsimple]

The maximum value for using a "main crop" in a methanizer is set at 15% of the annual tonnage treated.
For more info: https://www.legifrance.gouv.fr/jorf/id/ ... 0046144291

As a result, they will have to increase the distances to be traveled to supply the digesters, which is going in the wrong direction: increased consumption of fossil fuels.

We can think of it what we want, but I do not see a priori why it should increase the distances to be covered to feed the digesters?

[phil59]

I haven't read everything, I don't know enough, but I tried to see what an individual could produce, and conversely, in a lot of things, you have to invest a lot for a meager result.

Since that time, I forgot a little project I had for the house.

On a large scale, it must be another story, but to be seen.

[sicetaitsimple]

I haven't read everything, I don't know enough, but I tried to see what an individual could produce, and conversely, in a lot of things, you have to invest a lot for a meager result.
Since that time, I forgot a little project I had for the house.

It's a nerd, your biogas gas cumulus would look great!

[phil59]

It's a nerd, your biogas gas cumulus would look great!

But when you see, that per day, you have an hour or two of cooking, on a gas stove, it's not profitable in terms of investment, time spent. There are more urgent things to do, which have a much better return.

[sicetaitsimple]

But when you see, that per day, you have an hour or two of cooking, on a gas stove, it's not profitable in terms of investment, time spent. There are more urgent things to do, which have a much better return.

Uh, I was kidding huh?

[phil59]

Yes I saw them !

But I wanted to remember why, I don't try. If I did, it means that I will have time in front of me, and nothing else to test!