4.2 When will we run out of crude oil?
It has been estimated that the planet contains over 6.4 x 10^15 tonnes of organic carbon that is cycled through two major cycles, but only about 18% of that contributes to petroleum production. The primary cycle ( turnover of 2.7-3.0 x 10^12 tonnes of organic carbon ) has a half-life of days to decades, whereas the large secondary cycle ( turnover 6.4 x 10^15 tonnes of organic carbon ) has a half-life of several million years [4]. Much of this organic carbon is too dilute or inaccessible for current technology to recover, however the estimates represent centuries to millenia of fossil fuels, even with continued consumption at current or increased rates [5].
The concern about "running out of oil" arises from misunderstanding the significance of a petroleum industry measure called the Reserves/Production ratio (R/P). This monitors the production and exploration interactions. The R/P is based on the concept of "proved" reserves of fossil fuels. Proved reserves are those quantities of fossil fuels that geological and engineering information indicate with reasonable certainty can be recovered in the future from known reservoirs under existing economic and operating conditions. The Reserves/Production ratio is the proved reserves quantity divided by the production in the last year, and the result will be the length of time that those remaining proved reserves would last if production were to continue at the current level [6]. It is important to note the economic and technology component of the definitions, as the price of oil increases ( or new technology becomes available ), marginal fields become "proved reserves". We are unlikely to "run out" of oil, as more fields become economic. Note that investment in exploration is also linked to the R/P ratio, and the world crude oil R/P ratio typically moves between 20-40 years, however specific national incentives to discover oil can extend that range upward.
Concerned people often refer to the " Hubbert curves" that predict fossil fuel discovery rates would peak and decline rapidly. M. King Hubbert calculated in 1982 that the ultimate resource base of the lower 48 states of the USA was 163+-2 billion barrels of oil, and the ultimate production of natural gas to be 24.6+-0.8 trillion cubic metres, with some additional qualifiers. As production and proved resources were 147 billion barrels of oil and 22.5 trillion cubic metres of gas, Hubbert was implying that volumes yet to be developed could only be 16-49 billion barrels of oil and 2.1-4.5 trillion cubic metres. Technology has confounded those predictions [6a]. The US Geological Survey has also just increased their assessment of US ( not just the lower 48 states ),inferred reserves crude oil by 60 billion barrels, and doubled the size of gas reserves to 9.1 trillion cubic metres. When combined with the estimate of undiscovered oil and gas, the totals reach 110 billion barrels of oil and 30 trillion cubic metres of gas [7].
The current price for Brent Crude is approx. $20/bbl. The world R/P ratio has increased from 27 years (1979) to 43.1 years (1993). The 1995 BP Statistical Review of World Energy provides the following data [6,7].
Crude Oil Proved Reserves R/P Ratio Middle East 89.4 billion tonnes 93.4 year USA 3.8 9.8 years USA - 1995 USGS data 10.9 33.0 years Total World 137.3 43.0 years
Coal Proved Reserves R/P Ratio USA 240.56 billion tonnes 247 years Total World 1,043.864 235 years
Natural Gas Proved Reserves R/P Ratio USA 4.6 trillion cubic metres 8.6 years USA - 1995 USGS data 9.1 17.0 years Total World 141.0 66.4 years.
One billion = 1 x 10^9. One trillion = 1 x 10^12. One barrel of Arabian Light crude oil = 0.158987 m3 and 0.136 tonnes.
If the crude oil price exceeds $30/bbl then alternative fuels may become competitive, and at $50-60/bbl coal-derived liquid fuels are economic, as are many biomass-derived fuels and other energy sources [8].
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5.4 Why are evaporative emissions a problem?
As tailpipe emissions are reduced due to improved exhaust emission control systems, the hydrocarbons produced by evaporation of the gasoline during distribution, vehicle refuelling, and from the vehicle, become more and more significant. A recent European study found that 40% of man-made volatile organic compounds came from vehicles [72]. Many of the problem hydrocarbons are the aromatics and olefins that have relatively high octane values. Any sensible strategy to reduce smog and toxic emissions will also attack evaporative and tailpipe emissions.
The health risks to service station workers, who are continuously exposed to refuelling emissions remain a concern [73]. Vehicles will soon be required to trap the refuelling emissions in larger carbon canisters, as well as the normal evaporative emissions that they already capture. This recent decision went in favour of the oil companies, who were opposed by the auto companies. The automobile manufacturers felt the service station should trap the emissions. The activated carbon canisters adsorb organic vapours, and these are subsequently desorbed from the canister and burnt in the engine during normal operation, once certain vehicle speeds and coolant temperatures are reached. A few activated carbons used in older vehicles do not function efficiently with oxygenates, but carbon cannister systems can reduce evaporative emissions by 95% from uncontrolled levels.
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6.18 How can I increase the fuel octane?
Not simply, you can purchase additives, however these are not cost-effective and a survey in 1989 showed the cost of increasing the octane rating of one US gallon by one unit ranged from 10 cents ( methanol ), 50 cents (MMT), $1.00 ( TEL ), to $3.25 ( xylenes ) [108]. Refer to section 6.20 for a discussion on naphthalene ( mothballs ). It is preferable to purchase a higher octane fuel such as racing fuel, aviation gasolines, or methanol. Sadly, the price of chemical grade methanol has almost doubled during 1994. If you plan to use alcohol blends, ensure your fuel handling system is compatible, and that you only use dry gasoline by filling up early in the morning when the storage tanks are cool. Also ensure that the service station storage tank has not been refilled recently. Retailers are supposed to wait several hours before bringing a refilled tank online, to allow suspended undissolved water to settle out, but they do not always wait the full period.
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8.1 What causes an empty fuel tank?
* You forgot to refill it. * Your friendly neighbourhood thief "borrowed" the gasoline - the unfriendly one took the vehicle. * The fuel tank leaked. * Your darling child/wife/husband/partner/mother/father used the car. * The most likely reason is that your local garage switched to an oxygenated gasoline, and the engine management system compensated for the oxygen content, causing the fuel consumption to increase ( although the effect on well tuned engines is only 2-4% ).
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8.4 Should I store fuel to avoid the oxygenate season?
No. The fuel will be from a different season, and will have significantly different volatility properties that may induce driveability problems. You can tune your engine to perform on oxygenated gasoline as well as it did on traditional gasoline, however you will have increased fuel consumption due to the useless oxygen in the oxygenates. Some engines may not initially perform well on some oxygenated fuels, usually because of the slightly different volatility and combustion characteristics. A good mechanic should be able to recover any lost performance or driveability, providing the engine is in reasonable condition.
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8.5 Can I improve fuel economy by using quality gasolines?
Yes, several manufacturers have demonstrated that their new gasoline additive packages are more effective than traditional gasoline formulations. Texaco claimed their new vapour-phase fuel additive can reduce existing deposits by up to 30%, improve fuel economy, and reduce NOx tailpipe emissions by 15%, when compared to other advanced liquid phase additives [49]. The advertising claims have been successfully disputed in court by Chevron - who demonstrated that their existing fuel additive already offered similar benefits. Other reputable gasoline manufacturers will have similar additive packages in their premium quality gasolines [50]. Quality gasolines, of whatever octane ratings, will include a full range of gasoline additives designed to provide consistent fuel quality.
Note that oxygenated gasolines must decrease fuel economy for the same power. If your engine is initially well-tuned on hydrocarbon gasolines, the stoichiometry will move to lean, and maximum power is slightly rich, so either the management system ( if you have one ) or your mechanic has to increase the fuel flow. The minor improvements in combustion efficiency that oxygenates may provide, can not compensate for 2+% of oxygen in the fuel that will not provide energy.