This article is from car and driver mag. It brings up some good points. Not yet online so here is a summary.
Diesels are on the brink of making a big comeback. The Detroit show in Janyary featured all manner of diesel-powered machines, ranging from the Jeep diesel hybrid concept to the Audi R8. Americans will happily buy good diesels, as MB discovered in 1982 after thesecond gas crisis, when 79% of the cars it sold in the US were diesel.
But there are a couple of major differences betwen the diesel market today and the one 25 years ago. Diesel now costs more htan gasoline. As this is written, the avg price of reg gas is $3.11. Diesel is $3.38. That's quite a switch from the ealry 80s whendiesel was cheaper, avg 13% less than gas.
Most of the world's rapidly growing economies use more diesle and less gas from each barrel of oil than we do in the US, where 40-45% of each barrel is refined into gas. Today's push for energy conservation tends to reduce gas more than diesel use. Basic economics dictates that when one commodity has higher demand than another, its price will rise faster, and that's exactly what we've seen with diesel and gas. So why don';t te oil compaies just twist a few knobs to make more diesel?
Al Mannato, a fuel issues manager at API, explains that oil refineries tend to fall into two categories: catalytic cracking and hydrocracking. Most US refineries are set up for catalytic cracking, whih turns each barrel of crude into 50 gas, 15 diesel, and the rest into jet fuel, home heating oil, asphalt, etc. In Europe and the rest of the world, refineries use a hydrocracking process, which produces more like 25 gas 25 diesel. So the rest of the world is already maximizing diesel production. In fac, despite using a refining strategy that minimizes the promotion of gas, Europe still ends up withtoo much of the stuff, so it exports it to the US - about 1:8 of gas that we consume.
Meanwhile, Americans are already using most of the diesel fuel that our refineries produce, so if sales of diesel cars take off, keeping the diesel flowing here will put further demnds on tight worldwide supplies and probably cuase the price to rise even more. Our oil industry could, of course, start converting its refinereies from catalytic to hydrocracking and start producing more diesel andless gas.
Doing so-and here's the catch 22 - would reduce the output of gas and likely increase its price. Moreover, such a switch,MAnnato explains, amounts to a major refinery change that would take 5 to 10 years to accomplish. Building some new hydrocracking refineries would add diesel capacity without squeezing gasoline supplies, but due to their nearly universal unpopularity, there hasn't been a new refinery built in American since 1979.
Despite the merits of modern diesels, anyone who expects them to solve our energy problems stands to be disappointed.