THE BRAZILIAN EXPERIENCE WITH ETHANOL FUEL : ASPECTS OF PRODUCTION , USE , QUALITY AND DISTRIBUTION LOGISTICS

The reduction in the availability of fossil fuel increased the search for alternative fuel sources (for example, ethanol). In the Brazilian market, light duty vehicles can be fueled with gasohol (18 up to 27.5 %v/v of anhydrous ethanol in gasoline) and/or hydrous ethanol. To minimize the risk of water-induced phase separation of gasoline-ethanol blends, anhydrous ethanol is blended into gasoline at the distribution terminal, rather than distributing it through pipelines. Pure ethanol can be distributed through pipelines or trucks, and in pipeline cases almost all are not exclusive. To monitor the ethanol quality, several fuel sampling points are indicated: storage tanks, pipelines, and ship, if applicable. For these samples, it is important to evaluate the following parameters indicative of product quality: hydrocarbon and water amount, color, conductivity, and acidity. Monitoring ethanol storage, transport and distribution is important to maintain the ethanol quality until the final consumer.


INTRODUCTION
The reduction in petroleum reserves, the perspective of supply disruptions, price volatility, as well as environmental issues, have led to the consideration of alternative and renewable liquid fuels to replace conventional petroleum-derived fuels.
Oil remains the world's leading fuel, with 32.6% of global energy consumption.Renewable energy accounts for 3.0% of global energy consumption, but the trend is the growth of its use (BP Statistical Review of World Energy, 2015).
The dominant biofuel in many countries is ethanol, that has been used as blend component in gasoline or as pure fuel, as in Brazil.The main benefit of ethanol is that it can be produced from various renewable raw materials and the life cycle assessment (a tool for evaluating environmental effects of the fuel based on the production, usage and disposal) is an advantage for this fuel compared to fossil fuels (Larsen et al., 2009).Ethanol can be produced from biomass such as sugar cane (mainly in Latin America), wheat and sugar beet (mainly in Europe), corn (mainly in the United States), and other grains.The production of ethanol from biomass involves fermentation and distillation, basically.
Global production of ethanol in 2014 was 94 billion liters.Although the United States and Brazil dominated overall volume, Asia experienced particularly high production growth rates (Renewables, Brazilian Journal of Chemical Engineering 2015).In Brazil around 56% is hydrous ethanol and 44% is anhydrous ethanol (Boletim Mensal dos Combustíveis Renováveis, 2014;Brazilian Energy Balance, 2014).
The US Renewable Fuel Standard (RFS; Subtitle A) of the Energy Independence Security Act (EISA) of 2007 has made it a requirement to increase the production of ethanol and advanced biofuels, starting at 9 billion gallons in 2008, to 36 billion gallons for total renewable biofuels by 2022.Comparing 2000 and 2011, the sources of US gasoline supply (by volume) changed from 1% to 10% for ethanol, which reduced the imported crude oil.
In Europe, Directive 2009/28/EC (RED) requires a 20% share of total energy from renewable sources, and places a mandatory 10% minimum target, to be achieved by all Member States, for the share of biofuels in transport petrol and diesel consumption by 2020.A 10% share on an energy basis represents about a 14% share of road fuels on a volumetric basis (CONCAWE, 2009).At the same time, an amendment was adopted to Directive 98/70/EC1 ("The Fuel Quality Directive") which introduced a mandatory target to achieve by 2020, a 6% reduction in the greenhouse gas intensity of fuels used in road transport.Directive 2009/30/EC sets regular blend maxim at 10%v/v of ethanol (E10), or oxygen maximum content of 3.7 %m/m.
In Brazil, the total area is 850 million hectares and around 0.8% is used for sugar cane production.Nowadays, the sugar cane production is around 72 ton per hectare (635 thousand ton for 2014/2015 production) and ethanol production can reach 7 thousand liters per hectare (1 hectare = 2.47 acres).In 2014, the ethanol production was 28.1 billion liters (Boletim Mensal dos Combustíveis Renováveis, 2015).According to the Brazilian Sugarcane Industry Association (UNICA), for the 2012/2013 crop, 53% of the revenue was provided by sugar, 42% by ethanol, 3% by electricity, and 2% by others (Boletim Mensal dos Combustíveis Renováveis, 2014).
Figure 1 shows the location of ethanol plants in Brazil.They are concentrated in the center-south and northeast Brazil.

USE OF ETHANOL IN BRAZIL
The use of ethanol as an automotive fuel is a quite old practice and, in Brazil, since 1931 it has been the target of numerous government measures with respect to its addition to gasoline.
The addition of ethanol to Brazilian gasoline had the initial goal of reducing imports of petroleum derivatives and, in a second moment, solves the problem of ethanol over production due to the falling sugar price in the international market.
The addition of ethanol to Brazilian gasoline was random and the percentage added varied depending on the harvest of ethanol and sugar price on the international market.But in 1979, with the consolidation of ProAlcool (program to motivate the ethanol production and use, started in 1975), the government fixed the addition of 20 %v/v of anhydrous ethanol to gasoline.It is important to point out that, during the four years of the program, vehicles were converted to use neat ethanol and in 1979 the first ethanol powered car, with engine designed to run on neat ethanol, left the assembly lines.
In 2003 production started of flexible fuel vehicles (FFVs) that can operate with any mixture of hydrous ethanol and gasohol (blend of anhydrous ethanol and gasoline).The ethanol content in gasohol, which should be in the range of 18-27.5 % v/v, is fixed by the government and depends on market forces.
In response to these facts, Brazilian ethanol production has grown over the past decades.In 2013 ethanol represented 4.8% of the final energy consumption in Brazil, while gasoline represented 9.4%.In 2013, renewable energy (hydraulic, firewood, sugar cane products, and others) in Brazil represented around 46% of the total primary energy production (258.3x 10 6 toe) (Brazilian Energy Balance, 2014).
Figure 2 shows the Brazilian automobile fleet evolution in terms percentage depending on the fuel used.Recently, most new vehicles in Brazil are FFVs.Of the total amount of light vehicle licensing in Brazil, the FFVs accounted for something around 88%.

PRODUCTION PROCESS AND DISTRIBUTION LOGISTICS OF ETHANOL IN BRAZIL
It is known that water can be removed from ethanol only to a certain degree by traditional distillation methods, and then another relatively energy costly process removes the remaining water, a fact that makes anhydrous ethanol approximately 20-25% more energy demanding to produce than the ethanol/water azeotrope (hydrous ethanol) (Larsen et al., 2009).
According to ANP Resolution nº19/2015, anhydrous ethanol (EAC) can have up to 0.4 %v/v of water and hydrous ethanol (EHC) can have up to 4.9 %v/v.Thus, ethanol quality in the distribution system is routinely required.

ETHANOL QUALITY ASPECTS
For fuels to be useful in the transportation sector, they must have specific physical properties that allow efficient distribution, storage and combustion.
Ethanol storage, transport and distribution monitoring is important to maintain the ethanol quality until the final consumer.
Brazilian Ethanol Specification (ANP Resolution nº 19/2015) presents the parameters that are controlled by the producer/provider/operator, distribution and importer.
Producer/provider/operator and importer are responsible to emit the Quality Certificate, that must contain the results for color and appearance, total acidity, electrical conductivity, density, pH (hydrogen ionic potential), and alcohol, sulfate, iron, sodium, copper, and sulphur content.
Distribution is responsible for emiting the Accordance Bulletin that must contain the results for color and appearance, electrical conductivity, density, pH and alcohol content.
If the ethanol was transferred by pipelines or for imported fuel, the Certificate and the Bulletin must also contain the result for evaporation residue and hydrocarbon content.Otherwise, if the ethanol was transferred by waterway, it must also contain the result for evaporation residue, hydrocarbon, and chloride content.Water, ethanol, and methanol content are required in the case of doubts of quality, or imported fuel.
Petrobras also monitors, in pipelines, ship and trucks, parameters such as color, appearance, electrical conductivity, density, alcohol and hydrocarbon content.
Table 1 lists some ethanol parameters reported in the ANP Resolution, and their relation to fuel quality control.Table 2 shows ethanol characteristics and their effects on the vehicle.
In cases where ethanol is mixed with gasoline, the automotive industry's guiding document towards improved and harmonized market fuel quality is the Worldwide Fuel Charter (2013).Up to 10% by volume of ethanol is permitted by existing regulations, and ethanol should meet the Ethanol Guidelines published by the WWFC Committee (Ethanol Guidelines, 2009).
In the transport system, ethanol can be contaminated by products remaining in the tanks and lines, inadequate operational maneuvers, problems with  sealing systems, incorporation of solids due to corrosion of lines, relocation of cargo ships and product adulteration.
To monitor the ethanol quality in this system, several fuel sampling points are indicated: storage tanks, pipelines (at pumping units -beginning, middle and end of pumping ethanol), service station, and ship, if applicable.
Petrobras conducted a follow-up study of ethanol transported by pipelines after 1, 3 and 5 hours and in the final 500 m 3 .It was found that the conductivity, water content, hydrocarbons and acidity are higher in the beginning than at 3 hours.The reduction depends on the sample analyzed.Changes in the product quality were not observed during transportation after this period.As noted, the greatest contamination of the ethanol may occur at the start of pumping, as expected, and differences in color are caused by different pollutants or different concentrations.
It is important to mention that anhydrous ethanol in Brazil must receive a dye.In some cases the dye is added by the sugarcane industry and in others by the company responsible for the final product distribution.The anhydrous ethanol with dye cannot be transported by pipeline due to other products pumped in polyducts.
For storage of the ethanol in the production or distribution centers, tanks with floating ceiling and dome are normally used to minimize water absorption and vapor emissions.Another option is to use a fixed ceiling with floating membrane.
Carbon steel for tanks and pipelines works fine with ethanol fuel as long as it does not contain ionic impurities that increase its corrosiveness.Stainless steel is the best material for ethanol tanks, pipelines, and components, but it is expensive compared to most other materials used for fuel tanks and piping.Some carbon steel tanks are coated internally with an epoxy to prevent corrosion over time, but it is necessary to evaluate each epoxy type, because some are not compatible with ethanol.In Brazil, years of practical experience have shown that ethanol can be distributed using these materials without major problems.
Another material commonly found in fuel storage and dispensing is aluminum.When exposed by removal of nickel plating, aluminum was found to be susceptible to widespread pitting.The exposure of the substrate accelerated corrosion due to a combination of galvanic coupling of dissimilar metals and the increased conductivity of the environment (Kass et al., 2012).
If aluminum and magnesium alloys are attacked by alcohol fuel blends, another type of corrosion is observed, called ''dry corrosion'' (Kruger et al., 2012;Keuken, 2013).
Several studies show the corrosion behavior of several aluminum alloys in ethanol fuels.Kruger et al. (2012) investigated this topic by immersion and polarization tests with anhydrous ethanol with water content between 0.05 %v/v and 0.3 %v/v, and temperature in the range between ambient and 80 ºC.They noted that, while high alloyed stainless steels are regarded to be resistant to ethanol fuels of any mixture, for aluminum alloys the addition of water restrains the corrosion.Steels and other metals will corrode if the water content in the fuel mixture is high enough to promote phase separation.Park et al. (2011) examined the effects of dissolved oxygen on the corrosion of aluminum alloy at high temperature (100 ºC) for E20 fuel (a blend of 20 %v/v of anhydrous ethanol in gasoline) by electrochemical tests and surface analyses.They noticed that the water formed by dissolved oxygen in this fuel enhanced the corrosion resistance of the aluminum alloy by promoting the formation of a protective surface film.Keuken (2013) studied the conductivity of E10 (dry, with 0.2% and 0.5% of water) adding salt water (0.1 to 1.0%, of 3 grams per liter solution).For the same amount of salt water (0.5% to 1.0%, because for low concentrations the salt precipitates out), dry E10 presented higher conductivity than E10 with 0.2 and 0.5% of water.The author concluded that it is necessary to stipulate a minimum water content in fuel ethanol for direct blending of E5, E10 and higher blends to avoid alcoholate (alkoxide) corrosion, and it is also necessary to set a maximum water content for these fuels to ensure that phase separation issues will not occur.It is worth mentioning that E10 and E5, respectively, correspond to blends of 10 %v/v and 5 %v/v of ethanol in gasoline.
Concluding, to guarantee the quality of ethanol, avoiding contamination of the product, it is recommended to: (1) study in detail the history of ethanol batches in order to establish operational procedures for the ethanol transport logistics; (2) dry the storage tanks prior to receiving ethanol; (3) check the current cleaning procedures for storage tanks and, if necessary, establish new standards to prevent water contamination, corrosion products or degradation of coatings of tanks; (4) ensure the integrity of the seal coating and storage tanks; (5) avoid long-time stops of the pumping duct; (6) establish a procedure for passage and maintenance of pig cleaning and separation of products from batches of ethanol and hydrocarbons; (7) avoid chemical injection directly into ethanol and limit their use in products that are trans-

Brazilian Journal of Chemical Engineering
In E10, at the same temperature, water solubility is around 5 to 7 L×m -3 (5,000 to 7,000 ppm) due to ethanol´s hydroscopic properties; however, at -12 ºC a gasoline-ethanol blend will tolerate approximately 3 L×m -3 (3,000 ppm) water.Once the solubility limit is exceeded, phase separation occurs and two phases are formed: an upper gasoline-rich liquid layer and a bottom ethanol-water rich liquid layer (Passman et al., 2009).Tables 3 and 4 show experimental results of a study conducted by Petrobras that illustrates these statements about the water tolerance and phase separation tendency (indicated by the cloud point) of gasoline-ethanol blends.
Table 3 shows cloud point changes with the amount of hydrous ethanol and the gasoline composition in gasoline-ethanol blends.Increasing the hydrous ethanol fraction decreases the phase separation temperature, and increasing the concentration of aromatics and olefinic hydrocarbons (HCs) also decreases this temperature.
Table 4 shows that, upon increasing the water content in gasoline-ethanol blends by manual addition, the cloud point also increases.Investigations by the Process Design Center (PDC) led to research work that revised the understanding of water tolerances of ethanol-gasoline mixtures and the conditions under which phase separation occurs.To verify and validate this discovery, covered by international patents WO 2006/137725 A1 and WO 2009/096788 A1, HE Blends BV (a separate entity of PDC) pursued its continuing test programs in Europe, testing vehicles with hydrous blends.The Netherlands experience showed that HE15 (a gasoline-ethanol blend with 15 %v/v of hydrous ethanol) works well between -10 and +30 ºC ambient conditions (Source: PDC and HE Blends).
During the BEST project (Bio Ethanol for Sustainable Transport) more than 10.000 ethanol powered cars were evaluated.HE15 and E10 (a gasolineethanol blend with 10 %v/v of anhydrous ethanol in gasoline) showed any negative impact on engines in bench and fleet tests.Another conclusion of this study was that HE15 cannot be mixed with E10 or neat petrol and must have a separate infrastructure.Otherwise there is a risk of water separation in the fuel.In Rotterdam HE15 has been demonstrated and introduced successfully.The hydrous ethanol used to form this fuel has a maximum 6.5 %m/m of water.
The strategy behind this hydrous ethanol is to minimize production costs, because less effort/energy is needed to remove water from the ethanol.Because hydrous ethanol is less expensive and more CO 2 friendly to produce compared to anhydrous ethanol, there are economic and environmental incentives for the presence of water in the fuel blends.However, as mentioned previously, in cold climate conditions, phase separation of ethanol with high water content and gasoline blends may occur.

Volatility
Volatility refers to a fuel's ability to change from liquid to vapor, and it is commonly measured by the vapor pressure and the distillation curve.These properties can affect proper engine cold starting, vapor lock tendency in older engines without fuel injection (e.g., carbureted engines), and the quality of starting in engines with fuel injection.Vapor pressure is a critical factor in meeting evaporative emission requirements.
Fuels with excessively high vapor pressure may contribute to hot drivability/hot restart problems such as vapor lock.Fuels of too low volatility may contribute to poor cold starts and poor warm up performance in vehicles.
The distillation curve provides insight into the boiling range of the fuel and can be used to predict  Brazilian Journal of Chemical Engineering Vol. 33, No. 04, pp. 1091-1102, October -December, 2016 function (fluorinated for "O" rings).The base gasoline (gasoline without ethanol) had 324 ppm v/v of sulfur, 26 %v/v of aromatics, 23 %v/v of olefinics, and 51 %v/v of saturated compounds.
The elastomer samples were immersed in each fuel at 60 ºC for 7, 14 and 28 days, and the changes in the weight, hardness, and mechanical properties (traction) studied.In general, the aged samples showed a reduction in the hardness, and an increase in the mass variation, tensile strength and E-modulus.For the hardness, mass variation, tensile strength and E-modulus results, it was observed for all samples that the changes occurred with 7 days of immersion and, after that, the results remained almost unchanged.Maciel et al. (2013) indicated that this kind of change occurs by the first day and, after that, remains almost constant.
The mass variation increased after elastomer immersion, more for nitrile elastomers, and less for gasohol -hydrous ethanol blends.Maciel et al. (2013) observed that pure ethanol resulted in a decrease in weight, different from the one observed for gasoline samples with ethanol (gasohol).
Comparing the results obtained with nitrile and fluorinated elastomer, the latter showed the best fuel resistance.

CONCLUSIONS
This paper considers some issues related to ethanol: production, quality, use, logistics transportation and the effects of its addition to gasoline on some properties (miscibility, volatility and elastomeric materials compatibility).Procedures are indicated to minimize the risk of water-induced phase separation of gasoline-ethanol blends and to monitor the ethanol quality.
It is important to evaluate the following parameters indicative of ethanol quality: hydrocarbon and water amount, color, conductivity, and acidity.
Monitoring ethanol storage, transport and distribution are important to maintain the ethanol quality until the final consumer.