As automakers are contemplating more diesel models for the U.S., some in Europe are backing away as EU authorities admit failures after two decades of trying to curb emissions from a technology that could cause cancer.
Turbo diesels are the most thermally efficient engines available, deliver high torque, typically higher mpg, and lower CO2. In Europe they’ve risen to comprise roughly half of all new passenger vehicles sold.
Their cost-benefit equation has been far clearer in Europe, but America’s Corporate Average Fuel Economy (CAFE) standards make diesels a unique option for automakers to make the grade.
U.S. regulators however say they are crafting rules that should avoid pitfalls – including rising EU NOx levels despite quadruple-strength restrictions against them.
We’ve heard the alarm raised from diesel critics, but even those in the U.S. who otherwise believe diesel poses greater risks than acknowledged by the U.S. Environmental Protection Agency are signing off on CAFE as better than European standards.
U.S. diesel proponents have sought reduced taxation on diesel fuel and incentives to help “level the playing field” with hybrids and EVs – technologies they say get unfair breaks from the Obama administration.
So far little headway has been reported in giving new breaks to diesels, but modest U.S. growth is projected in the face of issues some say need more focus, and others say are little to worry about.
In June 2012, the World Health Organization’s International Agency for Research on Cancer raised diesel exhaust from “Group 2 “ – “probably carcinogenic to humans,” to Group 1, “carcinogenic to humans.”
This classified diesel emissions worse than those from Group 2B gasoline engines, and ranked it alongside compounds including plutonium, radium, arsenic, and asbestos.
Even before this, diesel emissions had already been blamed for smog, climate change, ozone depletion, and human health disorders including lung diseases, cancers, DNA mutations, blood problems, and more, up to and including death.
Of course gasoline engines and other sources accepted by modern society also emit gases and particles authorities attempt to control.
Also, the WHO study partly relied on decades-old cases of exposed workers, has since come under scrutiny, and its own researchers conceded they had insufficient data on modern diesels.
But the denouncement remains for academics, advocates, and EU authorities who highly respect the WHO – even if others raise eyebrows over WHO also naming “outdoor air pollution” in Group 1.
And regardless of the WHO, John Swanton, air pollution specialist for the California Air Resources Board (ARB), said his influential state has rigorously evaluated diesel emissions and formed its own conclusions.
The complex mix of particles and gases resulting from high-pressure diesel engine combustion has been shown to contain 41 “toxic air contaminants.”
“Diesels produce a legally identified toxic air contaminant,” Swanton said. “Once it becomes a legally identified toxic air contaminant we can go over and above [regulating] what can be addressed with regular pollutants.”
Meanwhile, the U.S. EPA has only gone so far as naming diesel exhaust a probable carcinogen.
The EPA and automakers are co-sponsoring a study at the Health Effects Institute examining diesel exhaust health effects.
Diesel proponents say this stands to disprove the WHO’s declaration – and some may hope the industry and government-sponsored study will discredit the WHO. HEI’s final report is expected at year’s end.
Historically, pinpointing human epidemiological effects has been challenging. After all, if someone breathes exhaust then years later contracts cancer or has other complications, how certain can one be one was caused by the other?
In 2012, the EPA was accused of allegedly risking the health of uninformed, low-income test subjects already in compromised health. These, said a suit, were paid $12 per hour to be exposed to PM2.5 particulate matter to measure whether it made them worse.
While we were able to get emissions certification data from an EPA department, its press office, after an initial reply, did not further reply or provide promised information, despite our followup.
How Clean is ‘Clean Diesel?’
To be “clean,” diesel fuel has “ultra low” sulfur levels of 15 parts per million compared to 500 ppm in regular diesel.
Ultra low sulfur diesel (ULSD) is the first step toward reducing particulate emissions and enables “after treatment” technologies that would be clogged by regular diesel.
These exhaust-scrubbing components may include particulate traps, catalytic converters and “selective catalytic reduction” that injects “diesel exhaust fluid” (urea) into the exhaust.
Since 2007 diesel passenger vehicles have had to meet the same standards as gasoline vehicles and must continue to meet tightening laws into the future.
“Clean diesel” emissions are therefore not the concentrated black sooty mix to which workers in diesel-intense environments were daily exposed – and which the WHO studied.
Diesel critics nonetheless say “clean diesel” is nothing but marketing jargon even if the term is used by the EPA. And, say watchdogs, while there may be fewer gases and particles escaping, these are still carcinogens.
If diesel opponents and proponents can agree on one thing, it is that clean diesel technologies do reduce the nasty stuff and it is potentially less harmful to the environment and health than “dirty diesel.”
Lessons From Europe
Although the WHO lacked data on clean diesels, and suggested public health may improve with them, the European Union admitted two months ago its emission policies have been ineffective for two decades.
Janez Potocnik, member of the European Commission in charge of Environment said in December 2013 that since 1992 Euro 1 through Euro 5 regulations have failed to spur improved diesel emissions, particularly regarding NOx. He said stricter “Euro 6” regulations to replace Euro 5 this September must correct this.
“The problem is, the tests which are done in the laboratory do not correspond to the actual performance on the street and that’s absolutely what we have to fix,” said Potocnik in a video clip (after the 9-minute mark). “The actual situation is such that the [emissions] performance on the street today its basically somewhere around the level of the standards that were set in Euro 1. This was by the way, in 1992.”
According to Allen Schaeffer, executive director of the Diesel Technology Forum in Maryland, European emission laws have emphasized different priorities over U.S. goals.
The U.S. has focused on reducing NOx and particulate matter since ULSD was mandated.
Generally, the Europeans have placed a higher priority on cutting CO2 and improving mpg, said Schaeffer.
But Simon Birkett, founder and director of Clean Air in London, said Americans should try to avoid mistakes from which Europeans now suffer.
“In terms of harmful air pollutants, diesel exhaust has been a public health catastrophe for Europe,” said Birkett.
In London, one hundred air monitors positioned around the city reveal air quality that is as much as 3-4 times higher than WHO guidelines.
“Mistakenly, Europe has allowed diesel vehicles to emit vastly more of the harmful pollutants than petrol vehicles in the same category in its pursuit for somewhat illusory CO2 emission reductions from diesel,” said Birkett. “Carcinogenic diesel exhaust is likely to plague European cities for the foreseeable future and campaigners are seeking to have it banned from the most polluted places by 2020.”
Birkett says he is “worried that European vehicle emission standards continue to underperform and won’t begin to require more realistic test cycles until 2017 or later.”
Back in the USA
Unlike in Europe, the U.S. does not have separate standards for diesel passenger vehicles, and greater optimism has been widely expressed.
The EPA and California approve of diesel when controlled to the same standards as gasoline vehicles under today’s tier 2 EPA standard and when certified by California’s ARB.
Tier 2 will be replaced by stricter Tier 3 standards for 2017. These are primarily targeting further reductions in hydrocarbons, non-methane organic gases (NMOG) and nitrogen oxide (NO) emissions.
As automakers including Volkswagen, Audi, GM, Mazda, among others, contemplate more diesels for America, both California’s ARB, and the Natural Resources Defense Council (NRDC) say U.S. laws now and pending are stronger.
“Tightening fuel economy and greenhouse gas emissions standards are prompting automakers to consider expanding their diesel offerings,” said the NRDC’s Luke Tonachel, director, Vehicles and Fuels, via e-mail. “… the standards specify performance levels (gCO2/mi or mpg) …”
“For criteria and GHG emissions and fuel economy, the performance standards approach makes sense because it encourages innovation in many areas,” he continued. “Automakers have the flexibility to choose from a broad range of technologies to make cars that are the most cost-effective while meeting the required pollution standards. As long as a technology can meet the standards, it should be allowed.
“Importantly, EPA has recognized that the current criteria pollutant standards need to be tightened to protect human health. Stronger Tier 3 standards have been proposed and should be finalized as soon as possible to ensure future cars are cleaner.”
In a phone follow-up we asked whether the NRDC might be taking it easy on the Obama administration because it has significantly ramped up CAFE standards for the first time in decades.
“No, no,” said Tonachel of emissions protocols also addressed by CAFE. “The standards are strong. We advocated strongly to make sure that we had strong standards, and the result was a good one.”
And similar support was heard by ARB’s Swanton. He said diesels do produce more smog-forming NOx and particulate matter than gas engines, but with proper after treatment, these do meet California regulations.
“Diesels do not get ‘a pass’ over any vehicles and we actually look at particulate matter coming from gasoline vehicles as well,” said Swanton. “As gasoline vehicles become more diesel like, we’re trying to be very vigilant in [monitoring] those changes to gasoline engines [to ensure] we’re not trading off the formation of particles for other benefits.”
Gasoline emissions have become “more diesel like,” said Swanton, as automakers add gasoline direct injection, increase combustion pressures and temperatures, and Tier 3 regulations will call for reduced sulfur in gasoline.
About 30 percent of new gas engines use GDI and more aggressive catalysts will be needed to reduce sulfur too. Some of these gas engines do emit more particles than diesels which have particulate filters.
In California, automakers must provide same-as-production examples of each vehicle proposed for sale. These must receive ARB “executive orders” certifying they passed.
While California accepts diesels, it does not say they are the cleanest.
California and seven other “CARB states” are mandating a percentage of zero emission vehicles (ZEVs).
Swanton said he’s personally owned two Jetta diesels, sold the last one in 2005, but now chooses to make a small contribution to his local air by driving a Nissan Leaf.
The Diesel Technology Forum’s Schaeffer acknowledged diesel engines emit, but so does gasoline which presents its own concerns.
In diesel engines’ favor, he said, they have near zero carbon monoxide emissions, no evaporative emissions, and inherently low HC and NMOG emissions.
Gasoline vehicles do produce evaporative emissions due to their volatile fuel, he said, and these contribute to ozone formation.
Schaeffer noted also myriad industrial pollution sources are also tolerated, and all diesel engines combined in the U.S. contribute less than 6 percent of fine particles in the air.
“It’s not a perfect mouse trap,” he said of extraordinarily complicated U.S. emission policies, “but it’s the best mouse trap that we have.”
Diesel vehicle engines’ extra after treatment also means extra cost over present gas vehicles, and in question is whether automakers can deliver viable products in the face of also-expensive fuel.
But according to David Carslaw, a professor at the UK’s Kings College deeply involved in emissions research, while acknowledging U.S. policy seems more progressive than Europe’s, he and colleagues Frank Kelly and Martin Williams urged caution.
“Europe has for light duty vehicles different emission limits for petrol and diesel vehicles. For Euro 5 diesel vehicle (from September 2009) the NOx limit is 0.18 g/km; Euro 6 from September 2014 is 0.08 g/km,” he said via e-mail. “In the U.S. they have different ‘tiers’ and a very different test cycle. As I understand it a manufacturer of vehicles must ensure the fleet average is below 0.07g/mile (0.04 g/km), i.e. no specific limit for diesels. On balance the USA tend to be ahead of Europe in terms of setting emission limits.
“Cleaner diesels (similar to Euro 6) have already been introduced in the USA and there are early ones being introduced now in Europe (we measured a few last summer).
“However, regardless of emissions standards, there is no doubt as far as NOx is concerned, that diesels will be much higher emitters cf. petrol,” said Carslaw, “I think if the USA had the same proportion of diesel as us and tougher air quality limits for NO2 there would be similar problems.”
Schaeffer however said if Carslaw speculated about America equaling Europe’s diesel acceptance rate and having similar problems, then that is a “huge hypothetical.”
“It’s never going to happen here, he said. “For one we’re never going to reach 50 percent, and two the U.S. emissions standards are far higher.”
Regarding the EU versus the U.S. question, Schaeffer said – this is a “challenging area.”
He summarized a few key points:
· U.S. emissions laws require all vehicles and fuels to comply with the same requirements (fuel neutral)
· U.S. emissions laws require significantly cleaner vehicles with longer emissions warranty periods, with advanced on-board diagnostics (OBDII) including 13 diagnostics for emissions; the EU’s diagnostic requirements are far less extensive and do not fully correlate with emissions
· The testing cycles in the U.S. encompass a far greater range of operation (altitude, high temps, etc.) requiring emissions performance from -10 to 95F than does Europe; the U.S. requires emissions durability for 120,000 miles/10 years; EU 62,500 miles/5 years
· The U.S. certifies vehicle emissions on a fleet-wide average basis. The EU does not use such a fleet-wide basis.
· The EU is focusing more on the number of particles emitted and the US on the mass of particles emitted.
Compared to Europe’s embrace of diesels, the U.S. represents a microcosm that is projected to see incremental growth against resistance.
Also in consideration is the far-larger market of heavy road-going trucks, buses, industrial equipment and others that rely on diesel.
Expert opinions vary on clean diesel emissions but the ARB’s Swanton said toxic air contaminants should not be dismissed.
“You can have various lobbyists get up there and say you are overreaching,” Swanton said of substances like benzene and toluene, “but I don’t know anyone who would willingly take anything that’s on the toxic air contaminant list and knowingly expose themselves to it.”
While some occupational or incidental contact may be unavoidable, Swanton said, “Anyone who knows better avoids the stuff [on the list] as fully as possible.”
But otherwise, Swanton on behalf of California, the NRDC, and others have said diesels should be permitted in America under proposed regulations. That they both now sign off on diesel as OK is significant.
However the proof of regulations is in the pudding, or so the Europeans found when they acknowledged real-world emissions readings compared to ostensibly strict policy.
Back in 1992 the LA Times documented California resisted using it. In 1996, the EPA reportedly did also and that same year the Cato Institute argued Stedman’s technology would better serve Clean Air Act goals.
In the ongoing fight for clean air, advocates have suggested on-site air testing would be the most definitive and cost-effective determinant of exactly how clean is clean diesel – not to mention all vehicles on the road.