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Ethanol vs Methanol
WARNING : Methanol is extremely toxic!
188.8.131.52 Health Issues - Methanol is extremely toxic.Exposure to very small amounts of methanol (less than one cup)have been known to cause blindness and permanent injury including death. Exposure to methanol can occur through inhalation of vapor, or through ingestion or skin contact with the liquid fuel.
Be careful not
to confuse ETHANOL with METHANOL!
Ethanol is a renewable energy fuel fuel made from sugar crops, such as sugar cane and corn. Methanol, on the other hand is made from fossil fuels such as coal and natural gas.
Below is an excerpt from an important recent study from the U.S. Department of Transportation:
Clean Air Program -- Assessment of the Safety, Health, Environmental and System Risks of Alternative Fuels
3.3.1 Methanol vs 3.3.2 Ethanol
Methanol 3.3.1 : General Description:
Methanol or methyl alcohol is a clear colorless liquid that can be made from a variety of fossil fuel sources including coal and natural gas. All methanol used commercially in the United States is manufactured from natural gas because this is by far the most economical feedstock. Wherever natural gas is unavailable methanol is manufactured from coal.
184.108.40.206 Health Issues - Methanol is extremely toxic.Exposure to very small amounts of methanol (less than one cup)have been known to cause blindness and permanent injury including death. Exposure to methanol can occur through inhalation of vapor,or through ingestion or skin contact with the liquid fuel.
The toxic effects of methanol are the same regardless of themeans of exposure. Considering the fact that methanol is quite volatile, it is most likely that the typical route for exposureis through inhalation of methanol vapors. The measure of fuel toxicity is the threshold limit value (TLV). For methanol vapor, the TLV value is 200 ppm, five times more toxic than other alternative fuels volatile at normal ambient temperature.
The major environmental issues of concern with Methanol is a fuel spill, particularly a spill that reaches a sewer or drainagesystem. One of the physical properties of methanol that affectsfuel spills is its water solubility. Normally, fuel handling facilitiesthat have an emergency drain connecting to a sewer will have aseparator to ensure that the fuel (gasoline or diesel) will notreach the sewer. This approach will not work with methanol since it is soluble in water and will pass directly through the separator.
Methods for separating methanol from water exist but they arequite complex and costly. Due to methanol's extreme toxicity, the best approach is to ensure that any spills in a facility are absolutely prevented from entering any drain through the use of impoundment systems to contain the entire volume of any potential above ground spill. In a bulk transport situation there is obviously no way to provide such assurance.
Often, methanol fuel is designated M-100 to identify it asessentially 100% pure methanol. A popular methanol blend composed of 85% methanol and 15% unleaded gasoline is designated as M-85.
220.127.116.11 Safety Issues General Properties Affecting Hazards One general physical characteristic that differentiates methanol fromother fuels is its corrosive characteristics.
Methanol is incompatible with several types of materials normally used in petroleum storage and transfer systems, including aluminum,magnesium, rubberized components, and some other types of gasket and sealing materials. Therefore it is necessary to take special precautions to ensure that methanol is transported or stored in containers and transfer lines that have been specifically selected for that purpose.
The other significant difference between methanol and otherfuels is that it is considered to be more toxic. However, exposure limits for inhalation of methanol vapor are only slightly lowerthan those for gasoline (200 ppm threshold limit value [TLV] formethanol vapor; 300 ppm for gasoline vapor). Since gasoline is much more volatile than methanol, it is likely that more gasolinevapors will be generated for an equivalent spill volume and therefore are more likely to be hazardous to the persons exposed. An other general property of methanol is the low flame luminosity of a pure (M-100) methanol fire.
This makes it difficult to see the fire or even estimate its size, particularly if it occurs in bright daylight. The methanol blends (M-85) have increased visibility to a certain degree because the burning of the gasoline fraction produces some luminance.Another negative aspect of interest is the relative vapor density of methanol compared to air; methanol vapor is heavier than air.Therefore the vapor will tend to accumulate at ground level or in low-lying areas such as maintenance pits.
If the methanol vapor is not quickly dissipated through adequate ventilation, it will linger in the low-lying areas creating an increasing opportunity for exposure to an ignition source andfire.
Fire Hazards During Transport Storage of Methanol One specific issue that must be considered is the possible use of materials that may not be methanol compatible in the tanker truck.
This could become a problem if there is a long-term exposureof methanol to seals and gaskets that may deteriorate and becomesubject to leaks. One physical characteristic of methanol that is an important fire hazard consideration during both transport and storage is the combination of vapor pressure and flammability limits. For M-100, vapor/air mixtures are potentially flammableat volume concentrations ranging from6.7 to 36 percent. In a fuel or storage tank, a methanol liquid temperature between 10C to43C(approximately 50F to 110F) at standard atmospheric pressure will create a flammable vapor/air mixture.
Therefore any ullage space in a container or storage tank thatis vented to the atmosphere will contain flammable vapor-air mixturesat normal ambient temperatures found in transpo