A point frequently lost in the excited talk about fuel cell vehicles is that a fuel cell is simply a device that allows for the controlled oxidation (burning) of Hydrogen, but that Hydrogen is not freely available. In fact, Hydrogen is tied up in water (H2O) and in fossil fuels (natural gas is CH4, for example), and to get pure Hydrogen into your fuel cell you need to first expend energy to separate it from the Oxygen in water or the Carbon in fossil fuels. Then you get that energy back in the fuel cell when you recombine the Hydrogen with Oxygen from the air. So, in a sense, fuel cells use Hydrogen as a battery. Because the Hydrogen is not freely available in atomic or molecular form, it is not a fuel, per se. We would use it as a carrier the same way a more conventional battery carries electricity that is produced through some other process (coal burning, hydroelectric, solar, wind). The problem with Hydrogen as the energy carrier is that we do not have the infrastructure to produce, transport, and store Hydrogen, while with conventional batteries the power is transported over the existing electric grid. One simply has to plug the battery in, and power is delivered to the storage device. The problem is, those plug-in cars aren’t available anymore.
The other problem is that the energy density of a Lithium-ion battery is about 200 times less than that of gasoline. That is, for 1 kg of gasoline you can go about 200 times farther than with a fully-charged 1 kg Li-ion battery. So purely electric cars typically have had a limited range compared to their gasoline counterparts, and less passenger and cargo space to make room for a big, heavy set of batteries. The great things about hybrids is that they give consumers the option of the long drive with the gasoline engine, and the electric motor is there to reduce gasoline consumption. However, carmakers have made their hybrids without a large battery and without the option to charge the battery through a power outlet. The Prius comes with a battery pack that, fully charged, could power the car for about 2 miles. 70 kg of additional batteries could give the car a 30-mile electric-only range. That may not seem like much, but it is the average distance driven by Americans each day. Since the Prius and other hybrids have the gas engine also, once those 30 miles have been driven the car would get the same fuel economy as a standard hybrid. Hopefully Toyota and Honda will start selling plug-in versions of their hybrids soon. In the meantime, some groups are doing conversions of the Prius to make them plug-in hybrids. If you’re driving 10-15 miles to work (or less), a plug-in hybrid would use almost no gasoline for a typically daily commute, but would be ready to go the long haul with the standard hybrid technology.
The energy to charge up those batteries comes from the electric power grid. A little over half of the U.S.’s electricity comes from burning coal, which is a pretty dirty prospect. Nevertheless, the electric motor makes the electric powered car, even on a coal-supplied electric grid, cleaner than conventional internal combustion engine cars. Calcars’ approach is to convert Priuses to make them operational plug-in hybrids to exert some pressure on the automakers to do this themselves. While the batteries are expensive, mass production, a growing market, and continued technical advances should bring these prices down and make plug-in hybrids an available and economical option – with any luck, by the time I need my next car.
Here is one company’s FAQ page with interesting details on their plug-in version of the Toyota Prius.
We can get the suspense, if there ever was any, out of the way in a hurry. All the usual suspects are mutually responsible for the death of the electric car. What is fascinating about this movie is how determined the car companies were to make sure that no electric cars remained on the streets. When the cars were recalled (after the companies succeeded in getting California to repeal its zero-emission-vehicle mandate), GM refused a hard-cash offer of $1.9 million for the last 78 electric cars and instead had the hauled off to be crushed. The movie also gives compelling first-hand accounts from people who had the GM EV-1 electric car and absolutely loved it. For the science and engineering and trade-offs of electric and hybrid vehicles, I’ll make a longer post here shortly. For now, I’ll just say that while the movie did not have the suspense of a murder mystery, it was a fascinating look at the power plays involved in keeping us all sucking at the oil pump.
I finally saw Dr. Al Bartlett’s famous talk on population last night at the University of Colorado. Dr. Bartlett is a Professor Emeritus at CU in the Physics Department. He begins and ends his talk with the sad assertion that the greatest failing of the human race is our inability to understand the exponential function. You might think that if that is our greatest failing we’re doing pretty well. But that is exactly the problem. Exponential growth of any kind against a finite resource leads to a rather dramatic and unhappy conclusion. One example in Bartlett’s talk is a colony of bacteria that doubles in population every minute. Consider the bacteria in a sample dish that starts growing at 11:00 a.m. and fills the dish one hour later. If it doubles every minute, then that means the dish is half empty at 11:59 a.m., and only 1/16-th full at 11:56 a.m. In other words, four short doubling times before the bacteria are completely out of space, they would look around their dish and see only 6.25% of it occupied. It is unlikely they would be worried about space or resources. This is the consequence of growth at a steady rate (sounds friendly) which is the same as exponential growth (sounds scary): at 3.5% annual growth, things double in 20 years.
The U.S. population is just about to break 300 million and the world population is over 6.5 billion. The current world population growth rate is 1.14% according to the U.S. Census Bureau. If that rate held steady we would see a doubling to over 13 billion people by 2066. However, the Census Bureau projects a continuing decline in the growth rate due to lower fertility rates. Women, on average, need to have 2.1 babies in order for the population to remain stable. The current global fertility rate is 2.6. However, even if it immediately dropped to 2.1 the population would continue to grow for a generation or so as a large population of women matures into child-bearing age.
I found the population numbers overall less alarming than the fossil fuel inventory in Bartlett’s presentation. Here we have a clear case of exponential growth against a finite resource. There’s only so much oil, and usage continues to rise. According to Bartlett we now have reliable means of estimating the quantity of undiscovered oil reserves, those undiscovered reserves are factored into projections of oil consumption and reserves in the future. The production of oil in the U.S. peaked in 1971 and will continue to decline until we are out. Drilling in the Arctic National Wildlife Refuge, for example, will supply the U.S. with, get this, one extra year of oil consumption at the current rate. That’s kind of like those bacteria getting another second or so of growth past noon. Some projections of the oil production in the world can be found in this Wikipedia article. We may be at the world peak production right about now. Check out these projections (no longer available at the Department of Energy website; draw your own conclusions). I suppose it’s dangerous to link to a Wiki site that is by definition a moving target, but a search for “Hubbert Peak” should give you the same general picture: we’re running out of oil, and in a hurry. The world oil consumption is a little less than 2 liters per day per person. That’s about a half a gallon. Americans of course use far more than that on average.
I have to say I came away from the talk a little bit daunted. Driving less is a good idea, but we’re going to need a more radical change in the way we generate and use energy over the course of the next century. Ultimately, the Sun is our main viable long-term power source. Oil is merely a fancy way of storing solar energy (grow some plants, have dinosaurs eat the plants, die, decay and create a nice hydrocarbon reservoir for us). We need to start implementing some simpler dinosaur-less schemes for harvesting large amounts of all that free energy raining down on us from the Sun. It’s going to be interesting.
Last night I got my first new measurement of Saturn’s rings from Cassini in almost a year. A couple of weeks ago I posted a prediction about what that measurement would look like. Here are the results. The black curve (new observation) shows excellent agreement with the prediction, particularly in the outer half of the A ring (right half of the plot). There is some disagreement in the inner half of the ring. This may be due to inaccuracies in the model. Another possibility has to do with instrument calibration. That gets down to the nitty-gritty work. Overall, this observation confirms our model by the good match with the prediction.
A mainstay of scientific critiques of movies that include space travel is the lament that we hear explosions and the roar of the spaceship’s engines. After all, in space no one can hear you scream, right? Right. But so what? Do we really want the movie to be dead silent when the Death Star annihilates a planet, or when the starship Enterprise goes to warp speed? Or even in a less fantastical science fiction movie like Deep Impact: would the movie really be better if all external shots of the spaceship and the comet were accompanied by silence interrupted only by the radio communications of the astronauts? I say that not only would it be less enjoyable, it would not truly be any more realistic. There may not be sound in space, but there’s also no movie camera. And there’s no orchestra to play the soundtrack. And there’s certainly no male voice choir to sing eerie music en route to Jupiter (which we couldn’t hear anyway because there’s no sound in space) in the timeless 2001: A Space Odyssey.
As members of the movie-watching audience we are participating in the charade that is the movie. How do we hear or see anything in a movie? We have made a contract with the filmmakers to ignore the camera, lights, and microphones that allow us to be shown the action. So, every time you hear the rumble of a spaceship’s engines while you’re seeing the spaceship from the depths of space, you can pretend that you’re hearing those sounds because they are transmitted by radio from microphones planted throughout the ship. It’s no more silly than the ability to see the ship, because while there is light in space, there aren’t many Hollywood movie cameras to let us see it.
There are plenty of potentially damaging (to public perceptions of science and reality) and definitely misleading elements of movies with scientific elements. Sound effects are not among them. Which are worse? You can check these sites for some ideas, or suggest your own.
Sci-Fi Science Blunders
I think the regular violation of the conservation of momentum in movies and TV shows has contributed to societal misconception about how things move.
If you haven’t already seen it, “An Inconvenient Truth” is a powerful and compelling movie. Everyone should see it. While there is uncertainty about the magnitude of future temperature changes due to increased CO2 in the atmosphere, there is virtually no uncertainty that we are forcing the climate into a new regime. Because our ecosystem has adapted to our current environment, any change is bad news. Climate change of any sort means moving from a system to which all species have adapted to one for which they are not adapted. It took hundreds of millions of years for the biotic Carbon to be stored in fossil fuels that are now being burned to release that Carbon in the form of CO2 back into the atmosphere in only a few centuries. The Carbon cycle is therefore being dramatically perturbed and putting us into uncharted territory. I urge everyone to go to climatecrisis.net and carbonfund.org to see what can be done to sequester some of that Carbon instead of dumping eons of natural Carbon sequestration back into the atmosphere all at once.