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What is the difference between biomass incineration and gasification?

To begin to answer this question, we first must take a look at what makes gasification and incineration different. Incineration is defined as high temperature destruction of biomass in a furnace to a non-burnable ash form that can then be disposed of in landfills. The main form of energy produced from incineration is heat.

Biomass gasification is a high temperature chemical conversion process, taking a carbon based feed and converting it to a gas called syngas. The syngas is a very flexible fuel source for generating electricity and more importantly, for high purity syngas, the basis for the synthesis of a wide variety of biofuels and chemical products like methanol, SAF and plastics. The only byproduct of gasification is activated carbon powder which can be reintroduced into the system or used for various other applications.

Does Torrgas gasification produce hazardous emissions?

Contrary to biomass incineration emitting particulate matter, nitrogen oxides, carbon monoxide, sulfur dioxide, lead, mercury, and other hazardous air pollutants the Torrgas gasification process converts all the biogenic matter into four high value sustainable products without any noticeable emissions. These sustainable products are: syngas for the production of synthetic products, biochar, liquid green CO2 and renewable steam. So Torrgas provides a complete circular closed carbon loop with a negative carbon footprint.

What is ligno-cellulosic biomass?

It is mainly composed of lignin, cellulose and hemicellulose. It includes a wide variety of biomass types such as wood, energy crops, forest-residues, agricultural residues, and industry (forestry, agri-food) residues and wastes like sludge and manure. In other words everything that grows due to sunlight and is not in our foodchain. Lignocellulosic biomass is expected to become an important source of renewable carbon to produce materials, chemicals and advanced fuels thereby reducing reliance on fossil feedstocks.

Why should we use ligno-cellulosic biomass residues?

Many ligno-cellulosic feedstock owners have presently no use for their residues. So most of it is burned directly on the fields, creating pollution and fine particle emissions that affect millions of people. The way we treat bio residues in large parts of the world they have little value and do much harm. Unlocking these residues by a torrefaction process is therefore very effective and advantageous to nature, farmer, local population and our planet.  By processing and densifying the residues at the place of harvesting and turning it into powerful matter.

How much lignocelluosic biomass is available?

Lignocellulosic biomass is the most abundantly and underutilezed available biomass resource. The IEA reported close to 3.5 billion tons of dry bone residue matter(IEA Bioenergy: To be or not to be a biobased commodity, March 2022 Task 43) from the ten largest food crops. The IES estimate that of agricultural residues 2.5 billion ton is burned and 1.5 billion ton is left on the field. These 2.5 billion tons form the basis to substitute globally all polluting bunker fuel and kerosene with a sustainable alternative.

This 2.5 billion tons is just agri-residue. Wood residues(including recycled wood waste), energy crops, forest-residues, invasive bush form another resource of billions of tons. A large part of these ligno-cellulosic resources are linked to phenomenal issues at the location of origin. By applying these feedstocks in high value conversion chains a circular solution is created that can be aligned with a wide variety environmental, social and  governmental targets.

What is exactly torrefaction?

Torrefaction of biomass, e.g., wood or grain, is a mild form of pyrolysis at temperatures typically between 250 and 300°C. Torrefaction changes biomass properties to provide a better fuel quality for combustion and gasification applications. Torrefaction converts heterogeneous lignocellulosic matter into homogeneous, high quality solid biofuel that are 6-50 times as energy dense as the original feedstocks. Very strictly, torrefaction is a partial removal of hemi-cellulose from ligno-cellulosic matter.

Why is torrefaction so important?

Although it is predicted that large quantities of lignocellulosic biomass are potentially available sustainably, mobilizing these biomass sources is the major bottleneck. Torrefaction converts the extremely heterogeneous variety of ligno-cellulosic feedstocks into a solid biofuel that meets the five requirements for a commodity:

1. Easy to store and transport; high energy density, dry, low volume, low ash, nutrient depleted
2. Standard quality
3. Standardization of transport, contracting, insurance, conversion systems
4. Functioning markets: trade systems, financial instruments (futures, etc.) high tradability
5. Sustainability: standard sustainability certification systems by commoditizing the wide variety of ligno-cellulosic feedstocks.

This commoditizing of the widely abundant biomass forms the basis for scalable production of biofuels and chemical products that can substitute fossil fuels on a large scale.

Is a torrefaction process energy efficient?

Given the condition of effective utilization of the torrefaction gas(i.e. the selectively removed hemi-cellulose), the thermal efficiency can be as high as 95% in case of a moisture content of 50%. The energy loss (via stack) that occurs is largely attributable to the drying operation. In the torrefaction process, a high efficiency is achieved (Nett Caloric Value basis) because the required energy for drying is transformed into the additional calorific value of the dried product. As long as the liberated torrefaction gas is combusted and does not contain excess heat over what is required for the entire process itself, the process can be run at a very high thermal efficiency.

Which ligno-cellulosic biomass can be used sustainable for torrefaction?

Lignocellulosic biomass includes a wide variety of biomass types such as wood(including recycled wood), energy crops, forest-residues, invasive bush, agricultural residues, and industry (forestry, agri-food) residues and wastes like sludge and manure. Just the agricultural residues from the ten largest food crops is 3.5 billion tons of dry matter. Invasive bush

Is the Torrgas process scalable?

Yes, and the reason is simply the exclusive application of torrefied biofuel. First the torrefied biofuel unlocks the opportunity to standardize and certify feedstocks and subsequent downstream gasification sourced from an almost unlimited number of locations. So the Torrgas process is completely independent of the volume and price of the locally available feedstocks; a problem that has so far limited the scale of conversion systems. Second, in a biomass gasification process the high energy density and dry torrefied biomass results in process stability, high conversion efficiency and smaller footprint than gasification system, critical improvements that do not apply to raw ligno-cellulosic feedstocks.

How can Torrgas gasification have a carbon negative footprint?

The Torrgas process has been assessed as carbon negative. Our planet has only a very few carbon negative options. This is due to a number of facts.

First the efficient torrefaction process results in an enormous reduction in logistic cost due to the 6-50 times bulk energy densification of the feedstock. So the amount of energy required to transport the product from torrefaction location to gasification location is marginalized compared to untreated biomass. This reduces the wheel to wheel carbon footprint but does not create a carbon negative solution.

Secondly the Torrgas gasification converts all carbon into high value products; syngas, biochar and liquid bioCO2. This means that carbon neutral biogenic carbon can be sequenced for long terms in sustainable products.

Why is the co-production of biochar so important?

Biochar can make substantial breakthroughs in reducing greenhouse gas emissions and global warming, reducing soil nutrient leaching losses, sequester atmospheric carbon into the soil, increasing agricultural productivity, reducing bioavailability of environmental contaminants and subsequently, becoming a value-added product sustaining bioeconomy. Bio-economy implies the exploration and exploitation of bio-resources, which involves the use of biotechnology to create new bio-products of economic value. Biochar is a marketable bio-product, which can be used in agriculture, industries and energy sector.

In the case of soil enhancement biochar creates the opportunity to close the circle of the minerals depleted from soils. Many gasification processes focus on the maximization of the syngas production and result in complete destruction of the minerals and therefore on the long-term not sustainable with respect to the mineral cycle.  

How can the Torrgas process compete on costs with fossil?

Building an infrastructure for the production of sustainable synthetic molecules will require phenomenal capital investments so the costs of the renewable products are largely contributed to the capital expenditure. The fossil industry is largely applying partly or fully depreciated assets and costs of final products are largely contributed to the operational expenditure. This is an enormous hurdle to overcome for the renewable future.

However, Torrgas has created a business model that results in four additional revenue streams on top of the syngas and its derivatives like for instance bio-methanol. These revenues are: biochar, liquid CO2, steam and carbon credits(ETS or CORC’s). Typically the co-product revenues are higher than the gasifier opex. This means that variable costs of the syngas produced is almost completely leveraged by the co-products and thus can be contributed to the Capex.

Indicatively the syngas costs for a 100 MW Torrgas gasifier lies in the range of €40-60 per MWh which is a fossil competitive price at many production locations around the globe.

Why does it take so long?

To validate a new process technology it will take typically take 10-15 years to lead the concept through all the Technology Readiness Levels (TRL). The Torrgas team started their journey in 2006 with the development of a torrefaction solution for its gasifier followed in 2012 by the ultimate goal; a scalable and affordable process for the production of synthetic biofuels and chemical products.