Celignis Analytical has a number of formulae which are used to predict, based on
sample compositional data, the potential product yields (on the basis of litres of biofuel and energy (GJ) of
biofuel output) that could be obtained when processing biomass samples in seven different biorefining technologies
(labelled 1 to 7).
These numbers are estimates and may not be representative of the actual yields that may be achieved in real-world conditions.
The data are presented online to customers, on the Celignis Database, in tabulated and graphical formats,
providing that the appropriate analysis packages have been selected.
Samples for which data regarding the elemental and ash contents have been obtained (e.g. Celignis Analysis Package: P40 - Combustion Package) will
have data for potential biofuel yields from 2 different representative gasification technologies (Technologies 6 and 7).
Summary of Technologies
Five of the technologies (1-5) involve the hydrolysis of biomass polysaccharides and the subsequent fermentation of the
liberated monosaccharides to ethanol. Technologies 6 and 7 operate via the thermochemical platform, specifically
via the gasification of the biomass and the subsequent catalytic synthesis of fuels.
These technologies are explained in the text below and the following table which compares them on the basis of: commercialisation status; minimum size for a commercial facility;
cost of biofuel produced; feedstock flexibility; and potential biofuel yield.
Five different hydrolysis technologies are examined:
1 - Dilute acid hydrolysis of biomass in two plug-flow reactors. This can be considered to representative of a near-commercial dilute-acid hydrolysis facility.
2 - Dilute acid hydrolysis of cellulose in a counter-current reactor with an uncatalysed steam hydrolysis pre-treatment. This more
efficient process (for cellulose hydrolysis) may be commercially viable in the future.
3 - Concentrated acid hydrolysis of biomass.
4 - Enzymatic hydrolysis of biomass. Involves a dilute acid pre-treatment and separate fermentation of the monosaccharides from cellulose
and hemicellulose (sequential hydrolysis and fermentation - SHF). Cellulase enzymes are produced in a separate reactor to that for hydrolysis. This is the likely setup of the first
commercial enzymatic hydrolysis facilities.
5 - Enzymatic hydrolysis and fermentation of biomass via consolidated
bioprocessing (CBP) with a liquid hot water pre-treatment step. Here hydrolysis of cellulose, fermentation of the sugars and production of
cellulases all take place in one reactor and involve a single micro-organism. This process can be considered to potentially be the most
efficient and economical enzymatic hydrolysis technology; however, it is currently not sufficiently developed for commercialisation. There
is substantial ongoing research, however, and it is expected that such a process could be viable before 2020.
The following formulae are used to calculate the yield of ethanol according to the hexose and pentose contents of the feedstock and the estimated efficiencies of the
technology (based on a literature review). Table 2 then outlines the efficiencies used for the hydrolysis processes based on these equations:
Conversion factors and yields for the hydrolysis technologies. Click to enlarge.
Technologies 6 and 7 are based on the gasification conversion process. Unlike the hydrolysis technologies, which specifically target the structural polysaccharides of feedstocks, the thermochemical processes degrade all volatile components of the feedstock (which includes the lignin, as well as the polysaccharides). Determinations of process yields for these technologies are based on the estimated heating values of the feedstock, as calculated from its elemental composition.
Where O* = the sum of the contents of oxygen and other elements (including S, N,
Cl, etc.) in the organic matter, i.e.
O* = 100%-C-H-Ash.
The Lower Heating Value (LHV), or effective heating value, is more relevant than the HHV in
practical operations. It considers the energy required to vaporise the water generated when the hydrogen and
elements of the biomass combine. Hydrogen content then becomes a reducing factor in the heating value.
The LHV can be calculated on a dry basis from the equation below:
The two representative gasification technologies used are described below:
6 - Synthesis of mixed alcohols via the catalytic processing of
syngas derived from the gasification of biomass. The efficiency of the process is based
on the LHV of the feedstock, giving a conversion efficiency of 48.8% to ethanol and 9.6% to higher alcohols, although the calculations
will only consider the ethanol produced. The process is considered to be beyond the current state of the art and more likely for commercialisation closer to 2023.
7 - The Fischer-Tropsch (FT) synthesis of a mixed range of linear hydrocarbons from biomass-derived syngas. We use data for an Institute of Gas Technology,
direct, oxygen blown, pressurised gasifier with full gas recycle. The overall conversion efficiency, based on the LHV of the feedstock,
has been estimated at 47.7%, with 37.92% for FT liquids and 6.65% for net power. Hydrocracking of the waxy FT product is necessary to maximise diesel yields with these cracking conditions producing
60% (by mass) diesel, 25% kerosene and 15% naphtha. Hence, yields (according to the dry LHV) will be 24.68% for diesel, 6.33% for naphtha and 10.04% for kerosene.
This conference is being organised under the auspices of the Interreg Northwest Europe-funded THREE C Project, entitled 'Creating and sustaining Charcoal value chains to promote a Circular Carbon economy in NWE Europe'.
The conference will highlight both Irish stakeholders who are currently working in the biochar and carbon products sector, but also partners from the THREE C project (covering Netherlands, Luxembourg, Germany, Belgium, France and Wales, as well as Ireland) who have interesting stories and products to share.
Read about the wide variety of analysis packages we have for biochar
Click here to read about the different analysis packages that Celignis offers for the evaluation on biochars. These analyses cover properties relevant to a wide variety of applications, including soil amendment, carbon sequestration, bioenergy, and biomaterials.
For a short period we are offering two TGA analyses for the price of one!
To celebrate the arrival of our thermogravimetric (TGA) equipment, we are offering, for a limited time period, two TGA analyses for the price of one. Click here to read more about TGA analyses at Celignis and to see the various packages on offer.
To avail of this special offer please mention the code (TGA-AUGUST) in an email or when placing an order via the Celignis Database.
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