Biomass gasification

Organic matter such as residues from wood, agricultural crops, etc. all contains chemical energy and is categorized as biomass. If we combust this biomass, the chemical energy is transferred into another energy carrier – heat. The heat can in turn do some type of work, for instance dry grains, heat a building, melt a material, run an engine or boil water. However, if we instead gasify the biomass we create an energy carrier – gas, that has a higher energy density and will result in a more complete combustion once the gas is combusted. To create a fire or combustion, three parts are needed: something burnable, oxygen and heat. Gasifying means that we expose the biomass (burnable material) to heat, but the amount of oxygen is lower than for combustion and thus a combustible gas is created. There are different gasification principles, for instance updraft, downdraft, fluidized bed, dual beds etc. Meva Energy’s uniqueness lies in our patented gasification technology that is based on an entrained flow gasifier.

Meva Energy’s gasification principle

Meva’s technology is a biomass gasification system of entrained flow gasifier type. The gasification reactions take place in a dense cloud of biomass particles that is blown into the preheated gasification reactor where it forms a vortex (whirl) spinning down the reactor and allowing the particles to be gasified into renewable syngas.

Meanwhile the resulting biochar is separated from the renewable gas due to the centrifugal forces of the cyclone. When reaching the bottom walls the almost particle free renewable gas changes direction and flows back up where it exits in a centrally located pipe. The separated biochar is however forced down towards the bottom where it is collected. Contrasting to most gasifiers of entrained flow type, the Meva technology is fed with air and not oxygen, thereby constituting a far less expensive solution. Meva Energy has filed several patent applications covering key functionality of the technology.

The most important feature of the technology is its ability to produce true high quality gas.

What does our technology lead to?

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What could you do with the decentralized produced renewable gas?

Key to get a profitable gasification process is to utilize low cost biomass. Meva Energy’s gasification technology could use fine fraction, second generation biomass residues, i.e. sawdust, wood fibers, agricultural residues etc.

The main use of biomass should be to create products such as food, houses, furniture etc. and only the residues and the used material should be used as an energy source. Today there are an excess of biomass residues, especially the low value biomass that Meva Energy utilize. A variety of feedstock could be used and if necessary it will be pre-processed, e.g. dryed (more than 15% moisture) or grinded (larger than 1,5mm). The biomass handling system will be adopted towards the local available biomass.

Opportunity to valorize excess biomass

According to the European Sawmill organization, about 85 million m3 of sawn softwood is being produced each year. This represents a production of saw dust and bark of about 30 million tons.

This feedstock resource is today representing a low value as it sits in the saw mills site and the low fraction character makes it difficult to transport. Pellets production is of limited value and the particle board industry is only in need of a small fraction of the saw dust produced.

A very large part of this resource is just being burned and destroyed. Utilization as fuel to produce power and heat locally at the sawmill without transport with Meva’s technology is an attractive option.

The continuous nature of Meva Energy’s gasification technology results in a really stable gas quality. The biomass particles are blown into the hot reactor continuously and inherently results in a stable character. This is important both for quality assurance in industrial process heat applications and to be able to use lean burn engines in an efficient combined heat and power process.

It is important to stress that our strategy is to make a gas with enough heating value. One might notice that a heating value of 6MJ/Nm3 is significant less than fossil alternatives such as LPG and NG. However, Meva Energy’s gas is produced at site of consumption and not aimed to being transported or entered into a grid.

The Meva process

Meva Energy´s technology is a complete system from gasifier to syngas cleaning for production of renewable fuel gas which is fed to a power engine genset for distributed production of power and heat. Alternatively the resulting renewable gas can be used to replace fossil gases such as natural gas or propane in e.g. an industrial drying process.

The system is designed as a closed loop leaving no residues other than biochar. Also, the entire system is fully automatized and is designed to be remotely and continuously operated.

The most important feature of the technology is its ability to produce true high quality gas. It all started with the fundamental engineering insight that in order to achieve a defined result you need to define the starting point.

For the Meva technology that is manifested by specifying the feedstock particle size to a maximum of 1 mm. If it is larger, it needs to be grinded. But the output of that extra effort is just great, the system produces gas with extraordinarily even quality. This is due to the inherent continuous character of cyclone gasification of small fraction feedstocks and the avoidance all sorts of batch-like injecting and ejecting resulting in sudden changes of process conditions. Thanks to this, we are able to use our syngas with highly effective lean burn combustion engines – a unique ability within the gasification industry.

Conventional biomass boilers can result in air pollution

Biomass, such as wood chips, logs, pellets etc. are often burn to warm a single home, a corporate facility or to power district heating and hot water boilers. Unfortunately, conventional biomass combustion results in air pollution and contributes to health issues. Therefore, the European union has imposed restriction on biomass combustion.

Many geographical areas today face restrictions on air pollution and need to take actions in order to improve the life quality of the citizens, e.g. China’s blue sky initiative. Unfortunately, traditional bioenergy boilers also contribute to this issue even though they are using renewable resources. Today’s limits within European Union on emissions on 50mg/Nm3 of dust/particles are quite hard for many existing bioenergy boilers to meet due to direct combustion of the biomass. Meva Energy gasification process is a solution to this problem. The hot flue gases from a Meva Energy plant is even below 1 mg/Nm3 of particles. Meva Energy CHP and gas units could therefore be placed in both rural and urban environment.