Original sentence: Furthermore, he notes that the recovery rate from existing world oil fields has increased from about 22% in 1980 to 35% today due to new technology and predicts this trend will continue.Maugeri claims that nearly all of the estimates do not take into account non-conventional oil even though the availability of these resources is (supposedly) huge and the costs of extraction, while still very high, are falling due to improved technology
Edited sentence: (Another major drawback to this position is that heavy oil sources will never be as profitable as current light oil sources, both in production rates and energy gain.)  Furthermore, he notes that the recovery rate from existing world oil fields has increased from about 22% in 1980 to 35% today due to new technology and predicts this trend will continue (though this is not enough to even stave off increases in global oil demand for one year).Maugeri claims that nearly all of the estimates do not take into account non-conventional oil even though the availability of these resources is (supposedly) huge and the costs of extraction, while still very high, are falling due to improved technology (This does not take into account the fact that the easiest wells to tap already have been or the fact that the remaining oil will be fought over by a growing population of consumers)