Energie ontwikkeling

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Energie ontwikkeling


by Loes Buijze en Bram Hillebrand, Geology students at Utrecht University, the Netherlands.

In this paper we discuss reserve lifetime predictions of some minerals and fossil fuels. We have calculated these lifetimes with the production rate of 2002 and an increasing population growth, calculated using a program called Demproj. In the case of predicting when fossil fuels will be depleted we have used a 2% increase of production rates for non USA countries. Calculating this we found the following results. Oil and gas will be depleted in respectively 2068 and 2057. We do have coal left for considerable more time, however when we take all fossil fuels together and use the production increase mentioned above we will run out by the year of 2074. Economically minable gold will be depleted in 2018 and almost all gold will be depleted by the year of 2034. Economically minable iron will be depleted in 2098 we do have other (non economically minable) iron left for quite some time. It is of great importance to realize these trends because we need to look for alternatives very soon.

In this paper we want to answer the following questions. Can we predict reliable lifetimes of reserves for some of the important minerals and fossil fuels we do use in our society today like oil, gas, coal gold, iron and rare earths. Are these predictions accurate? Might we be able to increase lifetime reserves a bit? And last when do we think we will run out of fossil fuels and these minerals? Will it be quick or do we have some time left yet?

Predicting population growth
Predicting population growth is always difficult. A system which is used today is based upon the population growth of Western Europe since the industrial revolution. Europe has followed a certain pattern in history, before the industrial revolution there was high birth rate and a high mortality rate. During the industrial revolution mortality rates dropped due to increasing sanitary and improved medicines. Birth rates also dropped because of other social reasons (for example: before the industrial revolution children were "cheap" workers on farmland, after the industrial revolution children became a "cost")

Predictions using this method are not always as useful for non Western Europe countries (with the exception of northern America) because they do not necessarily follow the same pattern. In Europe the industrial revolution came with great economic growth. This is not the case in for example a lot of African nations. Furthermore a lot of countries have entered the industrial revolution with considerable more population than most Western Europe countries did. A lot of countries are experiencing the change a lot faster than most western European countries did. Last, during the industrial revolution Western Europe redistributed a lot of its population by means of colonization. This is of course not possible anymore.

Reserves, reserve bases and recourses
When we calculate for how long we will be able to use a certain material at constant or increasing rate we first need to determine how much of the material we are able to use. In normal calculations of this type we find three different categories of determining the amount of material left. They are briefly discussed below.

The first category is reserves. Reserves are materials that have been geologically identified and can be extracted with profit at present time. Logically this category has the lowest amount of a certain material and predictions of the year we will run out will be the most pessimistic using this category as the available material. The second category is reserve base. Reserve base includes reserves as well as identified material of lower geological quality that might be extractable in the future depending on economic and engineering factors. This category includes sources of certain material which will only be profitable to mine when all other normal reserves are (almost) gone. Logically predictions using this as available material will provide more optimistic results. The last category is resources. Resources include the reserve base and any undiscovered deposits regardless of economic or engineering factors. This includes sources which we are at this moment unable to mine and might never be able in the future. Of course predictions using this category are the most optimistic of all.

Formation oil and gas
To form oil we need to follow a certain path. First dead plankton and clay accumulate in an oxygen free environment. Second sediment buries and compacts (burial) the plankton-clay layer, which lithifies under the pressure to become black organic shale. Black organic shale is also called source rock, as it contains the raw materials from which hydrocarbons are formed. As sediment accumulates, the black organic shale heats up. At temperatures of 60-200 C, a range called the oil or gas window, the organic material transforms into oil or gas. The oil or gas window is a very small window of temperatures and pressures by which oil or gas is formed. The formation of oil or gas takes over millions of years. Besides the right conditions and a source rock a few more things are needed to keep the oil or gas trapped so it is available for us to find. Oil and gas are kept in reservoir rocks which are highly permeable or porous rocks. To prevent the oil and gas from escaping (oil and gas are much lighter than the surrounding rocks and therefore tend to move upwards.) we need a sealing rock or a trap. A sealing rock is a very low to non permeable rock through which the gas or oil cannot migrate. A trap is a stratigraphic or structural feature which keeps the gas or oil from escaping to the surface. So as we can see not all potential oil source rock does form oil or gas. If a source rock does not produce oil or gas this can be because of a few reasons:

1)  The source rock has reached to high depths or not high enough temperatures.
2)  The source rock did reach the oil and gas window but was not trapped and therefore escaped.
3)  When during the process of burial of the organic matter hydrogen is lost eventually graphite will be formed in stead of oil or gas.

The first factor to be considered when doing calculations for the use of fossil fuels is the world's population and the population growth. We were provided with several data sets, including the world's population of the year 2002, life expectancy at birth, the total fertility rate, vital rates and events and the world demographic statistics. The data sets were both given for the entire world and for a few separate countries, such as China and the USA.

Next we entered these data in the program Demproj. and we modeled the world's population until the year 2155 (Appendix 1). We and other groups also modeled the populations of China, India, Netherlands, Nigeria and the USA. To make further calculations easier, we fitted trend lines to the curve of the world's population, so a linear population growth would be obtained. We used only the first, increasing trend line for our further calculations because we did not need to look forward beyond the point where the world's population starts decreasing. From this line the annual increase of the population could be measured.

Then we had to calculate when the world would run out of oil, gas or coal. We did the calculations for the oil. In Excel we calculated the annual consumption rate, taking into account the population growth. The consumption rate per person was kept constant and the following formula was used:

Consumption in 2002 * (Population in year n/Population in year 2002)

We also made a cumulative table of these consumption rates, so it could easily be seen how much oil is used since 2002 and when the EUR oil is finished. The same calculations were made for gold, taking the production rates as consumption rates. Next calculations were made for when the energy present in oil, gas and coal would be finished. The annual energy use of the world was calculated the same way as the consumption rates:

Annual world energy use in year n=World energy use in 2002 * (Population in year n/Population in year 2002)

We again made a cumulative table and a graph of these cumulative results, so it could easily be seen when the fossil fuels would be used up. We did this calculation again, but now taking into account an increase in consumption rate for the whole world except the USA. The consumption per person increases by 2 percent every year. First we separated the population and consumption rates of the USA and the rest of the world, using the world and the USA population forecasts. The consumption rate of the USA was kept constant per person and increased only because of population growth. The consumption of the world increased by 2 % per year and also increased due to population growth. For the USA consumption we used:

Annual energy consumption USA year n=Energy consumption USA year 2002*(Population USA in year n/Population USA year 2002)

And for the world without the USA we used:

Annual energy consumption world non-USA year n=(Energy consumption world non-USA 2002 * (1.02^years from 2002))*(Population world non-USA year n/population world non-USA 2002)

Again the results were summed and compared to the predicted energy left out of fossil fuels.


Figure 1 shows the amount of recoverable oil present over the coming years. The amount is decreasing more and more, because population grows and more oil is consumed over the years. Assuming the consumption rate per person per year is constant, world population growth is linear and not many more reserves are discovered, the world will run out of oil in the year 2068.

Wiki Petroleum geology
voorspelling oliereserves.

The gas calculations were done the same way as for the oil. Gas reserves will run out in the year 2057.

voorspelling aardgasreserves.

The coal calculations were done the same way as for the oil. Coal reserves will not run out before the year 2072, the population increase predictions after 2072 are too uncertain to base forecast upon.

voorspelling steenkoolreserves.

The world gold reserves are shown in figure 4. Two lines can be seen, one based on reserves and one based on reserve bases. The first line predicts the gold reserves will run out in the year 2018, the second line predicts the gold reserves run out in 2034.

voorspelling goudreserves.

The iron calculations were done the same way as for the gold. Iron reserves will run out around the year 2098. The iron base reserve will not run out for quite a time.

voorspelling ijzerreserves.

Rare Earths
The rare earths calculations were done the same way as for the gold. Rare Earths reserves will not run out for quite some time.

voorspelling ertsreserves.

The world's energy from fossil fuels

Voorspelling verbruik fossiele brandstoffen.

This graph (figure 7) shows the energy from fossil fuels (oil, gas and coal) present over the years. As the fossil fuel reserves decrease over the years, the energy provided by these fossil fuels also decreases. The blue line shows the energy from fossil fuels assuming the energy consumption per person is constant and taking into account the calculated population growth. In this case there will be no more energy from fossil fuels after 2083. The red line shows the energy from fossil fuels taking into account an increase in consumption rate per person, going towards an American lifestyle. The consumption rate for Americans was kept constant and the consumption rate of the rest of the world increased by 2 % per year. In this case the fossil fuels are finished in the year 2074.

Predictions are always hard and often readjusted. This graph (figure 8) shows the predictions when certain materials would run out of 1970 and again of 1992:

Voorspellingen reserves mineralen 1970 en 1992.

As is stated in the introduction, there are some reasons that might indicate that predictions concerning population growth for non western European countries (other than northern America) are not that accurate. However we believe that this has the following effects. Since economic growth is not that rapidly in (for example Africa) the mortality rate will not drop as quickly as the birth rate does. However since the thirs worlds is experiencing the change much more rapidly, lifestyles (which includes the number of children normal to have) will not change easy with them which would lead to a relative birth rate increase compared to Europe in the same period. The other two differences stated in the introduction are a little more difficult to interpret. They both have a negative effect on economic growth because this growth has to be divided over a greater number of people since nobody is able to move away (at least not in great quantities) and there were a lot more people to start with. Therefore it is difficult to say whether the predictions upon population growth are accurate. And since this is the best model we have we should use this. Because population growth might not be described completely accurate it is at least a good approximation.

As can be seen in the results (figure 4 and 8), the year in which we will run out of gold has been adjusted quite a bit. In 1970 it was 1980, in 1992 it was 2010 and our prediction is 2018 (considering reserves) and 2034 (considering reserve bases). The same counts for iron which was adjusted from 2045 in 1970 to 2140 in 1992 to a much higher year not really predictable with our calculations (when reserve base is considered). Trends like this can have many reasons. Older calculations could be to inaccurate, huge amounts of new material could have been found in the mean time, production rates could have decreased tremendously in the mean time or other mining techniques could have become economically available (so they could be used with costs lower than the profits) which doesn't necessarily mean that the techniques have become cheaper but could also imply that profits have raised. Finally new mining techniques could have been developed. Probably the difference in the predictions is caused by the latter two. It is not reasonable that the calculations where to inaccurate not is it reasonable that huge amount of every material has been found in the mean time. Almost all production rates will have risen since 1970 due to the increasing economic growth in countries like China, India and other southern Asian countries. So very likely some mining techniques will have became cheaper absolutely, some mining techniques became cheaper relatively (due to increasing of the value of the materials on the market) and some new mining techniques have become available. This would have as affect that some parts of the resources become part of the reserve base and some parts of the reserve bases would become part of the reserves which therefore would result in an increase of both the reserve and the reserve base and so increasing the predictions of both.

What is stated in the above does not mean that predictions on reserve lifetimes are not useful. Predictions are necessarily if only to remind us that our reserves are finite. It at least tells us that we might not no when it will run out, it will run out and we must start to look for other materials we can use instead. Furthermore predictions on reserve lifetimes are useful to give us a rough indication of the year we will ran out. In our calculations gold reserves are depleted in 2018 and gold reserves bases are depleted in 2034. These predictions might vary but it is very likely that young generations will witness the day we do ran out. Therefore it is useful because young generations must think how to fill the gap that gold will leave when we do ran out. In the case of oil, gas and coal, which to our calculations will be depleted in respectively 2068, 2057 and coal will probably run out somewhere in the 22th century, we must realize we might run out in our lifetimes but we will almost certainly run out in the lifetimes of our children and grandchildren. And because new techniques of producing energy take a lot of time developing we should start searching for alternatives right now.

The most important factor in predicting lifetime reserves are the initial reserves of the material. So it is of uttermost importance to keep the reserves as accurate as possible. All materials that are mined are mined against lower costs than there profits. If we can reduce the costs of mining by for example reducing the inaccuracy of finding the materials (like oil) so that when a company starts to drill the chance that they will in fact find minable oil increases. If the market value of materials drops, certain parts of the reserves will shift to reserves base which leads to a smaller reserve. Also when a material becomes cheaper, in some cases the production might increase. All mining operations of every material have an effect on the environment. Before people start mining at certain places we have to decide whether it is worth the impact it will have on the environment and whether we find that impact acceptable. If our environmental standard increases we "loose" minable material and there is a shift from reserves to reserve base or even to resources. This will decrease lifetime predictions.

The calculations we did are all based on the consumption rate in 2002. The consumption per person was kept constant, except in the last calculation of energy of fossil fuels. In the other cases the annual consumption grew only due to an increase of population. The assumption of a linear population growth is not a wrong assumption, because the line approaches the curve for the coming 70 years fairly closely. We also used the reserves that were known in 2002 and assumed these did not increase. With the assumptions we made we calculated the oil would run out in 2068, gas in 2057 and coal in 2072. This is incredibly close to the year we live in, so it is a really important problem. Taking into account an increase of consumption of 2% for countries other than the USA, all fossil fuels would be finished in 2074. So unless something is drastically changed in the way we use our resources, humanity will have to face living without oil, gas and coal and all the products and energy derived from them.

A few problems rise when predicting population growth however the model used is the best model present and at least gives a good approximation. A few problems do also rise when predicting reserves of materials since there is a big change in predictions from 1970 to 1992 to our predictions; this is mainly due to two factors. One, other mining techniques have become economically available and two, new mining techniques have been developed. Both factors results in a shift from resources to reserve bases and from reserve bases to reserves.

This does not mean that predictions are unnecessarily because it reminds us that our reserves are finite. It also tells us something about the time reserves will be depleted. Gold will be depleted to our calculations in 2018 (2034 if you consider reserve bases) which means young generations will very likely witness the day we ran out of gold. Oil, gas and coal will be depleted (to our calculations) in respectively 2068, 2057 coal will not run out for some time yet however when coal will replace the gaps oil and gas leave behind all fossil fuels will be depleted by the year of 2074. This means that our children and definitely our grandchildren will witness the day we ran out of fossil fuels. Certain factors might increase these lifetime predictions a bit. If we increase the accuracy in which we find fossil fuels, costs will drop and reserves will increase. However if our environmental standard would increase costs of mining fossil fuels will increase (because mining has a negative effect on the environment.) and reserves will drop. This implies that lifetime predictions would decrease.

The most important conclusion is that we will run out of fossil fuels and other materials and that we will run out within considerable time. Therefore it is of great importance that we do start to look for alternatives for fossil fuels and the other materials we will soon have to do without.

-Stover, J. and Kirmeyer, S., 1997. DemProj: A computer program for making population projections, The Futures Group International and Research Triangle Institute.
-Marshak, S, 2003. Oil formation and trapping.
-Meer de, S. System Earth and the Challenge of Sustainable Development.
-Wikipedia organization, Petroleum geology.
-United Nations, 1983. Manual X: Indirect techniques for demographic estimation, New York, United Nations
-U.S. Census Bureau

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