So you know I’ve been pushing ‘An Inconvenient Truth.’ (If they made a movie about YOUR HOUSE, would you go see it? Well, they have.)

And you may recall I’ve also been pushing the harder-to-find ‘Who Killed the Electric Car?‘ (Not only would GM not allow its lessees to renew their leases or purchase their cars outright . . . after they took back their cars and crushed them, they shredded them.)

Well, Mark Anderson gave me permission to cut and paste this fascinating piece from his Strategic News Service web site.

I don’t understand all the energy conversion factors (I thought rich women wore mega joules), but the gist is pretty clear and very cool. If only Ford had been thinking this way, they could be hiring 20,000 employees.

By Elon Musk


My day job is running a space transportation company called SpaceX, but on the side I am the chairman, primary financial backer, and assist with product and strategy at Tesla Motors. The initial product of the company is a high-performance electric sports car, called the Roadster, but the intent is to build electric cars of all kinds, including low-cost family vehicles.

(See video here, by Autoblog:

The overarching purpose of Tesla is to help expedite the move from a mine-and-burn hydrocarbon economy towards a solar electric economy, which I believe to be the primary, but not exclusive, sustainable solution.

As July’s unveiling of the Tesla Roadster demonstrated, reports of the death of the electric car have been greatly exaggerated. Moreover, this is a vehicle that defies all conventions associated with environmentally friendly cars, particularly those of a purely electric nature. My apologies for the brief commercial, but to understand what is possible, I must present the facts of the vehicle:

* 0 to 60 mph in 4 seconds
* 250 mile EPA highway range
* 135 mpg equivalent, per the conversion rate used by the EPA
* $2.50 for a full charge, assuming Northern California PG&E off-peak rates
* Fully DOT-compliant: crash tested, with airbags, crash structures, etc.
* $89,000 price (as low as $83,000 with rebates)

The Tesla Roadster is designed to beat a gasoline sports car like a Porsche or a Ferrari in a head-to-head showdown and, by the way, it happens to be electric with twice the energy efficiency of a Prius. In other words, it is a great sports car without significant compromises. Now, some may question whether this really does any good for the world. Are we really in need of another high-performance sports car? Will it actually make a difference to global carbon emissions?

Well, the answers are No and Not much. However, that misses the point. Almost any new technology initially has high unit cost before it can be optimized, and this is no less true for electric cars. The strategy of Tesla is to enter at the high end of the market, where customers are prepared to pay a premium, and then drive down market as fast as possible to higher unit volume and lower prices with each successive model.

Without giving away too much, I can say that the second model will be a sporty four-door family car at roughly half the above price point, and the third model will be even more affordable. In keeping with a fast-growing technology company, all free cash flow is plowed back into R&D to drive down the costs and bring the follow-on products to market as fast as possible. When someone buys the Roadster sports car, they are actually helping pay for development of the low-cost family car.

Emissions Elsewhere, a.k.a “The Long Tailpipe”

A common rebuttal to electric vehicles as a solution to carbon emissions is that they simply transfer the CO2 emissions to the power plant. An obvious counter is that one can develop grid electric power from a variety of means, many of which, like hydro, wind, geothermal, nuclear, etc., involve no CO2 emissions. However, let’s assume for the moment that the electricity is generated from a hydrocarbon source such as natural gas, the most popular fuel for U.S. power plants in recent years.

The H-System combined cycle generator from General Electric is 60% efficient in turning natural gas into electricity. (Combined cycle is where the natural gas is burned to generate electricity, and then the waste heat is used to create steam that powers a second generator.) Natural gas recovery is 97.5% efficient, processing is also 97.5% efficient, and then transmission efficiency over the electric grid is 92% on average. This gives us a well-to-electric-outlet efficiency of 97.5% x 97.5% x 60% x 92% = 52.5%.

Despite a body shape, tires, and gearing aimed at high performance rather than peak efficiency, the Roadster requires 0.4 MJ per kilometer or, stated another way, will travel 2.53 km per mega-joule of electricity. The full cycle charge and discharge efficiency of the Tesla Roadster is 86%, which means that for every 100 MJ of electricity used to charge the battery, about 86 MJ reaches the motor. By the way, the Tesla Lithium-Ion battery pack is landfill-safe, although dumping it would be pointless, since it can be sold to recycling companies (unsubsidized) at the end of its 100,000-mile design life. Moreover, the battery isn’t actually dead at that point; it just has a lowered capacity.

Bringing the math together, we get the final figure of merit of 2.53 km/MJ x 86% x 52.5% = 1.14 km/MJ. Now, let’s now compare that with the Prius and a few other options normally considered energy-efficient.

The fully considered well-to-wheel efficiency of a gasoline-powered car is equal to the energy content of gasoline (34.3 MJ/liter) plus the refinement and transportation losses (18.3%), multiplied by the miles per gallon or km per liter. The Prius, at an EPA-rated 55 mpg, therefore has an energy efficiency of 0.56 km/MJ. This is actually an excellent number compared with a “normal” car like the Toyota Camry at 0.28 km/MJ.

Note, the term “hybrid” as applied to cars currently on the road is a misnomer. They are really just gasoline-powered cars with a little battery assistance, and, unless you are one of the handful who have an aftermarket hack, the little battery has to be charged from the gasoline engine. Therefore, these cars can be considered simply as slightly more efficient gasoline-powered cars. If the EPA-certified mileage is 55 mpg, then it is indistinguishable from a non-hybrid that achieves 55 mpg. As a friend of mine says, a world 100% full of Prius drivers is still 100% addicted to oil.

The CO2 content of any given source fuel is well understood. Natural gas is 14.4 grams of carbon per mega-joule, and oil is 19.9 grams of carbon per mega-joule. Applying those carbon content levels to the vehicle efficiencies, including as a reference the Honda combusted natural gas and Honda fuel-cell natural gas vehicles, the hands down winner is pure electric:

Car Energy Source CO2 Content Efficiency CO2 Emissions
Honda CNG Natural Gas 14.4 g/MJ 0.32 km/MJ 45.0 g/km
Honda FCX NG Fuel Cell 14.4 g/MJ 0.35 km/MJ 41.1 g/km
Toyota Prius Oil 19.9 g/MJ 0.56 km/MJ 35.8 g/km
Tesla Roadster NG Electric 14.4 g/MJ 1.14 km/MJ 12.6 g/km

The Roadster still wins by a hefty margin if you assume the average CO2 per joule of U.S. power production. The higher CO2 content of coal-vs. natural gas is offset by the negligible CO2 content of hydro, nuclear, geothermal, wind, solar, etc. The exact power production mixture varies from one part of the country to another and is changing over time, so natural gas is used here as a fixed yardstick.

Now, I should mention that Tesla will be co-marketing sustainable energy products from other companies along with the car. For example, among other choices, we will be offering a modestly sized and priced solar panel from SolarCity, a photovoltaics company (where I am also the principal financier). This system can be installed on your roof in an out-of-the-way location, because of its small size, or set up as a carport, and will generate about 50 miles per day of electricity.

If you travel less than 350 miles per week, you will therefore be “energy positive” with respect to your personal transportation. This is a step beyond conserving or even nullifying your use of energy for transport – you will actually be putting more energy back into the system than you consume in transportation.

As an addendum, I will drill into two alternative solutions to the energy problem, one that used to be a lot more fashionable and one that is swiftly becoming so:

Hydrogen Fuel Cells: Always a Bridesmaid, Never a Bride

For half a century, stretching from the Gemini space program in the early ’60s to the present day, fuel cells have seemed to hold great promise only just out of reach. The claim would be made that as soon as such-and-such technology goes into production, the world will experience the wonder of hydrogen fuel cells.

Well, the truth is that even with impossibly optimistic assumptions, physics is not on your side when it comes to mobile fuel cells, although some stationary applications can make sense. The most efficient way to produce hydrogen in practice is from natural gas, which has an efficiency of 52% to 61%. The upper limit of a PEM fuel cell for producing electricity is 50%, and we can assume the same 2.78 km/MJ vehicle efficiency as with the battery-powered car. This results in a theoretical (perfect technology) maximum figure of merit for our hydrogen fuel cell car of 2.78 km/MJ x 50% x 61% = 0.85 km/MJ.

This is still worse than the Li-Ion battery powered car, but not bad when compared with gasoline vehicles. However, real-world fuel-cell cars have never gotten close to this good. The best fuel-cell car is the Honda FCX, at 0.57 km/MJ x 61% = 0.35 km/MJ – not even as good as its gasoline-powered equivalent. Moreover, using natural gas to obtain hydrogen means we are still dumping vast amounts of CO2 into the atmosphere. Although one can attempt to make hydrogen with a zero CO2 source of electricity, the poor efficiency of electrolysis means you end up even worse at 0.12 km/MJ, which is about one-tenth as good as a Li-Ion electric car.

The superiority of Li-Ion for storing electricity is empirically supported by the fact that, apart from isolated experiments or government-driven use, almost no one uses fuel cells in mobile applications. The value of extra energy in the ultra-competitive cellphone or laptop market is enormous, and many consumers would pay a significant premium for something better, yet we use Lithium-Ion batteries.

Ethanol, Ethanol, Everywhere, Nor Any Drop to Drink

Ethanol (a.k.a. alcohol) will certainly grow as a business and serve as a partial solution to our energy problem, particularly given that it is now taking the place of the gasoline additive MTBE. However, even if large-scale cellulosic ethanol technology is perfected, I don’t believe it will become the primary solution to the world’s needs.

The often-used example of Brazil does not apply to most parts of the world and may not even apply to Brazil if they see high economic growth with its attendant energy demands. Brazil is in the tropics with an all-year-round growing season and an enormous amount of arable land relative to its population food requirements and the number of cars on the road.

In contrast, domestic ethanol as the primary solution will definitely not work for the world’s most populous countries, such as Japan, China, India, Pakistan, Indonesia, etc. Those countries are either breaking even on domestic food production or are net importers. If you argue that ethanol is to be grown elsewhere and shipped, where are these vast tracts of unused arable land? And, bear in mind, the caloric requirements of cars are much higher than those of humans.

Another way to think about it is that plants are basically just a very inefficient way to convert sunlight into stored chemical energy. Their net efficiency is about 1/2% or so, compared with commercially available photovoltaics at 20%. That means you need about 40 times the land area in crops than you do in photovoltaics. Complicating the issue is that crops require arable land, which will apply great pressure to unplanted wilderness areas around the world. In contrast, photovoltaics can be installed on your home or business rooftop, efficiently delivering energy right where it is consumed and taking up no extra land at all.

If you want to use plants most effectively as an energy source for transportation, the best way is to burn them whole (no processing needed!) in a combined cycle biomass electric generator at 60% efficiency and use the output to charge electric vehicles. That requires no technology breakthroughs, uses the full energy content of the plant, and is vastly more efficient than refining a small part of the plant (or even the whole plant, using cellulosic technology) into ethanol to power cars directly.


No matter your preferred means of energy generation, electric cars are the answer: a hydrogen-fuel-cell car is simply an electric car with hydrogen as a poor energy storage technology. The most efficient way to use biomass or any chemical energy source is not to pour it in your tank and burn it at 20% efficiency, but rather to convert it into electricity in a combined cycle power plant at 60%, then charge your electric car. Moreover, the separation of source and use enabled by the electric car allows for zero emission (in operation) energy technologies, like wind, solar, geothermal, tidal, etc.

Lithium-Ion batteries are the most efficient way to store electricity today, but I suspect we will find that there are even better technologies down the road. In fact, my original reason for moving to Silicon Valley about a dozen years ago, before I got distracted by the Internet, was to do a Ph.D. at Stanford in the physics and materials science of high-energy density capacitors, specifically for electric vehicle applications.

Capacitors have the advantages of a quasi-infinite cycle and calendar life, extremely low charge / discharge losses, and charge times measured in minutes for a car-size pack. If the capacitor energy density problem is solved, the gasoline vs. electric contest goes from a fair fight to gasoline getting the WWF Smackdown.

Noteworthy References

* For a more detailed review of electric vehicles vs. other modes of propulsion, please see the white paper written by Martin Eberhard and Marc Tarpenning, available on the Tesla website.

* EPA mileage numbers are derived from

* The GE H system generator, an example of beautiful engineering:

* Efficiency of Hydrogen Fuel Cell, Diesel-SOFC-Hybrid and Battery Electric Vehicles, 20 Oct 2003, Ulf Bossel

About Elon Musk

Elon Musk has been the primary funding source for Tesla Motors, from when Tesla was just three people and a business plan to the present day, having led the Series A and Series B and co-led the Series C. Electric vehicles have long been one of Elon’s primary interests, stemming from his days in the early ’90s working on high-energy density capacitor technology in Silicon Valley. Elon is known for co-founding PayPal and Zip2 and founding SpaceX, which is in the business of developing and launching the world’s most advanced rockets for satellite and later human transportation. As chairman of the board of Tesla Motors, Elon helps develop the company’s business and product strategy, and assists with knowledge of composite and metallic structures, domestic manufacturing, and navigating federal regulations.

Copyright 2006 Strategic News Service LLC and Elon Musk. Redistribution
prohibited without written permission.


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