Bentec Bioenergies SLU · Introduction to the Biogas world · Biogas Power Plants BENTEC-BWE
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Carretera de Vic, 15
Sant Esteve d'en Bas
17176 · Girona · SPAIN
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Bentec Bioenergies SLU, a company formed in early 2008, is the Spanish subsidiary of the german company Biogas Weser-Ems GmbH & Co. KG (BWE) of Friesoythe (Germany).

Bentec-BWE specializes in design, construction and delivery ‘turn-key’ Biogas Plants for electricity production (you can also take the heat). Our projects are developed in several phases including: First phase of analysis of economic viability, the intermediate phase designing and planning, and the final phase of plant’s construction.

Furthermore, at customer’s requirements, we can work with them to optimize plant performance and for proper operation. We offer additional services such as: planning and strategy in the search for waste, consultancy, management, licensing and permits, routine maintenance, etc.

Our company has over 15 years of experience in the construction of Biogas Plants. The first plant was built in 1996. Today, after 15 years of uninterrupted service by digesting slurry and waste of food industry, continues to produce at full power. Our proven experience is based in more than 280 plants built, with a total installed electrical power of over 150Mw, and about 95% of them are built in the 'turnkey' mode.

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All Biogas power Plants Bentec-BWE are individually designed and tailored to meet the needs of each client, making an individualized assembly planning of all elements required in its proper location, so that the Biogas power Plant can be harmonized with the environment and get a maximum performance.

Access roads, peripheral construction and use of heat are always taken into consideration in order to optimize at all times the economic and ecological performance.

Principles of Biogas:
We get electricity from anaerobic digestion of organic waste.

Biogas is a mixture of gases produced by microbial digestion of organic matter under anaerobic conditions (without the presence of oxygen). This process is not immediate, but it goes through some stages: hydrolysis, acid genesis... to final methane genesis (methane generation). Each of these different phases is catalyzed by different bacteria. Depending on the temperature there are some work regimes: mesophyll regime (bacteria with an optimal metabolic around 40 ºC - 104 ºF) or thermophile regime (bacteria with an optimal metabolic around 55 ºC - 130ºF).

For optimum performance, we must also monitor the temperature, many other variables such as: pH, presence of inhibitors, the organic load, balance NH4-NH3 (Nitrogen excess in the substrate, etc.).

In the digesters (totally sealed deposits) from Biogas Plants the bacteria decompose gradually carbonated chains made of organic waste (proteins, carbohydrates, fats ...) to get smaller amount of carbon: Methane (CH4) in 50-70% with carbon dioxide (CO2) in 30-50% and other gases in small proportions (as NO2). Depending on the type of substrates introduced, we must determine the so-called HRT 'hydraulic retention time' (average time spent on the waste digesters) most appropriate for its proper digestion.

In our Biogas Plants can be digested a variety of organic substrates on an individual way or in a mixed one (co-digestion).

Some of these substrates can be: slurry and / or manure from farm animals (cows, pigs, calves, sheep, chickens, etc..), energy crops such as corn (silage, grain or his remains in the processing industry), cereals (wheat, barley, etc. in silage, grain and / or their remains in the processing industry), tubers (potatoes, beets, onions, carrots, etc.. and / or their remains in the processing industry), legumes (and their remains in industrial processes), remains of the food industry (bakery products, canned vegetables, juice, pulp, cheese, milk, molasses, breweries, slaughterhouses, sausage, etc.), sewage sludge of food industry (fats, secondary sludge...), glycerin, etc.

Depending on the type of substrate, it will take an additional sanitary treatment, for example pasteurization (70 ºC - 158ºF for 1 hour continuously) in case of industrial waste of animal origin. The liquid substrates (<15% dry matter) are introduced to the digester by pumping, while the solids are introduced by a solid feeder.

The type and composition of the substrate to be digested give us the final size of the digesters and the final sludge disposal, and thus the economic performance of the plant.

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Bentec-BWE is currently has 18 Biogas Plants, and we are responsible for the exploitation of others (including some Energy Parks up to 8.5 MW). In all these plants which we are entirely responsible, we are checking and researching the proper digestion of multiple organic substrates (and their mixtures).

However, whenever a customer requests some information about a substrate that we have no direct experience, we conduct a preliminary study of methane genesis in our laboratory. Depending on the results of this preliminary study, we decide for a real test or not in the Biogas Plant. Only in case where the real test works properly, we proceed to the continuous digestion of this substrate.

Once biogas is produced, is cleaned (removal of sulfide and condensation of water vapor) and is valued into a cogeneration engine, we get electricity for sale to the public network (or self consumption) and easily usable heat, as heating / cooling or industrial processes. On the other hand, we obtain digested sludge, a liquid organic fertilizer completely homogenized and stabilized, with virtually no odor, no weeds, non-corrosive (we removed the sulfide) and a determined N-P-K ratio easily assimilated by crops.

In the event that the ground for applying sludge is limited, sludge can be treated with various additional technologies to completely remove.


A good bussiness, economic and ecological.

In May 2007, was published on RD 661 which establishes the price of Kw for biogas and other renewable energies. This rate, guaranteed for 15 years, allow Biogas Plants to have a good economic performance, depending at any time on the type of introduced substrate. A complete Biogas Plant (fully automated) with 500 Kw/h electricity, has an investment cost of between 1.5-2.3 Million EUR (depending on the introduced substrates and their technological needs), generating revenues from sales of electricity of about 550,000 Euros (about 8000 hours of operation).

We can also have some extra income from sale of heat and for the management of some industrial waste. The annual cost of repayment of capital plus interest, maintenance and repairs, salaries and other expenses can amount about 400-450.000 Euros. Thus, the net profit before tax can amount to some 150,000 Euros.

This profitability is approximate. To have a comprehensive economic analysis (both initial investment and profitability) must have a list of substrates that we will introduce and their corresponding analysis.

But more importantly this is not economic efficiency, but the ecological profitability (our company thinks that in all likelihood in the near future will have a very high economic conversion).

The use of biogas in cogeneration reduces substantially the emission of greenhouse gases (methane, carbon dioxide and nitrous oxide). We must be aware that when methane combustion occurred, we are preventing its release into the atmosphere, and methane has a potential greenhouse effect 21 times greater than CO2. ___

Given this, there is nothing more to add!!

Contact us without obligation. We'll check the feasibilty of your Biogas power Plant.

Bentec Bioenergies SLU - Biogas Weser-Ems GmbH & Co.KG


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