Planning and Installing Bioenergy Systems

A Guide for Installers, Architects and Engineers

German Solar Energy Society, Ecofys

• Publisher: Routledge
• Year: 2004
• Print ISBN: 9781844071326
• eBook ISBN: 9781136559938
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

Bioenergy is relied upon worldwide as a modern solution for local energy supply and waste managements. With clear technical details, data tables and illustrative pictures explaining the fundamentals of different bioenergy projects, this guide reviews the main technologies and offers relevant best-practice examples.

Beginning with an overview of the technologies and types of systems available, the guide is packed with essential 'know-how' on anaerobic digestion, bio-fuel, small-scale ovens, large-scale boilers and gasifiers. Each technology is explained by examining the overall system and its components, planning, operation, maintenance, installation and economics. Information is given on both heat and combined heat and power. In addition, international legal framework and data on selected regional, national and international support programmes are provided.

In short, this book describes the key features of different bioenergy technologies and offers professionals expert guidance for installation. It will be a cherished resource for engineers and architects alike who are working in new projects, farmers keen to explore this technology and practitioners or students with a specialized and practical interest in this field.

1 Introduction

The solar power offered annually in the form of radiation on the earth’s surface exceeds the current energy demand of mankind by 11,000 times. Biomass is the stored energy of the sun. Plants convert solar energy with a mean efficiency of 0.1% by photosynthesis and store it lastingly in their parts – leaves, stalks and blossoms. At optimum boundary conditions the energy in the biomass can be stored almost infinitely without losses.

Figure 1.1. The green planet

Photo: NASA/www.nasa.gov

Biomass is the only renewable energy that can be converted into gaseous, liquid or solid fuels by means of well-known conversion technologies. Accordingly this universal renewable energy carrier can be used in a widespread field of applications in the energy sector. Already today it is possible to provide bioenergy carriers for the entire range of energy-demanding applications, from stationary heat and power supply to the fuelling of mobile applications for transport and traffic.

The annual global production of biomass exceeds today’s world’s energy consumption by a factor of 13!

The broad range of possible areas for use of biomass as an energy carrier, the advantage of secure and harmless storage, and the possibility of integrating agricultural and forestry enterprises into local energy supply offers a wide, sustainable field of application. The use of biomass as a renewable fuel can reduce the global energy footprint of all nations, and open the door to a sustainable and climate-neutral future.

In contrast to the direct use of solar energy or wind power, biomass as a renewable energy carrier is always available, and can be used to provide transmittable power. Usually, after the biomass has been treated, it is converted to one of these three major forms of energy:

• electricity
• heat
• fuel.

These energy carriers compete with fossil energy carriers in a broad range of applications.

The range of applications and the availability of biomass are only two important advantages of biomass. Another major argument for the use of this energy resource originates from its power regarding climate and environmental protection. When use is made of the stored energy in biomass, greenhouse gases such as carbon dioxide are emitted, but the amount is the same as that produced by natural decomposition processes. Thus bioenergy carriers can be considered neutral as far as the climate-damaging greenhouse effect is concerned.

1.1 The Challenge

Energy is the key to the long-term survival of our modern civilization. On average every single human being of the six billion people on earth accounts for 2 tonnes of carbon used for energy purposes each year. But of course there is a large difference between the industrialized and developing countries: for example, a European consumes more than 6 tonnes of carbon – 40 times more of our restricted global energy resources than a human being in Bangladesh.

Figure 1.2. More than 300 billion tonnes of CO₂ have been emitted to the atmosphere since 1990

Photo: creativ collection/www.sesolutions.de

Today, 90% of the energy carriers used are of fossil origin, and their use is associated with the emission of carbon dioxide to the atmosphere. Hence every year our earth’s atmosphere receives more than 15 billion tonnes of CO₂. Worldwide, scientists agree that proceeding in such a manner will lead to irreversible damage to our climate.

Yet satisfaction of the energy demand of our civilization does not necessarily need to be based on the climate-damaging fossil energy carriers. CO₂-neutral energy resources, such as the direct use of solar energy and wind power and the indirect use of solar radiation in the form of biomass, can provide the necessary energy. A mix of these renewable energy carriers is able to offer all sorts of forms of energy to meet the demands of our modern life.

The European Union (EU) has placed a strong emphasis in its energy policy on the use of bioenergy carriers and the development of a strong bioenergy market. The following ambitious targets were set in the EU’s white paper for the EU member countries regarding the use of biomass by the year 2010:

• 5 million tonnes of biofuels
• 10,000 MW_th of biomass-driven CHP plants
• 1 million houses supplied with bioheat
• 1 million jobs in the bioenergy sector.

Figure 1.3. Ambitious targets for bioenergy in the EU until 2010

Graphic: Dobelmann/www.sesolutions.de

1.2 The Universal Energy Carrier

The use of biomass is the oldest method of supplying energy to mankind. However, modern bioenergy carriers such as wood pellets or chips, logs, wood gas, biogas and plant oil or biodiesel offer interesting potential for providing innovative energy solutions to meet today’s energy demand. These natural fuels can be used in stationary applications to provide heat and power to households, to public buildings, in agriculture or in industry. Biodiesel can be used in series production engines for cars, and only minor modifications to car engines are needed for them to be able to drive on plant oil, so that already today mobility and transport problems can be solved fully by using energy crops without polluting the environment and without damaging our climate.

Figure 1.4. Applications of bioenergy

Photo: creativ collection/www.sesolutions.de

Biomass as a universal and renewable energy carrier is going through a renaissance regarding technology development and reputation. As well as the positive environmental effects of biomass-based energy supply there are several social and economical aspects, as the harvesting, treatment and transport of biomass are labour intensive. With 1.75 new long-term jobs per generated gigawatt-hour of bioenergy comes a significant net job creation – an important criterion for the sustainable development of rural areas both in the EU and in most other countries.

In general, regional areas profit directly from the positive economic effects of using bioenergy. In contrast to an added value of 20% in the fossil-fuel-based energy sector, bioenergy projects provide an added value of 60% to the region.

Figure 1.5. Photosynthesis: the natural power plant

Photo: creativ collection/www.sesolutions.de

Photosynthesis as a natural power plant offers considerable potential to support sustainable structural development and the reinforcement of rural areas in Europe. Hence bioenergy carriers present long-term advantages for rural development, for the security of energy supply, and also for the agricultural production of food, and will improve security of supply in the EU. Biomass as stored solar energy is thus showing its power as a universal element of a sustainable economic policy.

Figure 1.6. Types of biomass

Photo: creativ collection/www.sesolutions.de

1.3 The Potential

On the land areas of our planet grow about 200 billion tonnes of biomass with an energy content of approximately 30,000 EJ (1 EJ = 1 exajoule = 1 × 10¹⁸ J). This is equivalent to the energy content of the entire stock of fossil energy carriers on earth. Each year, growth of about 15 billion tonnes of biomass adds an energy potential of 2250 EJ to this amount through photosynthesis.

Unfortunately this vast potential cannot be used directly for energy purposes, as it is spread over the entire landmass of our planet. Only part of this potential is available for the use of biomass as an energy carrier; it is called the technical potential, and has been estimated to be of the order of 150 EJ.

Figure 1.7. Technical potential of biomass in Europe

Graphic: Dobelmann/www.sesolutions.de Data: M. Kaltschmitt

The part of the technical biomass potential that can be used in an economically feasible manner depends heavily on the relevant market conditions. Thus local oil and gas prices, and the supporting policy instruments such as subsidies and revenues, complement the environmental and social advantages of bioenergy. But one aspect is clear: with increasing prices for fossil energy carriers, the technical potential for bioenergy projects is enhanced, too.

1.4 The Market

Biomass is already making a significant contribution to the security of a sustainable energy supply in a number of European countries.

More than 2200 PJ (1 PJ = 1 petajoule = 10¹⁵ J) of stored energy in the form of biomass is being harvested in the EU each year; about 1700 PJ of this amount are used directly to generate heat and 500 PJ are used to generate electricity. The...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright
• Contents
• Foreword
• Chapter 1. Introduction
• Chapter 2. Biomass: energy from the sun
• Chapter 3. Anaerobic digestion
• Chapter 4. Liquid biofuels
• Chapter 5. Small combustion systems
• Chapter 6. Large-scale heaters
• Chapter 7. Gasification
• Chapter 8. Legal boundary conditions for bioenergy systems
• Chapter 9. Support measures for bioenergy projects
• Index