Volkswagen's shocking admission that they designed software to cheat EPA emissions tests, and thereby emit 15-35 times as much poisonous nitrogen oxides (NOx) as is legally allowed (and very possibly killing thousands of people), is by now well known. But how is this technology supposed to work?
Professor Martyn Poliakoff explains below. The problem with NOx formed during diesel combustion is that they are free radicals, meaning they each have an unpaired electron. This makes them extremely reactive — so if you breathe them in, they'll tear up your lungs (and in the open air, form smog and particulates). But that suggests a solution: get something to react with the NOx before it reaches the atmosphere. One low-emissions diesel engine design does just that, with a tank of urea — inject it into the exhaust stream, and the NOx is reduced to nitrogen, water, and carbon dioxide. It works great, but it reduces the efficiency of the engine, which is likely why VW cheated. Watch the full explanation below. Ryan Cooper
Subscribe to The Week
Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.
Sign up for The Week's Free Newsletters
From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.
From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.
-
Israel: Losing the American publicFeature A recent poll finds American support for Israel's military action in Gaza has fallen from 50% to 32%
-
Unmaking AmericansFeature Trump is threatening to revoke the citizenship of foreign-born Americans. Could he do that?
-
EPA: A bonfire of climate change regulationsFeature The Environmental Protection Agency wants to roll back its 'endangerment finding,' a ruling that lets the agency regulate carbon emissions
-
Lithium shows promise in Alzheimer's studySpeed Read Potential new treatments could use small amounts of the common metal
-
Scientists discover cause of massive sea star die-offSpeed Read A bacteria related to cholera has been found responsible for the deaths of more than 5 billion sea stars
-
'Thriving' ecosystem found 30,000 feet underseaSpeed Read Researchers discovered communities of creatures living in frigid, pitch-black waters under high pressure
-
New York plans first nuclear plant in 36 yearsSpeed Read The plant, to be constructed somewhere in upstate New York, will produce enough energy to power a million homes
-
Dehorning rhinos sharply cuts poaching, study findsSpeed Read The painless procedure may be an effective way to reduce the widespread poaching of rhinoceroses
-
Breakthrough gene-editing treatment saves babyspeed read KJ Muldoon was healed from a rare genetic condition
-
Sea lion proves animals can keep a beatspeed read A sea lion named Ronan beat a group of college students in a rhythmic dance-off, says new study
-
Humans heal much slower than other mammalsSpeed Read Slower healing may have been an evolutionary trade-off when we shed fur for sweat glands
