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New fuels were superior to coal in every respect: they had higher heat content (releasing more energy per unit mass when burned), were easier and safer to produce, cleaner and more convenient to burn and offered an incomparable flexibility of final uses.
Diesel engines work at a higher pressure and lower speed, and large stationary machines have best efficiencies just above 50% and automotive engines can approach 40%. Gasoline engines used to be 20–30% less efficient but their best new designs have almost closed the gap. Diesel fuel has other advantages: it contains about 11% more energy than gasoline in the same volume, it is slightly cheaper than gasoline and it is not dangerously flammable.
cars remained expensive, unreliable machines bought by small numbers of privileged experimenters. This changed only with Henry Ford’s introduction of the affordable and reliable Model T in 1908 and with the expansion and perfection of mass production techniques after World War I.
In 2015 worldwide passenger car registrations surpassed 900 million (see figure 2) and there were also about 350 million trucks, buses and cars in commercial fleets making a total of 1.25 billion road vehicles.
Frictional losses cut the overall efficiency by about 20%, and partial load factors (inevitable during the urban driving that makes up most car travel time) reduce this by another 25%; accessory loss and (increasingly common) automatic transmission may nearly halve the remaining total so that the effective efficiency can be as low as 7–8%.
In 2016 motor and aviation gasoline accounted for a third of global refinery throughput. The US share of global gasoline consumption was about 41% of the total, or more than 1,200kg/capita: the country now consumes more gasoline than the combined total for the EU, Japan, China and India.
Although passenger diesels are still rare in North America (just 3% of new vehicles in the US), in Western Europe (with more expensive gasoline) diesel cars have accounted for slightly more than 50% of the new car market since 2006 (and in Ireland more than 70% since 2012).
In jet engines the compression of air precedes the addition of fuel in a combustor, the combustion goes on continuously rather than intermittently, and the energy of the hot air flow is extracted by a turbine that is connected to the compressor by a shaft. Gas turbines first compress the air (up to 40 times above the atmospheric level) before forcing it through the combustion chamber where its temperature more than doubles.
Nearly two-thirds of the world’s refined products are now used in transportation (roughly 2.5Gt in 2005) and in the US that share is now more than 75%. Transportation’s dependence on liquid fuels is even higher: in 2015 about 93% of all energy used by road vehicles, trains, ships and planes came from crude oil.
The proportion of the US labor force in agriculture declined from nearly 40% in 1900 to less than 5% by 1970 and it is now only 1.5%, and similar rates of decline (albeit not to such a low share) have been recorded in all Western countries.
The four universal measures that revolutionized traditional agriculture are the mechanization of field and crop processing tasks energized by engines and motors; the use of inorganic fertilizers, above all of synthetic nitrogen compounds; applications of agrochemicals to combat pests and weeds; and the development of new high-yielding crop varieties.
In 1900 American farmers needed an average of about three minutes’ labor to produce 1kg of wheat, but by the year 2000 the time was down to just two seconds and the best producers now do it in one second. The price of this progress is that, as Howard Odum aptly put it, we are now eating potatoes partially made of oil.
Worldwide, about 8% of all refined fuels were consumed by the residential and commercial sectors in 2015, overwhelmingly for heating; again, this share will continue to decline as natural gas takes over.
The second most voluminous non-fuel use of a refined petroleum product is asphalt.
Indeed, asphalt, not aluminum cans or newspapers, is the most massively recycled material in affluent countries.
Even then refined products are still quite affordable in all high-income countries, but in the Netherlands in 2017 a barrel of gasoline was five times more expensive than a barrel of crude oil, with multiples ranging from less than 4.5 in the UK to about 3.5 in Japan, and to less than 2 in the US.
The US has been an exception: with federal and state taxes on gasoline amounting to 21% in 2016, the unit price of that fuel is mostly the cost of crude oil (about 43% in 2015) and the industry margin (about 36%). But in 2016, Japan’s taxes amounted to 40% of the price of gasoline, while in Germany it was 55% and in the UK, 67%. As a result, the taxes collected on liquid fuels by the world’s seven largest economies (G7) have surpassed the annual oil revenue of the 13 OPEC nations combined.
In 2015 the four largest ones – Saudi Aramco, National Iranian Oil Company (NIOC), Iraq National Oil Company (INOC) and Kuwait Petroleum Company (KPC) – held almost 40% of the world’s total conventional oil reserves, virtually all of them in conventional (liquid oil) deposits.
