He says knowing how to do this may be especially valuable if fossil fuel should become unavailable.

VOA: special.2009.04.14

(MOIVE SOUND) "This film depends on you not knowing where you are at in any given situation."

VOA: standard.2010.02.27

But knowing what percentage this is of the total amount leaking from the well will not be possible until a tight seal is on the well.

VOA: standard.2010.06.14