Why is it so difficult to wean ourselves from fossil fuels? The answer is a surprisingly simple one.
A clarifying insight comes from comparing different energy sources in terms of their energy content. Using 1 million BTUs as a standard for comparison, let’s look at how much it costs to get that much energy from various sources.
Coal contains about 12,000 BTU per lb. Roughly 83 lb. will get you 1 million BTU at a cost of less than $5.
Natural gas contains about 1040 BTU per cubic foot. Thus, about 960 cubic feet of natural gas produces about 1 million BTU. The cost is about $15.
Heating oil contains about 140,000 BTU per gallon. About 7 gallons will produce 1 million BTU.
Gasoline is no slouch in energy density. At 120,000 BTU per gallon, burning 8 gallons of gasoline delivers about 1 million BTU. At a cost of around $4 per gallon currently, deriving the energy from gasoline will set you back $32.
Now compare those numbers to the energy stored in a traditional car battery. A battery can deliver about 3412 BTU from a single charge. That means that a single battery charge offers about as much energy as 0.028 gallons of gasoline, equivalent to about 4 fluid ounces or half a cup. You can immediately see why these batteries can only start a car but not power it along the road. You can also see why it is so difficult to find replacements for traditional fossil fuels to power our vehicles.
Newer batteries developed for hybrids and electric cars are better. They can hold about 50,000 BTU. Putting several in a car can give you a 200-300 mile driving range for a light-weight vehicle. They also cost a LOT more than a small tank of gas that they can roughly replace. Before electric cars will offer performance and economy similar to gasoline-powered models, batteries must be developed that are much more efficient and cheaper. For now, you can power a small car for the cost of electricity if you are willing to make a large capital investment in the batteries required and accept some sacrifices in the performance in your car.
Put in this context, our addiction to biofuels is not so difficult to understand. Fossil fuels are, in fact, one of the most energy-dense materials available to us. They have been and still are plentiful, even if the cost is rising and we may be nearing the time of peak-oil.
What about biofuels? Do they offer us any hope? In fact, biofuels are, generally speaking, just fuels made from recently dead biomass by a fermentation conversion process instead of from long-dead biomass that is pumped or mined from deep in the earth. The more gasoline-like a biofuel is, the better a replacement it will be for traditional transportation fuels. Butanol is better than ethanol, and terpenes are better than either of those.
The take-away from this analysis for me is that biofuels offer the best realistic near-term hope to replace fossil fuels, and hybrid automobiles offer the best, cost-effective near-term opportunity to partially use battery power to displace some transportation fuel.
Source: Living Green and Saving Energy
Cost to the environment is an important feature missing from the above article. Renewable energy sources generally have a much lower ecological cost that fossil fuels. This will become more important and perhaps the ‘environmental cost’ will, the future, be translated into monetary terms as a standard procedure. Although people are becoming more eco-conscious, financial issues play a major role in decisions, often over-riding environmental considerations. Alternative energy for electricity generation is developing, at a rapid pace- solar energy probably being at the forefront. However, alternative fuel for cars is now also receiving more attention, especially with the rise in oil prices. In South Africa, biofuels are receiving renewed attention, also as a means of creating much needed employment opportunities.
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