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Electricity from wood: How does a biomass cogeneration plant work?

Biomass cogeneration plants that use solid, renewable fuels such as wood pellets, wood chips or wood briquettes not only save costs, but also make an important contribution to climate protection - around the clock. How does such a biomass cogeneration plant work? You can find out here.

Companies all over the world are facing major challenges: To meet climate targets while reducing price risks, they must fundamentally transform their energy supply – away from fossil fuels and toward renewable energies.

A climate-friendly and at the same time highly economical solution is provided by combined heat and power plants (CHP) that are operated with wood-based biomass – e.g. with wood pellets, wood chips or wood briquettes (in short: wood-fired power generation).

By combining electricity and heat generation, such biomass CHP units achieve higher efficiency than many other energy technologies. Operators therefore not only saveCO2, but also cash. In addition, biomass is the only renewable energy source that can provide energy all year round, regardless of the weather or time of day.

How does a biomass CHP unit work, using the example of wood stomification?

Basically, a combined heat and power plant (CHP) is a power plant in which heat is generated and used in addition to electricity. CHP units mainly consist of an internal combustion engine that uses either liquid or gaseous fuels and drives a generator to produce electricity with the energy generated.

In contrast to a pure motor CHP unit, which is usually operated with fossil fuels such as natural gas, diesel or similar, a biomass CHP unit is a plant that can generate electricity and heat simultaneously from a solid fuel (the biomass). This first requires the conversion of the solid biomass into a so-called lean gas. This process happens in a gasifier. In the case of wood as biomass, lean gas is also called wood gas.

Woody residues are mostly used as wood biomass. For example, residual wood, waste wood, damaged wood, dead wood or production residues. These materials enter the wood gasifier processed either in the form of pellets, wood chips or wood briquettes. In the gasification process, the substances are carbonized under lack of air, so that a combustible gas is produced.

Following the wood gasification, gas cleaning and cooling takes place so that the wood gas is suitable for use in the gas engine of the biomass CHP unit.

Vergaser

Wood gas generation

Wärmetauscher

Wood gas cooling

Filter

Wood gas is freed from ash

Ascheaustrag

Asche wird aus dem System ausgeschleust

Motor

Wood gas is burned in the engine

Generator

Power generation

Abgaswärmetauscher

Wärmegewinnung aus Abgas

Schaltschrank

Biomass cogeneration plant and its function: not letting waste heat go to waste

A great deal of heat – known as waste heat – is generated both during the gasification process, in the subsequent gas treatment process, and in the biomass CHP unit. On the one hand, this is hot exhaust air, hot water from the wood gas and engine cooling, and hot exhaust gases from the CHP unit. While other power plants often let this waste heat go to waste, our biomass CHP units convert it into usable heat thanks to heat exchangers.

If more heat is produced than necessary or if the heat consumption is not always constant, it can be temporarily stored in a buffer tank and used at another time.

Biomass cogeneration plants therefore have a decisive advantage over conventional power plants: they produce electricity and heat in a process called combined heat and power (CHP). If biomass, such as wood, is now used as a fuel instead of natural gas or crude oil, companies can produce electricity and heat in a climate-friendly, cost-saving way and, above all, around the clock.

If cold is also produced from the heat, one even speaks of CHP (combined heat, power and cooling) instead of CHP. Biomass cogeneration plants thus usually convert more than 85 percent of the renewable fuels used into usable energy – it hardly gets any more efficient than that.

Good to know: Wood as fuel

ENTRENCO’s biomass cogeneration plants operate predominantly on a wood basis. Wood in the form of wood pellets or wood chips is converted into wood gas in ENTRENCO’s CHP plants by means of a wood gasifier. This wood gas forms the fuel that powers the combustion engine in our CHP units. In this process, the wood is utilized almost residue-free and with a high degree of efficiency.

Would you like to learn more about our technology? Then we look forward to being able to advise you personally.

This is what a biomass CHP for wood conversion can do

A biomass cogeneration plant for wood-fired power generation is not only highly efficient in terms of economy and ecology, but also offers a wide range of possible applications.

Here are some examples of possible applications:

  • Wood chips drying
  • Drying or heating purposes in the production process
  • Generation of cooling energy via absorption chillers for cold storage, air conditioning, etc.
  • Conversion of waste heat into electricity (e.g. ORC)

We have summarized the most important applications for you:

Power and heat generation

Power and heat production Biomass CHP units can therefore supply buildings (e.g. hotels, residential complexes, hospitals) with electricity as well as heat their heating systems and drinking water. This makes biomass CHP plants among the most efficient and - when using biomass such as residual wood or waste wood - among the most climate-friendly energy producers.

Process heat generation

Biomass CHP units are by no means only suitable for use in buildings. On the contrary, a biomass CHP unit is particularly interesting for manufacturing companies because it works especially efficiently in generating process heat, usually in the form of hot water - in other words, heat that is needed for industrial and commercial processes. Process heat is usually consumed constantly throughout the year; ideal conditions for biomass CHP units.

Cold generation

If a combined heat and power plant is equipped with an absorption chiller, the heat generated can be converted into cold and used for cooling. This process is called combined heat, power and cooling (CHP). It makes optimum use of the energy generated. CHP plants are particularly useful in industries that have a cooling requirement for air conditioning or process cooling. These include hotels, office buildings and hospitals, but also the food industry. Heat can even be used to produce drinking water from the air via intermediate cooling.

For whom is wood-fired power generation worthwhile?

A biomass cogeneration plant with wood-fired power generation is particularly worthwhile for companies that require large amounts of thermal energy on a constant basis for their operations – even in summer. This is because a biomass cogeneration plant is only maximally economical if it operates at full load for a certain number of hours per year. Alternatively, excess heat energy can also be converted into cold in summer.

Good to know: Wood as fuel

It makes the most economic sense to consume the generated electricity and heat yourself, if possible. Therefore, wood-fired power generation via a biomass CHP unit is suitable for industry and agriculture with larger electricity and heat requirements or for somewhat larger properties. If the generated electrical energy is not completely consumed, it is possible to feed it into the public networks. For this, biomass CHP operators receive a feed-in tariff – a government-fixed subsidy for self-generated electricity.

A biomass cogeneration plant is worthwhile for the following companies and industries, for example:

Wood processing industry: sawmills, carpentry, furniture industry, pellet or wood chip plants

The wood processing industry requires a great deal of heat for its smooth operation - for example, for its wood drying kilns. In addition, there are often large quantities of residual wood or waste wood that can be used. Such productions rarely stand still and therefore there is a constant demand for heat. Thus, biomass CHP units with wood-fired power generation are efficient and environmentally conscious solutions for supplying energy - not only with heat, but also with cost-effective electricity.

Agriculture: livestock and poultry farming, greenhouses, nurseries

The use of a combined heat and power unit is particularly useful in agriculture and, for example, air-conditioned animal stables or greenhouses with a constant demand for heat, reports the Deutscher Landwirtschaftsverlag.

Leisure: hotels, spas, swimming pools, resorts

Energy costs in the leisure sector often account for five percent or more of total operating revenue, as reported by the Arbeitsgemeinschaft für sparsamen und umweltfreundlichen Energieverbrauch e.V. (Working Group for Economical and Environmentally Friendly Energy Consumption). Biomass-based CHP units are the ideal way to save money: With their help, the overall efficiency can be increased by up to 40 percent to a total of over 85 percent.

Public facilities: Schools, hospitals, homes, prisons

Public facilities must be supplied with electricity and heat around the clock and all year round. These are ideal conditions for a combined heat and power plant to work efficiently and make an important contribution to climate protection by using biomass such as wood. Schools also need to be supplied with energy almost all year round. Here, too, a biomass CHP is the ideal solution.

Local heating networks: Residential complexes, shopping centers

In larger residential complexes, there is a constant year-round demand for hot water and electricity. Due to this constant demand, a biomass cogeneration plant can therefore also operate economically here, as it is sufficiently utilized.

Wood gas and biomass cogeneration plant: advantages at a glance

Biomass cogeneration plants based on wood gas can score with a whole host of advantages. The biggest bonus is the combination of economic efficiency and climate protection. Biomass cogeneration plants usually convert more than 85 percent of the fuels used into usable energy. If you then also use the cost-effective and at the same time environmentally friendly wood pellets or wood chips as fuel, you save noticeable money.

Advantages of combined heat and power plants with wood-fired electricity generation:

High efficiency

The simultaneous production of electricity and heat results in the use of over 85 percent of the fuels.

Less CO2 emissions

By using wood as biomass, the raw material cycle is CO2-neutral. In addition, biomass CHP units primarily use residual and waste wood.

Value enhancement

A biomass CHP plant can be designed as an integral part of the building and increases the value of the property. Alternatively, biomass CHP units can also be built in containers and can be used flexibly.

Weather independence

Unlike wind energy and solar plants, biomass CHP units operate completely independently of weather conditions and the time of day. The biomass CHP units run when there is no wind, rain, snow and frost, and of course also at night.

Independence

Providers make themselves independent of the expensive electricity of the large energy suppliers. Another bonus in terms of independence: In the event of power outages, a biomass cogeneration plant continues to generate electricity.

Numerous funding opportunities

Those who decide in favor of a biomass cogeneration plant can count on subsidies and favorable loans from the federal and state governments. This means that the initial costs can usually be easily covered and short payback periods can be achieved.

Long maturities

The plants are designed to operate for 7,000 to 8,000 hours per year. In individual cases, there are plants that even exceed this in practice.

Are you interested?

Would you like to find out whether a biomass cogeneration plant with wood-fired power generation is worthwhile for your company and what type of waste wood you can use to generate energy particularly efficiently? Then get in touch with us. We will be happy to advise you personally.
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Which fuels are suitable for a wood-based biomass cogeneration plant?

The operation of a typical combined heat and power plant is possible with various fuels. Fossil fuels such as natural gas, heating oil or diesel are still the order of the day - but they do not contribute to environmental protection. This is where renewable raw materials come into play, which are ideally suited for biomass CHP units and thus make an enormous contribution to climate protection.

The following biomass fuels can in principle be used for wood-fired power generation in a CHP unit by means of an upstream gasification technology:

Wood pellets

Wood pellets are dry small sticks of wood made from sawdust and other wood waste that have been appropriately pressed into shape. This fuel is used in both larger wood gas cogeneration plants and mini cogeneration plants and is now a standardized, generally accepted and widely traded fuel.

Wood briquettes

Alternatively, wood residues from wood processing, such as planing or sawdust, can also be compressed into wood briquettes and used in a biomass CHP unit to generate electricity from wood.

Wood chips

Wood chips are produced by the so-called chipping of production residues up to whole trees in so-called chippers. Appropriate preparation, which usually consists of screening and drying, ensures the ideal fuel quality for the gasification process. Wood gas is then produced from the chopped wood by means of a wood gasifier. When waste wood (e.g. from bulky waste) is used, shredders are employed. In addition, metal residues are sorted out here.

How much does a biomass CHP unit for wood-fired power generation cost?

A wood-fired power generation plant is an individual solution, where the investment costs and also the running costs can be very different. In addition, the different fuels and, if applicable, their processing also result in different costs. Depending on the application in the process or in the building, however, different subsidy amounts also come into play, so that a generalization of the total costs is hardly possible.

You want to learn more?

Please feel free to ask us for a first rough cost estimate, which you can use for further planning.
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Environmental friendliness is rewarded: subsidies for wood-fired power generation plants

Companies that use a biomass cogeneration plant to generate electricity from wood and thus contribute to climate protection receive financial support at many levels in Germany. In addition to the feed-in tariff for surplus electrical energy, the German Federal Ministry of Economics and Export Control (BAFA) promotes corresponding projects, often in the areas of process heat or energy efficiency.

The Kreditanstalt für Wiederaufbau (KfW) also supports climate-friendly rethinking with promotional loans and repayment subsidies of up to 55 percent of the eligible costs. And the individual federal states and regions also reward the use of biomass CHP units as progressive and environmentally friendly energy generation.

Are you interested?

Would you like to find out whether a biomass cogeneration plant with wood-fired power generation is worthwhile for your company and what type of waste wood you can use to generate energy particularly efficiently? Then get in touch with us. We will be happy to advise you personally.
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