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Use of Ethanol Fuel for cars.
Conversion of biomass into ethanol
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Alcohol can be used as a liquid fuel in internal combustion engines
either on their own or blended with petroleum. Therefore, they have the
potential to change and/or enhance the supply and use of fuel (especially
for transport) in many parts of the world. There are many widely-available
raw materials from which alcohol can be made, using already improved and
demonstrated existing technologies. Alcohol have favourable combustion
characteristics, namely clean burning and high octane-rated
performance. | Internal combustion engines
optimized for operation on alcohol fuels are 20 per cent more energy-efficient
than when operated on gasoline, and an engine designed specifically to run on
ethanol can be 30 per cent more efficient. Furthermore, there are numerous
environmental advantages, particularly with regard to lead, CO2, SO2,
particulates, hydrocarbons and CO emissions.
 Ethanol as most important alcohol fuel can be produced by
converting the starch content of biomass feedstocks (e.g. corn, potatoes, beets,
sugarcane, wheat) into alcohol. The fermentation process is essentially the same
process used to make alcoholic beverages. Here yeast and heat are used to break
down complex sugars into more simple sugars, creating ethanol. There is a
relatively new process to produce ethanol which utilizes the cellulosic portion
of biomass feedstocks like trees, grasses and agricultural wastes. Cellulose is
another form of carbohydrate and can be broken down into more simple sugars.
This process is relatively new and is not yet commercially available, but
potentially can use a much wider variety of abundant, inexpensive
feedstocks.
Currently, about 6 billion litres of ethanol are produced
this way each year in the U.S. World-wide, fermentation capacity for fuel
ethanol has increased eightfold since 1977 to about 20 billion litres per year.
Latin America, dominated by Brazil, is the world’s largest production region of
bioethanol. Countries such as Brazil and Argentina already produce large
amounts, and there are many other countries such as Bolivia, Costa Rica,
Honduras and Paraguay, among others, which are seriously considering the
bioethanol option. Alcohol fuels have also been aggressively pursued in a number
of African countries currently producing sugar - Kenya, Malawi, South Africa and
Zimbabwe. Others with great potential include Mauritius, Swaziland and Zambia.
Some countries have modernized sugar industry and have low production costs.
Many of these countries are landlocked which means that it is not feasible to
sell molasses as a by-product on the world market, while oil imports are also
very expensive and subject to disruption. The major objectives of these
programmes are: diversification of the sugarcane industry, displacement of
energy imports and better resource use, and, indirectly, better environmental
management. These conditions, combined with relatively low total demand for
liquid transport fuels, make ethanol fuel attractive. Global interest in ethanol
fuels has increased considerably over the last decade despite the fall in oil
prices after 1981. In developing countries interest in alcohol fuels has been
mainly due to low sugar prices in the international market, and also for
strategic reasons. In the industrialized countries, a major reason is increasing
environmental concern, and also the possibility of solving some wider
socio-economic problems, such as agricultural land use and food surpluses. As
the value of bioethanol is increasingly being recognized, more and more policies
to support development and implementation of ethanol as a fuel are being
introduced.
 Since ethanol has different chemical properties than
gasoline, it requires slightly different handling. For example, ethanol
changes from a liquid to a gas (evaporates) less readily than gasoline. This
means that in neat (100%) ethanol applications, cold starts can be a problem.
However, this issue can be resolved through engine design and fuel
formulation. Changes in engine design will also allow for greater
efficiency. Although a litre of ethanol has about two-thirds of the energy
content of a litre of gasoline, tuning the engine for ethanol can make up as
much as half the difference. Furthermore, since ethanol is an organic product,
should there be a spill, it will biodegrade more quickly and easily than
gasoline.
Using ethanol even in low-level blends (e.g. E10 - which is
10% ethanol, 90% gasoline) can have environmental benefits. Tests show that E10
produces less carbon monoxide (CO), sulphur dioxide (SO2) and carbon dioxide
(CO2) than reformulated gasoline (RFG). These blends have helped clean up
carbon monoxide problems in cities like Denver and Phoenix. However E10
produces more volatile organic compounds (VOC), particulates (PM), and nitrogen
oxide (NOx) emissions than RFG. Higher blends (E85, which is 15%
gasoline), or even neat ethanol-E100 - burn with less of virtually all the
pollutants mentioned above.
 
The production of
ethanol by fermentation involves four major steps:
(a) the growth, harvest and delivery of raw material to an alcohol
plant;
(b) the pre-treatment or conversion
of the raw material to a substrate suitable for fermentation to
ethanol;
(c) fermentation of the substrate
to alcohol, and purification by distillation; and
(d) treatment of the fermentation residue to reduce pollution and
to recover by-products.
Fermentation technology and efficiency has improved rapidly in the past
decade and is undergoing a series of technical innovations aimed at using new
alternative materials and reducing costs. Technological advances will have,
however, less of an impact overall on market growth than the availability and
costs of feedstock and the cost-competing liquid fuel options.
The
many and varied raw materials for bioethanol production can be conveniently
classified into three types: (a) sugar from sugarcane, sugar beet and fruit,
which may be converted to ethanol directly; (b) starches from grain and root
crops, which must first be hydrolysed to fermentable sugars by the action of
enzymes; and (c) cellulose from wood, agricultural wastes etc., which must be
converted to sugars using either acid or enzymatic hydrolysis. These new systems
are, however, at the demonstration stage and are still considered uneconomic. Of
major interest are sugarcane, maize, wood, cassava and sorghum and to a lesser
extent grains and Jerusalem artichoke. Ethanol is also produced from lactose
from waste whey; for example in Ireland to produce potable alcohol and also in
New Zealand to produce fuel ethanol. A problem still to be overcome is
seasonability of crops, which means that quite often an alternative source must
be found to keep a plant operating all-year round.
Ethanol fuel production from non-food feedstocks.
Ethanol plant in Indiana (USA).
Sugarcane residue, called bagasse, feedstock for
methanol.
Sugarcane is the world’s largest source of fermentation ethanol. It is one
of the most photosynthetic efficient plants - about 2,5 % photosynthetic
efficiency on an annual basis under optimum agricultural conditions. A further
advantage is that bagasse, a by-product of sugarcane production, can be used as
a convenient on-site electricity source. The tops and leaves of the cane plant
can also be used for electricity production. An efficient ethanol distillery
using sugarcane by-products can therefore be self-sufficient and also generate a
surplus of electricity. The production of ethanol by enzymatic or acid
hydrolysis of bagasse could allow off-season production of ethanol with very
little new equipment.
METHANOL
 Methanol is another alcohol fuel which can be obtained
from biomass and coal. But methanol is currently produced mostly from natural
gas and has only been used as fuel for fleet demonstration and racing purposes
and, thus, will not be considered here. In addition, there is a growing
consensus that methanol does not have all the environmental benefits that are
commonly sought for oxygenates and which can be fulfilled by ethanol.
Brazil
Brazil
first used ethanol as a transport fuel in 1903, and now has the world’s largest
bioethanol programme. Since the creation of the National Alcohol Programme
(ProAlcool) in 1975, Brazil has produced over 90 billion litres of ethanol from
sugarcane. The installed capacity in 1988 was over 16 billion litres distributed
over 661 projects. In 1989, over 12 billion litres of ethanol replaced about
200,000 barrels of imported oil a day and almost 5 million automobiles now run
on pure bioethanol and a further 9 million run on a 20 to 22 per cent blend of
alcohol and gasoline (the production of cars powered by pure gasoline was
stopped in 1979). From 1976 to 1987 the total investment in ProAlcool reached
$6,970,000 million and the total savings equivalent in imported gasoline was
$12,480,000 million.
Apart from ProAlcool’s main objective of
reducing oil imports, other broad objectives of the programme were to protect
the sugarcane plantation industry, to increase the utilization of domestic
renewable-energy resources, to develop the alcohol capital goods sector and
process technology for the production and utilization of industrial alcohols,
and to achieve greater socio-economic and regional equality through the
expansion of cultivable lands for alcohol production and the generation of
employment. Although ProAlcool was planned centrally, alcohol is produced
entirely by the private sector in a decentralized manner.
The
ProAlcool programme has accelerated the pace of technological development and
reduced costs within agriculture and other industries. Brazil has developed a
modem and efficient agribusiness capable of competing with any of its
counterparts abroad. The alcohol industry is now among Brazil’s largest
industrial sectors, and Brazilian firms export alcohol technology to many
countries. Another industry which has expanded greatly due to the creation of
ProAlcool is the ethanol chemistry sector.
Ethanol-based chemical
plants are more suitable for many developing countries than petrochemical plants
because they are smaller in scale, require less investment, can be set up in
agricultural areas, and use raw materials which can be produced locally.
SOCIAL DEVELOPMENT
Rural job creation has been credited as a major benefit of ProAlcool
because alcohol production in Brazil is highly labour-intensive. Some 700,000
direct jobs with perhaps three to four times this number of indirect jobs have
been created. The investment to generate one job in the ethanol industry varies
between $12,000 and $22,000, about 20 times less than in the chemical industry
for example.
ENVIRONMENTAL IMPACTS
Environmental pollution by the ProAlcool programme has been a cause of
serious concern, particularly in the early days. The environmental impact of
alcohol production can be considerable because large amounts of stillage are
produced and often escape into waterways. For each litre of ethanol produced the
distilleries produce 10 to 14 litres of effluent with high biochemical oxygen
demand (BOD) stillage. In the later stages of the programme serious efforts were
made to overcome these environmental problems, and today a number of alternative
technological solutions are available or are being developed, e.g., decreasing
effluent volume and turning stillage into fertilizer, animal feed, biogas etc.
These have sharply reduced the level of pollution and in Sao Paulo. The use of
stillage as a fertilizer in sugarcane fields has increased productivity by 20-30
per cent.
ECONOMICS
Despite many studies carried out on nearly all aspects of the programme,
there is still considerable disagreement with regard to the economics of ethanol
production in Brazil. This is because the production cost of ethanol and its
economic value to the consumer and to the country depend on many tangible and
intangible factors making the costs very site-specific and variable even from
day to day. For example, production costs depend on the location, design and
management of the installation, and on whether the facility is an autonomous
distillery in a cane plantation dedicated to alcohol production, or a distillery
annexed to a plantation primarily engaged in production of sugar for export. The
economic value of ethanol produced, on the other hand, depends primarily on the
world prices of crude oil and sugar, and also on whether the ethanol is used in
anhydrous form for blending with gasoline, or used in hydrous forte in 100 per
cent alcohol-powered cars.
The costs of ethanol were declining at an
annual rate of 4 per cent between 1979 and 1988 due to major efforts to improve
the productivity and economics of sugarcane agriculture and ethanol production.
The costs of ethanol production could be further reduced if sugarcane residues,
mainly bagasse, were to be fully utilized. With sale credits from the residues,
it would be possible to produce hydrous ethanol at a net cost of less than
$0.15/litre, making it competitive with gasoline even at the low early-1990 oil
prices. Using the biomass gasifier/intercooled steam-injected gas turbine
(BIG/STIG) systems for electricity generation from bagasse, they calculated that
simultaneously with producing cost-competitive ethanol, the electricity cost
would be less than $0.0451kWh. If the milling season is shortened to 133 days to
make greater use of the barbojo (tops and leaves) the economics become even more
favourable. Such developments could have significant implications for the
overall economics of ethanol production.
Despite all the problems
ProAlcool is an outstanding technical success that has achieved many of its
aims, its physical targets were achieved on time and its costs were below
initial estimates. It has enabled the sugar and alcohol industries to develop
their own technological expertise along with greatly increased capacity. It has
increased independence, made significant foreign-exchange savings, provided the
basis for technological developments in both production and end-use, and created
jobs. Overall, Brazil’s success with implementing large-scale ethanol production
and utilization has been due to a combination of factors which include:
government support and clear policy for ethanol production; economic and
financial incentives; direct involvement of the private sector; technological
capability of the ethanol production sector; long historical experience with
production and use of ethanol; co-operation between Government, sugarcane
producers and the automobile industry; an adequate labour force; a plentiful,
low-priced sugarcane crop with a suitable climate and abundant agricultural
land; and a well established and developed sugarcane industry which resulted in
low investment costs in seeing up new distilleries. In the specific case of
ethanol-fuelled vehicles, the following factors were influential: government
incentives (e.g., lower taxes and cheaper credit); security of supply and
nationalistic motivation; and consistent price policy which favoured the
alcohol-powered car.
Zimbabwe
Zimbabwe is an example of a relatively small country which has begun to
tackle its import problem while fostering its own agro-industrial base. An
independent and secure source of liquid fuel was seen as a sensible strategy
because of Zimbabwe’s geographical position, its politically vulnerable
situation and foreign-exchange limitations, and for other economic
considerations. Zimbabwe has no oil resources and all petroleum products must be
imported, accounting for nearly $120 million per annum on average in recent
years which amounted to 18 per cent of the country’s foreign-exchange earnings.
Since1980 Zimbabwe pioneered the production of fuel ethanol for blending with
gasoline in Africa. Initially a 15-per cent alcohol/gasoline mix was used, but
due to increased consumption, the blend is now about 12 per cent alcohol. This
is the only fuel available in Zimbabwe for vehicles powered by spark-ignition
engines. Annually, production of 40 million litres has been possible since
1983.
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