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FAQs
Frequently Asked Questions

What are the physical parameters that influence the potential of my water mill?To determine the potential of your water mill, you must evaluate several key parameters that influence hydraulic power production: 1. Stream flow (Q) Flow rate is the amount of water that passes through a cross section of the stream per unit time. It is usually measured in cubic meters per second (m³/s). 2. Drop height (H) The head is the difference in height between the water level at the entrance to the mill and the level at the outlet. It is generally measured in meters (m). 3. System efficiency (η) The overall efficiency takes into account mechanical, hydraulic and electrical losses in the system. This factor depends on the efficiency of the different components of the mill and is typically between 0.5 and 0.9 for small installations.

How do I know the flow rate of the watercourse at my mill?In order to know the flow rate at a given time on your mill, you can measure the flow rate in several ways: Flotation method : Measure the time it takes a floating object to travel a known distance and estimate the crosssectional area. Speed and section measurement : Measure the flow speed and surface area, using a current meter for example. Weir or spillway : Use a calibrated structure to measure flow. Generally speaking, it is preferable to use a measuring station if available on your watercourse by going to the site: https://www.hydro.eaufrance.fr/rechercher/entiteshydrometriques A complete hydrological study will be necessary to refine the flow available at each time of the year at your water mill.

How do I determine the drop height of my mill?The gross head is the difference in height between the water level at the entrance to the mill and the level at the outlet. It is generally measured in meters (m). In order to know the net head of fall, it is necessary to model the pressure losses in the different hydraulic components of the system.

How do I calculate the potential electrical power of my water mill?Electric power (Pelec) can be calculated using the following formula: Pelec = η × ρ × g × Q × H where: P is the power in watts (W), η is the overall efficiency of the system (hydraulic, mechanical and electrical) which depends on the efficiency of the different components of the mill and is typically between 0.5 and 0.9 for small installations. ρ is the density of water (approximately 1000 kg/m³), g is the acceleration due to gravity (9.81 m/s²), Q is the flow rate of the watercourse in m³/s, H is the net fall height in meters (m).

What is the average production of a mill and how many homes can it supply on average?The average production of a water mill can vary considerably depending on several factors, such as stream flow, head, mill efficiency and the technology used. To give an order of magnitude, a water mill producing 20 kW can supply around 18 homes with electricity. This estimate obviously varies depending on local conditions, mill output and household consumption. For a more precise assessment, it is advisable to carry out a feasibility study to take into account the specific parameters of your site and the technological solutions that could correspond.

What does Moulins Demain do to help you with technical dimensions?Moulins Demain is not an equipment manufacturer. Thus, depending on the situation of your site and its characteristics, we determine which existing technological solutions on the market could be suitable, and what this implies in terms of developments to be carried out, costs and associated income. We then support you until the implementation of your project.

How do I know if I have a water right?The simplest way to know if your water mill is founded in title, and therefore has an inalienable water right, is to look on the Cassini map. https://gallica.bnf.fr/html/und/cartes/franceencartes/lacartedecassini If the mill is visible on this map, this means that the mill existed before the French Revolution and therefore that it was founded in title. If it is not, it is necessary to go to the departmental archives to try to find traces of water rights. Moulins Demain can assist you in finding your water right.

Are there any specific permits or regulations to follow for the installation of this turbine?Yes

Am I subject to any regulatory obligations with such an installation? In particular, are there any obligations on environmental issues?Yes

Que fait Moulins Demain pour vous aider sur les sujets administratifs ?Moulins Demain vous accompagne sur les sujets administratifs à différentes étapes de votre projet : Existence et consistance légale de votre droit d'eau Relations avec les services de l'Etat Constitution du dossier de porter à connaissance Autorisations relatives au raccordement et à l'obligation d'achat EDF N'hésitezpas à consulter la section "Nos services" pour en savoir plus.

How much does it cost to set up such a project?Cheap

Combien rapporte une installation hydroélectrique dans un moulin ?Cela dépend évidemment de la production de l'installation envisagée. En France, il existe un tarif de rachat garantissant au producteur la possibilité de revendre à EDF OA la production à un tarif garanti pendant 20 ans. Ce tarif est aujourd'hui valable pour les installations de moins de 400 kW. Le calcul de la rentabilité d'un projet doit être fait pour chaque site dans le cadre de l'étude de faisabilité.

What are the different means of valorizing the electrical energy produced?Selfconsumption / resale

What is the ROI of an installation on average?1 year
If you have any further questions, do not hesitate to contact us!
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