Biofuel Production
ETE02
IEA Energy Technology Essentials
The IEA Energy Technology Essentials are regularly-updated briefs that draw together the best-available,
consolidated information on energy technologies from the IEA network
© OECD/IEA 2007
January. 2007
Biofuel Production*
BIOFUEL TYPES AND PROCESS – Bioethanol production: conversion of starch or sugar-rich biomass (corn
(maize), other cereals, sugar cane, etc.) into sugar, fermentation, and distillation. Advanced process:
hydrolysis of ligno-cellulosic biomass, fermentation and distillation. Biodiesel production: extraction and
esterification of vegetable oils, used cooking oils and animal fats using alcohols. Advanced processes:
hydrogenation of oil and fat; gasification and catalytic conversion to liquid fuels (biomass to liquid, BTL).
Biomethane: biogas from anaerobic digestors and landfills used as compressed gas in natural gas vehicles.
ENERGY INPUT AND EMISSIONS – Because of the variety of feedstocks and processes, figures vary widely
and make it difficult to identify indicative values. Sugar-cane ethanol: fossil fuel input some 10%-12% of
final energy and up to 90% CO2 reduction compared with gasoline. Corn ethanol: high energy input and much
smaller CO2 reduction (15-25%). Ligno-cellulosic ethanol: total energy input may be higher than for corn
ethanol, but most such energy could be provided from biomass itself, with CO2 reduction up to 70% (100%
with power co-generation). Biodiesel: about 30% energy input and up to 60% CO2 reduction.
COSTS – High sensitivity to feedstock, process, land type and crop yield. Figures are only indicative (see Fig.
2). Sugar-cane ethanol (Brazil): $0.25-$0.35/litre of gasoline equivalent (lge), competitive with gasoline at
$40-$50/bbl oil prices. Higher cost in other regions. Ethanol from corn (US) and sugar-beet (EU): $0.6-
$0.8/lge. Ligno-cellulosic ethanol: at present over $1.0/lge (feedstock price $3.6/GJ), with potential reduction
to $0.50/lge in the next decade. Biodiesel from animal fat: $0.4-$0.5/lde; Biodiesel from vegetable oil: $0.6-
$0.8/lde; Biodiesel from BTL: > $0.9/lde.
POTENTIAL – Ethanol: Low ethanol-gasoline blends (5%-10%, E5-E10) can fuel gasoline vehicles with little
if any engine modification. New flexi-fuel vehicles run on up to 85% blends. Ligno-cellulosic ethanol (from
all kinds of biomass) may greatly increase feedstock variety and quantity, but requires further R&D. Several
pilot/demo plants in operation in 2006-2007. Potential market: 45 EJ by 2050. Biodiesel: Low biodiesel-diesel
blends (B5-B10) can fuel diesel vehicles with no engine change; low sulphur and particulate emissions.
Synthetic biodiesel (BTL) is fully compatible with diesel fuel and engines. Potential market: 20 EJ by 2050.
Global biomass potential is some 100-200 EJ per year by 2050 (10%-20% of total energy supply).
BARRIERS – Competition with food and fibre production for use of arable land; cost; regional market
structure; biomass transport; lack of well managed agricultural practices in emerging economies; water and
fertiliser use; conservation of bio-diversity; logistics and distribution networks.
PROCESS - Bioethanol conventional production –
cellulosic wastes, maize stover, cereal straw, food-
Bioethanol is the most common biofuel, accounting for
processing wastes, as well as dedicated fast-growing
more than 90% of total biofuel usage. Conventional
plants such as poplar trees and switch-grass. Cellulosic
production is a well known process based on enzymatic
feedstock could be grown on non arable land or be
conversion of starchy biomass into sugars, and/or
produced from integrated crops, which could
fermentation of 6-carbon sugars with final distillation of
considerably increase land availability.
ethanol to fuel grade. Ethanol can be produced from
many feedstocks, including cereal crops, corn (maize),
sugar cane, sugar beets, potatoes, sorghum, cassava. Co-
products (e.g animal feed) help reduce production cost.
If sugar cane is used, conversion into sugar is easier.
Crushed stalk (bagasse) can be used to provide heat and
power for the process and for other energy applications.
The world’s largest producers of bio-ethanol are Brazil
(sugar-cane ethanol) and the United States (corn
ethanol). Ethanol is used in low 5%-10% blends with
gasoline (E5, E10) but also as E-85 in flex-fuel vehicles.
In Brazil, gasoline must contain a minimum of 22%
bioethanol. Bioethanol advanced production -
While conventional processes use only the sugar and
starch biomass components, R&D focuses on advanced
processes that utilise the all available ligno-cellulosic
materials. These processes hold the potential to increase
Biomass Conversion Plant
variety and quantity of suitable feedstock including
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(*) For biogas production see also ETE03 Biomass for Power Generation and CHP
IEA Energy Technology Essentials – Biofuel Production Jan. 2007
Ethanol production from ligno-cellulosic feedstock
to the process used, suggest that ethanol from maize may
includes biomass pre-treatment to release cellulose and
displace petroleum use by up to 95%, but total fossil
hemicellulose, hydrolysis to release fermentable 5- and
energy input currently amounts to some 60%-80% of the
6-carbon sugars, sugar fermentation, separation of solid
energy contained in the final fuel (20% diesel fuel, the
residues and non-hydrolysed cellulose, and distillation to
rest being coal and natural gas) and hence the CO2
fuel grade.. To provide better conversion, new chemical
emissions reduction may be as low as 15%-25% vs.
and enzymatic processes (pre-treatment, hydrolysis,
gasoline. Ethanol from ligno-cellulosic feedstock –
fermentation) are being examined. Solid residues and co-
At present, the total energy input needed for the
products from the process such as lignin and other
production process may be even higher as compared to
components, particularly from forest materials, may
bioethanol from corn, but in some cases most of such
inhibit hydrolysis. They can be extracted and used as a
energy can be provided by the biomass feedstock itself.
fuel in the production process, thus reducing cost and
Net CO2 emissions reduction from ligno-cellulosic
emissions.
ethanol can therefore be close to 70% vs. gasoline, and
could approach 100% if electricity co-generation
Biodiesel production – Biodiesel production is based
displaced gas or coal-fired electricity. Current R&D aims
on trans-esterification of vegetable oils and fats through
to exploit the large potential from improving efficiency
the addition of methanol (or other alcohols) and a
in enzymatic hydrolysis. Energy input and overall
catalyst, giving glycerol as a co-product. Feedstock
emissions for biodiesel production also depend on
includes rapeseeds, sunflower seeds, soy seeds and palm
feedstock and process. Typical values are fossil fuel
oil seeds from which the oil is extracted chemically or
inputs of 30% and CO2 emission reductions of 40%-60%
mechanically. Advanced processes include the
vs. diesel. Using recycled oils and animal fats reduces
replacement of methanol of fossil origin, by bioethanol
the CO2 emissions.
to produce fatty acid ethyl ester instead of fatty acid
methyl ether (the latter being the traditional biodiesel). In
COST – Costs of biofuels are highly dependent on
order to expand the relatively small resource base of
feedstock, process, land and labour costs, credits for by-
biodiesel, new processes have been developed to use
products, agricultural subsidies, food (sugar) and oil
recycled cooking oils and animal fats though these are
market. Ethanol energy content by volume is two-thirds
limited in volume. Hydrogenation of oils and fats is a
that of gasoline, so costs refer to litre of gasoline
new process that is entering the market. It can produce a
equivalent (lge). Sugar cane ethanol in Brazil costs
biodiesel that can be blended with fossil diesel up to
$0.30/lge free-on-board (FOB). This cost is competitive
50% without any engine modifications. Synthetic
with that of gasoline at oil prices of $40-$50/bbl ($0.3-
biofuel production via biomass gasification and
$0.4/lge). In other regions, costs can be more than $0.40-
catalytic conversion to liquid using Fischer-Tropsch
$0.50/lge, although potential exists for cost reduction.
process (biomass conversion to liquids BTL) offers a
Ethanol from maize, sugar-beet and wheat cost
variety of potential biofuel production processes that
around $0.6-$0.8/lge (excl. subsidies), potentially
may be suited to current and future engine technologies.
reducible to $0.4-$0.6/lge. Ligno-cellulosic ethanol
The largest biodiesel producer is Germany, which
currently costs around $1.0/lge at the pilot scale,
accounts for 50% of global production. Biodiesel is
assuming a basic feedstock price of $3.6/GJ for
currently most often used in 5%-20% blends (B5, B20)
delivered straw (whereas cereals for ethanol production
with conventional diesel, or even in pure B100 form.
may cost $10-$20/GJ). The cost is projected to halve in
the next decade with process improvement, scaling up of
ENERGY INPUT AND EMISSIONS – Fossil energy
plants, low-cost waste feedstock and co-production of
inputs and emissions levels from biofuel production are
other by-products (bio-refineries). Biodiesel from
sensitive to process and feedstock, to energy embedded
animal fat is currently the cheapest option ($0.4-
in fertilizers, and to local conditions. Production of
$0.5/lde) while traditional trans-esterification of
ethanol from sugar cane (Brazil) is energy-efficient
vegetable oil is at present around $0.6-$0.8/lde. Cost
since the crop produces high yields per hectare and the
reductions of $0.1-$0.3/lde are expected from economies
sugar is relatively easy to extract. If bagasse is used to
of scale for new processes. The cost of BTL diesel from
provide the heat and power for the process, and ethanol
ligno-cellulose is more than $0.9/lde (feedstock
and biodiesel are used for crop production and transport,
$3.6/GJ), with a potential reduction to $0.7- $0.8/lde.
the fossil energy input needed for each ethanol energy
unit can be very low compared with 60%-80% for
STATUS AND POTENTIAL - Ethanol is a fuel with
ethanol from grains. As a consequence, ethanol well-to-
a high octane number and a low tendency to create
wheels CO2 emissions can be as low as 0.2-0.3
knocking in spark ignition engines. Oxygen in its
kgCO2/litre ethanol compared with 2.8 kg CO2/litre for
molecule permits low-temperature combustion with
conventional gasoline (90% reduction). Ethanol from
reduction of CO and NOx emissions. Low-percentage
sugar beet requires more energy input and provides 50%-
ethanol-gasoline blends (5%-10%) can be used in
60% emission reduction compared with gasoline.
conventional spark-ignition engines with almost no
Ethanol production from cereals and corn (maize)
technical change. New flex-fuel vehicles of which there
can be even more energy-intensive and debate exists on
are over 6 million running mainly in Brazil, United
the net energy gain. Estimates, which are very sensitive
States and Sweden, can run on up to 85% ethanol blends
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IEA Energy Technology Essentials – Biofuel Production Jan. 2007
having had modest changes made during production.
2050 primary energy supply) are based on the
Ethanol combustion offers fuel and emissions savings
assumption of no water shortage and increased food
due to the high octane number, the high compression
agriculture yields in the coming decades, partly due to
ratio and the combustion benefits from ethanol vapour
genetically modified crops. In this case, large amounts
cooling which partly offsets its lower energy content per
(20%-50%) of arable land would be available for
litre. Further R&D is needed to improve ligno-cellulose
biomass production. Some 50 EJ per year could be
conversion into sugar (enzymatic hydrolysis, micro-
produced from ligno-cellulosic feedstock. The possible
organisms) and to improve conversion of 5-carbon sugar
use of marginal, non-arable land could also play a role.
to ethanol. Several pilot and demonstration plants with
The IEA’s World Energy Outlook 2006 Reference
capacities ranging from 1 to 40 million litres of ethanol a
Scenario projects the world biofuels output to climb at a
year will be operating in 2007. Fully commercial plants,
rate of 7% per year to meet 4% of road-transport fuel
however, need to scale up by a factor of 5-10 and no
demand by 2030. In the WEO Alternative Scenario,
definite plans have been announced. Securing sufficient
annual growth is 9% and output reaches 7% of road-fuel
low cost biomass supply over a long period will need to
use in 2030. The IEA’s Energy Technology Perspectives
be resolved. Ethanol could experience rapid expansion in
(2006) suggests bioethanol and biodiesel could meet
North America and Europe by leapfrogging a number of
some 13% of global transport fuel demand and
traditional barriers faced by alternative fuels for
contribute some 6% of global emission reductions by
transport. In the period 2004-2005 global ethanol
2050. Projections are very sensitive to assumptions.
production increased by 8% a year from 30.5 to 33
Yields of biofuels from purpose grown crops depend on
billion litres. By the end of 2005, there were 95
the species, soil type and climate. Cereals and maize can
operating plants in the United States with total capacity
yield around 1500-3000 lge/ha; sugar cane 3000-6000
of 16.4 billion litres per year (bnl per year). In mid-2006,
lge/ha; sugar beet 2000-4000 lge/ha, vegetable oil crops
35 additional plants were under construction with further
700-1300 lde/ha, and palm oil 2500-3000 lde/ha.
capacity of 8 bnl per year. Brazil has over 300 plants in
operation, of which 80 licensed in 2005, and is expected
BARRIERS - Ethanol supply is constrained by arable
to increase sugar cane production by 40% by 2009 as a
land availability. Competition with food production for
part of a new national plan. The potential market for
land use could drive possible increases in both ethanol
bioethanol is estimated at around 45 EJ by 2050.
and food prices (already occurring in the sugar market).
Biodiesel offers full blending potential with
Ethanol markets still have a regional structure (ethanol
conventional diesel, a high cetane number giving
shipping $0.02-$0.03/l). Transport of biomass remains a
improved combustion in compression ignition engines,
logistics barrier that limits the size of ethanol production
and low emissions of sulphur and particulates. Biodiesel
plants and economies of scale. A more liberalised market
is the fastest growing biofuel but from a lower base than
would create opportunities and incentives for producers
ethanol. Global production passed from 2.1 bnl in 2004
in emerging economies especially Brazil, India, and
to 3.9 bnl in 2005, increasing by 75% in Germany,
Thailand. Transfer of advanced agricultural practices to
France, Italy, and Poland and tripling in the United
developing countries could considerably help.
States. The potential market for biodiesel is estimated to
Conversely, producing more biofuels from conventional
be in the order of 20 EJ by 2050, assuming development
feedstocks could conflict with conservation of bio-
of synthetic biofuel production technologies. Several
diversity and call for increased amounts of water,
countries have adopted policies such as tax exemptions,
pesticides and fertilisers, thus raising sustainability
mandates and incentives for biofuels in 2005–2006. For
issues. In scenarios having 25% of transport fuels
example, France targets 5.75% biofuels by 2008 and
derived from biomass, the use of fertilisers increases by
10% by 2015; Germany requires 2% ethanol and 4.4%
about 40%. On a fuel-cycle basis, ethanol, with its high
biodiesel in 2007, increasing to 5.75% by 2010; Italy
vapour pressure, reduces NOx and volatile organic
mandates 1% blend for both ethanol and biodiesel in
compound (VOC) emissions but this is partly offset from
2006; and in the beginning of 2007, the European
increased N2O emission from increased use of
Commision proposed a 10% target by 2020. In the US,
nitrogenous fertilisers. Developing cost-effective ethanol
fuel distributors are required to increase the annual
production from ligno-cellulose via enzymatic
volume of biofuels up to nearly 30 bnl by 2012 with the
hydrolysis would therefore increase the variety and
targets for “renewable and alternative fuels” raised in
availability of feedstocks and hence expand the
2007 to 140 bnl by 2017. Targets and mandates also
production of biofuels. Other ethanol drawbacks include
exist in non OECD countries (e.g., Brasil, China).
miscibility with water, aldehyde emissions, compatibility
issues with some plastics or metals (Al-alloys, brass,
Global potential for biomass production - Present
zinc, lead) and high latent vapourisation heat (cold start
global modern bio-energy production is estimated at
issues). Ethanol use in compression ignition engines
some 9 EJ/year of which industrial biofuel production is
needs additives due to the low cetane number and is
only 1 EJ per year (around 1% of transport fuels from
impractical. Biodiesel production depends on
crops grown on some 1% of all arable land - 14 million
feedstock and land availability even more than
hectares). Estimates of global potential for industrial
bioethanol production. The Fischer-Tropsch BTL
biomass production by 2050 vary considerably.
technology and other advanced processes hold the
Estimates of 100-200 EJ per year (roughly 10%-20% of
potential to increase biofuels production basis.
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IEA Energy Technology Essentials – Biofuel Production Jan. 2007
Fig. 1 – World Production of Biofuels
Bioethanol
Biodiesel
Source: IEA analysis based on F.O.Lichts – IEA World Energy Outlook 2006
Fig. 2 – Current and projected costs of biofuels compared with conventional wholesale gasoline and diesel prices (fob)
1.1
1.0
0.9
US $/l
0.8
0.7
0.6
0.5
0.4
0.3
Brent crude $/bbl
0.2
40
50
60 70
Table 1 –Feedstock production, costs, and emissions data for bioethanol and biodiesel production
Data Confidence – Bio-ethanol and biodiesel production from conventional feedstocks are already commercial in some
countries, but subject to further improvement and optimisation. Data refer to typical, current technologies. Biofuels produced from
ligno-cellulosic feedstocks are still in the demonstration phase and require further R&D to reduce cost and increase efficiency.
Performance
Bioethanol
Biodiesel
Feedstock
Cereals, maize
Sugar beets
Sugar cane
Ligno-cellulosic
Vegetable oils
Fossil energy input (%)
60-80
na
10-12
(a) 30-40
Co-products
Heat and power
Heat and power
Installed capacity (bn l
19.5 US, 5
na
18 Brazil
1.9 Germany;
/yr)
China
2.1 rest of world
Cost
Production cost ($/lge)
0.6-0.8
0.6
0.3-0.5
1.0 (b) 0.7-1.0
($/lde)
Environmental Impact
CO2 reduction (%c)
15-25 50-60 90
70
40-60
Pollutant abatement
CO
CO
CO
CO, NOx
SOx, particulates
Land use (lge/ha)
1500-3000
2000-4000
3000-6000
Na
700-1300 lde/ha (3000
palm)
Further Information
www.iea.org; www.ieabioenergy.com; International Bio-Energy Partnership (www.fao.org); Energy
Technology Perspectives (IEA, 2006); World Energy Outlook (IEA, 2006); REN21 – Global Status
Report 2005, 2006 (www.ren21.net)
(a) Energy input may be higher than final ethanol energy, but most such energy comes from the biomass itself.
(b) Twice gasoline cost at $ 60/bbl. (c) Compared with gasoline (2.8 kg CO2/l) or conventional diesel.
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