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Use of Life Cycle Assessment to determine the environmental impact of thermochemical conversion routes of lignocellulosic biomass: The gasification step

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LCA

Raw materials / energy Manufacturing Transportation Use Disposal Recycling Goal and Scope Definition Impact Assessment Inventory Analysis Interpretation

LCA: environmental aspects and potential impacts for all the stages of a product's life. Energy and material fluxes for the entire life-cycle analysed (environment / human health)

4 interdependent steps (ISO 14040 and 14044 norms [1,2])

Use of Life Cycle Assessment to determine the environmental impact

of thermochemical conversion routes of lignocellulosic biomass:

The gasification step

S. Gerbinet

1

, H. Jeanmart

2

and A. Léonard

1

1 Laboratory of Chemical Engineering – Processes and sustainable development - University of Liège, B6, allée de la

chimie 3, 4000 Liège, Belgium - Saicha.Gerbinet.ulg.ac.be

2 Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium

First generation Biofuel:

- Limit energy dependence - High transformation losses - Low yield

- Competition with food crops

Lignocellulosic biomass (second generation technologies)

Abundant, cheap, and available in non-food plants: wood and energy crops such as miscanthus.

Conclusions and perspectives:

Lignocellulosic biomass gasification: Promising processes for substituting fossil fuels

(building blocks for the chemical industry and fuels).

Their environmental impact remains uncertain

LCA methodology needed

Numerous possibilities

sensitivity and uncertainity analysis.

Take into account the impact of biomass production.

LCA : - Allows comparison bewteen biomass development and fossil technologies;

- Allows a better understanding of the environmental impact of the processes;

- Takes into account several impact categories.

Environmental impact ?

LCA (Life Cycle Assessment)

Sustainable development

Issues:

- Population growth

- (Fossil) resources depletion - Climate change

Lignocellulosic

biomass

conversion processes

Scope of the study

Biomass + Oxidizing agentSyngaz

Component % (volume) CO 31-40 33-36 23-35 2-3 Oxidizing agent: - Air - Oxygen - Steam Heat supply: - Allothermal or autothermal - Direct or indirect

Gas cleaning and reforming Dependent on gas use

- Particle removal: biomass (ash and char)+ bed  plugging - Alkali removal

- Nitrogen and sulfur compounds: small amount

- Tar elimination: primary (in gasifier) or secondary technologies

- Reforming: Water-shift reaction ∶ CO + H2O ↔ CO2 + H2  H2/CO

Pretreatment

- Size reduction: particle size between 20 and 80 mm - Drying: water content < 10%

Gasification

Process

Reactor type Fixed-bed updraft [3] Fixed-bed downdraft [3] T= 600 – 1000 °C Fluidized-bed bubbling [4]

Our study

Lignocellulosic Biomass Pretreated biomass Syngaz Landfill Field fertilization OR OR Fertilizer Heat Electricity Car fuel Diesel or DME Building block chemical industry Propylene or Ethylene Substitution/credit

Downdraft, fixed-bed two-stage gasifier  Very low amounts of tar. This gasifier is generally considered to work close to the equilibrium state.

Ashes end of life  Presently, in the Belgian legislation context, the ashes must be landfilled but, in the future, it may possible to use them for field fertilization Different gas uses are compared with their fossil equivalent.

Co-product: system expansion by substitution (avoiding allocation procedure): the avoid impact, due to the co-product is subtracted to the system impact.

Bibliography

1. ISO, ISO 14040 : Management environnemental - Analyse du cycle de vie - Principes et cadre, ISO, Editor. 2006.

2. ISO, ISO 14044 : Management environnemental - Analyse du cycle de vie - Exigences et lignes directrices, ISO, Editor. 2006

3. Bioenergy Primer: Modernised Biomass Energy for Sustainable Development, UNDP, 2000

4. Bright Hub, Mobile Biomass crop or Waste Processing, cited 2012; Available from:

http://www.brighthub.com/environment/renewable-energy/articles/85799.aspx

5. Sustainable development. Glossary 2011, cited 2012 31-01-2012, Available from:

http://www.greentimes.com.au/lifestyle/sustainable-development.html.

6. Xylowatt, http://www.xylowatt.com/

7. Naik, S.N., et al., Production of first and second generation biofuels: A comprehensive review. Renewable and Sustainable Energy Reviews, 2010. 14.

8. Kumar, A., D.D. Jones, and M.A. Hanna, Thermochemical Biomass Gasifiction: A Review of the Current Status of Thechnology. Energies, 2009. 2

[5]

Fixed-bed multistage [6]

+ inertes

Scope of the study

Ash AND AND OR gasification pretreatment

Références

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