*Review of Biofuel Technologies in WtL and WtE DOI: http://dx.doi.org/10.5772/intechopen.84833*

*Elements of Bioeconomy*

**34**

**Technology**

Anaerobic

Solid waste reduction, high moisture

Need to treat and clean the

Biogas,

Heating, electricity,

transportation, fuels, and

high-value chemicals

bio-digestate

biogas; unstable system; large

facilities are unattractive

Limited to sugar, starch, or

Liquids and CO2

Additives, high-value

TRL9/CRI2-3

chemicals, transportation,

heating, and electricity

Additives, high-value

TRL6/CRI1

chemicals, transportation,

heating, and electricity

Additives, high-value

TRL5/CRI1

DiSAA Milan, Italy;

LanzaTech, New

Zealand

TRL9/CRI2

PROESA™, Italy;

Kalundborg

Bioethanol, Denmark

TRL6/CRI1

chemicals, transportation,

heating, and electricity

cellulose-rich feedstocks

content feedstock, methane- and carbon

dioxide-rich biogas, low-cost organic

fertilizer as by-product

Does not contribute to increase of

greenhouse gas emissions

Fermentation Photofermentation

Dark fermentation

Capable of converting a wide range of

wastes, scalable technology, independent

of light

Enzyme treatment

Microbial

Hydrogen production, low-energy

consumption, effluent degradation

*TRL, technological readiness level; CRI, commercial readiness index.*

**Table 2.**

*Comparative summary of different biological conversion technologies [8–10].*

electrolysis

Low power consumption, low by-product

High cost of the enzymes, slow

Ethanol, amino

High-value chemicals,

transportation, heating, and

electricity

acids

reactions, necessity of high

purity, limited in temperature

and pH range

High internal resistance,

Hydrogen,

Wastewater treatment,

high-value chemicals,

transportation, heating, and

electricity

methane,

acetate, formic

acid

high capital cost, production

greatly affected by substrate

composition

production, does not require toxic catalysts,

can result in a reduced solvent

The photosynthetic bacteria can use a range

Low efficiency, inhibited in the

Hydrogen,

carbon dioxide,

organic acids

Hydrogen, acetic

acid

presence of oxygen

Low theoretical limit, immature

technology

of the electromagnetic spectrum

digestion

**Benefits**

**Limitations**

**Products**

**Applications**

**TRL/CRI/**

**demonstration** 

**projects**

TRL9/CRI3

**Figure 1.** *Example scheme of incineration/combustion technology.*
