I won't argue whether Americans are wasteful or not. Ultimately, that is a value judgement. But Goldberg should read Joseph Pearce before simply dividing American energy consuption by the sum of our economic output:
GNP is the total price (not value, since value is qualitative not quantitative) of all the traded goods and services produced in a country during a year. Any economic activity that does not involve a monetary transaction is not included. On the other hand, any activity that involves the spending of money is included even if it has a detrimental effect in socioeconomic terms. This is a peculiar view of what is deemed "economic."
More from Pearce here.