Advances in Bioenergy (eBook)

The Sustainability Challenge

Goeran Berndes, JOHN BYRNE, Peter D. Lund, Iacovos Vasalos (Herausgeber)

eBook Download: EPUB

2015
Wiley (Verlag)
978-1-118-95785-1 (ISBN)

Infos

The increasing deployment of bioenergy frequently raises issues regarding the use of land and raw materials, infrastructure and logistics. In light of these sometimes conflicting interests Advances in Bioenergy provides an objective and wide-ranging overview of the technology, economics and policy of bioenergy. 

Offering an authoritative multidisciplinary summary of the opportunities and challenges associated with bioenergy utilization, with international researchers give up-to-date and detailed information on key issues for biomass production and conversion to energy.

Key features: 

*Discusses different bioenergy uses such as transportation fuels, electricity and heat production. 

*Assesses emerging fields such as bio-based chemicals and bio-refineries. 

*Debates conditions for the mobilization of sustainable bioenergy supply chains and outlines governance systems to support this mobilization.

* Dedicated chapters to sustainability governance and emerging tools such as certification systems and standards supporting growth of a sustainable bioenergy industry.

*Considers the political, environmental, social and cultural context related to the demand for energy resources, the impact of this demand on the world around us, and the choices and behaviours of consumers.

This book will be a vital reference to engineers, researchers and students that need an accessible overview of the bioenergy area. It will also be of high value for politicians, policymakers and industry leaders that need to stay up to date with the state-of-the-art science and technology in this area.

Professor Peter Lund
Research interests:  Energy systems and innovations. Science, technology, business and policy issues related to large-scale schemes of new and renewable energy; nanotechnology for energy applications; solar cells and fuel cells; distributed energy generation systems; sustainable energy for urban areas; energy system modelling; commercialization and innovation strategies; green energy economy; market penetration and technology diffusion.

Professor John Byrne
Director of the Center for Energy and Environmental Policy (CEEP) and Distinguished Professor of Energy and Climate Policy at the University of Delaware. He has contributed to Working Group III of the United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC) since 1992 and shares the 2007 Nobel Peace Prize with the Panel’s authors and review editors. He is chairman of the board of the Foundation for Renewable Energy and Environment (FREE), an international organization established to promote a better future based on energy, water and materials conservation, renewable energy use, environmental resilience, and sustainable livelihoods.

Inhalt

About the editors

List of contributors

Preface

I. Promising Innovation in Biomass Conversion

1. WENE-5 Metabolic engineering: Enabling technology for biofuels production

2. WENE-49 Hydrolysis and fermentation for cellulosic ethanol production

3. WENE-29 Lipid-based liquid biofuels from autotrophic microalgae: energetic and environmental performance

4. WENE-16 Catalytic pyrolysis of biomass for transportation fuels

5. WENE-119 Integrated biomass hydropyrolysis and hydrotreating: a brief review

6. WENE-74 Transportation fuels from biomass via fast pyrolysis and hydroprocessing

7. WENE-97 Biomass gasification for synthesis gas production and applications of the syngas

8. WENE-111 Hydrogen generation from biomass materials: challenges and opportunities

9. WENE-93 Production of renewable hydrogen by reformation of biofuels

10. WENE-69 Fischer-Tropsch conversion of biomass derived synthetic gas to liquids

11. WENE-28 Critical factors for high temperature processing of biomass from agriculture and energy crops to biofuels and bioenergy

12. WENE-59 Second-generation biofuels: why they are taking so long

13. WENE-73 Separation technologies for current and future biorefineries--status and potential of membrane-based separation

14. WENE-361 Catalysis at room temperature: perspectives for future Green Chemical processes

15. WENE-100 Co-firing of biomass with coal in thermal power plants: technology schemes, impacts and future perspectives

II. Challenges and solutions for biomass supply

16. WENE-41 Bioenergy and land use change - state of the art

17. WENE-24 Forest energy procurement: state of the art in Finland and Sweden

18. WENE-25 Options for increasing biomass output from long rotation forestry

19. WENE-157 Recovery rate of harvest residues for bioenergy in boreal and temperate forests: A review

20. WENE-26 Forest Bioenergy Feedstock Harvesting Effects on Water Supply

21. WENE-77 Best management practices for forest bioenergy programs

22. WENE-3 Principles of nutrient management for sustainable forest bioenergy production

23. WENE-88 Crop coefficients of Jatropha (Jatropha curcas) and Pongamia (Pongamia pinnata) using water balance approach

24. WENE-87 Brazilian sugarcane ethanol: developments so far and challenges for the future

25. WENE-17 The climate benefit of Swedish ethanol: present and prospective performance

26. WENE-107 Performance of small-scale straw-to-heat supply chains in Norway

27. WENE-84 Transport sector in Ireland: can 2020 national policy targets drive indigenous biofuel production to success?

28. WENE-138 Prospects for domestic biofuels for transport in Sweden 2030 based on current production and future plans

29. WENE-55 Land and the food-fuel competition: insights from modeling

30. WENE-155 The impact of biofuel demand on agricultural commodity prices: a systematic review

31. WENE-118 How do sustainability standards consider biodiversity?

32. WENE-166 A global survey of stakeholder views and experiences for systems needed to effectively and efficiently govern sustainability of bioenergy

Index

Textauszug

1
Metabolic Engineering: Enabling Technology for Biofuels Production

Mitchell TaiGregory N. Stephanopoulos

Department of Chemical Engineering, Massachusetts Institute of Technology, USA

ENGINEERING THE FUTURE OF BIOFUELS

The past few years have introduced a flurry of interest over renewable energy sources. Biofuels have attracted attention as renewable alternatives to liquid transportation fuels. There are numerous potential advantages over fossil fuels: sustainable supply, diversification of energy sources, energy independence and security, rural development, and reduction in greenhouse emissions.1 However, achieving adequate scale requires a tremendous effort in research and development beyond what has thus far been achieved. The field of metabolic engineering is well suited to develop the future technologies that will give us widespread, cost-effective, and sustainable transportation fuels.

Metabolic engineering is the improvement of cellular activities by manipulation of metabolic networks through the use of recombinant deoxyribonucleic acid technology.2 Interdisciplinary advances in metabolic engineering have yielded powerful strategies and methods to understand and manipulate whole metabolic pathways with confidence.3,4 To date, numerous efforts have successfully engineered and optimized metabolic networks to produce high-value targets for use in the pharmaceutical and fine chemicals industries.5 However, attention is now being turned toward commodity-scale processes, which require both cost-efficiency and robustness.1

Currently, the most prevalent biofuels are ethanol produced from corn or sugarcane and biodiesel produced from vegetable oils. Under current production processes, however, neither biofuel is economically competitive or well integrable into existing petroleum-based technologies and infrastructure.6 Two developmental challenges underpin these shortcomings: (1) the need for a better feedstock and (2) the need for a better fuel. However, these challenges also represent key opportunities to develop the next generation of biofuel technologies. A central element in these technologies will be the use of metabolic engineering to develop the biological platforms that produce these biofuels.

Engineering for Improved Feedstocks

For the past few years, production of ethanol from corn and biodiesel from vegetable oils has been increasing rapidly. Last year, the United States production capacity of corn ethanol exceeded 13 billion gallons per year (bgy), approaching 10% of the national gasoline demand.7 Meanwhile, global biodiesel production is approaching 5.0 bgy, with a majority coming from Europe.8

However, production of these biofuels from plants like corn or rapeseed also competes for arable cropland needed for food. This adds undesirable price sensitivities between biofuels and food and has already shown adverse effects on food prices. Transforming forests or existing cropland can also sometimes have the effect of increasing greenhouse gas emissions, counteracting the carbon emissions benefit of biofuels.9

The primary cost for producing biofuels is the cost of the feedstock: 60% in the case of corn ethanol and 80% for soybean biodiesel.10,11 Even with gains in process yield, current crop-based feedstocks will still limit the overall profitability of biofuels. Currently, upward of half of the production cost of these biofuels needs to be supported by government subsidies.6

The next generation of feedstocks will need to have lower land requirements and lower production cost, yet maintain high production capacity to bring biofuels closer to economic viability. Metabolic engineering allows us to bridge the feedstock gap by enabling the utilization of cheaper and more sustainable substrates by introducing catabolic pathways and optimizing metabolic networks for the conversion of feedstock to fuel. Indeed, yield optimization has been a critical aspect of virtually all biochemical engineering processes in recent history. Metabolic engineering of organisms toward this end only serves to continue this tradition, pushing yields beyond what is naturally observed. Furthermore, microbe-based biofuel production also reduces the cropland requirements compared to crop-based methods, decreasing competition with food production.

Engineering for Improved Fuels

Although new feedstocks are explored, a simultaneous search continues for the next generation of fuel types. Current biofuels have some persistent disadvantages that limit their incorporation into existing infrastructure.

Ethanol, although widely produced, has relatively poor fuel characteristics. Ethanol is hygroscopic, capable of absorbing water, which can lead to corrosion. The energy content is also low, containing only 70% of the energy per volume of gasoline. Also, as ethanol is produced by fermentation, the resulting beer is dilute, containing roughly 10% ethanol. Subsequent distillation to separate the ethanol is very energy intensive.10

Biodiesel is a better fuel, but also has some disadvantages. It is not well suited for use at low temperatures because of a high cloud point, and still often requires large quantities of petroleum-derived methanol as part of its production. It also has only 89% of the energy content of its analog, petrodiesel.11

Current biofuel characteristics limit their integration into existing infrastructure. Because of this, there is a high transition barrier to adoption of biofuels, and both ethanol and biodiesel are often blended only at low concentrations into conventional fuels.

Development of better fuels that have high energy density and can be integrated into existing pipelines and engines will be needed if biofuels are to be more widely adopted and have a reasonable hope to replace fossil fuels. Through metabolic engineering of production pathways, alternative products can be made that have characteristics closer to their petroleum equivalents, easing the barrier for adoption. These alternatives range from slight modifications to existing metabolites, to new pathways that create naturally unique compounds. These naturally rare products will also require extensive pathway engineering and optimization to achieve effective production capacities—one of the central strengths of metabolic engineering.

TOOLS OF METABOLIC ENGINEERING

To understand how metabolic engineering plays a role in biofuels development and how it takes an interdisciplinary approach to problem solving, it is important to first understand its main strategies and tools. The strategies of metabolic engineering can be compartmentalized into three steps: (1) understanding, (2) designing, and (3) engineering the metabolic network. Each of these steps uses tools and technologies adopted from a range of disciplines. An overview of the strategies of metabolic engineering can be found in Figure 1.1.

Figure 1.1 Strategies of metabolic engineering revolve around the understanding, design, and engineering of metabolic networks and pathways to produce desired molecular products from biological platforms. These strategies employ techniques and technologies from a range of disciplines, from omics technology to synthetic biology.

Understanding the Metabolic Network

The first step in metabolic engineering is to understand the complex network of enzymatic reactions that compose a cell's metabolism. In addition to the enzymology of participating enzymes, this requires information on the structure and behavior of the pathways that connect these enzymes. Knowledge of the pathway chemistry and stoichiometry allows us to calculate theoretical yields, which are often used as benchmarks for pathway engineering efficacy. Comprehensive systems-level data about these complex networks is acquired through omics technologies and bioinformatics. Omics technologies involve using genomic, transcriptomic, proteomic, or metabolomic data to quantify the system behavior of the cell along various functional axes (e.g., growth, tolerance, productivity).12 Bioinformatics is the method of extracting biological meaning by identifying significant patterns, motifs, and connections within these large, complex data sets. These techniques enable us to develop a systems-level perspective on cellular activity and an understanding of important contributing networks.4

As an example, metabolic flux analysis derived from metabolomic data allows us to observe the flow of material through cellular metabolic pathways. Like a material balance, these fluxes describe the distribution of material throughout the cell's metabolic network and can help identify branch points and competing pathways relevant to our desired product. Fluxes also help to determine the degree of engagement of various enzymes in the pathway, allowing us to identify rate-limiting steps and control points.3

Because any biological manipulation will rarely ever produce only an isolated response, it is important to observe the system-level response of our engineering efforts. Using bioinformatics and omics technologies allows us to understand the interactions, connections, and responses between different parts of the system to predict and control the metabolic network.

Designing the Metabolic Network

Once we have sufficient understanding of the organism and its cellular activities, we are then able to develop and design specific strategies to obtain our desired product. Although we can introduce, remove, or otherwise modify pathways, identifying the most effective actions a priori can help save much time and effort. Modern methods to do so are found in...

Produkt-Details

• Erscheint lt. Verlag: 10.12.2015
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik ► Elektrotechnik / Energietechnik
• Schlagworte: Bioenergie • bioenergy • Bioenergy resources • Biofuels • climate change • Energie • Energy • Environment • Erneuerbare Energien • Green economy • land use • renewable energy • sustainability
• ISBN-10: 1-118-95785-7 / 1118957857
• ISBN-13: 978-1-118-95785-1 / 9781118957851