Agriculture Reference
In-Depth Information
Fourthly, recent policies on fuels are promoting those produced from plants non eli-
gible to food and animal feed (grass or woods), and from agriculture residues (straw or
corn stover). The Energy Independence and Security Act of 2007 in USA have man-
dated their progressive use to limit the extension of ethanol production from corn (in 2008
mandated volume for 2014 should have been 6.5 M
·
m
3
). Feedstock are mostly made of
ligno-cellulosic materials, which is assumed to be converted into ethanol either by thermo-
chemicals processes or by fermentation of sucroses produced from plants. However, due to
the difficulty to modify the material, at the difference of starch or sugar, quantities remain
currently negligible (below 2 k
·
m
3
in USA) [3, 4]. The amount provisioned by the Act of
2007 in USA has had to be reduced. Fuels and ethanol derived from any forms of biomass
except agriculture crops are labeled bio-fuel and bio-ethanol, respectively.
A last precaution about statistics on agro-ethanol production concerns the inclusion of
other liquids in small quantities (about 5% in volume) such as denaturant in USA and water
in Brazil, the two main producers. In Brazil volumes of hydrated and anhydrous ethanol are
added without accounting for the difference of LHV.
Table 3. Production in 2012 and yields of agro-ethanol from sugar beet, can and corn
Production
a
Agriculture
b
TRS
c
Ethanol
d
2012
Dry matter
Mtoe
yield Y
A
fraction
fraction
yield
Beet, France
0.25 [3]
75.4 [5]
0.25
0.183
3.8
Cane, Brazil
10.7 [6]
71 [6]
0.30
0.14
2.8
Corn, USA
23.9 [4]
7.75 [7]
0.85
0.62
1.6
b
a
Low heating value LHV of agro-ethanol without added water or denaturant: 21.3 MJ
·
l
−
1
or 0.51 toe
·
m
−
3
at 15
◦
C and 1 atm.
b
Country averaged agriculture yield Y
A
for 2012 in t
·
(ha
·
y)
−
1
from data of national agri-
culture departments. In the case of cane Y
A
accounts for all cultivated surface, including the
fallow area at the end of a cycle and before next one. Corn yield was abnormally low in 2012
due to exceptional droughts. It reached 10.0 t
A
·
(ha
·
y)
−
1
in 2013.
c
Total Recoverable Sugar for sugar plant or Starch for cereals
d
in toe
LHV
·
(ha
·
y)
−
1
obtained from data in previous columns. See text.
Table 3 shows the LHV quantities of agro-ethanol produced from beet in France, cane
in Brazil and corn in USA for 2012, after deduction of water and denaturant volumes. The
global production was close to 40 Mtoe
LHV
. They have remained roughly constant since
2010. British Petroleum BP Statistical Review of World Energy published in June 2014
reports for all fuels produced from agriculture crops in 2012 a quantity of 61.5 Mtoe
LHV
.
Agro-fuels also comprise modified oils from oleaginous plants such as soya, sunflower
and rapeseed. By comparison BP review indicates a production of oil (crude oil, bitumen
and liquids separated from natural gas) of about 42 000 Mtoe
LHV
, of which about 45% is
dedicated to produce road transportation fuel. Surface limitation of agriculture crops make
difficult the substitution of agro-fuels for fossil oils. They can be only a - small, even a very
small - part of the solution.
Actually, it is very difficult to determine the exact quantity in the case of beet in France,
even looking deeply in the reports of CGB. In 2012 the country produced 2.0 M
·
m
3
of
agro-alcohols of which agro-ethanol volume - processed mostly from cereals and beet -
