Advances in Biorefineries

Biomass and Waste Supply Chain Exploitation

Keith W. Waldron

• Publisher: Woodhead Publishing
• Year: 2014
• ISBN:
  9780857097385
• Topic: Technik & Maschinenbau
• Subtopic: Regenerative Energieressourcen

Biorefineries are an essential technology in converting biomass into biofuels or other useful materials. Advances in Biorefineries provides a comprehensive overview of biorefining processing techniques and technologies, and the biofuels and other materials produced.

Part one focuses on methods of optimizing the biorefining process and assessing its environmental and economic impact. It also looks at current and developing technologies for producing value-added materials. Part two goes on to explore these materials with a focus on biofuels and other value-added products. It considers the properties, limitations, and practical applications of these products and how they can be used to meet the increasing demand for renewable and sustainable fuels as an alternative to fossil fuels.

Advances in Biorefineries is a vital reference for biorefinery/process engineers, industrial biochemists/chemists, biomass/waste scientists and researchers and academics in the field.

• A comprehensive and systematic reference on the advanced biomass recovery and conversion processes used in biorefineries
• Reviews developments in biorefining processes
• Discusses the wide range of value-added products from biorefineries, from biofuel to biolubricants and bioadhesives

Part I

Development and optimisation of biorefining processes

Outline

1 Green chemistry, biorefineries and second generation strategies for re-use of waste: an overview

2 Techno-economic assessment (TEA) of advanced biochemical and thermochemical biorefineries

3 Environmental and sustainability assessment of biorefineries

4 Biorefinery plant design, engineering and process optimisation

5 Current and emerging separations technologies in biorefining

6 Catalytic processes and catalyst development in biorefining

7 Enzymatic processes and enzyme development in biorefining

8 Biomass pretreatment for consolidated bioprocessing (CBP)

9 Developments in bioethanol fuel-focused biorefineries

10 Developments in cereal-based biorefineries

11 Developments in grass-/forage-based biorefineries

12 Developments in glycerol byproduct-based biorefineries

1

Green chemistry, biorefineries and second generation strategies for re-use of waste: an overview

L.A. Pfaltzgraff and J.H. Clark, University of York, UK

Abstract:

Today fossil resources supply 86% of our energy and 96% of organic chemicals. Future petroleum production is unlikely to meet our society’s growing needs. Green chemistry is an area which is attracting increasing interest as it provides unique opportunities for innovation via use of clean and green technologies, product substitution and the use of renewable feedstocks such as dedicated crops or food supply chain by-products for the production of bio-derived chemicals, materials and fuels. This chapter provides an introduction to the concepts of green chemistry and the biorefinery and, based on examples, discusses second generation re-use of waste and by-products as feedstocks for the biorefinery.

Key words

green chemistry; clean technologies; biorefinery; renewable and sustainable resources; food supply chain waste; resource intelligence

1.1 Introduction

Through the combination of low environmental impact and safe technologies, the use of biomass can provide a renewable alternative to fossil resources. It can establish a new sustainable supply chain for the production of high value chemicals, including fuels and energy as well as materials.

1.1.1 Green chemistry

Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances (Anastas et al., 2000). The concept emerged 20 years ago with the introduction by Paul T. Anastas and J. C. Warner of the 12 principles of green chemistry (see Table 1.1). The subject continues to develop strongly around these principles (Anastas and Warner, 1998). Green chemistry aims to achieve (Clark and Macquarrie, 2002):

• maximum conversion of reactants into a determined product,

• minimum waste production through enhanced reaction design,

• the use and production of non-hazardous raw materials and products,

• safer and more energy efficient processes, and

• the use of renewable feedstocks.

Table 1.1

The 12 green chemistry principles

1. Prevention It is better to prevent waste than to treat or clean up waste after it has been created. 2. Atom economy Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product. 3. Less hazardous chemical syntheses Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment. 4. Designing safer chemicals Chemical products should be designed to effect their desired function while minimizing their toxicity. 5. Safer solvents and auxiliaries The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used. 6. Design for energy efficiency Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure. 7. Use of renewable feedstocks A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable. 8. Reduce derivatives Unnecessary derivatization (use of blocking groups, protection/deprotection, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste. 9. Catalysis Catalytic reagents (as selective as possible) are superior to stoichiometric reagents. 10. Design for degradation Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment. 11. Real-time analysis for pollution prevention Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances. 12. Inherently safer chemistry for accident prevention Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions and fires.

Efficiency is the key, and green chemistry has continued developing around the principles, which guide both academia and industry in their pursuit of more sustainable processes. In an ideal case, according to these principles, a reaction would only produce useful material. Waste and pollutants would be prevented, improving the reaction yield and reducing losses, thus improving the overall economics of a process. Since our society and industries are governed by increasing efficiency and profit, green chemistry therefore theoretically fits the agendas of most manufacturing companies these days, not only appealing to chemical producers.

Today, 20 years after their publication, the 12 principles of green chemistry are as meaningful as ever in the light of the increasing interest the area attracts due to concerns over sustainability (Anastas and Kirchoff, 2002). Misunderstandings have arisen due to the attractiveness of the area to sectors dealing directly with public demands for ‘greener and more environmentally friendly’ products. It is therefore of vital importance that the message is not distorted by common misconceptions over what is or is not ‘green’, thus altering their original goal: to aim towards safer and cleaner chemistry.

The implementation of REACH (Registration, Evaluation, Authori- zation and Restriction of Chemicals), or Directive (EC 1907/2006), ROHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) or Directive 2003/108/EC, and other initiatives highlighting the hazardous character of some chemicals used in day-to-day consumer products, such as the SIN list (n.d.) , are pushing hard for their replacement to avoid further risks to human and/or environmental health. However, we should make sure the substitutes used are genuinely safer across the whole life cycle and as effective as what they are replacing. Investing in R&D focused on finding truly greener alternatives, thus eliminating rushed and weak substitutions that can even increase the number of components present in formulations when ingredients are added to compensate for a lack of performance in the ‘greener’ formulation, is important. The same applies to the substitution of fossil-derived chemicals with more sustainable bio-derived chemicals: when using renewable feedstocks such as biomass, we have to use clean and efficient synthetic routes, minimizing the amount of unwanted by-products and the use of scarce resources (i.e., scarce metals).

Scarce metals are increasingly used in clean alternative energy-producing technologies. Their reserves are sometimes only estimated to last another 50 years, or even less for key elements such as indium (a key component in solar panels) (Dodson et al., 2012) and we must take this into accoun...