Dreamer - sorry I come off as confrontational- I'm as committed to my positions as you are to yours, and I get a little strident - it's nothing personal.
Anyway, I wanted to show you some research that's out there regarding BD emissions - it's a PDF, so type it into your browser - I've excerpted a part of it below:
Exhaust Emissions of Biodiesel, Petrodiesel, NeatMethyl Esters,and
Alkanes in a New Technology Engine
www.biodiesel.org/resources/reportsdatabase/reports/gen/20051130_gen-372.pdf -
"The soluble organic fraction(SOF) of the PM was signifi-
cantly higher with the biodiesel and neat methylester fuels
28 (Table5).This result corresponds with previous research
which showed that the SOF increases with biodiesel,although a
dependence on the engine test conditions and PM sampling
parameters can be observed. Although the exact mechanism
requires some research in light of some varying results concern-
ing petrodiesel versus bio diesel components, the higher SOF
observed with biodiesel and the neat methylester fuels can
probably be attributed to the lower volatility (higher boiling
28 point)of biodiesel."
Additional research ( it's out there, trust me) indicates the following emission changes with BD:
SOLID ( “ DRY” ) INORGANIC CARBON PARTICULATES ( SOOT ) – DECREASE
ORGAINC ( “WET” ) CARBON PARTICULATES ( SOF’S ) – INCREASE - SOF’S ARE THE MOST HARMFUL COMPONENTS OF PM.
TOTAL PARTICULATE NUMBER – INCONCLUSIVE ( if you increase one and decrease the other, what other answer would you expect?)
NITROGEN OXIDES – ( NOX ) - INCREASED
BIODIESEL ALSO NEGATIVELY AFFECTS THESE EMISSIONS: HCL – HYDROCHLORIC ACID
HC – HYDROCARBONS NH3 – AMMONIA
SO2 - SULFUR DIOXIDE EMISSIONS FROM BIODIESEL BLEND FUELS ARE COMPARABLE TO PETROLEUM DIESEL.
It's helpful to understand how PM is defined - PM is defined as:
Diesel particulate matter (DPM), as defined by the EPA regulations and sampling procedures, is a complex aggregate of solid and liquid material. Its origin is carbonaceous particles generated in the engine cylinder during combustion. The primary carbon particles form larger agglomerates and combine with several other, both organic and inorganic, components of diesel exhaust. Generally, DPM is divided into three basic fractions
- Solids - dry carbon particles, commonly known as soot,
- SOF - heavy hydrocarbons adsorbed and condensed on the carbon particles, called Soluble Organic Fraction,
- SO4 - sulfate fraction, hydrated sulfuric acid.
The actual composition of DPM will depend on the particular engine and its load and speed conditions. "Wet" particulates can contain up to 60% of the hydrocarbon fraction (SOF), while "dry" particulates are comprised mostly of dry carbon. The amount of sulfates is directly related to the sulfur contents of the diesel fuel.
here's why all of this matters - SOF's are a large component of PM 2.5, otherwise known as fine level particulates. PM 2.5, and VOC's are toxicologically significant. States having counties with higher than allowable inventories of NOx and PM 2.5 face big time losses of federal highway funds, if they don't reduce these emissions. "non attainment" mandates exist, because the EPA knows that ULSD fuel and 2007 tier III engines can't solve the problem.
here's the big question - if states face sanctions for too much Nox and PM 2.5, why are states mandating the use of a fuel that raises these very emissions? ( ethanol has the same emissions effects, btw)
I've never gotten a straight answer on this question.
One solution to the carbon emission problem with biodiesel your professor will tell you about is to slap a DPF on there, and all will be well. What he doesn't understand, is that DPF's are very application specific, and have caused more operational problems than they solve, especially on low duty cycle applications like school buses and underground mining equipment.
here's where the anecdotal stuff starts, so everything I say has some context, and you'll understand why I care about this stuff:
I appreciate the fact you are majoring in green technology, and I applaud your enthusiasm,( and the fact you want to stick it to the man) but I come at it from a different perspective. I'm deeply involved with a company that solves emissions issues for fleets, without biofuels or retrofits. I get a front row seat for the unintended consequences of all of the green mandates.
I have read up on algae diesel, and yep, it sounds good..my issue is this.. when I hang out at clean air stakeholder meetings, they are well attended by engineers who work on things like fuel cells, biofuel projects, etc.. they all sit there, pat themselves on the back for doing gods work, and admit, " hey, none of this works in the real world, but we need more research dollars"... and the EPA guys sit there and say " if you guys want job security, get ready - once we figure out how to solve for non attainment, the clear skies initiatives will kick in, and we'll really clean the air with even newer rules".. these are the same people who want gas to be 5 bucks a gallon so everyone uses less..
to say I'm skeptical about the claims of biofuel technology advocates being on the side of the people is an understatement..
meanwhile, the guys with the trucks are quaking in their boots because they don't know what will happen next..those are the guys I stand with.. I talk to equipment operators who use biodiesel, and can't figure out why their PM emissions keep going up..they use more, and the problem gets worse..a BD rep told this one customer to " ignore the high organic carbon readings, just pay attention to the inorganic"..
I've met one, who went to B50, and every piece of equipment shut down, when the injectors coked.. and the fuel was a commercial blend, using a base diesel fuel known the world over.
it's funny - biodiesel never had to go through the EPA's verification program for emission reduction technologies - the EPA totally relied on industry supplied data, and rubber stamped it as good. when a school district buys it, they never come back and measure anything - they just parrot the propaganda.. industries that ARE measuring actual emissions using biodiesel in the real world are really upset right now..
The only positive outcome companies get from using BD is good PR, and everyone gets to feel good - otherwise, it's a net loss. biofuels only flourish in markets where fleets are made to use it, and if it wasn't subsidized, there would be no reason for the industry to exist.
I will be happy to see the biofuel fad flame out - as a nation, we need to get serious about coal to diesel..I also don't believe we're running out of oil, so I say we stop letting the sierra club run our energy policy, and get to drilling.