Oil Energy Independence -- Can You Spare a 31-Mile Square?

Imagine that every car in America was an Electric Vehicle (EV) powered by a electric battery like the Tesla’s (Nasdaq: TSLA) Roadster. Imagine also that each and every car was powered with solar energy. Here’s a question: what amount of land would you need to generate the solar energy to power every electric vehicle in America? And how would that solar acreage compare with the land surface that the oil industry uses to drill today?

I did the numbers and the answer will surprise you.

Part of the angst with the recent BP (NYSE: BP) oil spill in the Gulf is that many think we are addicted to oil and therefore can’t stop drilling. U.S. Presidents since Nixon have proclaimed our addiction to oil and after announcing their plans for energy independence oil demand has gone up. I have a different view.

We’re not addicted to oil. We are addicted to driving.

It is highly unlikely that as a society we’ll stop driving anytime soon. The good news is that we can drive as we have been while not polluting the Gulf, import oil or use oil at all. The way to do it is to shift the way we power our cars – from gasoline to electricity – and power those cars with the sun. I have previously predicted that the last commercial Internal Combustion Engine Vehicle (gasoline car) will be built around 2030.

So assuming all cars in America are battery electric vehicles and we drove exactly the same number of miles we do today, let’s calculate how much electricity we would need to power all of them.

Electric Vehicle Battery Power

Americans drive around 3 trillion miles (4.8 million Km) per year, according to the U.S. Department of Transportation. How much electricity would be consumed driving all those miles?

I assume that Lithium-Ion battery can power an electric vehicle for about 4 miles (6.4 Km) per kilowatt-hour (kWh). This is slightly lower that the advertised mileage of three battery electric cars as shown on the following table.

Battery Size(kWh)Miles per chargekm per chargeMiles per Kwhkm per kWh
BYD E6482053304.36.8
Tesla Roadster532453924.67.4
Nissan Leaf241001604.26.7

So 3 trillion miles divided by a mileage of 4 miles per kWh means that Americans will need 750 billion kWh annually for driving.

Now let’s calculate the total land needed by solar power plants to generate this much electricity in a year.

Solar Land Needs

The total power generated for a given land area will be given by the following formula

Power Generation = Land Area * DNI * Sunlight-to-power efficiency

(see the definitions and my assumptions below):

I’m using 15% efficiency and a DNI of 2,000 kWh/ m2/yr (see notes below for more).

Resolving for Land Area we get:

Land Area = Power Generation / (DNI * Sunlight-to-power efficiency)

= 750 billion kWh/year / (2,000 kWh * 0.15)

= 2,500,000,000 m2

= 2,500 Km2

= 965 square miles

So here’s the number: 965 square miles (2,500 Km2). That’s less than 1,000 square miles! What this means is that a solar square with 31.1-mile sides (50 Km) could generate all the power that would power every single car in America (assuming they were all electric vehicles.)

Ted Turner’s ranch in New Mexico is about 244 square miles – so he alone could generate enough electricity to power 25% of all cars in America. A solar plant the size of King Ranch in Texas with its 1,289 square miles could generate all of America’s electric vehicle power with 30% extra electricity to spare – maybe export it to Mexico?

The solar number is 1,000 square miles. Let’s compare this number with what the oil and gas industry uses today to power our gasoline cars.

Oil & gas land use

According to the U.S. House of Representatives, oil and gas companies lease 74,219 square miles (47.5 million acres) of land in the United States to drill oil. They also lease a further 44 million acres (68,750 mi2) for offshore drilling (2). Adding these two numbers we get that the oil and gas industries lease 143,000 square miles from the U.S. government—to meet just about a third of America’s transportation needs.

So to power just about a third of our cars, oil companies need 143 times the land that solar would need to power every single car in America (assuming they were all electric vehicles.)

Needless to say, oil drilling leaks and spills damage more land and water than the above numbers reveal. The BP (NYSE: BP) Gulf Oil disaster has damaged tens of thousands of square miles beyond its drilling permits. As of June 2010 the U.S. National Oceanic and Atmospheric Administration (NOAA) Fisheries Services had closed an area around 80,000 square miles of water from commercial fishing.

The BP Oil Spill alone is eighty (80) times larger than the desert land that solar CSP plants would need to power every car in the United States (assuming they were all electric). And no one has ever heard of a solar spill.

The conclusion is simple: oil is not just dirty – oil is a land and water hog. Solar is more than 100 times more land efficient than oil – without the pollution.

What does this mean to entrepreneurs?

When the most abundant source of energy on earth (solar) is also is 100 times more resource efficient than the competitor (oil) the message is clear: the transition from oil to solar to is going to happen. It’s just a matter of when not if. As the car industry also transitions to electric vehicles keep in mind this solar number: just 1,000 square miles of solar plants in the desert can power all the (3 trillion) vehicle-miles driven every year in America. That’s what I call ‘Solar Trillions’!

Definitions and Notes

Battery Electric Vehicle range and mileage like gasoline car mileage will depend on many factors, including the car itself (weight, quality), driving conditions (city, highway, traffic, weather), driver, and so on. Furthermore, not all Lithium-Ion batteries are made equal. The number I came up with was based on a decidedly unscientific sample of three battery electric vehicles (Tesla Roadster, BYD E6, and Nissan Leaf) from three different countries (US, China, and Japan). I used 4 miles per kWh of battery.

DNI = Direct Normal Incidence radiation. DNI depends on the location. I’m assuming the solar plants are built in desert land in the U.S. Southwest, which generally have high DNI. A solar plant in Barstow, CA, may receive more than 2,700 kWh/m2/yr while Las Vegas, NV, or Tucson, AZ, receive about 2,560 kWh/m2/yr. I used 2,000 kWh/m2/yr.

Sunlight-to-power efficiency = What percent of the solar radiation (DNI) is converted to power. This number also depends on the technology used. Thin film photovoltaic might convert less than 10% while Dish Sterling CSP efficiency may be closer to 30%. Solar CSP with Combined Heat and Power (CHP) can have an efficiency of 75%-80%.

However, you need extra land for things like roads, power block, offices, and so on. I used 15% efficiency. Expect this number to go up over the next few years as new innovations, learning curve, and scale advantages kick in.

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