common use for ethanol is as a fuel or fuel-additive. Ethanol for use as a fuel is generally dosed with a ‘denaturant’ to render it unsuitable for human consumption.
As we have mentioned previously, there has been significant experience worldwide in the use of ethanol as a fuel or fuel-additive. In the USA there has been over ten years successful use of gasoline containing up to 10% ethanol (E10), and in Brazil blends containing up to 85% to 100% ethanol (E85 and E100) are commonly used in flexible-fuel vehicles. The current European gasoline specification, EN228, allows up to 5% ethanol by volume (E5).
Whilst bioethanol can be produced from a number of raw materials, including sugar cane, corn and wheat, the raw materials do not impart the same variation in properties of the end product fuel as is the case with FAME. However, there are still a number of potential hazards for consideration.
Bioethanol problems
Water contamination: Issues with regard to the carriage of bioethanol and bioethanol-gasoline blends include the potential for damaging water contamination. We mentioned previously that ethanol is hygroscopic
and highly soluble in water. Small quantities of water can be dissolved in gasoline/bioethanol blends, but, dependent upon temperature and the gasoline/ bioethanol blend ratio, there is a critical threshold level of water that can be dissolved. Once this threshold level has been exceeded, irreversible phase separation will occur whereby the water causes the ethanol to separate from the gasoline, forming an alcohol rich water/ethanol aqueous phase and an alcohol poor gasoline phase. The alcohol rich aqueous phase will collect at the bottom of the ship’s tank or storage tank. This phase is likely to be highly corrosive and will not be able to be used as fuel. In addition, if such phase separation does occur it is possible that the gasoline phase will be classed as Pollution Category Z, which means that it is considered to present a “minor hazard to either marine resources or human health” if discharged into the sea from tank cleaning or deballasting operations and therefore “justifies less stringent restrictions on the quality and quantity of the discharge into the marine environment”. Whilst the regulations do not require ethanol to be carried on a chemical tanker, ethanol is generally shipped on chemical tankers to maintain the integrity of the product.
It should be noted at this juncture that the terms biodiesel and bioethanol do not appear in the IBC Code. As it is a requirement that the proper shipping name be used in the shipping document for describing any product to be carried which appears in the IBC Code, these terms cannot be used to describe the products being carried.
The situation becomes somewhat more confusing when we consider how blends of conventional fossil fuels and biofuels are shipped, and which Annex of MARPOL they fall under. MARPOL Annex I covers the prevention of pollution by oil and MARPOL Annex II covers the control of pollution by noxious liquid substances carried in bulk. Blends of biofuels and
26
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32