Catalytic converters are quite common for gasoline engines but diesel catalysts are less known, in part because they face greater challenges. Still, diesel catalysts have not disappeared because they are efficient and, when you start your car, they don't produce heaps of CO₂. Their main problem is the large amount of carbon particulates (soot) and nitrogen oxides in the exhaust gas. Standard three-way converters are not effective because of the high oxygen content of these gases. BASF is on the case, though. BASF's catalyst researcher Bob Farrauto said, "To solve this problem, we have developed special diesel oxidation catalysts combined with particulate filters which trap the soot and periodically oxidize it using a combination of catalysts and engine controls."

What about nitrogen oxides, which are the main source of acid rain? NOx storage devices or traps are incorporated into the catalyst to first store the nitrogen oxides which are then converted to nitrogen. The storage catalyst is regenerated afterwards. Alternatively an ammonia-carrying liquid (i.e. urea) can be injected into the exhaust and passed over a highly selective catalyst which converts the NOx into N₂.


[Source: BASF]

Could urea be a savior when it comes to reducing atmospheric carbon dioxide? By now we all know about injecting urea into diesel engine exhaust to reduce emissions of nitrogen oxides. An Australian company has now received permission from the government of the Philippines to dump urea into the Sulu Sea of that country's coast.

However, this isn't just a scheme to dump waste offshore. This is actually being done in an attempt to mitigate global warming. The idea is pour the urea into the water to promote plankton growth, because plankton absorb a lot of atmospheric carbon dioxide as they grow. In theory this should be a good thing. In practice, however, little is understood about the possible side-effects of the plankton growth. But of course those sorts of side-effects never happen in the real world. Do they? This seems like a prime candidate for the law of unintended consequences.

More on plankton:

• Using geoengineering to combat climate change?
• One more feedstock to consider: biofuel from plankton

[Source: Wired]

Before the low sulfur diesel fuel that has become common here in the United States, it was impossible for automakers to install filters which would allow diesel engines to meet the requirements which were being imposed upon them. Fortunately, everything is coming together here in the States to allow for new clean diesel technology. Particulate filters, urea based injection systems and other technologies, combined with the low sulfur content in modern diesel fuel available here, have come together all at the same time.

Unfortunately, this article states that these technologies have not been adopted as of yet in Australia as they have been in Europe and in the U.S. The sulfur content in Australian diesel fuel also is of concern. Until the government there mandates changes in the emissions requirements from diesel engines, manufacturers are not as likely to install the expensive after-treatment devices and filters that they already use in Europe and America. As the article states, some manufacturers have stepped up the the plate, so the speak, but not all. Never having been in Australia, I can't really add any personal experience here, maybe a reader can give some insight into what is happening in Australia at the present to change the current state of diesel affairs.

[Source: Drive]

Whether or not you believe in global warming, nitrogen-oxides, or NOx, definitely does contribute to acid rain and smog, which are not debatable. Because NOx is emitted in large quantities from the exhaust of diesel engines, something needs to stop it from entering our atmosphere. One way to do this is with urea, which is being used in the Bluetec systems installed by various automakers. Because people don't like to think about carrying around a container of urea (think urine, although it is usually created chemically, not gathered "naturally"), it is often referred to as Adblue, and because it is a source of ammonia, must be metered properly as ammonia is rather toxic by itself. Are there any other solutions?

The Chemical Engineering Division of Argonne National Laboratory in the U.S. has come up with a possible alternative to ammonia and urea. Their process uses Cu-ZSM-5, a zeolite with copper ions attached within its micropore structure, "with an external coating of cerium oxide", according to Christopher Marshall, who helped develop the technology. The technology also does not contain platinum, which is expensive and not compatible with the older diesel fuels which contained high amounts of sulphur.

This catalyst is currently under testing, but is proving to work out well enough that Argonne is expecting to have the product commercially available in as little as two years. I think it sounds pretty promising myself, because while I don't mind using urea at all, I think it is good that the consumer would not be left in charge of being sure that the Adblue tank was not empty.

[Source: Argonne National Laboratory]

While perusing "the internets" for green-like automotive news, I stumbled upon a post about making batteries using various components, including urine. Urea is already in use for the BlueTec system in diesel cars and trucks, how about a hybrid with a urea tank for "rechargeable" batteries. Would this be the answer for all those complaining about the limited range of hybrid cars? Kill two birds with one stone: stop for a potty-break and top-up the batteries!

Alright, in all seriousness now, if this works, there really is no reason not to research and develop it further. Like I alluded to above, if urea can be stored in a tank for use in diesel exhaust filtering, it could surely be used for batteries, right?

Back to being funny: This post extends our history of bringing you strange human (!) and animal-waste derived methods of automotive greenery! YUMMY!

[Source: Weird Asia News via Hugg]

While DaimlerChrysler announced at the start of this year it would be introducing its E320 BLUETEC with clean diesel technology as a 50-state vehicle, the car will be hitting showrooms as a 45-state compliant car. BLUETEC, DaimlerChrysler's aftertreatment system promises to meet the upcoming EPA Tier 2 Bin 5 emissions, which would make it 50-state compliant. However, to meet these tough new standards, a urea selective catalytic reduction system is needed. The 45-state version of the Mercedes E320 comes equipped with a nitric oxide absorber, which converts nitric oxides into nitrogen. This brings the emissions close to the strict new standards, but not quite all the way there, according to a 2004 test of a prototype. In an Autoweek article, found here, EPA guidelines for urea systems are a few weeks away. The uncertainty regarding the EPA direction on urea might have led to the decision by Mercedes-Benz to reduce the E320 BLUETEC to a 45-state vehicle.

[Source: Green Car Congress]

Following up on Derrick's post from yesterday, one other option the Environmental Protection Agency (EPA) may use is to require the urea refill interval to be at least as long as the manufacturer's oil change interval, allowing the urea refill to coincide with oil changes.

If you missed yesterday's post, it was about diesel engines and how urea selective catalytic reduction systems (SCR) can reduce nitric oxide emissions from the engine's exhaust very effectively. The trouble is that SCRs require the user of the car to be responsible for keeping the on-board urea tank replenished. The EPA plans to issue guidelines for urea SCR systems that could be as drastic as requiring a vehicle to stop running if drivers don't keep the tank filled. Manufacturers are opposing this measure, citing safety issues. While the need to fill an additional tank is clearly a drawback of the urea SCR systems, they allow diesel engine manufacturers to meet the strictest worldwide emissions regulations without fuel economy penalty and at an acceptable price.

Related:

• EPA to set urea guidelines by October

[Source: Autoweek]

By 2010, all diesels sold in the U.S. will have to meet Tier 2 Bin 5 emissions levels, the same standards as their gas-powered counterparts. Even though we're used to talking about diesels as green machines, they still have the issue of nitrous oxide (NOx) emissions with which they need to overcome.

As a result, the Environmental Protection Agency is looking to publish urea guidelines as early as October of this year. Over the past few years, urea injection has been considered the cheapest effective way of scrubbing NOx emissions from diesel tailpipes. Because urea requires driver involvement (it needs to be refilled), the guidelines will address penalties to ensure urea tanks never go empty. Margo Oge, director of the EPA's Office of Transportation and Air Quality, said that one possibility would be to disable the engine. Another is to lock the fuel filler door until there's urea in the urea tank. Auto manufacturers are notably opposed to these types of restrictions citing safety issues. However, Oge says that the EPA can't allow cars that don't meet emissions standards to be driven. Once the guidelines are published, the automakers will have a an opportunity to petition for changes.

It will be interesting to see if Honda really can develop a clean diesel that won't require urea or a costly NOx trap. The Mercedes E320 BLUETEC which was unveiled at the 2006 New York Auto Show uses Adblue, a water-based urea solution, and can travel roughly 11,000 miles before its 6.8 gallon Adblue tank needs to be replenished.

Related:

• Honda's environmental strategy includes diesels, affordable hybrid
• BMW diesel cars in U.S. by 2008
• Volvo diesel for the U.S. by 2010

[Source: AutoWeek]

Reports from the British International Motor Show, which starts tomorrow, revealed BMW plans to have diesel-powered cars available in the U.S. by 2008. The company plans to use a urea-based additive system to meet the strict U.S emissions standards. The system will make the cars available in all 50 states. The BMW decision follows an increased interest in diesel cars in the U.S. market, with a 95% increase in light duty diesel registrations from 2000 to 2005. Clearly, the European manufacturers have the edge when it comes to diesel engine technology, with a large number of production-ready products already available across the old continent. Just look at one the cars on offer in Europe: a 5 Series with the smallest available diesel engine achieves a U.S. fuel economy of 39.9 mpg, with respectable acceleration times, for example. You can sign me up for one of those right now.

[Source: Just-Auto]

Ford Motor Company's Volvo unit wants to launch a diesel car in the U.S. by the end of the decade. The challenge is meeting the stringent emissions standards, which are focused more on regulating oxides of nitrogen in North America. The European Euro 5 standards, the upcoming standard for European vehicles, are more focused on reducing carbon dioxide, where diesel engines have a clear advantage due to their lower fuel consumption. To meet both standards simultaneously with one emission system requires most likely the use of a urea injection system. While urea systems effectively clean up the nitric oxide emissions, they do require periodic filling, a concern to the EPA. Current urea systems under development by DaimlerChrysler require filling every 12,000 to 15,000 miles, which means the fill-up could be done during routine oil changes.

Note, the article claims nitric oxides are the black soot coming out of diesel engine exhaust, which is definitely incorrect. Nitric oxides are the precursor of smog, but they are not the soot emissions people associate with diesels. Most modern diesel engines produce very little smoke, due to very high injection pressures. The little smoke that is formed is generally cleaned up with a diesel particulate filter.

[Source: Autoweek]