How It Works: Ethanol

Not everthing that goes into your car's fuel tank is liquefied dinosaurs

by JIL MCINTOSH | OCTOBER 24, 2018

Although gasoline is a fossil fuel, not everything you put in your tank is liquefied dinosaurs. Almost all fuel sold in Canada contains a percentage of ethanol, a plant-based renewable fuel.

The federal government requires a minimum of 5 per cent renewable fuel in gasoline and 2 per cent in diesel, across each fuel producer or importer’s overall volume. Provinces can set standards above that if they choose: Manitoba’s minimum is 8.5 per cent, while Saskatchewan is 7.5 per cent. Many fuel companies initially concentrated ethanol in their lower-grades and kept their premium-grade fuel ethanol-free, but that’s no longer a guarantee, and you’ll have to check to see what you’re getting.

Ethanol isn’t new — Henry Ford advocated for it in the 1920s — but Canada’s mandatory requirement only arrived in 2010. The US makes about 60 billion litres annually, but in Canada, production is mostly a niche industry. We made 1.9 billion litres in 2017 but used three billion, and imported American ethanol to make up the shortfall.

Ethanol can be made from almost any type of plant, but the U.S. almost exclusively makes its fuel from corn, as does Eastern Canada. Producers in Western Canada mostly use wheat. Brazil, which makes about 30 billion litres a year, uses cane residue from sugar processing.

Most grain-based ethanol is produced by dry milling, grinding the grain and fermenting it to produce alcohol that’s then processed into fuel. It can also be made by wet milling, where the grain is soaked and separated for processing into several different products, including corn sweeteners and corn oil, along with the alcohol base. For ethanol made with cellulosic biomass — such as wood, straw, switchgrass, cornstalks, or paper — the feedstock is ground up, chemically treated to free up the cellulose, and fermented to produce alcohol. Alternatively, some producers dry the feedstock and then burn it to create synthetic gas, which is passed over a catalyst to form ethanol molecules.

Ethanol-blended fuel is named for the percentage of renewable fuel in it. E10 is composed of 10 per cent ethanol and 90 per cent gasoline, while E85 is 85 per cent ethanol and 15 per cent gasoline. Most engines made after 2001 can handle E10 or even E15, but E85 can only be used in engines that are prepped for it, known as “flex-fuel engines.” B5 indicates five per cent biofuel mixed into 95 per cent diesel. For diesel engines, B5 is considered acceptable for all, but some automakers warn against using B20 — 20 per cent biofuel in diesel — and drivers should check their owners’ manuals.

Flex-fuel engines can run on any mixture, from straight gasoline right up to E85, without the driver doing anything to switch over, and that’s a good thing, because very few stations actually sell E85 fuel. Rather confusingly, vehicles with flex-fuel engines usually have a yellow fuel filler cap, and while E85 pumps often use yellow fuel nozzles — as do many diesel pumps, so be sure you’re pulling up to the right pump.

A high concentration of ethanol, such as E85, creates an issue for conventional engines because it’s corrosive and has approximately 30 per cent less energy than gasoline, although it has higher octane rating. Flex-fuel engines have special seals to handle ethanol’s corrosive properties; their control modules are calibrated for ethanol’s higher oxygen content, and their fuel pumps and injectors can handle the higher volume of fuel required with lower-energy ethanol. As an example, Natural Resources Canada rates a Chevrolet Silverado with GM’s 5.3L flex-fuel V8 engine at 12.7 L/100 kilometres on gasoline, but 17.1 when using E85.

Ethanol can be as controversial as it is common. On the plus side, it’s made from renewable feedstock and can be produced from waste products, such as discarded paper or forestry by-products. As long as a processing facility exists, it can be made virtually anywhere, since not every country has accessible oil reserves but all can grow feedstock crops. It burns cleaner than gasoline and creates fewer harmful emissions. Because it has higher octane, it can be blended with slightly lower-octane gasoline to bring it up to an 87-octane rating.

On the minus side, its detractors cite such issues as dedicating acreage to fuel rather than food production, and these crops require petroleum-fuelled machinery, as well as fertilizer and pesticides. Ethanol is hygroscopic, meaning that it attracts water, and can only be transported through pipelines under specific conditions; it’s mostly carried by truck or train.

Many small-engine manufacturers recommend using nothing higher than E10 in lawnmowers and other equipment, and since these engines are seldom used daily, ethanol’s love of water can create issues if the fuel sits in the tank for too long. It can create similar issues in antique cars that are only driven occasionally, and owners have found that ethanol can affect cork gaskets and fuel floats on older engines.

If you’re not sure about your vehicle, check your owner’s manual. For small engines, you can buy small cans of ethanol-free fuel. There are also several websites that track stations and the availability of pure gasoline at specific locations.

Article cited from: https://goo.gl/np7u8w