Electric cars: night-time charging better - study

A A A

Charging electric cars at night eases a smog problem caused by fossil-fuel plants which provide the power for these vehicles, researchers reported on Tuesday.

Plug-in cars are viewed as a key tool in the fight for a cleaner planet as they do not emit tailpipe pollution when they run on electricity.

But they contribute indirectly to pollution, as well as global warming, if their electricity comes from a power station that runs on coal, oil or gas.

In a study published in a British journal, scientists in the United States simulated the local impact from "plug-in hybrid electric vehicles," or PHEVs, which are cars that can switch from battery power to petrol.

Their computer model was based on predictions for 2018 of emissions of nitrogen oxides, the basic ingredient for ground-level ozone, in four major cities in Texas: Dallas/Forth Worth, Houston, Austin and San Antonio.

Power generation for this grid in 2009 was provided by gas (46 percent), coal (35 percent), nuclear (13 percent) and wind (4.5 percent).

The study compared likely pollution levels when 20 percent of mileage in the region was carried out either by PHEVs or by vehicles that were only petrol-powered.

Regardless of the scenario, ozone pollution improved when PHVs were used, because they did not emit nitrogen oxides.

As for when PHEVs should be recharged, the paper found it was smarter to plug in the vehicle at night.

Extra demand from fossil-fuel power stations at night did cause levels of nitrogen oxides to rise compared to the typically shorter recharging periods in daytime.

But much of the gas emitted at night time had dissipated by daybreak. This eased the smog problem by a small but detectable margin.

Ozone, a triple molecule of oxygen, is protective when it is in the stratosphere, because it filters ultraviolet rays that can cause skin cancer and DNA mutations in plants.

But at ground level, where it forms from a reaction between sunlight and nitrogen oxides from fossil fuels, ozone irritates the body's airways, becoming a hazard for people with cardiac or respiratory problems.

The finding will guide policies on how to encourage cleaner cars, say the authors.

"This further supports efforts to develop regulation to encourage night-time charging - an example would be variable electricity pricing," said Tammy Thompson of the Massachusetts Institute of Technology (MIT).

"As more of the fleet switches over to PHEVs and larger demand is placed on the electricity grid, it will become more important that we design and implement policy that will encourage charging behaviours that are positive both for air quality and grid reliability."

The paper appears in the journal Environmental Research Letters.

Have you tried new the Independent Digital Edition apps?
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
SPONSORED FEATURES
iJobs Job Widget
iJobs General

Recruitment Genius: UX Consultant

£35000 - £45000 per annum: Recruitment Genius: You will be working with a 8 st...

Recruitment Genius: Part-time Editor

£8000 - £12000 per annum: Recruitment Genius: A unique opportunity has arisen ...

Recruitment Genius: Field Sales Executive

Negotiable: Recruitment Genius: An exceptional opportunity has arisen for a pa...

Recruitment Genius: Kitchen and Bathroom Installers

£18000 - £20000 per annum: Recruitment Genius: This provider of designer kitch...

Day In a Page

Orthorexia nervosa: How becoming obsessed with healthy eating can lead to malnutrition

Orthorexia nervosa

How becoming obsessed with healthy eating can lead to malnutrition
Lady Chatterley is not obscene, says TV director

Lady Chatterley’s Lover

Director Jed Mercurio on why DH Lawrence's novel 'is not an obscene story'
Farmers in tropical forests are training ants to kill off bigger pests

Set a pest to catch a pest

Farmers in tropical forests are training ants to kill off bigger pests
Mexico: A culture that celebrates darkness as an essential part of life

The dark side of Mexico

A culture that celebrates darkness as an essential part of life
Being sexually assaulted was not your fault, Chrissie Hynde. Don't tell other victims it was theirs

Being sexually assaulted was not your fault, Chrissie Hynde

Please don't tell other victims it was theirs
A nap a day could save your life - and here's why

A nap a day could save your life

A midday nap is 'associated with reduced blood pressure'
If men are so obsessed by sex, why do they clam up when confronted with the grisly realities?

If men are so obsessed by sex...

...why do they clam up when confronted with the grisly realities?
The comedy titans of Avalon on their attempt to save BBC3

Jon Thoday and Richard Allen-Turner

The comedy titans of Avalon on their attempt to save BBC3
The bathing machine is back... but with a difference

Rolling in the deep

The bathing machine is back but with a difference
Part-privatised tests, new age limits, driverless cars: Tories plot motoring revolution

Conservatives plot a motoring revolution

Draft report reveals biggest reform to regulations since driving test introduced in 1935
The Silk Roads that trace civilisation: Long before the West rose to power, Asian pathways were connecting peoples and places

The Silk Roads that trace civilisation

Long before the West rose to power, Asian pathways were connecting peoples and places
House of Lords: Outcry as donors, fixers and MPs caught up in expenses scandal are ennobled

The honours that shame Britain

Outcry as donors, fixers and MPs caught up in expenses scandal are ennobled
When it comes to street harassment, we need to talk about race

'When it comes to street harassment, we need to talk about race'

Why are black men living the stereotypes and why are we letting them get away with it?
International Tap Festival: Forget Fred Astaire and Ginger Rogers - this dancing is improvised, spontaneous and rhythmic

International Tap Festival comes to the UK

Forget Fred Astaire and Ginger Rogers - this dancing is improvised, spontaneous and rhythmic
War with Isis: Is Turkey's buffer zone in Syria a matter of self-defence – or just anti-Kurd?

Turkey's buffer zone in Syria: self-defence – or just anti-Kurd?

Ankara accused of exacerbating racial division by allowing Turkmen minority to cross the border