Environmental Engineering Reference
In-Depth Information
investigated with calculations of product yields and mass, energy, exergy and C
conversion efficiencies. Since the biorefinery system co-produces many high value
products, an allocation issue must be addressed. Different allocation procedures
(substitution method, and energy, exergy, economic allocation) are therefore used and
final results compared. The evaluation of the environmental performances reveals that
relevant environmental benefits can be gained with a shift from oil refinery to
biorefinery: almost 89% of GHG emissions and 96% of fossil energy demand can be
saved.
1.
I
NTRODUCTION
Our strong dependence on fossil fuels results on the intensive use and consumption of
petroleum derivatives which, combined with diminishing petroleum resources, causes
environmental and political concerns. As a consequence, new renewable sources of energy
and chemicals are object of research and development activities. Electricity and heat can be
provided by a variety of renewable alternatives (wind, sun, water, biomass and so on), while
the fossil resource alternative for production of transportation fuels and chemicals is biomass,
the only C-rich material source available on the Earth, besides fossils.
The term “biorefinery” is raising importance in the scientific community and the concept
embraces a wide range of technologies able to separate biomass resources (wood, grasses,
corn…) into their building blocks (carbohydrates, proteins, fats…) which can be converted to
value added products, biofuels and chemicals (see Figure 1). A biorefinery is a facility that
integrates biomass conversion processes and equipment to produce transportation biofuels,
power, and chemicals from biomass. The biorefinery concept is analogous to today's
petroleum refinery, which produces multiple fuels and products from petroleum. The
replacement of oil with biomass as raw material will require some changes from the today's
production of goods and service: biological and chemical sciences will play a leading role in
the generation of future industries and new synergies of biological, physical, chemical and
technical sciences must be elaborated (Kamm et al., 2006a).
A first generation of transportation biofuels and chemicals is today produced from sugars,
starches and vegetable oils, giving rise to several issues: these raw materials compete with
food for their feedstock and fertile land, their potential availability is limited by soil fertility
and per hectare yields and the effective savings of CO
2
emissions and fossil energy
consumption are limited by the high energy input required for crop cultivation and conversion
(Lange, 2007).
Biomaterials
Biomass
components
Conversion
technologies
Biomass
Pretreatment
Bioenergy
Biochemicals
Figure 1. Simplified scheme of biorefinery: conversion of biomass into bioproducts.
