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A Future Look at Chemical Energy

Like electrical power distribution, the distribution of chemical energy is highly regulated by government. The primary reason your car is powered by gasoline or diesel, rather than some other compound is, these forms of energy seemed the easiest and cheapest at the time the automobile was initially developed. So to some degree, this is just the habit and practice we have evolved into. Automobile producers, fuel refineries, and filling stations have all adapted to use commonly defined standards so we can buy a car from the manufacturer of our choice and still fill up with fuel nearly anywhere in the country. In order to assure this standardization, government regulations have evolved to dictate how it will all be done. They determine not only the formulations of the fuels the car will use, but also that the cars will meet certain emission and safety standards. And like most other government regulations, they make it easier for existing big business to continue earning profits, and harder for new, smaller startups to get into the business.

Initially, the fuel distribution infrastructure focused on gasoline, at least where personal automobiles were concerned. But trucks were better suited for operation on diesel fuel and so fuel stations in common trucking corridors catered to both gasoline and diesel. Due to the laws of supply and demand, diesel fuel initially cost less than gasoline even though it provided some improved economies. Eventually automobile manufacturers caught on to using diesel powered engines to offer these advantages to their customers. As diesel powered cars became more popular, demand for diesel fuel increased and so more and more fuel stations offered it for sale. Now decades later, a new equilibrium has been reached where diesel is often more expensive than gasoline and diesel powered automobiles are fairly common.

So are these two fuels the only viable options for operating a vehicle? Recently some manufacturers have been developing cars that run on stored electrical power. A notable example is the Tesla, but many more are rapidly being introduced. Other cars are now being operated on compressed natural gas. It turns out to be relatively easy to convert a gasoline automobile to natural gas. But still, there are a number of challenges to overcome. For example, it requires costly energy and an expensive machine to compress natural gas into a tank small enough to fit in a car. Electric cars tend to be fairly slow to recharge. And they require massive banks of batteries which can be dangerous, caustic to the environment, and very expensive when they wear out and have to be replaced. If you own a car powered by natural gas, you may be able to find a place to fill up if you are careful. But the number of locations offering it, at this writing, are a tiny fraction of those offering only gasoline and diesel fuel.

The primary challenge surrounding the operation of automobiles on alternative storage methods has to do with a concept called energy density. It describes how much energy you are able to fit into a space of a given size. For example, the energy your car uses is stored in your gas tank. If you have ever looked under your car, you may know about how big that tank is. It might fit under your trunk or one of the fenders. And you know about how far you can drive on a tank full of gas. That gives you kind of an intuitive sense of how potent a form of energy gasoline is.

If you buy a car powered by natural gas, you will quickly come to realize that your trunk, or truck bed, may be partially or entirely consumed by the tank you will use to hold your supply of fuel. In other words, you have to use up more space in the vehicle just to store the fuel. And you may well find that in spite of this increased space requirement, you can actually travel fewer miles than you could in your gasoline or diesel powered car. If you are brave enough to be an early adopter of an electric car, you have probably noted that while acceleration and efficiency are good, your driving range is even worse than a natural gas car. Your electric car may be quite heavy as a result of its massive battery bank. And you are probably limited to driving a few miles around locally before you have to return home for a recharge. Furthermore, while you can refill your gasoline, or even a natural gas car in just a few minutes, it may take an hour or several hours to recharge your electric car. This makes it impractical for longer journeys.

A brief study of energy densities quickly reveals why we like gasoline so much as an energy storage mechanism for our cars. And make no mistake, gasoline is not an energy source—it is just a storage medium. The energy came from the sun. It is just stored in the molecular bonds of the hydrocarbons in the fuel. So whether you drive a conventional car or one powered by alternative means, such as electricity, the power still has to come from somewhere. And most likely it will be coming from the energy stored in a fossil fuel, at least for a while until we find a more efficient way to get it directly from the sun as it shines. So you may think your new Tesla isn’t polluting the environment in Los Angeles. But somewhere in Nevada, a coal-fired power plant may be generating the electrical energy you are using to recharge your batteries.

Gasoline boasts a density of about 34 MJ/L (Million Joules per liter). A Joule is a measure of energy, just like a Kilowatt-hour, but on a much smaller scale. Diesel fuel is around 38 MJ/L. By comparison, natural gas is only 0.03 MJ/L. When we compress the natural gas in order to put it in our vehicles, we can raise it all the way up to about 9 MJ/L. But it takes a some energy to do that. And 9 is still a lot less than 34. If we can compress it so much that it becomes a liquid, we can get all the way up to about 22 MJ/L. This is still less than 34, and the pressures are too high to efficiently deal with and are very dangerous. For reference, a Zinc-air battery can be found in the range of 6 MJ/L. This is still a lot less than 34. Battery technologies and their associated energy densities are constantly increasing. But it looks like for the moment, the chemical bonds of gasoline and diesel fuel maintain a difficult standard for alternative technologies to compete with.

But are there other ways of storing chemical energy we have not yet sufficiently explored? This is where we might peek into one possible future alternative. If you enjoy chemistry or physics, maybe you will get excited about some possibilities: Theoretically, elemental carbon (think of coal, but without any of the impurities) has an energy density near 73 MJ/L! Is it any wonder why we rely so heavily on coal for our energy industry? While most people probably don’t get that excited about the idea of a coal-powered car, let us consider one powered by pure elemental carbon, or graphite, as it is commonly called. When coal is burned, it often emits a number of noxious fumes including sulphur dioxide which, among other bad things, causes acid rain. Graphite however, emits only one thing when burned: Pure carbon dioxide.

Now you’re probably thinking “CO2, that’s bad too.” There are two reasons why not. First CO2 is not noxious or toxic. It has only been characterized as a pollutant because of its possible implications in causing global warming. But there seems to be some degree of disagreement about whether human-caused global warming is an indisputable fact or perhaps more of an article of one’s individual Faith. Although CO2 concentrations in the atmosphere do currently seem to be on the increase, it is not entirely clear whether this is causing a warming of the planet. In fact, it may be possible we are in a cooling period rather than one of warming.

The temperature variations being measured are of such a small size and distributed over such a large and varying geographical distribution, it can be nearly impossible to determine with certainty. One thing is for sure: global warming has become a very hot political topic. It has been used by various power brokers in the political arena to factionalize society, to garner votes, and to enact legislation that has helped prop up the price of energy for big business. So to the degree big business is involved in the process, we should be very skeptical of the true motivations.

Secondly, we all need to remember, CO2 is what we exhale when we breathe. It is all around us and in reasonable concentrations, it is harmless to living things. In fact, the plants and trees around us couldn’t survive without it. Due to either a fortunate chance of evolution or the design of an intelligent creator, plants use the stuff to convert sunlight into the energy they need to survive. And they put off oxygen in the process, making it possible for us in the animal kingdom to breathe, oxidize the high-energy molecules derived from our food, and produce the energy we need to go on living.

The more CO2 is in the atmosphere, the more plants and trees will flourish. And the more they flourish, the more CO2 they will eat up and the more pure oxygen they will emit back into the air. It is another system of negative feedback, acting literally on a global scale. And as we have learned, it is not at all negative in the sense of being bad. It is only negative in that when one thing happens, like CO2 buildup, it causes another thing to happen, such as an increase in foliage that pushes the first thing (CO2 levels) back in the opposite, or negative direction until it brings things back into equilibrium. The system stays stable because it is regulated by the natural forces of nature. If it were not, it would surely have run off to one temperature extreme or another long ago by such catastrophic events as volcanoes, forest fires, and meteors.

When we monitor changes in CO2 concentrations in the atmosphere, what we are likely observing is a component of the error signal in the earth’s natural feedback system of temperature regulation. And like all error signals, it is never exactly where we might think it should be. Rather, it looks like a sine wave, or a combination of sine waves, gradually moving up and down in slight adjustments around some kind of set-point.

If you measured the temperature inside your home, you would see similar fluctuations each time the furnace turns on or off. But in the case of the earth, these adjustments may happen over such a slow and lumbering scale that we cannot fully comprehend them in our relatively short life spans. One thing we do know, there have been times in the past when the earth has been hotter and there have also been times when it has been colder. Somehow, the planet manages to maintain things in such a way that life can continue to flourish.

So consider this: What if we could develop a type of solar collector that would act a lot like a plant? It would collect sunlight and use it to split CO2 molecules into their constituents of pure carbon, and pure oxygen. Whereas, the CO2 represents a low-energy state, the separated carbon and oxygen represent a much higher energy state. In other words, when we let them combine back together in the process called oxidation, we are going to get that energy back out. And according to our research on energy densities, we could get double or more of what we are getting out of gasoline for the same amount of storage space!

Regardless of what your Faith tells you about CO2 being bad or good, this process is neutral because the only CO2 it produces is what it has already removed from the air previously. And if it turns out CO2 really is bad for the environment, maybe we can take some of that pure carbon we are producing and hide, or sequester it down in the ground where it won’t cause us any more trouble. Wouldn’t it be ironic if a future industry evolved to haul synthetically produced carbon down into the earth to fill up old, abandoned coal mines?

As it turns out, this kind of technology has already been developed in various early forms. It is theoretically possible to build large collectors which can separate CO2 out of the air. And it is now possible to use an energy source such as sunlight to split that CO2 into its separate constituents of pure carbon and pure oxygen. As this technology progresses, it may become efficient enough to make solar plants that synthetically produce pure carbon. As nuclear forms of energy such as fusion become feasible, they could also to store energy in these types of synthetic fuel.

So what would our future look like with carbon powered cars? First, we would have to develop an engine that produces mechanical power from the kind of energy stored in carbon. The traditional internal combustion engine is well suited to liquid fuels, but it could pose potential difficulties for a fuel that is naturally in a powdered or solid form. Perhaps some technologies do already exist that could be adapted to this use. A variant of the steam engine would clearly work but may not be very efficient and you would always have to keep filling it with water. Proponents claim the Stirling engine would work at the desired efficiencies. And it has the advantage of not using internal combustion. Some have called the Stirling engine an “external combustion” engine. All it really requires is heat in order to operate. You can about any kind of fuel that will burn and it will begin to produce mechanical power.

Imagine if a solar powered, carbon generating reactor could be created on a small enough scale that it too could become a cottage industry. Similar to the traditional solar model discussed previously, small business entrepreneurs could devote relatively small pieces of otherwise undesirable land into solar collectors. The output would be elemental carbon and oxygen. The oxygen could safely be gassed of into the atmosphere improving things for the animal kingdom, at least. Or if it were in demand, it could be compressed, bottled and sold as a valuable byproduct. The carbon would be in a relatively safe form. Imagine small pellets or granules of a black powder.

You could buy it by the bag or pull your fancy new graphite-powered car up to a dispenser and fill it up much the same way as you might at a gasoline filling station. The fuel that powers our cars could be sold very informally and without layers of government regulation. You might see a farmer on a corner selling melons, apples, and bags of graphite. Not only would your fuel tank take you twice as far as it used to, but the supply of fuel could be ubiquitous throughout the economy—easy to find and easy to buy. And because it could all be produced domestically, we would be free from the tyranny of outside oil cartels—free to choose what we put in our fuel tank, free to live and enjoy the blessings of a civil society.
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