onoway, on 2013-October-18, 13:38, said:
You also managed to miss the point. ... snip
Actually neither of us missed "the point". We were discussing a question raised that was
on topic. Reminder the topic is [global] climate change and what we can do about it.
Whether converting CO2 (and some form of hydrogen) to methane and some form of oxygen might help was on topic.
The question was whether CO2, a waste gas produce burning carbon and hydrocarbons in power plants and transportation could be usefully converted to methane to use as a fuel for electric generation or transportation. That question is on topic because increasing the atmospheric concentration of CO2 is believed by many to be a driver for climate change by reducing the amount of incident energy received from the sun that is re-emitted back into space. In other words, there is not a balance between the energy that hits the earth and the energy that leaves the earth. If the balance is positive the earth must get warmer globally, if not locally. It is also on topic because if we could convert the CO2 to methane, there might be a hope that we could achieve energy neutrality. As was pointed out in the answers, it is possible to convert CO2 to methane, but it can't meet the thermodynamic requirement to be energy neutral. So the question has been answered.
Chicken farms, and other popular media items do not make the hurdle of being on topic.
You were offered the chance to demonstrate by proposing that chicken farms were globally significant but declined to do so for reasons we can only guess at. To be clear about it, we can now settle the chicken farm question. Can chicken farm production of methane be globally significant? What was offered was that some farmer somewhere ran his tractor or farm equipment from [only?] the waste from his chickens. Applying a bit of numeracy here, let's assume that if we could power 1/4 of the US cars on chicken manure, we would consider this globally significant. What would that mean? Well for starters half of the two car families and one quarter of the one car families would need to become chicken farmers. OK, so now what? Now the waste from the chicken is taken care of, but we have chickens that are now waste instead of manure.
Look at that! We are able to see, without even using an envelope or pencil, that the question was off topic. We did not even need to resort to knowing how much motor fuel we use each day, nor how many chickens it would take to replace some given percentage of that.
All we had to do was ask ourselves a simple question and work out the answer. Not all questions are that easy, because for some we really do need to do the math and research.
How else could we have known that the chicken farm solution was off-topic for not scaling?
If one does not have the science or math skills to really work out whether an approach is feasible, the best thing is to assume that there are many smart people anxious to start their own company and make their fortunes - and investors willing to fund them to make theirs. If an idea has been published, i.e. you know about it, assume that there are a 1000 people far brighter than you that also know about it, and that one percent of those (10)
are out there trying to create a startup to "monetize" the idea - even if the idea won't work!