ENCH4BG Biorefinery Concepts and Green Technologies Comprehensive Exam Study Guide

VOCABULARY style flashcards covering biorefinery definitions, biomass composition, conversion platforms, LCA metrics, biofuel processing, green chemistry principles, and industrial symbiosis based on the ENCH4BG course transcript.

Biorefinery

A facility that integrates biomass conversion processes and equipment to produce fuels, power, chemicals and materials from biomass (NREL definition).

Biomass

Any biological material from living or recently living organisms, including plant materials (lignocellulose), sugars, oils, and animal waste.

Bioeconomy

An economy where the basic building blocks for materials, chemicals, and energy are derived from renewable biological resources rather than fossil resources.

Cellulose

A polymer of glucose that is the most abundant organic compound on Earth and constitutes approximately $40-50\%$ of the plant cell wall.

Hemicellulose

A branched polymer of various sugars (pentoses and hexoses), such as Xylan, comprising approximately $20-35\%$ of the plant cell wall.

Lignin

A complex aromatic polymer that provides structural rigidity to plant cell walls, making up approximately $15-25\%$ of their composition.

Biochemical Platform

A conversion route using enzymes and fermentation (processes like anaerobic digestion) to produce products such as bioethanol, lactic acid, or biogas.

Thermochemical Platform

A conversion route using heat and chemical reactions (processes like combustion, pyrolysis, and gasification) to produce syngas, bio-oil, or char.

Chemical Platform

A conversion route using chemical reactions and catalysis (processes like acid hydrolysis and transesterification) to produce biodiesel or platform chemicals like furfural.

Bagasse

The fibrous residue remaining after sugarcane juice extraction, used as fuel for steam and electricity generation via co-generation.

Molasses

The residual syrup from sugarcane processing used for animal feed or the production of ethanol through fermentation.

Filter cake

Also known as press mud, this is a byproduct of sugarcane juice clarification used as a soil amendment or fertiliser.

Sustainability

The quality of not being harmful to the environment or depleting natural resources, thereby supporting long-term ecological balance.

Sustainable Development

Development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs.

Life Cycle Assessment (LCA)

A methodology standardized by ISO 14040 that assesses the environmental impacts of a service, process, or product throughout its entire life cycle.

Cradle-to-grave

A system boundary in LCA that considers environmental impacts from raw material extraction through to the final disposal of the product.

Cradle-to-gate

An LCA system boundary that includes environmental impacts from raw material extraction to the factory gate, excluding use and disposal.

Primary Energy Demand (PED)

An LCA impact category measuring all energy and fuels required to produce a product, including conversion efficiency and energy content of materials.

Global Warming Potential (GWP)

An LCA impact category measuring the contribution of greenhouse gas emissions (in $CO_2$-equivalents) to climate change.

Eutrophication Potential (EP)

The contribution of excess plant nutrients like nitrogen and phosphorus to the depletion of oxygen in water bodies due to algae growth.

Acidification Potential (AP)

The contribution of acid-forming gases like $SO_x$ and $NO_x$ to the acidification of rain and water, causing eco-toxic stress.

Atom Economy

A green chemistry metric representing the percentage of atomic mass of reactants that end up in the desired final product.

E-Factor (Environmental Factor)

A metric defined as the ratio of the mass of waste generated to the mass of the desired product produced.

Furfural

A furan-based platform chemical produced from the acid hydrolysis and dehydration of hemicellulose ($C_5H_{10}O_5 \rightarrow C_5H_4O_2 + 3H_2O$).

Polylactic Acid (PLA)

A biodegradable bioplastic produced from the fermentation of glucose to lactic acid, followed by ring-opening polymerisation of lactide.

Biofuels

Fuels produced from biomass such as agricultural or forestry plants, residues, and organic waste for use in transport or power generation.

First Generation Biofuels

Biofuels produced directly from food crops (e.g., sugarcane, corn) that compete with the food supply.

Transesterification

The chemical process of reacting triglycerides with an alcohol like methanol and a catalyst to produce FAME (biodiesel) and glycerol.

Second Generation Biofuels

Biofuels produced from non-food sources, such as cellulosic biomass grown on marginal land or organic residues and waste.

Anaerobic Digestion (AD)

A biological process where microorganisms break down organic material in the absence of oxygen at $30-65\,^{\circ}C$ to produce biogas and digestate.

Hydrolysis (AD Phase 1)

The first phase of anaerobic digestion where enzymes break down complex polymers (proteins, fats, carbohydrates) into simple monomers.

Acidogenesis (AD Phase 2)

The second phase of anaerobic digestion where simple molecules are fermented into volatile fatty acids (VFAs) and alcohols.

Acetogenesis (AD Phase 3)

The third phase of anaerobic digestion where VFAs are converted into acetate, $CO_2$, and $H_2$ as direct precursors for methane.

Methanogenesis (AD Phase 4)

The final and rate-limiting step of anaerobic digestion where methanogenic archaea convert acetate and $CO_2/H_2$ into methane ($CH_4$).

Gasification

Thermal conversion of biomass at $650-1400\,^{\circ}C$ in oxygen-deficient conditions to produce syngas ($CO + H_2$).

Pyrolysis

Thermal decomposition of biomass at $400-800\,^{\circ}C$ in the absolute absence of oxygen, primarily producing bio-oil ($70\%$), char, and gas.

Waste Valorisation

Industrial processing activities aimed at reusing, recycling, or composting waste to create useful high-value products or energy sources.

Industrial Symbiosis

A resource efficiency approach where two or more facilities associate so that the waste or by-products of one become the raw materials of another.

Chemical Leasing

A business model where the supplier sells the function performed by a chemical rather than the volume, with payment based on functional units.

Mechanical Recycling

A plastic waste management route involving collection, sorting, cleaning, and re-melting plastic into pellets for new products.

Chemical Recycling

A plastic waste management route where plastic is converted back to monomers or simpler chemicals via processes like pyrolysis or gasification.