Thermal Gasification Of Biomass Ppt

[Cristoforo Kanoy]

Task33: Gasification of Biomass and Waste monitors the current status of the critical unit operations and unit processes that constitute biomass and waste gasification (BMG) process, and identifies hurdles to advance further development, operational reliability, and reducing the capital cost of BMG systems. The Task meetings provide a forum to discuss the technological advances and issues critical to scale-up, system integration, and commercial implementation of BMG processes.

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The IEA Bioenergy Technology Collaboration Programme (TCP) is organised under the auspices of the International Energy Agency (IEA) but is functionally and legally autonomous. Views, findings and publications of the IEA Bioenergy TCP do not necessarily represent the views or policies of the IEA Secretariat or its individual member countries.

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Biomass gasification is a mature technology pathway that uses a controlled process involving heat, steam, and oxygen to convert biomass to hydrogen and other products, without combustion. Because growing biomass removes carbon dioxide from the atmosphere, the net carbon emissions of this method can be low, especially if coupled with carbon capture, utilization, and storage in the long term. Gasification plants for biofuels are being built and operated, and can provide best practices and lessons learned for hydrogen production. The U.S. Department of Energy anticipates that biomass gasification could be deployed in the near-term timeframe.

Biomass, a renewable organic resource, includes agriculture crop residues (such as corn stover or wheat straw), forest residues, special crops grown specifically for energy use (such as switchgrass or willow trees), organic municipal solid waste, and animal wastes. This renewable resource can be used to produce hydrogen, along with other byproducts, by gasification.

Gasification is a process that converts organic or fossil-based carbonaceous materials at high temperatures (>700C), without combustion, with a controlled amount of oxygen and/or steam into carbon monoxide, hydrogen, and carbon dioxide. The carbon monoxide then reacts with water to form carbon dioxide and more hydrogen via a water-gas shift reaction. Adsorbers or special membranes can separate the hydrogen from this gas stream.

Pyrolysis is the gasification of biomass in the absence of oxygen. In general, biomass does not gasify as easily as coal, and it produces other hydrocarbon compounds in the gas mixture exiting the gasifier; this is especially true when no oxygen is used. As a result, typically an extra step must be taken to reform these hydrocarbons with a catalyst to yield a clean syngas mixture of hydrogen, carbon monoxide, and carbon dioxide. Then, just as in the gasification process for hydrogen production, a shift reaction step (with steam) converts the carbon monoxide to carbon dioxide. The hydrogen produced is then separated and purified.

Biomass is an abundant domestic resource.

In the United States, there is more biomass available than is required for food and animal feed needs. A recent report projects that with anticipated improvements in agricultural practices and plant breeding, up to 1 billion dry tons of biomass could be available for energy use annually. For more information, see U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry.

Biomass "recycles" carbon dioxide.

Plants consume carbon dioxide from the atmosphere as part of their natural growth process as they make biomass, off-setting the carbon dioxide released from producing hydrogen through biomass gasification and resulting in low net greenhouse gas emissions.

As biomass gasification is a mature technology, feedstock costs and lessons learned from commercial demonstrations will determine its potential as a viable pathway for cost-competitive hydrogen production.

One of the most important challenges of this transition is to decarbonize EU gas capacities, with an ambitious target of 35 billion cubic meters (bcm) of biomethane production by 2030 that was set in REPowerEU1, of which only 3.5 bcm is produced today2,A significant effort is needed to improve technology, regulations, and incentives across the EU to scale-up the market.

Thermal gasification is a promising technology whose expected potential has led to several demonstration-scale projects in the EU, particularly in France and the Netherlands, where the associated emerging market has made important progress in recent months.

This article presents thermal gasification technology along with its associated market, its production potential in France by 2030 and 2050, the benefits of the technology compared to some alternative solutions, and targeted recommendations to unlock the potential in France.

High-maturity technology retains potential for further optimization

Thermal gasification is a versatile gas production technology that can utilize dry biomass or Municipal Solid Waste (MSW). These feedstocks are heated to 1000C with a controlled amount of oxygen to break down organic molecules to produce syngas (consisting of hydrogen, carbon dioxide, and carbon monoxide). The syngas then undergoes methanation and purification steps to produce biomethane (or Bio-SNG).

Considering all the energy and non-energy usages of dry biomass and MSW, where a considerable portion is currently allocated to direct combustion of biomass (around 90% of the energy use), analysis performed by Guidehouse has shown a potential ranging from 17 million tons (Mt) to 30 Mt of feedstock by 2050 that could be mobilized to produce green gas from thermal gasification. This potential will ultimately depend on the demand level, Levelized Cost of Energy (LCOE) reduction, as well as regulatory and incentive framework development that would play a significant role in increasing the competitiveness of the technology.

Using low-carbon gas from the network offers better resiliency and energy access

The gas infrastructure allows an almost uninterrupted supply for its customers with an unplanned outage time of 0.07 minutes per year/customer (as opposed to 4 minutes per year/customer for electricity network). Thermal gasification-injected gas thus offers much better resiliency compared with biomass boilers that need to be supplied by trucks, which may be more susceptible to being impacted by logistics problems (e.g., resulting from bad weather).

In addition to the adaptation needs that are necessary to move from a fuel/gas boiler to a biomass one, several risks regarding the continuity of biomass-sourced heat production should be considered, primarily around scheduled maintenance periods for which manufacturers must have backup solutions to supply their process or even unplanned interruptions due to technical problems (quality of inputs for MSW installations, etc.).

The objectives of Task 33 are (1) to promote commercialisation of biomass gasification, including gasification of waste, to produce fuel and synthesis gases that can be subsequently converted to substitutes for fossil fuel based energy products and chemicals, and lay the foundation for secure and sustainable energy supply; (2) to assist IEA Bioenergy Executive Committee activities in developing sustainable bioenergy strategies and policy recommendations by providing technical, economic, and sustainability information for biomass and waste gasification systems.

Biogas is a mixture of methane, CO2 and small quantities of other gases produced by anaerobic digestion of organic matter in an oxygen-free environment. The precise composition of biogas depends on the type of feedstock and the production pathway; these include the following main technologies:

The methane content of biogas typically ranges from 45% to 75% by volume, with most of the remainder being CO2. This variation means that the energy content of biogas can vary; the lower heating value (LHV) is between 16 megajoules per cubic metre (MJ/m3) and 28 MJ/m3. Biogas can be used directly to produce electricity and heat or as an energy source for cooking.

Biomethane has an LHV of around 36 MJ/m3. It is indistinguishable from natural gas and so can be used without the need for any changes in transmission and distribution infrastructure or end-user equipment, and is fully compatible for use in natural gas vehicles.

A wide variety of feedstocks can be used to produce biogas. For this report, the different individual types of residue or waste were grouped into four broad feedstock categories: crop residues; animal manure; the organic fraction of MSW, including industrial waste; and wastewater sludge.

Using waste and residues as feedstocks avoids the land-use issues associated with energy crops. Energy crops also require fertiliser (typically produced from fossil fuels), which needs to be taken into account when assessing the life-cycle emissions from different biogas production pathways. Using waste and residues as feedstocks can capture methane that could otherwise escape to the atmosphere as they decompose.

Most biomethane production comes from upgrading biogas, so the feedstocks are the same as those described above. However, the gasification route to biomethane can use woody biomass (in addition to MSW and agricultural residues) as a feedstock, which consists of residues from forest management and wood processing.

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