Idling a waste of gas, money

The Prince George Citizen - - Science - TODD WHITCOMBE

One of the most im­por­tant chem­i­cal re­ac­tions is com­bus­tion. It re­quires three things: a fuel, an ox­i­dant and a source of ig­ni­tion.

For a camp­fire, the fuel is the wood you are us­ing, the ox­i­dant is the oxy­gen in the air around us and the source of ig­ni­tion is usu­ally a match or lighter.

In the case of an au­to­mo­bile en­gine, the fuel is now gaso­line or some equiv­a­lent ma­te­rial, the air pro­vides oxy­gen and the source of ig­ni­tion is a spark plug.

The chem­i­cal re­ac­tion is pretty much the same. The com­bus­tion of ev­ery hy­dro­car­bon com­pound uses oxy­gen to pro­duce car­bon diox­ide and wa­ter if ev­ery­thing is in bal­ance. If the bal­ance is out a lit­tle bit, then the re­ac­tion might have too lit­tle oxy­gen and soot is gen­er­ated di­rectly. Or the re­ac­tion might be tweaked to get re­ac­tive hy­dro­gen in­stead of wa­ter.

The av­er­age ve­hi­cle does pro­duce a num­ber of other byprod­ucts dur­ing com­bus­tion. Var­i­ous ox­ides of ni­tro­gen emerge from the tail pipe. They pro­vide the dis­tinc­tive pur­plish colour to smog and ac­count for some spec­tac­u­lar sun­sets in the Lower Main­land.

These com­pounds are also a health haz­ard. In suf­fi­ciently large quan­ti­ties, they can kill but even at low doses they are po­ten­tial car­cino­gens. For­tu­nately, they are also re­ac­tive and wa­ter sol­u­ble. Gen­er­ally we don’t have to worry about NOx un­less we live in a city with ex­ces­sive smog.

Ozone is an­other by-prod­uct of com­bus­tion. It re­sults from the com­bi­na­tion of molec­u­lar oxy­gen with a sin­gle atom of oxy­gen mak­ing this al­lotrope. Ozone is also pro­duced while weld­ing and a num­ber of in­dus­trial pro­cesses.

In wa­ter, its ox­i­diz­ing power al­lows it to de­stroy con­tam­i­nants so it is used as a dis­in­fec­tant. In the strato­sphere, it forms in a pro­tec­tive layer which shields the Earth from ul­tra­vi­o­let ra­di­a­tion. But at ground level, ozone is a res­pi­ra­tory ir­ri­tant which can lead to headaches and nau­sea. In high enough con­cen­tra­tions, it, too, is deadly.

Car­bon monox­ide is an­other con­sis­tent by-prod­uct of the in­ter­nal com­bus­tion en­gine. This gas is deadly as it pref­er­en­tially binds to he­mo­glo­bin block­ing oxy­gen up­take. Too much car­bon monox­ide re­sults in as­phyx­i­a­tion and death.

Tailpipes are also a source of par­tic­u­late mat­ter. PM 2.5 and smaller par­ti­cles are able to by­pass the hairs in our lungs in­tended to sweep away solid ma­te­rial. They set­tle on the sur­face of the lung, act­ing as ir­ri­tants and lead­ing to a va­ri­ety ail­ments in­clud­ing in­duc­ing lung can­cer. Fur­ther, the par­ti­cles usu­ally host a slew of poly-aro­matic hy­dro­car­bon com­pounds re­sult­ing from in­com­plete com­bus­tion. These are known car­cino­gens.

All of these com­pounds are found in vary­ing amounts in au­to­mo­tive ex­haust. For ex­am­ple, car­bon monox­ide makes up be­tween one and two per cent of tailpipe emis­sions, de­pend­ing upon the en­gine type and its op­er­at­ing con­di­tion. A well-tuned en­gine gen­er­ates fewer emis­sions. It also de­pends, to some ex­tent, on the time of year and the com­po­si­tion of the gaso­line be­ing used.

But it is car­bon diox­ide we mostly con­cern our­selves with when con­sid­er­ing the ef­fects of emis­sions from trans­porta­tion. Ev­ery liter of gaso­line we burn gen­er­ates about 2.3 kg of car­bon diox­ide. For diesel fuel, it is 2.7 kg per liter. Ve­hi­cles ac­count for 20 per cent of our car­bon diox­ide emis­sions.

At this time of year, though, peo­ple tend to idle their cars. It is both un­nec­es­sary and waste­ful. A car’s en­gine doesn’t need to be warmed up for 10 min­utes be­fore be­ing driven. Idling in the drive through line is noth­ing more than a waste of gaso­line and a good source of green­house gases.

It is hard to find ac­cu­rate data on just what “per minute” emis­sions are for an idling en­gine but En­vi­ron­ment Canada es­ti­mates if we all idled for three min­utes less each day we would re­duce car­bon diox­ide emis­sions by 1.4 mil­lion tonnes per year.

Per­haps more to the point, we would save 630 mil­lion litres of gaso­line which would di­rectly im­pact our wal­lets.

I have heard the ar­gu­ments against turn­ing a car’s en­gine off – it will cool off, it takes more fuel to start a cold en­gine, turn­ing an en­gine on-and-off will burn out the starter mo­tor – but these re­ally don’t hold wa­ter.

The amount of time it takes to get out of a car, go into a Tim Hor­ton’s to get a cof­fee, and then get back into your car is far less than the time it takes for the en­gine to cool down. Try it some time.

Idling an au­to­mo­bile con­trib­utes to cli­mate change as well as emit­ting a wide va­ri­ety of nox­ious sub­stances. While in a city like Prince Ge­orge we don’t gen­er­ally gen­er­ate enough ve­hi­cle smog for it to be truly no­tice­able, the cu­mu­la­tive ef­fects of par­tic­u­late mat­ter and gases are not healthy ei­ther. Es­pe­cially when they are un­nec­es­sary.

Af­ter all, idling doesn’t get you any­where.


A truck idles on the shoul­der of a lo­cal street in this 2007 photo.

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