BioMatNet Item: FAIR-CT96-2000 - Production of fatty acid esters usable as fuels by fermentation of biomass

FAIR-CT96-2000
Production of fatty acid esters usable as fuels by fermentation of biomass

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Agricultural Residues : Biological Conversion : FAIR Area 1.1 - Biomass and Bioenergy Chain : Liquid Biofuels and Biogas : Process Engineering : Straw : Sugar

	Type of Project	Shared Cost
	Contract No	FAIR-CT96-2000
	Total Cost	2,375,000 ECU
	EC Contribution	1,350,000 ECU
	Start Date	01/01/97
	Duration	36 Months

Production of fatty acid esters usable as fuels by fermentation of biomass

Background

It is known that methyl esters of both rapeseed and sunflower oil are good gas-oil substitutes. Several microorganisms are known to produce fatty acids or triglycerides from biomass that could be used in the same way. It is expected that the characteristics of biofuels based on such products will be better than those derived from rapeseed and sunflower methyl esters because of better yields and reduced emissions. It is also anticipated that, when wastes are used as substrates, the costs of such esters will be appreciably lower that those of current liquid biofuels. The process can also be used to produce acids (acetic, propionic, butyric) and esters that can be used in the bulk chemical market.

If the project is successful, the long-term impact in Europe could be considerable. Several million tons oil equivalent could be produced, depending on the legislation that may develop this type of biofuel.

Objectives

The objective of the project is to develop fermentation technology using biomass raw materials, for production of fatty acid esters for use as liquid biofuels and chemicals.

Specifically, two types of products will be made:

short chain fatty acid esters, for blending with gasoline (octane enhancers)
middle or long chain fatty acid esters, for blending with transportation fuels or heating gas oil

Technical Approach

The substrates are sugars or lignocellulosic crops or by-products such as straw or agro-industrial and municipal solid wastes. The process consists of three stages:

if necessary, for lignocellulosic substrates, hydrolysis of hemicellulose and/or cellulose to derive sugars from biomass
production of fatty acids by fermentation of these sugars (using bacteria and yeasts)
esterification of the fatty acids with various alcohols

The work to be carried out under this project covers only the second and third stages, that is fermentation and esterification. It is made up of the following tasks:

Optimisation of fermentations producing fatty acid esters, with trials made at laboratory scale and in small industrial fermenters.
Genetic modification of yeasts in order to obtain almost pure lauric or oleic acid
Design and construction of a pilot unit to produce fatty acids and esters, in order to the laboratory results
Development of methods for extraction/ esterification of fatty acids
Completion of laboratory and bench tests using the esters in engines in order to establish their technical and environmental properties.
Technical and economic evaluation of the process, taking into account the result from each step of the research

Results to Date

The following tasks have been undertaken:

growth of Clostridium thermoaceticum and C. tyrobutyricum has been optimised using glucose and hydrolysed molasses as substrate
organic acids and residues derived from wastes
extraction of acids from simulated broth and esterification
definition and engineering studies of the pilot plant
bench test of short-chain and middle chain fatty acid esters in engines and boilers
cost estimates have been calculated for an industrial plant producing 40 000 ton/year of acetic acid for methyl or ethyl acetate production.

The main results to date are as follows:

Bacteria strains have been selected in the laboratory for the production of acetic acid and butyric acid with good yields and productivity. These strains will be used in the pilot unit.
Initial results have been obtained concerning genetic modification of a yeast strain for the production of oleic and palmitic acids, but further work is required before scaling up.
The production of mixtures of short chain acids by mixed bacteria cultures growing on residues and agro-industrial by-products (solid waste from sweet corn processing, municipal sludge,...) has been investigated at laboratory and small pilot scale.
Laboratory scale experiments have been carried out concerning extraction of acids from the broth and esterification of acids with methanol, ethanol and ethylene glycol, in order to optimise the yields prior to pilot experiments.
Positive results have been obtained from combustion tests with blends of esters used as fuel in boilers and car engines (good combustion, in some cases reduction of pollutant emissions, no problems associated with driving, etc.).
The pilot unit, that includes a 5 m³fermenter, extraction equipment and distillation columns, has been designed. Construction will be completed in December 98 and pilot experiments will start in January 99.
A cost estimate has been complete for an industrial unit with a capacity of 47 000 t of methyl acetate/year: the investment cost is estimated at ~25 MECU. The production cost, including re-payment of investment costs, has been evaluated (using a substrate cost of 0.15 ECU/kg of sugar), at 0.5 ECU/kg for methyl acetate and 0.65 ECU/kg for ethyl acetate. .

A sensitivity analysis has also been carried out taking into account the main economical parameters, which confirmed the good economic prospect of the process.

Process scheme for production by fermentation
of biomass of esters usable as fuel (Bertin)

Contacts

Coordinator

DR. N MILANDE / BERTIN ET CIE FRANCE

Participant