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Politics : The Environmentalist Thread -- Ignore unavailable to you. Want to Upgrade?

To: Wharf Rat who wrote (32086)	2/5/2011 11:50:51 PM
From: Wharf Rat	Respond to of 36917

Speaking of embarrassingly low EROEI's, ... We lose energy on every transaction, but we'll make it up on volume. 1. How Much Energy is Returned for the Energy Invested (EROEI)? Have all energy costs been taken into account? This is where too many alternative energy sources fall flat after the simplest examination. Commercial hydrogen offers one clear example of how it takes more energy to produce the fuel than can be obtained from burning it. The current feedstock from which hydrogen is produced is natural gas. The natural gas is then treated with steam. Steam is water that is boiled using more natural gas, oil, or coal, either in the form of direct fuel or to generate electricity which is used to boil the water. Common sense dictates that this cannot be a solution because it still relies on fossil fuels. Converting water to hydrogen is done through electrolysis. Scientist David Pimentel has established that it takes 1.3 billion kWh (Kilowatt hours) of electricity to produce the equivalent of 1 billion kWh of hydrogen. (BioScience, Vol. 44, No. 8, September 1994.) fromthewilderness.com Some enthusiasts acknowledge that hydrogen is not a source, but that coupled with renewable sources, it's the perfect fuel. Unfortunately, that's just not the case. Hydrogen's low energy density makes it exceedingly inefficient to transport. To illustrate this, consider that a 40-ton tanker truck loaded with gasoline contains nearly 20 times the energy of a 40-ton truck loaded with compressed hydrogen. If both trucks deliver fuel to a filling station 800 miles away, the gasoline truck consumes about three percent of the energy in its payload to make the roundtrip. But the hydrogen truck traveling the same route would consume all of the energy in its payload. Put another way, if you tried to run the hydrogen delivery truck on hydrogen, it would consume its entire payload making the trip, and have no fuel to deliver.1 energypulse.net