• Aug 19, 2009
It may not be a particularly glamorous definition of the automobile, but it's true on some level that cars and trucks are individual little power generators on wheels, a fact pointed out here by Wired staff writer Alexis Madrigal. Interestingly, when viewed in that light, the United States has an embarrassment of riches when it comes to overall latent power availability.

In fact, Madrigal calculates that the U.S. has 35 times more horsepower sitting there in our driveways than in all our power plants combined. Like numbers? Says Madrigal:
Turns out we have something on the order of 51 billion peak horsepower sitting in our driveways. That's an incredible 38,276 gigawatts of power available. That absolutely dwarfs the nameplate capacity of our electrical power plants, which total up to a mere 1,087 gigawatts. In fact, each week of 2008, a horrible year for car sales, almost 38 gigawatts of capacity rolled into the streets of America.
That's mighty impressive, no? While we're not sure we'd follow the logic all the way to the conclusion that we should all be driving Tata Nanos, we do agree that the average passenger car doesn't really need 200 horsepower to get its lone occupant to work on time. We also can't help but consider the potential of a national electric car infrastructure as a way to store excess power that could be called into action in a jiffy if required.

[Source: Inventing Green]


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  • 31 Comments
      • 5 Years Ago
      This is actually a very deceiving and a bit inaccurate comparison. While on the surface it appears true and a surefire way of saying that we don't have the infrastructure for all electric car charging, we need to look a little closer at how we use this power. We need to look at the average power output over a known amount of time. You may have a 200 HP car but when it's not running it is producing 0 hp. When it is running it's almost never producing 200 HP. Only when pushed extremely hard at one point will it produce that. Most people don't drive like that. You might only have used an average of 30 HP on a long trip. Once you know how much average power output your car does on any given trip of known length, then calculate how long it was sitting there not running. Add all of these up for any given amount of time and the numbers get very different.

      Power plants on the other hand, while also not always running at full power, are always running. Their actual output over any given amount of time will be far closer to their total potential than cars will. FAR closer! While "potential" peak horsepower may be 34 times higher than our powerplant peak outputs, I'm willing to bet that when you factor in average over time, including when cars aren't running, we've got far more average used power from powerplants than from cars which should mean that we've got enough reserve capacity to charge electric cars. Especially at night when we don't use all of the available power potential anyways. However this isn't to say that if we add in electric cars to the already existing electrical power requirements that we won't exceed capacity. We've already seen brown outs that suggest this is true.

      The point is that these numbers when applied practically in the real world are pretty worthless.
        • 5 Years Ago
        I think Joel's being kinda negative about it, but I personally would estimate the increase in electricity generation needed to go to EVs to be about 100% (double existing) also. This is a lot, but it's not nearly as bad as the scary 10X numbers on here.

        You guys are getting way off track bothering with engine output. That's just not necessary. All you need to do is look at "filling your tank". They don't have to build new gas stations or create larger filler nozzles if a guy on my block buys a 600HP Mercedes SL. It just takes a little longer for him to fill his tank compared to his range.

        So it doesn't matter if a guy commutes for 60 seconds at 600HP or an hour at 60HP, the stress on the grid or at the gas station is the same. So we don't need to look at peak outputs at all. If the average commuter uses 12kWh a day (a figure I made up from the Volts 40 miles at 8kWh and the alleged average commute of 53 miles), then you just need to be able to deliver 12kWh to each house (per car, some houses might have two cars) per day.

        That's about $1 worth of electricity. So what is your current electric bill? Is it $30/month and you're getting one EV? If so, you need twice as much electricity as you currently get. If your bill is $90/month right now and you're getting two EVs, then you only need about 66% more electricity then you get right now.

        And again, you're getting it at night in these cases. If the draw can be managed smartly, the night draw might not exceed the day draw much if at all, meaning we don't have to overhaul the actual wires or plants in the grid at all.
        • 5 Years Ago
        You're on the right track but slightly wrong. For an example usage, my truck has run about 5000 hours over the last 6 yrs = 833 hr/yr. There are 8760 hrs in a year, so average uptime of my truck is ~10%. You're right that a car doesn't usually use anywhere near full hp. I'd say an average of 50hp generation is about right (try the iPhone app if you want some real numbers in your own car). If avg max hp is 200, then avg car power usage is ~960 GW based on the total cap given above.

        A given power plant is not run all the time either, but baseline plants have an avg uptime of ~95% and they ARE run at full power most of the time. Running a plant at partial capacity is a waste of resources and avoided. They shut a unit down in order to keep others running at full load to balance generation vs demand.

        This gives an auto consumption about equal to the gross generation of electricity. This means there is NOT enough power generation to convert to an all electric auto fleet. Some areas of the country are already low on power and surplus in one area can't always be sent to another area. We are currently building quite a bit of new generation capacity in this country.
      • 5 Years Ago
      Oddly enough 78% of that power coming from American cars comes entirely from LS engines.
      • 5 Years Ago
      MORE POWERRRRR
      • 5 Years Ago
      this is retarded. how much power does it take to light a light bulb or two? now how much power do you think it takes to move a 2-ton hunk of metal? i rest my case [slams portfolio shut, exit dramatically].
      • 5 Years Ago
      What about a torque comparison? Huge construction equipment with massive engines will put out 200 hp and 1000 ft/lbs. There is not enough information here to make any kind of legitimate comparison.
        • 5 Years Ago
        You cannot compare torque in the way that you mention. It doesn't have any meaning.
      • 5 Years Ago
      This mostly came about this decade. Most cars in the early 2000s had less than 200hp. Now even Accords drive around with that.

      I say, screw HP. I REQUIRE MORE TORQUE ASAP
        • 5 Years Ago
        @PPP and LS2LS7

        Of course I realize that fuel consumption in cruise is diferent than at peak hp. This is why I did not use their 35x factor from the article. Nevertheless, thinking that the current power plant capacity will suffice when most will switch to plug-in hybrids and electric cars is a pipe dream. The moment a household will switch to electric vehicles its power requirement will go up by a factor of 3 to 5.

        Then you have the load balancing problems. Again, not everybody will charge at night, quite the contrary. They will charge during the day at work, because most of these vehicles will be bought by an urban population that does not have its own garage or simply because they will prefer to charge the car quicker using an industrial outlet (less than 30 minutes per charge are possible today, who knows how quick will they be in 10 years) than the one in their garage.

        In other words, in order to meet all these challenges an increase in power plant capacity by an order of magnitude is a more realistic requirement. I'm optimistic but cautios at the same time.
        • 5 Years Ago
        You're assuming each car operates at maximum output and does so for 24 hours a day. For each second an Accord is actually pumping out 230 whatever HP, you probably have a thousand where it's maybe putting out 20. This really has very little to do with the feasibility of transitioning to electric powered vehicles and is more a case of interesting trivia, nothing else.
        • 5 Years Ago
        Unfortunately this also says that if we want to replace gas with electricity for our cars we need at least 10 times more power plants. We'll see how this turns out.
        • 5 Years Ago
        Due to the additional power being used at night when demand is low, I don't think it's nearly as bad as you think. I think your assumption of 3-5x usage is true, but since most of the usage at homes comes at night, I think it won't cause the peak draw to go up nearly as much as the total draw (power versus energy here).

        As to "on the go charging", it will just have to be smart. Yeah, people will want to charge, but the charging will just have to slow down when a lot of cars are plugged in at lunch. You won't necessarily be able to charge your car in 30 minutes any time you want.

        Also, plug-in hybrids are peanuts, especially at night. I don't think we need any grid upgrade for that. Pluggin in a Volt for the night is basically just like running your air conditioner, and since your air conditioner will be working far less hard at night, it just won't matter.

        In the end, since power plants can't really increase and decrease their power output per hour as much as you make out, going to 10X for peak usage just isn't realistic. Most large plants take 24 hours to restart if they are turned off.

        Compromises will have to be made. That's just basically the end of it.
        • 5 Years Ago
        Dondonel,
        Thats exactly what I was thinking
        • 5 Years Ago
        My house has 100A service at 220V. That's 22kW of power. That's about 33HP.

        Even if my house had more modern 200A service I'd still have 66HP service of elecricity. That's less power than any car sold in the US. Additionally, many people have two cars in their garage/driveway, widening the gap even more.

        This isn't just a new thing, although it's worse lately.

        People don't realize how much power a car engine can produce. This is part of why it takes all night to charge your EV, and why we'll need a smarter power grid as we deploy more EVs. To put in a grid so powerful that everyone can charge their EV at peak rate at once would cost a lot of money. But with just a tiny bit of brains, the peak charging rates can be staggered a bit and reduce the amount of grid capacity needed run support EVs 3-fold or more.
      • 5 Years Ago
      It's not how much hp you have, it's how you use it.
        • 5 Years Ago
        Alex,

        This is exactly what the Volt can do, operate the IC engine for peak efficiency in any driving condition to extract electric power. Electric motors put out max torque at 0 rpm and it linearly decreases as rpms increase which is exactly what a car needs to drive around, and they don't require as many gears in the transmission.
        • 5 Years Ago
        The legal range is 1 mph to 75 mph. You must not have gotten a highway speeding ticket lately.
        • 5 Years Ago
        Agreed!

        * resumes washing his Golf *
        • 5 Years Ago
        That is actually a very good point. A car's engine has to be able to operate at very wide performance band. From 1 mph to 120 mph and under a large variety of conditions. A car's engine is never working at both peak hp and peak efficiency at the same time. The same is not true for something like a hydroelectric motor. That motor is operating at a specified range and is designed to operate at peak efficiency while in that constant range.
      • 5 Years Ago
      I dont understand why anyone would want to commute from the suburbs to chicago. Where i am i see one person per car. Its ridiculous. I take the metra which gets me to chicago from naperville in 33mins compared 2hrs in traffic jams.

      I love cars but i do not take mine to work, its for the weekends and holidays and offcourse going around in the suburbs.

      • 5 Years Ago
      You're absolutely right. 25 years ago an Accord wasn't even making 100HP, now a Corrolla makes 135 and it's called lame and underpowered. I think it's the same reason median house sizes and prices have doubled or more - everybody wants more whether they need it or not. Do you really need a 5000lb vehicle that makes 350HP when 90% of the time you're going 20mph alone in traffic back and forth to work? People whine about the prices of cars and housing and gas yet consistently insist on buying way more than they ever need.
      • 5 Years Ago
      Gas contains about 120 MJ per US gallon, which is 33 kWh. Less than a quarter of which is converted to spinning the crankshaft in your car, but that's how much was in it to begin with.

      The US consumes about 140 billion gallons of gasoline per year which works out to about 4.5 trillion kWh. For all purposes, not just cars.

      US electrical generation is about 4 trillion kWh per year.

      So despite that 35:1 disparity in theoretical capacity, power plants are producing at least four and probably more like six times the energy of the car fleet.
        • 5 Years Ago
        Exactly what I was figuring out.

        And Cars are not as efficient as a gas turbine - 20% compared to 55%-90% (if a boiler re-claim system is used.)

        So, while 'Potential' energy is shown, energy production used is another matter.
      • 5 Years Ago
      What's the point? It's not a useful resource from a power production point of view. The efficiency of an automobile engine at peak horsepower is awful relative to even an ancient coal plant.

        • 5 Years Ago
        Coal may be unlimited but Water is not.
        Coal uses water in processing and pollutes it because of the mining.
        There's also Peak Coal coming, it's not limited by coal reserves but water.
        • 5 Years Ago
        From a grid generation perspective, the problem isn't that small engines aren't efficient. It's that oil is expensive, production is limited, and a large part of the supply is controlled by third world thugs like Chavez, Putin, and the Saudis.

        Coal sells for less than 1/4 the price of oil per unit of energy, and domestic reserves are for all practical purposes unlimited.



      • 5 Years Ago
      I know Autoblog is the wrong forum to say modern cars are too powerful on average, but I'll say it anyhow.

      When people wonder why average fuel economy has remained roughly stagnant for 20 years despite all the advancements in engine and transmission technology, there are 2 primary culprits: a notable increase in average automobile weight (for good and bad reasons) and a HUGE increase in average automobile power. I'd argue that the latter issue is a bigger factor, especially because more power facillitates more aggressive driving habits.

      Back in the day, when you bought a truck, you were making a trade-off -- utility over speed. Today, people want 4,500-5,000 lb. family SUVs that do 0-60 in 7 seconds or less. That was Porsche 944S or Ferrari Mondial territory back in the 1980s. Today, too many people have expectations that all cars should be fast regardless of size or weight, and that has caused a HP arms race.

      A BMW M3 had a 192HP 4 cylinder in 1988 -- Today it has a 400HP V8
      A BMW M5 had a 256 HP I6 in 1988 -- today, the Honda Accord and Toyota Camry offer more power and near equivalent straight line speed (seriously, think about that).

      As a related matter, many manufacturers usually don't want to certify multiple drivetrains for each model, so aside from economy-oriented cars, many models are only offered with a relatively high powered drivetrain and an even more powerful drivetrain. Even worse, many manufacturers only offer more desirable options like sports packages, leather, nav and upgraded sound systems if you opt for a more powerful engine -- what does one have to do with the other? This further promotes the purchase of more powerful engines that most people don't really need (or possibly want).

      Again, I know this may be unpopular on Autoblog, but I think the easiest thing auto manufacturers could do to reduce fuel economy is to offer and PROMOTE well equipped, nicely appointed cars with less powerful, more fuel efficient and less expensive engines. Hybrids are great, but they are complicated and expensive relative to regular gas engined cars. Diesel is also great, but it also adds cost and fuel prices vary relative to gas (though i do like diesel torque).

      There are signs of hope -- Audi is heavily promoting their great new turbo 4 in the A4 and A5 and ditching, to some extent, their fuel sucking, heavy V6 (which is really no quicker with its lack of torque). Acura has done fairly well with a 200HP I4 in the TSX, but now a V6 is being offered -- I wonder what the sales mix will be. There are rumblings that BMW will bring turbo 4s to the 1 and 3 series.

      I'm still hoping someone can build a mid-90s BMW 3 series equivalent but with modern safety and convenience options. I'd be happy to drive a turbo 4 or small inline 6 with ~200HP, a good manual tranny, great brakes, handling and steering, and a realistic weight of ~3,200 lbs. Average fuel economy for a car like that could easily reach the mid to high 20s and the car would still be plenty of fun.
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