Aug
6
Energy Density and Capital Investment of Fuels
August 6, 2007 | 9 Comments
In an answer to some very sincere emails about fuel fundamentals I will lay out the basic facts and how they relate to each other.
Today we’re using fuel in primarily three ways. Foremost in our minds is the portable or transportation fuels such as gasoline, diesel, and ethanol because they are immediately affecting our budgets. Then we are using electricity that is generated for most of us by a utility and sent to us on a wire over a distribution grid that powers most things in our homes and at work. Finally there are the gases such as natural gas that’s piped to our homes and workplaces and propane that we access from various sizes of metal bottles.
To grasp effectively what these fuels are worth needs a common measure. The most useful is the ‘joule,” a standard unit for an amount of energy. With this we can list and see what is worth what. The measure mega joule nicely expresses energy density as the amount of energy stored in a given weight or mass (MJ/kg). The greater the energy density the more energy may be stored or transported for the same amount of weight or mass. (Values from IOC energy equivalents page. Assigned values can vary by testing methods, making listings and comparisons from different sources unreliable.)
Gasoline is about 34.2 mega joules per kilogram, diesel is over 38.6, and ethanol about 23.4. If you have a diesel engine you will get more joules to carry you further and ethanol will carry you less far.
When generating electricity we can measure the coal, which is usually about 24 depending on the quality and the mix of hard and soft coal. Natural gas is about 25.7 and varies by the proportions of components like propane, butane and ethane. Fuel oil is about 40. What is interesting is the nuclear fuel numbers. It’s about 560 mega joules per kilogram of metallic uranium.
When we look at the energy densities by weight, the greater the energy density the more energy stored or transported for the same amount of weight is important in transportation fuel as we take the unused portion’s weight with us. For electricity the amounts used in one place are much larger – the fuel is taken to one place and used.
The first point then is to be aware of the amount of joules you will need to move your stuff and you, and heat and cool your home. We’ll be coming back to this principle often, which is why the point is important.
But the fuel cost is just the end result of a long list of investments and costs to make fuel available to buy.
All the fuels listed excepting ethanol have to be” found” or discovered and ethanol has to have feed stocks grown. This costs a great deal of money and must go into the price. At this point in time the “discovered” price of what we’re using now is far less money than the amount of money it’s taking to find more. Then the products must be drilled or mined – more investment of money, processed with more costly and sophisticated equipment – more money, shipped, stored and sold to you, and that costs money. Then you must have bought a car, likely a garage, paid insurance and license, maintenance, and all the personal gear to go with it. The same kind of list applies to your home heating and air conditioning. There is a lot of money invested in using fuel to move our stuff and us, warm us and cool us, and keep those salaries and pensions coming.
The second point I’m trying to make is the “cost” of fuel is lots more than the fuel itself. If I could find a number that showed the part of a gallon of gasoline’s price that is the invested money to get it to you, and the money you’ve invested to use it, the relationship would be much more clear. But it’s not so simple. A gallon of gas made from crude oil in Kansas has a very different cost structure than a gallon made from tar sands in Canada. Nor do you and the neighbor have the same investment for using the fuel you buy. About the only thing you have in common is the tax on the fuel and even that is a difference from state to state and hugely different country to country.
So the point – the cost of fuel is more than the fuel itself – deserves our strict attention. That’s because fuel is a political issue. Its more than the tax, its governments ability to shift attention, push certain investments by its tolls of incentives and penalties, and assist or deny advances in technologies with things like grants or the awarding of patents.
Things will change, that much is sure. As we go forward keep in mind that the owners of the money invested in cars and furnaces, oil refineries and coal mines are going to want to keep that investment worth something in the first instance and in the second, each of us will need time to invest in the new technologies that replace the old. None of us are going to pitch our investments over the side without some thought about how the new investment will be better or cheaper. There’s a long chain of investments from your furnace and car back to the oil or gas well, coal or uranium mine, and corn or sugarcane field. It’s going to take a lot longer than many would hope.
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[…] cellulosic ethanol is unlikely to have the field (so to speak) to itself. Ethanol’s low energy density and difficulty of transport will be continuing barriers to its adoption as the cellulosic fuel of […]
please give the comparision between energy density of ethanol and bio-gas
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