At this time (2017) the supply of normal easily obtainable crude oil is estimated to last at least another 40 years with current yearly demand at some 1000 barrels per second. At some point in time, increasing demand together with higher oil prices, will make alternative resources possibly economically attractive. Recent shale oil discoveries and production methods changed this picture and extended the time we can use ordinairy oil.
Even current assumed depleted oil wells still contain enough oil, some 40% of the oil could still be in the well requiring new techniques to extract it. Other theories claim that oil is being replenished by processes deep in the Earth (abiogenic petroleum), making it virtually renewable and of almost unlimited supply.
It is important that a stable price of oil should be set by the oil producing and consuming countries for a certain period of time in stead of being set by daily fluctuating and wildly speculating markets, which introduce too much economic uncertainties and with a negative result for the world economy as a whole.
The current oil futures trading seems flawed and legislation should be created to control it and create a more transparent and stable system.
As an indication of how much oil reserves there are available, we have a comparison of worldwide distribution of normal conventional crude oil and thick heavy oil reserves
Heavy Oil Reserves.
Currently there are three processes: gas to liquids, coal to liquids and biomass to liquids. We will scratch the surface of these three processes and the effects of aviation on the environment.
GTL uses a process developed by two German scientists in the 1920s, Franz Fischer and Hans Tropsch, and thus called the Fischer-Tropsch process. This process converts natural gas into synthesized gas and this syn-gas is then converted into hydrocarbon products like diesel fuel, wax and other products. This process produces very pure synthetic hydrocarbons free of sulfur, aromatics and more usually found in 'normal' hydrocarbon fuels.
This process is commercially in operation since 1992 in South Africa and 1993 in Malaysia. Both plants produce somewhere around 60000 bpd total. Recent projects are being started by different companies (Chevron, Shell and Exxon-Mobil) to increase production with another 400000 bpd the next few years.
The proven natural gas world reserve is enough for another 60 years with current demand. Speculative reserve indicates enough gas for some 200 years to come. Shale (fine sedimentary rocks) is being investigated as possible source and worldwide reserves are more than abundant.
Coal reserves are far bigger than natural gas or oil together. Coal is mainly (80%) used to generate electricity, but efficiency is low and emissions are at a high level. Not a very clean solution. Gasification of coal via this process is the cleanest solution to use coal. It uses the same process as GTL.
Coal to liquids process is not as clean as for natural gas. There are more issues to it than with GTL, more investments, more solid byproducts and higher CO2. CTL will be limited the next 10 - 15 years but as oil and gas resources deplete it is likely to become an important source for energy.
Coal reserves on this planet should be enough, with current demand, for another 80 years. Speculative reserves indicate coal reserves for another 500 years.
Biomass has been used in the last century when it was replaced by oil and natural gas. At this time the only visible use of biomass energy source is in biodiesel and gasoline. Its either being used at 100% (B100) of mixed in any ratio with petroleum diesel, usually 20 % (B20). Gasoline is also mixed with fuel derived from biomass in the form of alcohol or ethanol, which is not always a good thing for engines and fuel systems.
There are a number of benefits from using biomass as an energy source:
Although biofuel itself may be CO2 neutral to the atmosphere. In the end, with producing, transporting and refining the fuel it may well be even worse off than crude oil.
A number of factors influences it attractiveness: inconsistent energy densities depending on resource used, it therefore burns inconsistently. It might be possible to meet part of the worlds energy requirements but the technical and economical potential indicates that the results are much less. It is expected that biomass can supply around 15 - 25% of the energy demand, maybe lower.
2013: Research from NASA has shown that the planet is a greener place with more CO2 in the atmosphere. (source: ScienceDaily, click here: Deserts Greening.)
Some biomass sources are: Algae (the best option), Jatropha or Camelina (contains human inedible lipid oil), wood, straw, organic waste, sugar beet, rapeseed, sunflower. These can be converted using processes like: combustion, gasification, pyrolysis, digestion, hydrolysis and fermentation (bio-ethanol) and extractification and esterification (biodiesel).
But it must be said that fuel made from biomass absolutely may not have an impact on world food supply or prices. Anyone with good farmland growing food crops and purposely grows plants for fuel (and thus artificially raising food prices) must realize this. We should guard against the use of a human edible source as a fuel, this will hurt the economy, human existence and in the end helps no one.
In 2014 it became known that the IPCC made a complete u-turn on biofuels and stated that the scientific consensus was wrong. (source: WUWT, WattsUpWithThat, click here: IPCC backpedals on Biofuels)