BlueGreen World

Tuesday, July 11, 2006

Biodiesel vs Gas Hybrids

Many people have been wondering about this, seemingly from a standpoint of hoping to keep gasoline in their transportation mix. It's sometimes confusing. Anyone not looking for a way out of the petroleum matrix is either pegged by Resident Bush as an addict or making money from the petroleum industry. Whatever the case may be, here's the most authoritative statement on biodiesel vs hybrid-gasoline technology I've personally found to date.

From BiodieselNow Forum, 10-19-2004

From : Dr. Jon VanGerpen of Iowa State University on gasoline vs. biodiesel

"If you set a modern gasoline engine and a modern diesel engine with equal
power side-by-side and measure the emissions coming from the engine, this
is what you will find. The gasoline engine will produce much more carbon
monoxide and unburned hydrocarbons, the diesel will produce more
particulate matter, and the oxides of nitrogen will be about the same
(those are the 4 regulated pollutants). Now, when the catalytic converter
is added to the gasoline engine, it greatly reduces the carbon monoxide,
unburned hydrocarbons, and oxides of nitrogen. So, the gasoline engine
becomes very clean. ( Note by pjs: A catalytic converter and particulate matter (PM) filters can be added to diesel cars that strictly use a sulfur free fuel such as biodiesel reducing PM by 90%). Today, most passenger car emissions come from the
first 20 seconds of operation when the catalytic converter is warming up or
from older cars that were built before strict emissions controls. Modern
gasoline-powered car engines, when they are running properly, are actually
very clean. So, if you are making your decision based only on tailpipe
emissions, then the gasoline engine will win. Even when biodiesel is added
to the diesel engine to reduce carbon monoxide, unburned hydrocarbons, and
particulates, the NOx will still be higher than the gasoline vehicle. When
only comparing tailpipe emissions, and only looking at ozone production, a
gasoline-powered vehicle will produce less ozone.

If this is the case, you might ask why diesels are considered to be "the
Green option" in Europe? It is because they are looking at more than
tailpipe emissions and ozone. Another major source of emissions from
gasoline vehicles is from the evaporation of the gasoline during refueling,
from spills, and even while the engine is running. These emissions do not
exist for diesel engines since the fuel is not volatile. Since ozone
comes from reactions between oxides of nitrogen and unburned hydrocarbons,
the gasoline vehicle can be a contributor to ozone production even when its
tailpipe is clean. The Europeans also believe strongly in diesels because
they are much more efficient that gasoline cars. You should get 30-50%
better mileage with a diesel-powered vehicle than with a gasoline-powered
car. The mileage with biodiesel will be slightly less than with diesel
because of its lower energy content, but still much better than
gasoline. This means that you are emitting less carbon dioxide,
contributing less to global warming, and consuming fewer fossil
resources. Add to this the fact that the carbon in biodiesel originates
from carbon dioxide in the air instead of from petroleum, and you have a
major environmental advantage. Most researchers have concluded that when
you look at the total environmental impact, that diesels are a better
choice than gasoline engines. And, as noted before, the emissions from a
biodiesel-fueled diesel are less than a diesel fueled with conventional
diesel fuel.

I'm sorry this answer is so long. I've never had someone ask the emissions
question this way. Most people are interested in comparisons between
regular diesel and biodiesel, not between gasoline and biodiesel. Good
luck with your decision making!"


The domesticity of biodiesel, the role it stands to play in individual small-scale fuel production, self-reliance, and sustainability is not even mentioned. The volatility of gasoline vs. biodiesel goes unmentioned as well, but of course biodiesel is not a volatile fuel (unlike ethanol, methanol, and other alcohols). Renewability, sources from waste/used vegetable and other oils, and job creation in the states and small communities are not mentioned either.

The sociocultural ramifications of biodiesel use and its variable role in our energy solutions is vast and not to be underestimated. SVO also shows more promise than most mainstream press has given it. Diesel engines will continue to build this - and other countries - infrastructure. There is no substitute for these powerful engines on the horizon. They will continue to move the earth, water, snow, rock, and forests with effectiveness unoffered by other types of vehicles, like it or not. Change the public policy and how it's all done, by all means. But recognize that these engines will power on, and if nothing else, the toxins they spew while operating can be minimized for the benefit of everyone simply breathing the air on this planet.