Biogas plant

Biogas plant is used for the treatment of municipal and industrial organic waste, agricultural biomass and sewage sludge and their conversion into renewable energy.

Biogas plant – from organic waste and side streams to income

With a biogas plant organic waste and side streams are converted into income by producing renewable energy and organic fertilizer cost-effectively. Produced biogas can be utilized for electricity and heat production. Biogas can be also upgraded to biomethane that can be used as vehicle fuel or fed into the natural gas grid as a substitute for fossil gas. Since biogas plant size is scalable almost limitlessly, biogas producers typically include:

  • Waste management companies
  • Agricultural sector
  • Sewage treatment plants
  • Food industry companies
Biogas plant – from organic waste and side streams to income

What is biogas and where does it come from?

What is biogas and where does it come from?

Biogas is a gas mixture that occurs when organic waste rots in oxygen-free environment. Biogas formation occurs naturally for example in landfills, but in biogas plants it is produced in a controlled and efficient way from waste streams that would often be unused. Depending on the feedstock material, biogas is 50-70 % methane with excellent fuel properties. One cubic meter of methane is equivalent to one liter of diesel fuel, and requires about 7 kg of biowaste, for example. The rest of the gas mixture is mainly carbon dioxide.

Almost all organic materials, except wood, are suitable for biogas production. Typical input materials include:

  • Organic fractions of municipal solid waste
  • Agricultural manure and energy crops
  • Food industry side streams
  • Wastewater treatment plant sewage
  • Slaughterhouse waste
  • Fish processing waste

Environmental impacts of biogas

The use of biogas as a fuel is undoubtedly a positive environmental impact. It is 100 % renewable and therefore carbon-neutral, its combustion does not generate any particulate matter and it does not contain sulfur or heavy metals. Biogas refined to biomethane is suitable as transport fuel and can reduce greenhouse gas emissions by 85-95 % throughout the entire production process. In addition, biogas production prevents the release of methane into the atmosphere resulting from the decomposition of organic waste. This is an ecological effort in itself, as methane is 25 times more potent than carbon dioxide.

Profitability of the biogas plant

The payback period of a biogas plant can be a few years. However, it depends on several factors, the most important of which are:

  • Feedstock reception (gate fees)
  • Savings in waste management costs
  • Feedstock properties, methane yield
  • Gas utilization method and revenue flows
  • Income flows and / or savings related to the fertilizer
  • Technology used and energy efficiency of the plant

You can be in touch with us, and we will be happy to help you evaluate your biogas project profitability.

Gas, please →

© FWE Energy Solutions

Strong partners

In biogas plants, Biovoima’s partners are FWE Energy Solutions and Schmack Biogas. These companies have dozens of reference deliveries across Europe, and they have advanced and reliable biogas technologies in their product portfolio. These solutions cover well-established wet fermentation reactors, newer dry fermentation biogas plants, as well as dry and wet combination plants with excellent organic material decomposition properties.

Take a closer look at the technologies below.

Dry fermentation, or plug flow reactor, as a challenger to the traditional wet fermentation process

Biogas has traditionally been produced by cylindrical so-called wet fermentation reactors (CSTR, continuous stirred-tank reactor). It is a highly established technology and often an optimal production process for wet feedstock materials that are handled at the point of origin. The most common of these are liquid manure and sewage sludge. For better biogas reactor functionality, its content must be very uniform and more than 90 % of it must be water.

However, because of the smaller required reactor volume and higher loading rate, slurries are now often dried prior to the process, whereby they are more advantageous for transporting and can be handled using the so-called plug flow (PFR, plug flow reactor) technology. Dry fermentation process allows handling even challenging feedstocks in the biogas process as it is less susceptible to contamination than the wet fermentation process, where difficult feedstocks can cause floating and sedimentation challenges. Dry fermentation process can handle feedstocks with total solids up to 35 %, such as dry hay and a wide range of biowaste streams, without adding extra water. The gas yield of dry fermentation process per cubic meter of reactor volume is significantly higher than in the wet fermentation process.

Advantages of dry digestion and wet digestion in a combination plant

Our partners build a lot of top-of-the-line dry and wet digestion technology plants combining the key benefits of both technologies. High loading rate of the dry fermentation process ensures high usability and gas production per cubic meter of reactor volume. The long retention time of the wet fermentation process, in turn, allows a larger portion of the organic feedstock material to biodegrade.
Among other things, the combination plant has the following advantages:

  • Plug flow reactor handles reliable, difficult feedstocks.
  • Post-digester reactor ensures long retention time, thus, the optimal decomposition of organic material and the best possible biogas yield.
  • Horizontal compact modular reactor structure. In a small size BIOGASTIGER® biogas plant, the wet fermentation reactor is also horizontal, making the plant extremely compact and efficient.
  • Automated and remotely controlled process.
  • Very low total energy consumption.
  • Possibility to recycle liquid digestate within the process, reducing the need for adding extra water and often even removing it completely.