First, even WVO is cleaner burning that #2 and Biodiesel is much better than either WVO or #2. Out of the numerous components of diesel exhaust, only one NOx is
slightly more, but the total reduction of the other pollutants is a much bigger issue, especially the soot issue. NOx can be taken care of with a cat, when the soot is out of the equation. The main reasons that cats are not on more diesels is their tendency to get blocked with soot (First hand experience, 99 F-350 had a cat. Almost total blockage at 125K miles)
As to using the WVO for feed stock, most other countries do not allow this to happen. Not sure exactly why, but from some of the WVO I've seen, I would hate to have it feed to something I was expected to eat later.
For everything there is some trade off. Some are better than others. If NOx was a primary issue, then EGRs would be required to be in operation, regardless of the age of the vehicle or the availability of parts. Once again, with the EGR, having it working is a trade off for other issues such as fuel mileage or power. I personally think the EGR engines get to a point of diminishing returns, especially with older engines.
If soot buildup was a major reason to eliminate the EGR, to help the engine breath better, then a switch to Biodiesel would have eliminated virtually all of the soot problems with the recirculating exhaust gas.
You could look at it this way. Last week Congress voted to cease stockpiling oil in the Strategic Oil Reserve, which was 77,000 barrels of oil per day. To equate the amount of diesel saved from that same amount would only egual 11,800 barrels or just under 0.5 million gallons. Ironically, the overall Biodiesel production was averaging over 1.3 million gallons a year although the actual production capacity is closer (or will be within the year) or 9.5 MGPD.
Every little bit helps.
