This is the third in a series of posts noting some random highlights from the BAQ2008 conference. Here I’d like to feature a few great slides I saw presented by Dr. Anup Bandivadekar of the International Council on Clean Transportation (ICCT). (Side note: Dr. Bandivadekar is the lead author of MIT’s “On the Road in 2035: Reducing Transportation’s Petroleum Consumption and GHG Emissions.“)
The presentation I heard by him was called “Diesel Passenger Cars: Safeguarding Air Quality and the Global Climate in a Shifting Market.“
The presentation begins with an introduction to the “diesel dilemma,” which I will briefly summarize as follows: diesels are more efficient than gasoline vehicles (therefore are better for energy security / CO2 emissions reductions), but pollute more, especially NOx and PM (therefore are worse for air quality). Certain areas of the world (most notably Europe and countries which have followed Europe’s precedent) have promoted diesels for the former reason by subsidizing the cost of diesel fuel and setting higher emission limits for diesel vehicles as compared with gasoline vehicles.
As diesel engine technology and emissions control systems improve, though, there is a growing call to eliminate any special policy treatment afforded to diesels, and instead adopt “technology neutral” environmental standards. (Note: the US and Japan’s technology neutral standards are one reason diesel passenger vehicles have not had large penetration in those markets.)
Indeed, Dr. Bandivadekar’s conclusion states:
Diesels don’t have to be the problem…
The trade-off between air pollution and GHG reduction is artificial — solution lies in strict, technology-neutral emission standards
But there are two additional key points that Dr. Bandivadekar makes that I want to feature.
The first is that low sulfur diesel fuel is required if advanced diesel emission control systems are to be installed on vehicles. His presentation features an excellent slide showing graphically the PM reduction potential vs. diesel fuel sulfur content:
As standards become more and more stringent, it is critical that fuels and vehicles be treated as a system, especially with regard to sulfur content. Unfortunately, however, many Asian nations still have extremely high sulfur content in their fuels:
This high sulfur content in many areas, including China outside of Beijing (this point to be expanded on in another post), is a major limiting factor to the introduction of cleanest technology diesel vehicles.
Another fascinating point that Dr. Bandivadekar raised is that greenhouse gas emissions from diesel vehicles are more than just CO2. Incomplete diesel combustion also results in the emission of “black carbon,” another powerful contributor to global warming. When considering total greenhouse gas emissions, diesels only have an advantage over gasoline when black carbon emissions are controlled:
(In the above slide, “DPF” refers to “diesel particulate filter,” an emissions control device that requires low sulfur fuel to operate properly.)
Therefore, the need for immediate implementation of low sulfur diesel fuel and advanced diesel emission control technology is supported from both air pollution and greenhouse gas reduction perspectives.
Lastly, I’m posting up one of Dr. Bandivadekar’s first slides, the ICCT’s excellent Bellagio Principles: