The possibilities and limits of substituting fossil energies by bioenergy

Term Paper (Advanced seminar), 2014
17 Pages, Grade: 1,3


Table of contents

1. Introduction

2. Theoretical background
2.1 The sources of our energy
2.2 What are fossil energies?
2.3 What is bioenergy?

3. Practical feasibility
3.1 Biogas as substitute for natural gas and coal in the power generation
3.2 Biofuels as substitute for fossil fuels in the transport sector

4. Conclusion

5. References

1. Introduction

The population of the world is growing while fossil energies are getting less. The world already has more than 7 billion people and the maximum has not been reached yet. In the year 2050 there will be more than 9 billion people (Birg, 2004, p. 90; UN DESA, 2013, p.5). The growing population combined with some other effects like technologisation will lead to an increasing demand for energy (Sorensen et al., 2009, p. 7.). But how can we meet this increasing demand? Fossil energies are limited, becoming more and more expensive (BDEW, 2013, p. 19) and their use may even have to be reduced because of the effects on the climate worldwide, especially global warming. Besides nuclear power, which produces radioactive waste and can be very dangerous as we could see in nuclear disasters such as Chernobyl and Fukushima, the renewable energies could be a possible alternative to fossil energies.

Renewable energies include energy by biomass. Could biomass be an alternative for fossil fuels? There are a lot of different ways how bioenergy can be produced and used. The use of energy from biomass is much older than from fossil fuels. It was not until the 20th century that fossil fuels in particular mineral oil started to dominate the world’s energy market (Quaschning, 2010, p. 17). The oldest and best-known example of using energy from biomass is the burning of wood. Beside wood and other energy crops there is also the possibility of using biological residues to produce energy. This can be done by transforming the biomass into biogas to use it in power plants. But what about liquid fuels? We cannot drive our cars with wood. It is possible to drive with biogas but almost the whole transport sector relies on liquid fuels. One idea is the substitution of fossil fuels with biofuels. For a few years biofuels has been used in Germany, but is the use of biofuels really better for our environment? And is it possible to substitute fossil fuels completely?

Before we can start with the analysis of how energy from biomass could be substituted for fossil energies we have to define different types of bioenergy and fossil energies. After this we will take a look at energetic assessments of concepts for the substitution of fossil energies and how complicated such evaluations can be. Then we will analyse possibilities and limits of biogas as substitute for coal and natural gas used in the power generation and biofuels as substitute for diesel fuel and gasoline. Both of these applications are already in use so we can take a look at their benefits and drawback. We will analyse their environmental impact, their costs, and their potential to meet the actual and the future energy demand.

2. Theoretical background

2.1 The sources of our energy

The world’s primary energy (raw energy without any treatment) comes from fossil energies, nuclear power, and renewable energies. By far most of the primary energy is produced from fossil energies. Germany’s primary production, for example, is produced from almost 80 % fossil energies (hard coal, lignite coal, natural gas, mineral oil) (fig. 1). Only about 12 % come from renewable energies, the rest is produced from nuclear power and other sources (fig. 1). Within the renewable energies the energy from biomass (biomass solid/gaseous + biofuels) contributes the biggest part with 8.4 % of the total primary energy. Even this exceeds the rate of nuclear power (7.6 %). By the example of Germany, figure 1 gives us a first impression of the ratios of the energy sources we use. It seems that there is great potential in energy from biomass, perhaps as alternative to fossil energies. If not now then maybe in the future.

illustration not visible in this excerpt

Fig. 1: A: Proportion of primary energy consumption of Germany in 2013. Last year almost four fifths of the primary energy consumption of Germany came from fossil energies. B: Distribution of renewable energies in Germany. The energy from biomass contributes the biggest part of the renewable energies in Germany (8.4 %) (modified from BMWi, 2014a, p. 1).

In this paper the possibilities and limits of substituting fossil energies with bioenergy will be discussed. So we exclude the nuclear power completely as well as other renewable energies besides biomass. Before we can go closer in detail, we have to clarify the terms bioenergy and fossil energies. We will take a closer look at their different types as well as their benefits and drawbacks.

2.2 What are fossil energies?

According to Quaschning (2010, p.16, 25) fossil energies are concentrated energy sources that result from animal or vegetable remains over a long time period. The starting materials of fossil energies get their energy by transformed solar radiation, which means that fossil energies are saved solar energy. The fossil energies include mineral oil, natural gas, hard coal, lignite coal, and peat. The consumption of fossil fuels leads to heat energy, but also to a release of carbon dioxide and other combustion products. In the 20th century the combustion of fossil fuels replaced the use of traditional renewable energies like windmills and water wheels (Quaschning, 2010, p. 16, 25).

Because of the low primary energy percentage of peat this will not be further elaborated.

Mineral oil is today’s the most important energy source (Quaschning, 2010, p. 18). It is the basis for the worldwide transport of goods and passengers, it is used for heating, and it is very important for the petrochemicals sector (Wolff, 2006, p 56). In the year 2012 only 2.8 % of the mineral oil consumption of Germany was produced by domestic resources (LBEG, 2013, p 30). This leads to a strong dependency, which can be very problematic. We could see this in the worldwide oil crises in the years 1973 and 1979 (Quaschning, 2010, p. 18).

Natural gas is the youngest and cleanest fossil energy; the combustion of natural gas produces less carbon dioxide than the combustion of mineral oil or coal (Quaschning, 2010, p.20). Natural gas is a blend of different gases like methane (main component), hydrogen sulphide, and other gases (Quaschning, 2010, p. 20). Natural gas is used for the heating of houses, the generation of electricity, and as propulsion of vehicles (Wolff, 2006, p.55). To meet the demand of the next 50 years 565 billion t carbon equivalent would be required, but the known stock is just 175 billion t and the estimated stock is just 320 billion t (Wolff, 2006, p.55). It is well known that a decreasing supply and increasing demand will lead to an increasing price. This requires either a substitution of natural gas or a change to new techniques for heating, generating electricity, and propulsions. In 2012 the natural gas consumption of Germany was covered with only 11 % of domestic resources (LBEG, 2013, p 31). This again leads to a dependency as we could see with mineral oil above.

Coal appears in different types, it is mostly divided in hard coal and brown coal. Brown coal or lignite is softer with much lower energy content than hard coal. Coal is mainly used for the generation of electricity, steel manufacturing, and in the chemical sector (Wolff, 2006, p. 57). It makes around 20% of the global energy consumption (Wolff, 2006, p. 57). The actual known stock is around 1000 billion t carbon equivalent and the estimated stock is 5000 billion t. That implies that the demand for coal of the next years would be met (Wolff, 2006, p. 57). The brown coal used in Germany is 100% domestic whereas 85% of the hard coal has to be imported (Statistik der Kohlewirtschaft e.V., 2013, p. 8-9). In the case of coal neither the price nor the availability is problematic but the effects on the climate are. The combustion of coal leads to the strongest CO2 emission of all fossil energies. In general, the combustion of fossil fuels always leads to an emission of CO2. Without a reduction of their use the 2° C climate target cannot be fulfilled. But beside these facts, there is one big advantage of fossil fuels: their continuous availability (Quaschning, 2007, p. 35, Wolff, 2006, p. 54).

In the previous paragraph we talked about the different types of fossil energies and we saw that fossil energies have at least three big disadvantages: The limited availability and the resulting increase of the price (except coal), the negative effect on the global climate and the dependence on states that are energy suppliers. Because of these disadvantages technical development has to find new energy sources to be substituted for fossil energies. One possibility, bioenergy, will be discussed in the next paragraph.

2.3 What is bioenergy?

Bioenergy is defined as energy, which is produced by biomass (Byrnett et al., 2009, p. 7). In Germany biomass is strictly defined in the Biomasseverordnung (BiomasseV) as energy from phyto- and zoomass. It includes secondary products and by-products, residues, and waste whose energy content is derived from phyto-and zoomass (BMJV, 2012, p. 1). Biomass receives its energy from the sun, so that bioenergy belongs to renewable energies. Renewable energies are energy sources that are inexhaustible in the human time period (Quaschning, 2011, p. 34).

Biomass is very diverse and can be subdivided differently. One possibility is to classify biomass in primary and secondary products (Rode et al., 2005, p. 14). Primary biomass gets its energy directly from the sun (algae, plants and floral remains), secondary biomass gets the energy by transforming primary biomass into higher organisms (zoomass and its excrements) (Rode et al., 2005, p. 14). Other divisions of biomass are into remnants and energy crops or into solid, liquid and gaseous. The biomass has to be converted depending on the raw material and the required end product (Rode et al., 2005, p. 14). In figure 2 several conversion routes of biomass are illustrated. The end product can be divided into heat or power, into liquid fuels, and into gaseous fuels.

To get the energy which is stored in biomass, there are several ways of usage. The easiest one is to combust the biomass (fig. 2). This is often done for wood or other lignocellulosic materials. Another way to use the biomass is to transform it (fig. 2). This can be done by transesterification, hydrogenation, fermentation, gasification, pyrolysis, digestion etc. depending on the starting- and end product (fig. 2). The gained heat or power can be used directly. The liquid fuels can be used as substitutes for example for diesel or can be added to other fuels like gasoline. Compared to the variety of petroleum-based fuels and products the range of liquid fuels made by biomass is much more limited (Chum et al., 2011, p. 238). The gaseous fuels can be used as substitutes for natural gas or in power plants.

illustration not visible in this excerpt

Figure 2: From biomass to the endproduct (modified from Chum et al., 2011, p. 218). The solid lines show the commercial, the dotted lines show developing bioenergy routes from biomass feedstocks through various conversions to the endproduct like heat, power and different fuels.

An argument that is often mentioned against the use of biomass is the competition between biomass as energy source and food supply. Increasing energy prices can lead to spillovers into food markets, which can increase the insecurity of food (Chum et al., 2011, p. 273). Because of the globalisation of the markets countries which do not use bioenergy can be also affected (Chum et al., 2011, 273). The right choice of land for the cultivation is not just important for the food price but also for the climate. The negative greenhouse gas impact can be stronger than the positive greenhouse gas impact, if the converted land has a high stock of carbon in the soil or the plants (European Parliament, 2009, p. 23).


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The possibilities and limits of substituting fossil energies by bioenergy
University of Koblenz-Landau  (Institute for Environmental Sciences)
Environmental Economics
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Daniel Sigmund (Author), 2014, The possibilities and limits of substituting fossil energies by bioenergy, Munich, GRIN Verlag,


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