At a workshop in Midrand, Johannesburg, on Wednesday, it said: "It would appear that a tax of 75 rand per ton of C02 and increase (sic) to 200 rand per ton C02 (at 2003 prices) would be both feasible and appropriate to achieve desired behavioural changes and emission reduction targets."

Presented by Cecil Morden, chief director of the Treasury's economic tax analysis unit, the presentation also stated that a carbon tax based on measured and verified emissions was preferred, though a proxy tax base based on the carbon content of fuel inputs could be considered.

While a carbon emissions tax could be phased in over time, the Treasury admitted that monitoring and measuring of CHG (greenhouse gas) and CO2 emissions would be a challenge.

The workshop, which follows on from a discussion paper entitled "Reducing Greenhouse Gas Emissions: The Carbon Tax Option" released for public comment last December, also comes after Finance Minister Pravin Gordhan said in last month's Budget that the design features of a proposed tax and a schedule for its introduction would be announced in the 2012 Budget.

"Carbon tax seeks to level the playing field between carbon intensive (fossil fuel-based) and low carbon-emitting sectors (renewable and energy efficient)," said the Treasury.

It said it favoured a carbon emissions tax, or proxies thereof, over a carbon emissions trading system which "would not be feasible in the medium term", adding that a carbon emissions tax "will provide a strong signal to producers and consumers to change behaviour over the medium to long term".

Factors favouring a carbon tax included price certainty, emissions reduction, being able to "piggy back" administration on existing systems, and the visibility of the tax.

According to the Treasury, SA emits about 1% of the world's greenhouse gas and is the fourteenth largest GHG emitter in the world. However, it is ranked third in the world in terms of total emissions per capita. This appears to be largely due to the country's reliance on coal-fired power stations.

"SA has one of the highest energy intensities in the world - energy consumption per unit of output - and improvement in energy efficiency and promotion of renewable energy sources are highlighted as important parts of future energy policy," the Treasury said, adding the proposed Energy Bill would contribute towards the establishment of a National Energy Efficiency Programme to regulate energy efficiency matters.

Written comments on the proposed carbon emissions tax were due by the end of February, leading to the Treasury receiving 79 submissions from around the country.

One of the submissions said: "It is crucial that there is policy coherence between government's industrialisation, growth, job creation, energy security and beneficiation policies and its policy on addressing climate change."

While the carbon emissions tax could eventually become the country's largest environmental tax, it will by no means be the first. Environmentally related taxes already in place include the general fuel levy, the electricity generation tax, the motor vehicle emissions tax and the incandescent globe tax.