Ari's Planet

According to Joe Romm in Hell and High Water, we need to reduce carbon emissions by 8 billion tons per year, which he suggests can be accomplished by implementing 8 "wedges", each of which reduces emissions by 1 billion tons per year. It was unclear whether this needed to be done worldwide or whether he was referring only to steps the US must take. One of the wedges involves replacing vehicles with cars getting 60 mpg (miles per US gallon), or 25.4 km / L or just about 4 L / 100 km. Here, it was unclear , or I cannot recall, if this applied to all vehicles' average fuel efficiency (including trucks and cars, etc.) At any rate, the main point was that he said vehicles need to get 60 mpg and that this can best be accomplished, given current technology, using hybrid vehicles. Does converting to hybrid vehicles make sense?

The Australian Royal Automobile Club's magazine, Horizons, issue 7, 08/08 , gives operating costs for various vehicles. Of interest is the Toyota Prius for model year 2006, the latest version available in Australia. All values are in AUD, rounded, with the current exchange rate at around 0.77 USD per AUD. The list price is $37400 with an "on road" price of nearly $42000 and a trade-in value after 5 years of $14455. The big hit comes from depreciation, at around $105 per week plus interest at $48 per week, while registration and other fees are $22 per week. The running cost per week is $19.79 for fuel plus $17.12 for servicing and repairs (there are a few smaller costs but I'll ignore them as they don't vary much across the models reviewed). The Prius, according to a review in the same issue, gets 4.4 L / 100 km, but is expected to get around 5.5 L / 100 km in"real world" driving.

The Prius can be contrasted with two other vehicles described in the issue. The Hyundai Getz S TB with a 5 speed manual transmission costs $14000 with an on-road cost of $16500 and a trade-in value after 5 years of $5100. Depreciation, interest, and fees are $44, $19, and $17 per week, respectively. Fuel and servicing and repairs are $27.44 and $10 per week. Fuel efficiency is not given, but can be approximated from the fuel costs, $27.44 / $19.79 * 4.4 L / 100 km = 6.1 L / 100 km up to 7.6 L / 100 km. The third vehicle I will compare is the Fiat 500. With a 1.2 L petrol engine it uses 5.1 L / 100 km and costs $23000, while with a 1.2 L diesel engine it uses just 4.2 km / 100 L and costs $26000. Of the cars whose running costs is given in the issue, the Volkswagen Polo TDi comes closest to the Fiat at a list price of $23000, for which its trade-in value after five years is $9100. Assuming the Volkswagen and Fiat are comparable, we get depreciation, interest, and fees of $65, $30, and $19 per week, with servicing costing $16 per week.

The following chart summarizes the main numbers.

* Note: values for Fiat partially based on Volkswagen Polo data combined with 1.2 L petrol model of Fiat.

The article assumed 15000 km are driven per year. For each car, I calculated the amount of carbon dioxide released into the atmosphere as a result of driving 15000 km for each car's fuel consumption rating. I used the calculator at Carbon Footprint. I don't know if this is a particularly good calculator, or if it includes the full costs of production and distribution for fuel. This web site also provides a means to calculate the cost of purchasing offsets equal to a particular amount of CO2; I used the cheapest option, which provides funds to renewable energy projects, and converted the amounts from GBP to AUD using current exchange rates.

Also available in Australia are vehicles that run on LPG. For comparison, a car consuming 4.2 L / 100 km would have a CO2 footprint of only 0.944 tons, which is much less than the 1.66 tons from a diesel vehicle with the same volume of consumption (but that doesn't mean that 1 L of LPG is actually energy-equivalent to 1 L of diesel, I need to do further investigation).

Let's say you need or want a car, but also want to reduce the amount of CO2 in the atmosphere. You could do as is implied by Romm's recommendations and go out and purchase a hybrid vehicle such as the Toyota Prius. You will be emitting about 1.53 tons of CO2 in a year of typical driving at an annual cost of $11200 . Alternatively, you could purchase a Hyundai Getz, which will emit about 2.12 tons of CO2 in a year at an annual cost of $6200. Purchasing a Prius to reduce annual CO2 emissions by 0.59 tons would cost $5000. Alternatively, you could offset 0.59 tons of CO2 at a cost of $10 for alternative energy, $19 for reforestation in Kenya, or $28 for planting trees in the UK. Purchasing a new Prius in order to reduce CO2 emissions costs 500 times more than an equivalent offset in CO2. For the $5000 difference in yearly cost you could have offset 295 tons of CO2. The Toyota Landcruiser GX (petrol) consumes 13.6 L / 100 km and emits 4.8 tons CO2 driving 15000 km. For that difference in cost of $5000, you could have offset the entire emissions of 61 Toyota Landcruisers, which are classed as large SUVs. There are further benefits to investing in carbon offset schemes rather than a more expensive car. An investment in alternative energy would encourage a nascent industry, an investment in reforestation in Kenya could benefit entire ecosystems as well as bring income to developing countries, and an investment in reforestation closer to home could have similar benefits as wells as a forest that you might get to walk through in a few years. Your investment in a Toyota Prius would benefit primarily Toyota shareholders and the bank that lent you the money to buy the car.

But why stop there? If you bought a used car, one that had mostly depreciated, then you could save even more money. A used Hyundai Getz, model year 2002, which consumes 7.8 L / 100 km, is $9000 at Automotive Holdings Group. That's another few thousand dollars in your pocket you could apply toward further carbon offsets. Buying a used vehicle also avoids all the carbon and other pollutants generated in the manufacture of a new vehicle. You might even be able to do without a car entirely, saving even more money and producing even less emissions of your own. You could ride a bike or participate in one of the shared vehicle schemes available in some cities.

In conclusion, it appears that there are currently more financially efficient means to reduce carbon emissions than by the purchase of a hybrid vehicle over a low-cost vehicle. This conclusion applies to individuals and to societies, though societies and governments can affect the costs of various fuel-efficient technologies in a manner that is not available to individuals. Hybrid vehicles are part of the long-term solution to carbon emissions, but first their cost has to become more competitive with other carbon reduction approaches. To be clear, what I am saying is that if the choice is between a cheaper less fuel-efficient vehicle and a more expensive but more fuel efficient vehicle, and the goal is reduction of carbon emissions, then it is better to get the cheaper vehicle and spend at least some of the difference in cost on carbon offsets. Purchasing a costlier vehicle, or one that is not fuel efficient but is close to the fuel-efficient option in cost, is not consistent with the goal of carbon emission reduction: you should choose the more fuel-efficient vehicle (to reduce emissions at a comparable cost) or the cheaper vehicle (to reduce emissions by purchasing carbon offsets). One caveat is that I used somewhat diluted sources--an automobile magazine, a few web sites--and did not reference sources of better quality. The differences, however, are quite spectacular, and I doubt they would alter so much as to invalidate my results. Another reservation is that the true cost of carbon emission is not currently reflected in the price of fuel. Carbon caps/taxes/trading will capture some of these costs, but even with these anticipated, and hoped for, changes it will not close the gap in costs.

It's not like I'm the first person to figure this out. Chuck Squatriglia, in Go Green -- Buy a Used Car. It's Better Than a Hybrid, references an article by Matt Power Don't Buy That New Prius! Test-Drive a Used Car Instead. Producing a new Prius would consume the equivalent energy of about 3800 liters of gasoline. If you purchased a used car, that carbon debt would already have been incurred. A 1998 Toyota Tercel consumes about 13 L / 100 km. It would take you over 10 years of driving 15000 km per year in your Prius to match the carbon savings of the Tercel. You might as well just get a 1994 Geo Metro XFi, which the blog says matches the Prius' fuel consumption. Then the Prius would never catch up. Andrew Markel points out in his blog entry Carbon Footprint: Old cars better than new? that there are also costs associated with transporting a new car to its destination. Which got me to thinking about all that time I spend in the vegetable aisle wondering how far the fruits and veggies traveled to get to me. There are also all waste produced and materials that go into a new car, such as metals, plastics, chemicals used in batteries, etc. Carbon is not the only pollutant. All of the components of a new car could be put to other uses or not used at all.

In my opinion, a Prius is a nice idea, perhaps for early adopters to help get the automotive industry moving toward more efficient vehicles, though this is really more the role of government. A more cynical view is that the Prius is a marketing scam intended to rip-off hapless do-gooders or allow fleet-buyers to claim that they are helping the environment without actually accomplishing this. At the end of the day, we need to dramatically reduce emissions of, and stabilize the atmospheric levels of, greenhouse gases. Romm's 8-wedge plan is one approach to accomplish this goal. In the meantime, when making individual choices, it is important to consider the many factors that impact on emissions, waste, and a shift toward sustainable living. For now, I cannot recommend a new hybrid vehicle over other alternatives. I can, however, recommend investing in much cheaper carbon offset schemes.