Elsevier

Computers & Chemical Engineering

Volume 34, Issue 9, 7 September 2010, Pages 1393-1396
Computers & Chemical Engineering

An NSF perspective on next generation hydrocarbon biorefineries

https://doi.org/10.1016/j.compchemeng.2010.02.025Get rights and content

Abstract

Next generation hydrocarbon biofuels have the potential to fulfill not only the biofuels production mandate of the Energy Independence and Security Act (EISA) of 2007, but also would not have to be exempted from the EISA-mandated increase in the corporate average fuel economy. Producing “green gasoline”, “green diesel” and “green jet fuel” from non-food lignocellulosic feedstocks such as forest waste and agricultural residue, and energy crops such as short rotation trees and perennial grasses grown on marginal or abandoned cropland will substantially lower greenhouse gas emissions and will not affect food prices. In this paper the development of the new paradigm of green gasoline from lignocellulose will be reviewed, the potential pathways to these infrastructure-compatible fuels will be discussed, and critical process design needs will be outlined.

Introduction

It is estimated that about 1.3 billion tons per year of lignocellulosic biomass can be produced each year from agricultural residue, forest waste, and energy crops grown on marginal or abandoned cropland with minimum land use change (US Department of Energy, 2005, the “Billion Ton Study”). The energy content of this amount of biomass represents about 60% of our current petroleum use, and is roughly equal to the amount of petroleum imported by the U.S.

The Energy Independence and Security Act of 2007 (EISA 2007) (Public Law, 2007) mandates the production of 36 billion gallons per year production of biofuels by 2022, of which 21 million must come from feedstock other than corn starch and at least 16 billion gallons must come from lignocellulose. EISA 2007 has been often mischaracterized as an ethanol mandate; it is not. The renewable fuels standard calls for cellulosic biofuel. As will be shown in the next section, those cellulosic biofuels can be drop-in replacements for gasoline, diesel, and jet fuel which come not from crude oil but from biomass. Not only do green gasoline, diesel, and jet fuel fit into existing engines, pipelines, and refineries, obviating the need for altered engines and ethanol pipelines, they have much higher energy density than ethanol (about 30% higher for gasoline, and 50% higher for diesel), giving much higher gas mileage. These biofuels would not have to be exempted from the mandated increase in fuel economy (from a fleet average of 25 mpg at present to 35 mpg by 2022) of EISA 2007.

The production of liquid hydrocarbon transportation fuels from biomass was first summarized in the comprehensive review of Huber, Iborra, and Corma (2006). The Catalysis and Biocatalysis program at NSF has been active in promoting catalytic applications for biofuels (National Science Foundation, 2004, National Science Foundation, 2005) and with DOE/EERE, sponsored a workshop in the summer of 2007 titled “Breaking the Chemical and Engineering Barriers to Lignocellulosic Biofuels: Next Generation Hydrocarbon Biorefiners” (National Science Foundation, 2008). This report was the principle document which informed the rewriting of the National Biofuels Action Plan of the Biomass R&D Board (Biomass Research and Development Board, 2008) to include next generation hydrocarbon biofuels.

The workshop report was also central input to the 10 years R&D plan of the Biomass Conversion Interagency Working Group, which operates under the aegis of the Biomass R&D Board and is chaired by the author. This report, titled “Biomass Conversion – Challenges for Federal Research and Commercialization” is in the final stages of review in late 2009 and should be publicly available in early 2010. The 22-page report contains detailed barriers to research, development and deployment of a wide variety of pathways to the production of advanced alcohol and hydrocarbon biofuels. A summary version of the pathways and research barriers to hydrocarbon biofuels is presented in this paper.

Section snippets

Biofuel production pathways

The main pathways for the production of liquid transportation fuels from biomass are shown in Fig. 1. On the left are the various types of feedstock; examples of lignocellulosic feedstocks in the upper left are forest residue from lumber and thinning operations, agricultural residue such as corn stover, and energy crops such as switch grass. These are the most abundant and non-food biomass feedstocks, as reported in the Billion Ton Study (US Department of Energy, 2005). Sugar and starch, left

Research needs in process design

At the “Breaking the Chemical Barriers” workshop (National Science Foundation, 2008) the priorities determined by the Process Engineering and Design breakout group are summarized in Table 1. Priority was established by order of precedence; higher priority areas are needed in order to accomplish the lower priority ones.

Prior to any process simulation, physical properties and the chemical composition of novel materials such as pyrolysis oil are needed. Even beyond this, analytical methods are

Conclusions

Green gasoline, green diesel, and green jet fuel have a number of advantages over cellulosic ethanol. While federal funding for hydrocarbon biofuels from lignocelluosic feedstocks has lagged behind ethanol, that trend is changing and in fact a number of small and large companies have immanent and significant production goals. As a consequence of the funding lag and in spite of the analogy of many pathways to petroleum refining, research in process design is greatly needed for the widespread

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