rogersavage wrote:Hi
Why does the topic of depleted oil reserves necessarily mean that we need to give up our cars?
Vehicles can be made to run on virtually anything - renewables included - so why does this debate on oil running out appear to resemble more a back-slapping exercise for those who want to stop people using their cars?
Regards
Roger
The short answer to why cars don’t fit very well with energy depletion is there is no combination of fuels that can run what were running now, at least at the time of writing. I write some pretty ‘anti-car’ stuff, not because I dislike them, far from it, it’s because the sort of way we are using them now is unsustainable. The more we base society around cars, the worse the end result is going to be.
The first problem with private transport: Its use is ‘at will’. A large proportion of car journeys are replacing journeys which are less than 5 miles and could be walked or cycled. Because it is such a convenient mode of transport, it is by its very nature wasteful.
Now, most people here, me included, would like to carry on the way we are doing now. However the current prospects of that are not especially good.
The most important concept is ENERGY RETURNED ON ENERGY INVESTED, or EROEI. In short, this is how much energy you are getting in return for energy you are putting in. Most alternative liquid fuels are net energy losers. IE You are putting in more energy than you are getting back.
It can be summed up like this:
ENERGY INVESTED is this -
In order to ACQUIRE energy, it TAKES ENERGY.
In order to TRANSPORT a form of energy, TAKES ENERGY.
In order to STORE energy, TAKES ENERGY.
In order to USE energy, also TAKES ENERGY.
ENERGY RETURNED is this -
After you have taken into account all the energy used above...how MUCH ENERGY do you have left? OR How much energy does it actually COST in order to USE a particular form of energy?
For more info see:
http://www.eroei.com/the_chain/eroei.html
Biofuels and hydrogen tend to be (but are not always) net energy losers.
The other thing to consider is scalability: How much land do you need for biofuels? The answer is an awful lot. For hydrogen, you need to make the element and store it, which is energy intensive and problematic. You need a lot of extra power sources against a crunch in sourcing natural gas, oil and at some stage other fossil fuels.
A lot has been written about hydrogen both in favour and against.
http://www.energybulletin.net/2563.html
http://www.energybulletin.net/4541.html
Here is a quick primer, but there’s plenty on this site about Hydrogen and Biofuels as well as energy sources. Most people would be delighted to be able to keep running cars, but as it stands the current way the road and air system is being run is unsustainable.