Mainly, the reason behind the development of alternative fuels has been the price and pressure of foreign oil dependency. The political ramifications are far-reaching, and sometimes devastating. However, the environmental costs could be even more destructive than any war fought over petroleum supplies. Global warming is just that, global, and scientists disagree whether or not it is already too late to make changes.
August 28, 2012 was a landmark event for the US Environmental Protection Agency [EPA] and Department of Transportation [DOT]. Adding to the previous mandate to achieve 35.5 miles-per-gallon [mpg] average light vehicle fuel economy by 2016, the new mandate is requiring that by the year 2025, the average light vehicle fuel economy will need to meet 54.5 mpg. Considering that the average fuel economy for light vehicles on the road in 2008 was only 22.8 mpg, this more than doubles the fuel efficiency standard we see in the light vehicle fleet today.
Alternative Fuels Today
One alternative fuel already in widespread use is ethanol. Ethanol, or grain alcohol, is typically made from corn crops and other grain distillations. Think white lightning, which back in the early days of automobile manufacturing, Henry Ford proposed as an ideal and readily available vehicle fuel, before gasoline became a viable alternative. Nearly all the gasoline in the US is blended up to fifteen percent ethanol, to oxygenate the fuel, reduce emissions, and extend the fuel supply. Gasoline-powered vehicles require no modifications to run these blends and drivers report no performance problems with them.
Because ethanol contains about 35% less energy per gallon, unmodified vehicles can’t run concentrations much higher without serious performance problems. Flex-fuel vehicles have been modified to run blends up to 85% ethanol. Sensors in the fuel system detect the fuel concentration and adjust the ignition and timing systems electronically to extract the most energy from the less energy-dense fuel blend.
Bio-diesel is another widely-available alternative fuel which, instead of being refined from petroleum sources, can be refined from vegetable and animal oils. Used restaurant grease is a common source of bio-diesel feedstocks. Because bio-diesel contains slightly less energy than petro-diesel, it is often used to blend with petro-diesel up to 20% with no discernible loss in performance. Diesel-powered vehicles require no modifications to run pretty much any blend percentage or even pure bio-diesel.
Availability of some other non-petroleum-based alternative fuels is limited. Natural Gas, Propane, Bio-Gas, and xTL Fuels are either in development or used in a very limited capacity, such as fleet vehicles. One thing all these fuels have in common is that they still make use of carbon-based fuels. While the net carbon-dioxide [CO2] may be offset by the use of bio-mass feedstocks, there is still CO2 being generated. What if we could eliminate the carbon completely?
Alternative Fuels Tomorrow
Electrified vehicles are a major step in the elimination of carbon from the transportation sector. Hybrid Electric Vehicles [HEV] were the first step, and as battery and control technologies were advanced, it became more feasible to build Pure Electric Vehicles [EV] that had sufficient range and power to be useful. Part of the drawback of an EV, though, is that it is only as clean as the power grid it is plugged into. If the power grid is supported by clean sources, then CO2 emissions are minimal, but some parts of the grid aren’t so clean, and CO2 emissions there can be even worse than half the gasoline-powered vehicles in the US.
Hydrogen is an interesting alternative fuel under development, because it can be used, not only in internal combustion engines, but also in electrified vehicles. Additionally, there are no CO2 emissions, because Hydrogen [H2] doesn’t have any carbon. Hydrogen, the most abundant element in the universe, almost never exists in a free state as H2, but is typically locked up in other molecules, such as water [H2O] or even hydrocarbons [CHx]. Freeing the hydrogen from these sources efficiently and cleanly is a major obstacle that needs to be overcome before hydrogen can be a viable alternative.
As manufacturers put more effort into reaching the new mandates for fuel efficiency and greenhouse gas emissions, we’ll begin to see some of these new alternative fuels come into widespread use. Consumer attitudes will have to change as well, but it will be for the better, to stop damaging the atmosphere and hopefully make the future a little safer for our grandchildren.