Is a Carbon Tax the Answer to Climate Change?

Increasing Interest in a Carbon Tax

Fossil fuel combustion causes 82% of the greenhouse gas emissions in this country.  Those that believe that human activity causes climate change agree that we must reduce those emissions. While there is no consensus on how to achieve these reductions support has been growing for a carbon tax. See the Environmental Defense Fund’s explanation of a cap and trade program, which is another viable method to reduce greenhouse gases.

Pollution from power plant that could be reduced with carbon tax

A carbon tax is a fee imposed on the burning of fossil fuels. Such a fee forces users of carbon-based fuels to pay for the detrimental impact on the environment of their use.  For a detailed explanation of how a carbon tax might be used to reduce greenhouse gas emissions visit the Carbon Tax Center web site.

Forms of a carbon tax are already in effect or proposed in numerous countries including England, Ireland, Australia, Chile, Sweden, Finland and New Zealand. Forms of a carbon tax are also in effect in 10 states. And several bills have been introduced in Congress which would implement a national carbon tax.

How a Carbon Tax Would Work

There are numerous versions of a carbon tax. However, in this Post I will focus on a form of the tax that is assessed at the time that fossil fuels are mined or imported into the country. Presumably, those that pay the tax will pass the cost along in their sales price. Ultimately, the cost of the tax will be reflected in the of the price of gasoline and electricity.

The tax would also affect the cost of certain plastics that use fossil fuels but capture the carbon and do not emit greenhouse gases. This use of fossil fuels does not add to greenhouse gas emissions. Therefore, most carbon tax proposals provide credits for such plastics that zero out the cost of the tax.  

Impact on the Price of Electricity

Electric power production from coal, oil and natural gas causes one-third of the greenhouse gas emissions associated with fossil fuels. If a carbon tax is enacted the cost of electricity produced by coal, oil and natural gas will undoubtedly increase.

Opponents of a carbon tax base most of their opposition on the impacts that these price increases could have upon the economy.  For a good argument against a carbon tax see the article entitled 10 Reasons to Oppose a Carbon Tax on the American Energy Alliance web site. For a detailed discussion of the impact of a carbon tax see the paper entitled Effects of a Carbon Tax on the Economy and the Environment prepared by the Congressional Budget Office.

Opponents of the carbon tax contend that the cost of the tax will simply be passed along to electric customers in the form of price increases. However, such an argument does not fully consider the operation of deregulated markets that govern most of today’s electric consumption.

In the competitive markets each regional Independent System Operator (ISO) manages a power exchange where electricity is bought and sold. Hundreds, or even thousands, of generating plants participate in each of these ISO markets. These plants operate on fossil fuels, nuclear or renewable resources.  They all hope to sell their production to the market at or above their operating costs.

Each ISO follows a set of rules that dictates the order in which it will purchase power from these plants. These rules require the ISO to dispatch the plants in reverse order of their cost of production. Thus, during hours when electric consumption is low the ISO will dispatch only the lowest cost production. The ISO will dispatch higher cost production only during hours when consumption increases.

The following graph shows how an ISO dispatches different types of generation at different prices as consumption varies throughout a 24 hour period:

Carbon tax could impact economic dispatch position of fossil fuel plants

As can be seen from the above, the ISO dispatches low cost renewable and nuclear power during low usage hours.  The ISO adds more expensive natural gas combined cycles, coal and combustion turbine oil plants only during higher usage hours.  

If a carbon tax causes the fossil fueled plants to become expensive it would certainly increase the price of electricity during hours when those plants are in operation. However, there is good reason to believe that the fossil fueled plants’ hours of operation may decrease. Their increased operating costs should increase opportunities for additional renewables to compete, and be dispatched, at price levels that are lower than the new cost of fossil fueled generation. This would limit the use of fossil fuel generation to hours when consumption reaches very high levels. In other words, the carbon tax would increase renewable generation and reduce the hours in which high priced fossil fueled generation is in use.

The Level of the Carbon Tax

One argument against a carbon tax is that it constitutes a political decision to force certain behavior – in this case reduced use of fossil fuels. However, it could also be argued that the current failure to recover the societal cost of carbon usage from its users constitutes a political decision to subsidize the use of fossil fuels.

The Environmental Defense Fund estimates that the detrimental societal cost of carbon usage is currently around $40/ton of carbon dioxide. Other estimates are both higher and lower. However, whatever the true cost of carbon emissions, it would seem that that cost should be borne by the carbon users rather than by society in general. Implementation of a carbon tax that at least equates to the societal cost of carbon usage would not be a new political decision. It would reverse an existing political decision to subsidize fossil fuel use.

Where Will the Revenues Go?

Revenues from a carbon tax could be substantial. Estimates are that a modest tax of $15/ton of carbon dioxide would result in $80 billion in tax revenues. There is a question of how that $80 billion should be used. Suggestions include using the funds to reduce the national debt, using the funds to finance renewable generation projects, and using the funds as tax credits for low income families to partially offset the increased costs of gasoline and electricity caused by the tax. Any carbon tax legislation will have to include the answer to the question of where the tax dollars go.


I. David Rosenstein worked as a consulting engineer and attorney in the electric industry for 40 years. At various times during his career he worked for utility customers, Rural Electric Cooperatives, traditional investor owned regulated utilities and deregulated power generation companies. Each of his posts in this blog describes a different aspect of the past, present or future of the electric industry. 

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