Introduction
Having identified a realistic level of energy consumption that represents an equitable division of resources and offers reasonable growth for developing economies, we now have to consider if the primary energy demand can be supplied using fossil fuels, and, if not, whether there are alternative energy sources available.
Fossil Fuel Reserves
Fossil fuel is highly concentrated solar energy and the natural production process so slow as to be considered non-renewable, hence the consumption of fossil fuel at the current rate is clearly unsustainable. When will it run out?
Nobody can know precisely how much oil exists under the earth's surface or how much it will be possible to produce in the future. All numbers are, at best, informed estimates. Within the broad concept of oil 'reserves', there are several key distinctions, most notably those of proved, probable, and possible reserves.
Proved reserves are quantities of petroleum anticipated to be commercially recoverable by application of development projects to known accumulations from a given date forward under defined conditions”. A probability cut-off of 90% is often used to define proved reserves, meaning that the proved reserves of a field are defined as that volume with a 90%, or greater, chance of being produced over the lifetime of the field. In this sense, these proved (1P) reserves are a conservative estimate of future cumulative production from a field.
Probable reserves have been variously designated as 'indicated' or 2P reserves, the latter referring to reserves which are estimated to have a better than 50% chance of being technically and economically producible.
Possible reserves have been designated as ‘inferred’ reserves, sometimes referred to as 3P. These volumes include reserves which, at present, cannot be regarded as ‘probable’, but are estimated to have a significant (albeit less than 50%) chance of being technically and economically producible. Frequently, a 10% cut-off is used for 3P reserves.
Fig. 1 shows the proven oil reserves divided between the OPEC group of countries and others. Note that a ‘barrel of oil’ is 0.146 toe, and about 7 barrels are needed to get one tonne of oil equivalent energy. The proven oil reserves currently is between 190 to 200 Gtoe. According to current estimates, 79.4% of the world's proven oil reserves are located in OPEC Member Countries, with the bulk of OPEC oil reserves in the Middle East, amounting to 64.5% of the OPEC total.
Fig. 2 shows that during the period 2009-2018, OPEC Member Countries added 186.2 billion barrels to their total proven crude oil reserves, a significant addition compared to other crude oil producers
Figure 1: OPEC is an organisation made of countries that work together to control oil production and price. The diagram shows their estimation of proven reserves in 2018.
Figure 2: shows world proven crude oil reserves for Non-OPEC and OPEC countries from 2009 to 2018.
Images under public domain. Source.
Activity 1
- Transport sector places the greatest demands on energy supply and only oil will do. A more likely and sooner crisis point is associated with the depletion of oil. Calculate how long the proved oil reserves will last. Repeat the calculation to include probable and possible oil reserves. Discuss the results. Assuming the; annual rate of consumption is 4Gtoe, Proved supply is 200Gtoe, Probable and Possible supply is 1000Gtoe.
- Investigate the feasibility of making oil from other types of fossil fuels such as coal. What are the disadvantages? Could the demand be satisfied by manufacturing biodiesel?
Solution
a. The calculation is straightforward:
Lifetime (in years) = Total supply / Rate of consumption (per year)
Using the proved reserves, the result is
Lifetime = 200 Gtoe / 4 Gtoe = 50 years
Including the possible and probable reserves, the result is
Lifetime = 1,000 Gtoe / 4 Gtoe = 250 years
However, this calculation is based on the assumption that the rate of use remains constant. Oil will last a very long time, and the rising cost suggests the lifetime could be even longer. You should note that oil reserves are not evenly distributed around the planet. This does not mean that there are potentially many new fields to find in unexplored areas. In fact, much is known about the geology associated with oil deposits (though the process by which oil forms, pyrolysis, is not well understood) and favourable geology only occurs in specific regions. In the regions where the presence of oil is ‘probable’, it is unlikely that huge new deposits will be found in the future (because larger fields are easier to find and have already been found leaving only the smaller ones to discover). The possible reserves are therefore not going to be greater than the figure quoted.
An example for the North Sea during 2006; (for comparison with alternative forms of fossil fuels).
Extrapolating the data from the North Sea where the geology and the technology is well understood (2006: Proven — 479 Mtoe, Probable—221 Mtoe, Possible— 370 Mtoe), the global figure of 200 Gtoe can safely be doubled to give an estimate of the total reserves, and applying Caspian Sea projections along with potential deep-sea wells could give a final total of 1,000 Gtoe available in the ground. There is also oil shale and oil sand which is discussed later.
The proven coal reserves are 700 Gtoe, though the possible coal reserves are again likely to be many times greater than this.
The proven natural gas reserves are equivalent to 180 Gtoe.
There may also be 1,000 Gtoe of peat accessible.
Crudely adding up all the energy sources, the total energy equivalent of the combined proved fossil fuel reserve is 2,080 Gtoe. Depending on consumption and usability, this could significantly last a long time.
b. It is possible to produce oil from coal but the disadvantage is that some of the energy contained in coal is lost and additional energy has to be put in to power the conversion. The process is therefore inefficient and brings forward the date when fossil fuel reserves are gone. Oil is available from oil shale and oil sand but costly (in energy) to extract.
Is biomass a better option? This is created when a crop which contains a significant amount of oil is grown. The common example in the UK is rapeseed. This will typically produce 1100 litres of oil per hectare (= 100 m x 100 m area). Subtracting the oil used to grow the crop, the net gain is 900 litres per hectare. 1 toe is equivalent to 1,282 litres of biodiesel [https://en.wikipedia.org/wiki/Tonne_of_oil_equivalent] thus 1 km2 of rapeseed will produce 900 x 10 x 10 / 1282 toe = 70.2 toe.
The UK consumes approximately 80 Mtoe per year, and assuming one crop per year, the land required to grow this quantity of oil is 80 M / 70.2 km2 = 1.14 million km2. But the total area of the country is only 244 thousand km2. It is just not feasible to grow this amount of oil. Nor is it desirable to grow it elsewhere and import.
Energy Balance
The previous calculations indicated that if care is taken to limit consumption, the remaining oil will last for a long time. So where is the problem? To understand the concerns, it is necessary to work with a more sophisticated model that takes into account supply and demand (production and consumption).
The production history of an oil well, or field, or even a country or a region, can be described using by the Hubbert Curve (Fig. 3). This is similar to a normal distribution or bell curve.
Once a field is ready for exploitation, production increases rapidly as oil wells are sunk and the distribution infrastructure is built up. Production peaks at a point referred to as ‘Peak Oil’, then steadily declines as the remaining oil becomes progressively harder to extract.
Eventually, one toe of energy is required to extract one toe of oil when extraction is impractical regardless of the price of oil.
Fig. 3 traces the world production history and suggests we are already near the peak oil point. OPEC forecast oil demand will plateau in 2040 at 109.3 million barrels a day—some 10% above its 2019 level. It said that in 25 years non-OECD oil demand will have increased 43% from last year’s levels, partly driven by economic booms in China and India.
Figure 3: A 1956 world oil production distribution, showing historical data and future production, proposed by M. King Hubbert (as a Hubbert Curve)– it had a peak of 12.5 billion barrels per year in about the year 2000. As of 2016, the world's production was 29.4 billion barrels per year (80.6 Mbbl/day), with an oil glut between 2014 and 2018.
"Production of Crude Oil including Lease Condensate 2016" U.S. Energy Information Administration. Retrieved 27 May 2017. Public Domain.
If more oil is produced than is used, the excess is stored, but in the oil industry, the storage capacity is small and production tends to match consumption. Prior to 2020, it was predicted that peak demand would plateau at 2040. Although Covid-19 has had a significant affect on the production of fossil fuels due to the significant decrease in consuming energy, it is difficult and too vague to determine the outcome in the future, especially with a date. What energy source can then be used for transportation? Forcing the wells in order to increase production is not an option; wells are then damaged and do not release all the oil potentially available. There is really no solution except to reduce oil consumption to delay the crisis point, or find an alternative power or fuel mechanism for vehicles. Oil can be synthesized by laboratory means or from coal, oil sand or oil shale, or produced from crops (biofuel). Reducing fuel use is certainly not the current trend and would be difficult to achieve.
But if consumption is to be cut, we must look in detail at the energy balance and find where there is waste, and try to eliminate this. Below is a Sankey diagram (Figure 4) of the energy flow and shows where oil is used.
Figure 4: Sankey diagram from 2018 illustrating the areas in which fossil fuels are used worldwide. [Source] (public domain)
Activity 2
- Analyse the Sankey diagram representation of the world economy and assess the fraction of primary energy actually used.
- What does the area enclosed by the Hubbert curve represent?
- List materials made from oil.
Solution
a. The Sankey diagram is complex, and it is best to focus on a single element and consider the energy balance. Let us consider the transport sector with information from 2018. Ideally, this would be expressed as a percentage of all the primary energy used that year but only consumption values are available: https://www.iea.org/sankey/ for a closer look
- Oil Products 2650Mtoe
- Natural Gas 117Mtoe
- Coal 0Mtoe
- Biofuel 90Mtoe
- Electricity 34Mtoe
- TOTAL 2891Mtoe
It is therefore easy to see where transport derived their energy. Total final consumption account for 9939Mtoe, while only 2891Mtoe only go to transport after losses and distributions elsewhere. Of transport, 92% comes from oil products, 4% natural gas, and the rest biofuels and electricity.
The transport sector is marginally the largest consumer closely followed by industry but it is obvious that oil products are the main contributor. Exports are also a significant contributor. Therefore, reducing the oil consumption will greatly impact the transport sector has on the environment. Ideally this should be accomplished over time by converting to another power source such as synthetic fuels, hydrogen, or pure electricity.
These have their own complications and should be looked at in more detail.
b. The diagram shows the Hubbert curve for a realistic model of world oil production. The vertical line for example (filled in red) is the quantity consumed in 2007, about 4.8 Gtoe. With each year, the line moves to the right and the light green area on the left grows by the amount consumed each year. The light green area is therefore a measure of all the oil that has been consumed to that point. The area on the right of the vertical line is the remaining reserves.
c. Oil is used to make many products, many of which we consider essential:
- Plastics
- Fertilisers
- Pesticides
- Candles
- Detergents
- Food additives
- Cosmetics
- Medicines
- Dyes
- Lubricating oil
- Tar
- Adhesives
Recent Alternative Energy Sources
We have seen there is the probability of an impending energy crisis arising from the excessive consumption of oil. One reaction might be to reduce consumption, but the most realistic long-term solution is to move to a diverse range of alternative and sustainable energy sources, sources that are replenished as least as fast as they are consumed.
It would be possible to rely for a while almost entirely on nuclear power, but the basic fuel, uranium-235, is not plentiful: The current estimate is only 100 years supply. But this could be extended to 10,000 years by transforming the more plentiful and stable uranium-238 into plutonium in a fast breeder reactor. Creating such a dangerous material as plutonium as well as the difficulty in dealing even with lower grade radioactive decay products makes this for most people a last-ditch solution, plan ‘C’. Note that nuclear power can mitigate the effect of declining oil supplies even though the output of a nuclear reactor is electricity— it is possible to produce synthetic oil by a variety of processes assuming a plentiful supply of electricity. Consequently, the transport sector would require to change very little in this scenario [see https://en.wikipedia.org/wiki/Synthetic_oil for more on this topic].
Another possibility is to rely on some new technology such as fusion, the process by which the sun releases energy. The basic fuel is hydrogen, plentiful in water, but though experimental systems have been constructed, commercial exploitation is many years away. A breakthrough in solar cell technology is another possibility.
Potentially the most attractive alternative energy sources are wind power, wave power, tidal power, hydroelectricity, solar power, geothermal energy and biomass production. These are renewable energy sources, and all could be exploited to produce energy from natural processes in real time.
The pros and cons of each method will be considered in detail in later sections, but we can make some general points at this stage. The cost of energy generation from renewable energy is greater than using fossil fuel. However, the balance is liable to shift as the cost of fossil fuels rise.
The other problem is that we have limited control over natural processes and it is difficult to match supply with demand. It is important to balance production and consumption and if they cannot be matched, a storage mechanism is required to act as a buffer to maintain continuity of supply at times when generation is inadequate. Pumped-storage (Fig. 5) is one possibility, but another approach is to produce hydrogen gas by electrolysis (Fig. 6). The hydrogen is stored until required. It may be burnt for heat or converted directly to electricity using a fuel cell (Fig. 7) or used to run an adapted vehicle. This is one vision of the hydrogen economy [https://en.wikipedia.org/wiki/Hydrogen_economy].
Figure 5: In pump storage, excess electricity is used to pump water into an uphill reservoir.
When required, the energy is recovered by letting it flow back down through a turbine.
[Image https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity]
Figure 6 When direct current is passed through water, water molecules are broken down releasing hydrogen and oxygen gas. An electrolyser is a commercial device used for electrolysis. [Image https://www.energy.gov/eere/fuelcells/hydrogen-production-electrolysis
Figure 7: A fuel cell recombines hydrogen gas with atmospheric oxygen to create electricity. The process is potentially close to 100% efficient. [Image https://www.fchea.org/h2-day-2019-events-activities/2019/8/1/fuel-cell-amp-hydrogen-energy-basics]
Hydrogen in this context is an energy carrier, not an energy source, because hydrogen is merely storing energy produced by other means. Whilst using hydrogen for energy storage overall is potentially 80–90% efficient, fuel cells and electrolysers currently are respectively only 50% and 75% efficient.
Activity 3
- Calculate the solar energy incident on the Earth each year and compare this with the primary energy demand. Take the radius of the Earth as 6,300 kilometres, and the solar constant to be 1366 Wm-2.
- Compare the efficiency of using electricity to drive an electric car and drive an hydrogen vehicle. Note that a battery and electric motor are about 90% energy efficient. A combustion engine is about 10-25% efficient.
Solution
a. Area cutting the parallel rays from the distant sun is:
Multiply this by the energy incident on each square metre and the number off seconds a year to get the total energy incident on the Earth in one year:
Convert to Gtoe:
The annual primary energy consumption of the world is about 11 Gtoe, a factor of 10,000 less. However, there are huge conversion losses through many stages before this energy can become useable [https://en.wikipedia.org/wiki/Solar_energy]. In fact, it is remarkable we use/need such a significant portion.
b. The diagram shows how primary energy from a renewable source could be used for transportation. Best case efficiencies of 60% have been applied to the fuel cell and electrolyser.
There are three ‘paths’:
- The electricity can directly charge a battery which then drives a car’s electric motor. This is 81% efficient (=0.9 x 0.9).
- The electricity can be converted to hydrogen by an electrolyser, stored, converted back to electricity when needed to drive an electric motor. This is 33% efficient (=0.6 x 1 x 0.6 x 0.9).
- The electricity is converted to hydrogen which is burnt in a modified combustion engine. This is 30% efficient (=0.6 x1x 0.5).
This analysis assumed 50% efficiency for the combustion engine. Though it is possible to get this efficiency in theory, in practice most engines are 25% efficient. And with normal use with delays etc, only 10% of the available energy is used to drive the car. Because the car is 10 times heavier than the person, only 1% of the primary energy goes towards moving the payload.
Paris Agreement
We will later consider in detail environmental aspects of fossil fuels consumption and the installation of renewable energy systems, but at this stage it is useful to provide an overview of the government and local policies on energy generation and consumption. It is widely accepted that the reduction of non-renewable energy use is a critical objective, if only because of the limited fossil fuel supply.
The Paris Agreement is a legally binding international treaty on climate change. It was adopted by 196 Parties at COP 21 in Paris, December 2015 and entered into force November 2016. Its goal is to limit global warming to well below 2, preferably to 1.5 degrees Celsius, compared to pre-industrial levels. To achieve this long-term temperature goal, countries aim to reach global peaking of greenhouse gas emissions as soon as possible to achieve a climate neutral world by mid-century. The Paris Agreement is a landmark in the multilateral climate change process because, for the first time, a binding agreement brings all nations into a common cause to undertake ambitious efforts to combat climate change and adapt to its effects.
Implementation of the Paris Agreement requires economic and social transformation, based on the best available science. The Paris Agreement works on a 5-year cycle of increasingly ambitious climate action carried out by countries. Countries submit their plans for climate action known as nationally determined contributions (NDCs).
In their NDCs, countries communicate actions they will take to reduce their Greenhouse Gas emissions in order to reach the goals of the Paris Agreement. Countries also communicate in the NDCs actions they will take to build resilience to adapt to the impacts of rising temperatures.
The Katowice package adopted at the UN climate conference (COP24) in December 2018 contains common and detailed rules, procedures and guidelines that operationalise the Paris Agreement.
Figure 9: Wind power or wind energy is the use of wind to provide mechanical power through wind turbines to turn electric generators for electrical power. Wind power is a popular sustainable, renewable energy source that has a much smaller impact on the on the environment compared to burning fossil fuels.
It covers all key areas including transparency, finance, mitigation and adaptation, and provides flexibility to Parties that need it in light of their capacities, while enabling them to implement and report on their commitments in a transparent, complete, comparable and consistent manner.
It will also enable the Parties to progressively enhance their contributions to tackling climate change, in order to meet the agreement's long-term goals.
So what has been achieved so far?
Although climate change action needs to be massively increased to achieve the goals of the Paris Agreement, the years since its entry into force have already sparked low-carbon solutions and new markets. More and more countries, regions, cities and companies are establishing carbon neutrality targets. Zero-carbon solutions are becoming competitive across economic sectors representing 25% of emissions. This trend is most noticeable in the power and transport sectors and has created many new business opportunities for early movers.
By 2030, zero-carbon solutions could be competitive in sectors representing over 70% of global emissions.
Activity 4
- Explain the key elemental agreements of the Paris Agreement. Mention; Mitigation of reducing emissions, Transparency and global stocktake, Adaptation, and Loss and Damage.
- The EU’s initial commitment to the Paris Agreement was to reduce greenhouse gas emissions by at least 40% by 2030 compared to 1990. Explain whether the EU has accomplished this and by how much?
Solution
a.
Mitigation: reducing emissions
Governments agreed
- a long-term goal of keeping the increase in global average temperature to well below 2°C above pre-industrial levels;
- to aim to limit the increase to 1.5°C, since this would significantly reduce risks and the impacts of climate change;
- on the need for global emissions to peak as soon as possible, recognising that this will take longer for developing countries;
- to undertake rapid reductions thereafter in accordance with the best available science, so as to achieve a balance between emissions and removals in the second half of the century.
As a contribution to the objectives of the agreement, countries have submitted comprehensive national climate action plans (nationally determined contributions, NDCs). These are not yet enough to reach the agreed temperature objectives, but the agreement traces the way to further action.
Transparency and global stocktake
Governments agreed to
- come together every 5 years to assess the collective progress towards the long-term goals and inform Parties in updating and enhancing their nationally determined contributions;
- report to each other and the public on how they are implementing climate action;
- track progress towards their commitments under the Agreement through a robust transparency and accountability system.
Adaptation
Governments agreed to
- strengthen societies' ability to deal with the impacts of climate change;
- provide continued and enhanced international support for adaptation to developing countries.
Loss and damage
The agreement also
- recognises the importance of averting, minimising and addressing loss and damage associated with the adverse effects of climate change;
- acknowledges the need to cooperate and enhance the understanding, action and support in different areas such as early warning systems, emergency preparedness and risk insurance.
b.
The EU’s initial nationally determined contribution (NDC) under the Paris Agreement was the commitment to reduce greenhouse gas emissions by at least 40% by 2030 compared to 1990, under its wider 2030 climate and energy framework. All key EU legislation for implementing this target was adopted by the end of 2018.
In December 2020, the EU submitted its updated and enhanced NDC the target to reduce emissions by at least 55% by 2030 from 1990 levels, and information to facilitate clarity, transparency and understanding (ICTU) of the NDC. The EU and its Member States, acting jointly, are committed to a binding target of a net domestic reduction of at least 55% in greenhouse gas emissions by 2030 compared to 1990.
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