«-1Helios e.V. Reader Sunfuel April 2005 Inhaltsverzeichnis: 1. Einführung zur Allgemeinen Nutzung von Biomasse unter besondere Berücksichtigung der ...»
Stand: April 2005
-1Helios e.V. Reader Sunfuel April 2005
1. Einführung zur Allgemeinen Nutzung von Biomasse unter besondere
Berücksichtigung der verflüssigung- SEPS
2. PlanetArk – German Biofuel Firms to Become Large Grain Buyers (http://www.planetark.com/dailynewsstory.cfm/newsid/29999/newsDate/18-Marstory.htm)
3. Ethanol Research Breakthrough: Wood Feedstock (http://www.renewableenergyaccess.com/rea/news/story;jsessionid=a_ZpXd_uIPH _?id=22228)
4. Green Car Congress - DaimlerChrysler Emphasizes Synthetic Diesel BioFuel Commitment (http://www.greencarcongress.com/biomasstoliquids_btl/index.html), 03.2005
5. USDA: BTL Diesel Could Replace 13% of Germany’s Diesel Use (http://www.greencarcongress.com/biomasstoliquids_btl/index.html), 03.2005.....68
6. Sunfuel aus Sicht von VW (www.sunfuel.de), 2005
7. Stellung von Sunfuel aus Sicht eines VW-Experten (Dr.-Ing. W. Steiger) 2002 (http://www.world-council-for-renewable-energy.org/downloads/WCRE-Steigerd.pdf)
8. Beitrag des SüdWestRundfunks (SWR) 06/2003 (http://www.swr.de/rasthaus/archiv/2003/06/28/print2.html)
9. Artikel der Zeit (Wirtschaft), 16/2002
10. Ethanol - Ethanol Around the World
11. Air Quality and Ethanol in Gasoline
12. The New Liquid Biofuel Age
13. Liquid biofuel from Biomass & Waste.
14. Well-to-Wheel Analysis of Biofuels and Hydrogen
15. The Decomposition of wood by acidx. Wood Saccarification
16. Herstellung von Biotreibstoffen (http://www.energieschweiz.ch/imperia/md/content/statistikperspektiven/9.pdf)
17. Kraftstoffe au erneuerbaren Ressourcen – Potentiale, Herstellung, Perspektiven (http://www.fvsonnenenergie.de/fileadmin/fvsonne/publikationen/ws2003/01_a_kraftstoffe_01.pdf )
1. Einführung zur Allgemeinen Nutzung von Biomasse unter besondere Berücksichtigung der verflüssigung- SEPS (http://www.seps.sk/zp/fond/dieret/biomass.htm)
3.1 INTRODUCTION Biomass as the solar energy stored in chemical form in plant and animal materials is among the most precious and versatile resources on earth. It provides not only food but also energy, building materials, paper, fabrics, medicines and chemicals. Biomass has been used for energy purposes ever since man discovered fire. Today, biomass fuels can be utilised for tasks ranging from heating the house to fuelling a car and running a computer.
THE CHEMICAL COMPOSITION OF BIOMASS
The chemical composition of biomass varies among species, but plants consists of about 25% lignin and 75% carbohydrates or sugars. The carbohydrate fraction consists of many sugar molecules linked together in long chains or polymers. Two larger carbohydrate categories that have significant value are cellulose and hemi-cellulose. The lignin fraction consists of non-sugar type molecules. Nature uses the long cellulose polymers to build the fibers that give a plant its strength.
The lignin fraction acts like a “glue” that holds the cellulose fibers together.
WHERE DOES BIOMASS COME FROM?
Carbon dioxide from the atmosphere and water from the earth are combined in the photosynthetic process to produce carbohydrates (sugars) that form the building blocks of biomass. The solar energy that drives photosynthesis is stored in the chemical bonds of the structural components of biomass. If we burn biomass efficiently (extract the energy stored in the chemical bonds) oxygen from the atmosphere combines with the carbon in plants to produce carbon dioxide and water. The process is cyclic because the carbon dioxide is then available to produce new biomass.
In addition to the aesthetic value of the planet’s flora, biomass represents a useful and valuable resource to man. For millennia humans have exploited the solar energy stored in the chemical bonds by burning biomass as fuel and eating plants for the nutritional energy of their sugar and starch content. More recently, in the last few hundred years, humans have exploited fossilized biomass in the form of coal. This fossil fuel is the result of very slow chemical transformations that convert the sugar polymer fraction into a chemical composition that resembles the lignin fraction.
Thus, the additional chemical bonds in coal represent a more concentrated source of energy as fuel.
All of the fossil fuels we consume - coal, oil and natural gas - are simply ancient biomass. Over millions of years, the earth has buried ages-old plant material and converted it into these valuable fuels. But while fossil fuels contain the same constituents - hydrogen and carbon - as those found in fresh biomass, they are not considered renewable because they take such a long time to create.
Environmental impacts pose another significant distinction between biomass and fossil fuels.
When a plant decays, it releases most of its chemical matter back into the atmosphere. In contrast, fossil fuels are locked away deep in the ground and do not affect the earth’s atmosphere unless they are burned.
Wood may be the best-known example of biomass. When burned, the wood releases the energy the tree captured from the sun’s rays. But wood is just one example of biomass. Various biomass resources such as agricultural residues (e.g. bagasse from sugarcane, corn fiber, rice straw and hulls, and nutshells), wood waste (e.g. sawdust, timber slash, and mill scrap), the paper trash and
-3Helios e.V. Reader Sunfuel April 2005 urban yard clippings in municipal waste, energy crops (fast growing trees like poplars, willows, and grasses like switchgrass or elephant grass), and the methane captured from landfills, municipal waste water treatment, and manure from cattle or poultry, can also be used.
Biomass is considered to be one of the key renewable resources of the future at both small- and large-scale levels. It already supplies 14 % of the world’s primary energy consumption. But for three quarters of the world’s population living in developing countries biomass is the most important source of energy. With increases in population and per capita demand, and depletion of fossil-fuel resources, the demand for biomass is expected to increase rapidly in developing countries. On average, biomass produces 38 % of the primary energy in developing countries (90 % in some countries). Biomass is likely to remain an important global source in developing countries well into the next century.
Even in developed countries, biomass is being increasingly used. A number of developed countries use this source quite substantially, e.g. in Sweden and Austria 15 % of their primary energy consumption is covered by biomass. Sweden has plans to increase further use of biomass as it phases down nuclear and fossil-fuel plants into the next century.
In the USA, which derives 4 % of its total energy from biomass (nearly as much as it derives from nuclear power), now more than 9000 MW electrical power is installed in facilities firing biomass.
But biomass could easily supply 20% more than 20 % of US energy consumption. In other words, due to the available land and agricultural infrastructure this country has, biomass could, sustainably, replace all of the power nuclear plants generate without a major impact on food prices.
Furthermore, biomass used to produce ethanol could reduce also oil imports up to 50%.
BIOMASS - SOME BASIC DATA
* Total mass of living matter (including moisture) - 2000 billion tonnes * Total mass in land plants - 1800 billion tonnes * Total mass in forests -1600 billion tonnes * Per capita terrestrial biomass - 400 tonnes * Energy stored in terrestrial biomass 25 000 EJ * Net annual production of terrestrial biomass - 400 000 million tonnes * Rate of energy storage by land biomass - 3000 EJ/y (95 TW) * Total consumption of all forms of energy - 400 EJ/y (12 TW) * Biomass energy consumption - 55 EJ/y ( 1. 7 TW)
BIOMASS IN DEVELOPING COUNTRIES
Despite its wide use in developing countries, biomass energy is usually used so inefficiently that only a small percentage of its useful energy is obtained. The overall efficiency in traditional use is only about 5-15 per cent, and biomass is often less convenient to use compared with fossil fuels. It can also be a health hazard in some circumstances, for example, cooking stoves can release particulates, CO, NOx formaldehyde, and other organic compounds in poorly ventilated homes, often far exceeding recommended WHO levels. Furthermore, the traditional uses of biomass, i.e., burning of wood is often associated with the increasing scarcity of hand-gathered wood, nutrient depletion, and the problems of deforestation and desertification. In the early 1980s, almost 1.3 billion people met their fuelwood needs by depleting wood reserves.
Share of biomass on total energy consumption.
Nepal 95 %
Malawi 94 % Kenya 75 % India 50 % China 33 % Brazil 25 % Egypt 20 % There is an enormous biomass potential that can be tapped by improving the utilization of existing resources and by increasing plant productivity. Bioenergy can be modernized through the application of advanced technology to convert raw biomass into modern, easy-to-use carriers (such as electricity, liquid or gaseous fuels, or processed solid fuels). Therefore, much more useful energy could be extracted from biomass than at present. This could bring very significant social and economic benefits to both rural and urban areas. The present lack of access to convenient sources limits the quality of life of millions of people throughout the world, particularly in rural areas of developing countries. Growing biomass is a rural, labour-intensive activity, and can, therefore, create jobs in rural areas and help stem rural-to-urban migration, whilst, at the same time, providing convenient carriers to help promote other rural industries.
FOOD OR FUEL?
A major criticism often levelled against biomass, particularly against large-scale fuel production, is that it could divert agricultural production away from food crops, especially in developing countries. The basic argument is that energy-crop programmes compete with food crops in a number of ways (agricultural, rural investment, infrastructure, water, fertilizers, skilled labour etc.) and thus cause food shortages and price increases. However, this so-called “food versus fuel” controversy appears to have been exaggerated in many cases. The subject is far more complex than has generally been presented since agricultural and export policy and the politics of food availability are factors of far greater importance. The argument should be analysed against the background of the world’s (or an individual country’s or region’s) real food situation of food supply and demand (ever-increasing food surpluses in most industrialized and a number of developing countries), the use of food as animal feed, the under-utilized agricultural production potential, the increased potential for agricultural productivity, and the advantages and disadvantages of producing biofuels.
The food shortages and price increases that Brazil suffered a few years ago, were blamed on the ProAlcool programme. However, a closer examination does not support the view that bioethanol production has adversely affected food production since Brazil is one of the world’s largest exporters of agricultural commodities and agricultural production has kept ahead of population growth: in 1976 the production of cereals was 416 kg per capita, and in 1987 - 418 kg per capita.
Of the 55 million ha of land area devoted to primary food crops, only 4.1 million ha (7.5 per cent) was used for sugarcane, which represents only 0.6 per cent of the total area registered for economic use (or 0.3 per cent of Brazil’s total area). Of this, only 1.7 million ha was used for ethanol production, so competition between food and crops is not significant. Furthermore, crop rotation in sugarcane areas has led to an increase in certain food crops, while some byproducts such as hydrolyzed bagasse and dry yeast are used as animal feed. Some experts (Goldemberg,1992) believe that “In fact, the potential for producing food in conjunction with sugarcane appears to be larger than expected and should be explored further,”. Food shortages and price increases in Brazil have resulted from a combination of policies which were biased towards commodity export crops and large acreage increases of such crops, hyper-inflation, currency devaluation, price control of domestic foodstuffs etc. Within this reality, any negative effects that bioethanol production might have had should be considered as part of the overall problem, not the problem.
It is important to mention that developing countries are facing both food and fuel problems.
Adoption of agricultural practices should, therefore take into account this reality and evolve efficient methods of utilising available land and other resources to meet both food and fuel needs (besides other products), e.g., from agroforestry systems.