Need for a more accurate way to levy carbon surcharge

While the Land Transport Authority (LTA) is progressing from a gantry-based Electronic Road Pricing (ERP) system to a sophisticated satellite-based one so it can more accurately price for congestion, why then is its Carbon Emissions-Based Vehicle Scheme (CEVS) so primitive?

Under the CEVS, LTA assigns a carbon rebate or surcharge according to a vehicle's estimated carbon emissions.

While the intention is sound, the method is flawed, as it fails to account for large variations in actual emissions.

Apart from a vehicle's fuel efficiency, emissions depend on factors such as total distance driven, driving conditions and driving style.

Since we know the carbon content of a litre of petrol or diesel, the most practical and accurate way to levy a carbon surcharge on vehicles is to add a specific carbon tax to fuel.

The plot thickens in the latest furore over the carbon surcharge LTA applied to a recently imported Tesla Model S ("Tesla slapped with $15k tax surcharge"; March 5).

Vicom Emission Test Laboratory tested its electricity consumption and derived a precise 444 watt-hour/km (Wh/km).

The figure shocked many people who understand that Tesla rates its new cars at only 181Wh/km.

LTA then applied a grid factor of 0.5g/Wh to determine the Tesla's carbon emissions at 222g/km.

Why didn't LTA apply the latest grid factor according to the Energy Market Authority, of 0.4322 in 2014, which would result in only 192g of CO2 per km for the Tesla, and drop the surcharge from $15,000 to $10,000?

How to treat hybrid cars, which consume a mix of fuel and electricity?

How about electricity consumed for non-transport purposes? After all, carbon emissions are the same per kWh of grid electricity consumed, no matter what consumes them.

Apart from a vehicle's fuel efficiency, emissions depend on factors such as total distance driven, driving conditions and driving style.

What about hybrid vehicle owners who also use a rooftop solar power system to charge their vehicles, with zero carbon emissions for solar electricity?

The existing CEVS captures none of these variants, whereas it is simple to get a more accurate carbon surcharge by setting an appropriate tax both per litre of fuel and per kWh of electricity supplied via SP PowerGrid.

This would properly and accurately account for carbon emissions of petrol, diesel, hybrid and pure electric vehicles.

Christophe Inglin

A version of this article appeared in the print edition of The Straits Times on March 17, 2016, with the headline 'Need for a more accurate way to levy carbon surcharge'. Print Edition | Subscribe