Dendro Power for Industrial Printing
Press at Wijeya Newspapers Ltd.
Sri Lanka
Piladuwa Parana Hewage Janaka Aruna Rathnakumara
Master of Science Thesis
KTH School of Industrial Engineering and Management
Energy Technology EGI_2016-103 MSC EKV1173
Division of Heat and Power Technology
SE- 100 44 Stockholm
Master of Science Thesis EGI_2016-103 MSC EKV1173
Dendro Power for Industrial
Print-ing Press at Wijeya Newspapers Ltd.
Sri Lanka
Piladuwa Parana Hewage Janaka Aruna Rathnakumara
Approved Date: December 21st, 2016
Examiner:
Assist. professor Peter Hagström
Supervisor:
Assist. professor Peter Hagström
Dr. N.S. Senanayake Eng. Ruchira Abeyweera
Commissioner: Contact person:
Piladuwa Parana Hewage Janaka Aruna Rathnakumara
Abstract
Wijeya Newspapers Limited (WNL) is one of the leading newspaper and magazine publish-ers in Sri Lanka. The company has their main factory (printing plant) located at Hokandara which is 15 km from Colombo City. Total power requirement of the factory is 3000 kVA (2.4 MW) and the Company’s annual energy demand is 3.8 GWh which is currently sup-plied by the Ceylon Electricity Board (CEB). As a strategy of the higher management, the company is moving in to renewable power generation projects such as biomass, solar and wind energy in addition to their existing energy conservation and management practices in the factory. In order to fulfil the vision of WNL, a 2 MW alternative green and clean bio-mass energy generation facility is going to be installed as the first pilot energy project of the company. The Proposed biomass power plant site will be on the company’s own coconut plantation site and is to be within 15 to 20 km of the main electric substation in the North Western province. The goals of WNL are to develop economically viable energy produc-tion facilities using readily available renewable biomass fuel sources at an acceptable cost per kilowatt hour, to use green and clean energy in their printing operations and provide new revenue generation for their business portfolios. The Biomass power project (Dendro) will provide needed green energy supply system to their printing operations and additional revenue while providing energy in an environmentally sound manner. In addition to help-ing meet the company goals, the project will help reduce dependency on imported non-renewable energy sources in the country. In this backdrop, this research is conducted to as-sess the present situation of Dendro power generation and its applications in Sri Lanka and to evaluate the feasibility of utilizing Dendro power to meet the power requirement of the printing industry. This study concludes that Dendro power generation for the operations at WNL is economically and technically feasible and that the optimum plant capacity for this biomass fuel based electricity generating plant would be 2-5 MW
.
It was also revealed that there is good social acceptability for biomass based electricity generation in the local com-munity. As recommendations, the study proposes that the government takes action to inte-grate renewable energy in the national electricity generation plan.Sammanfattning
Wijeya Newspapers Limited (WNL) är en av de ledande tidnings- och tidskriftsförlagen på Sri Lanka. Företaget har sin huvudfabrik (tryckeri) i Hokandara, 15 km från Colombo City. Totalt effektbehov för fabriken är 3000 kVA (2,4 MW) och bolagets årliga energibehov är 3,8 GWh, som för närvarande tillhandahålls av Ceylon Electricity Board (CEB). Som en strategi av den högre ledningen genomför företaget projekt rörande förnybar elproduktion, såsom bioenergi, sol- och vindenergi utöver sin befintliga energitillförsel och energianvändning i fabriken. För att uppfylla WNL:s vision om 2 MW alternativ grön och ren energiproduktion skall en biomassabaserad anläggning installeras som det första pilotenergiprojektet i företaget. Det föreslagna området för detta kraftverk kommer att vara på det egna kokosplantaget, och kommer att förse den nordvästra provinsen med elektricitet inom en radie av 15 – 20 km. Målet för WNL är att utveckla ekonomiskt bärkraftiga energianläggningar som använder lättillgängliga förnybara biomassbränslen till en acceptabel kostnad per kilowattimme, att använda grön och ren energi i sin tryckeriverksamhet och att ge ny intäktsgenerering för sina affärsportföljer. Biomassa-kraftprojektet (Dendro) kommer att generera ett grönt energiförsörjningssystem till sin tryckeriverksamhet och samtidigt skapa extra intäkter. Förutom att bidra till att uppfylla företagets mål kommer projektet att bidra till att minska beroendet av importerade icke-förnybara energikällor i landet. Mot denna bakgrund utförs denna forskning för att bedöma den nuvarande situationen för Dendros kraftproduktion och dess tillämpningar i Sri Lanka och att utvärdera möjligheten att utnyttja Dendros makt för att möta effektbehovet från den grafiska industrin. Denna studie drar slutsatsen att Dendros kraftgenerering för verksamheten vid WNL är ekonomiskt och tekniskt genomförbart och att den optimala anläggningskapaciteten för biobränslebaserade kraftverk skulle vara 2-5 MW. Det har också visats att det finns god social acceptans för biomassabaserad elproduktion i det lokala samhället. Som en rekommendation föreslår studien att regeringen vidtar åtgärder för att integrera förnybar energi i den nationellaelproduktionsplanen.
List of Abbreviations
ADB Asian Development Bank
AFBC Atmospheric Fluidised Bed Combustion ASME American Society of Mechanical Engineers AVR Automatic Voltage Regulator
BEASL Biomass Energy Association of Sri Lanka
BIG/STIG Biomass Integrated Gasification Steam Injected Gas Turbine BIGCC Biomass Integrated Gasification Combined Cycle
BOI Board of Investment BSI British Standard Institution
CC Carbon Credit
CDM Clean Development Mechanism CEB Ceylon Electricity Board
CER Certified Emission Reduction CRI Coconut Research Institute DOE Department of Energy
EIRR Economic Internal Rate of Return ENPV Economic Net Present Value
EU European Union
FBC Fluidised Bed Combustion FIRR Financial Internal Rate of Return FNPV Financial Net Present Value GDP Gross Domestic Product GHG Greenhouse Gas
GWh Giga Watt hour
ha Hectare
IAPL Informatics Agrotech (Pvt) Ltd
IC Internal Combustion
IMF International Monetary Fund IOS International Standard Organization IPP Independent Power Producers
kV kilo Volt
kW kilo Watt
MASL Mahaweli Authority of Sri Lanka MOST Ministry Of Science and Technology MPE Ministry of Power and Energy
MV Medium Voltage
MW Mega Watt
MWh Mega Watt hour GWh Giga Watt hour
NGO Non-Government Organisation NPV Net Present Value
OPEC Organization of Petroleum Exporting Countries
PV Photo Voltaic
RERED Renewable Energy for Rural Economic Development SLR Sri Lankan Rupee
SPPA Small Power Purchase Agreement SRC Short Rotation Coppice
T Tonne (1000 kg)
UNFCCC United Nations Framework Convention for Climate Change USD United States’ Dollars
Table of Content 1 Introduction ... 9 1.1 General Overview ...9 1.2 Wijeya Newspapers Ltd. ...9 1.3 Problem Statement ... 10 1.4 Objectives ... 10 1.5 Methodology ... 10
1.6 Significance of the Study ... 11
2 Literature Survey ... 12
2.1 Dendro / Biomass Energy ... 12
2.1.1 Dendro Power ... 12
2.1.2Dendro/Biomass Power Generation Technologies ... 12
2.1.3 Conclusions of the Technology ... 20
2.1.4 Dendro Power in the world Scenario ... 21
2.2 Dendro Plantation in Sri Lanka ... 23
2.2.1 Availability of Land for Bio Mass Plantation ... 23
2.2.2 Climate Condition for Gliricidia Sepium ... 24
2.2.3 Cost of biomass fuel ... 24
2.2.4 Environmental aspects... 26
2.3Supply chain management ... 27
2.3.1 Resources for Dendro power plants ... 27
2.3.2Potential sources of supply ... 27
2.4 Alternative fuels for Gliricidia ... 27
3 Analysis and Results ... 28
3.1 Present situation of Dentro power in Sri Lanka... 28
3.1.1Dendro Potential in Sri Lanka ... 28
3.1.2Dendro powered Gasification projects in Sri Lanka ... 28
3.1.3Dendro Power for Electrification ... 33
3.2 Feasibility on generating power of using Denro power for printing press. ... 33
3.2.1 Power requirement ... 33
3.2.2 Designing of Power plant capacity ... 33
3.2.3 Dendro fuel harvesting and supply chain management to the power plant ... 34
3.2.4 Output of the Project ... 35
3.3 Technology Assessment ... 35
3.3.1 Direct Combustion ... 36
3.3.2 Pyrolysis/Gasification ... 36
3.3.3 Selected Technology ... 36
3.3.4 Facility Description ... 36
3.3.5 Design Criteria of the 2 MW Power Plant ... 36
4 Economic, social and environmental benefits of the project ... 37
4.1 Economic and social benefits ... 37
4.1.1Adequate electricity supply ... 37
4.1.2Organic nitrogenous fertilizer ... 38
4.1.4Conservation of foreign exchange in the country ... 39
4.1.5Energy security in the country ... 40
4.1.6Social benefits ... 41
4.1.7Providing employment for rural poor ... 41
4.2 Environmental benefits and Involvement to Sustainable Development ... 42
4.2.1 Helps to long-term GHG and local pollutants reduction... 42
4.2.2 Environmental benefits ... 42
4.2.3 Abatement of emissions of GHG and other pollutants ... 43
4.2.4 Reversing land degradation ... 45
4.2.5 Renewable energy source and carbon sink ... 46
4.2.6 Organic nitrogenous fertilizer to replace chemical urea fertilizer ... 47
4.3Other impacts of the project ... 47
4.3.1 Positive impacts ... 47
4.3.2Negative impacts ... 47
5 Financial Analysis ... 48
5.1 Risks ... 48
5.1.1Threat of fire ... 48
5.1.2Failure of the grid connection... 48
5.1.3Tariff... 48
5.2 Scenario analysis ... 48
5.3 Estimation of overall costs ... 49
6 Key Factors Impacting Project & Baseline Emissions ... 56
6.1 Factors affecting the project and baseline emission ... 56
6.1.1Legal factors ... 56
6.1.2Economic factors ... 56
6.1.3Political factors ... 56
6.1.4Socio-demographic factors ... 57
6.1.5Technical key factors ... 57
6.2 Project uncertainties ... 57
7 Conclusion, Recommendations and Suggestions for Future Works ... 58
8 Acknowledgments ... 60
1 Introduction
1.1 G eneral Overview
This report is prepared as a feasibility study to establish a commercial scale biomass based electricity-generating facility to be located in a rural locality for a private sector company called Wijeya Newspapers Ltd to run their printing presses. The biomass power project would improve the energy security in the company and support the company’s sustainable energy goal of producing a green factory in the country through generating electric power using indigenous and sustainable Short Rotation Coppice (SRC) biomass energy planta-tions. Fuel wood harvested from sustainable SRC energy plantations will be used as fuel for the power plant. SRC energy plantation for power plants has been proven a viable technol-ogy in the world. Out of several species of coppice plants tested for SRC energy plantation in Sri Lanka, Gliricidia has been identified as the most commercially viable species.
Out of several mature technologies of biomass conversion, combustion technology is se-lected as the suitable conversion mechanism for power generation. Almost all the electricity generation power plants use the steam turbine technology for biomass used power genera-tion in the world at present. This technology is well-established due to availability of cheap or waste biomass in the world. As an example, USA has the installed capacity of electricity generation from biomass around 7000 MW with efficiency of 20 to 25 percent [14]. The
biomass boiler steam turbine systems are expected to find more applications for electricity generation in future, particularly in situations where cheap biomass, e.g. agro industrial res-idues, and waste wood, are available. On the technology side, efficiency of these systems is expected to improve through incorporation of biomass dryers, where applicable, and larger plant sizes as well as higher steam conditions.
1.2 W ijeya N ew s papers Ltd .
Wijeya Newspapers Limited (WNL) is one of the leading newspaper and magazine publish-ers in Sri Lanka. WNL is the market leader of Sinhala weekends and daily newspappublish-ers in the local market. The company has their main factory (printing plant) located at Hokandara which is 15 km from Colombo City. Total power requirement of the factory is 3000 kVA (2.4 MW) and the Company’s annual energy demand is 3.8 GWh which is currently sup-plied by the Ceylon Electricity Board (CEB). The energy demand of the company has been increased dramatically with its rapid development in the last ten years. The company energy consumption is projected to increase by 30% in 2020. By having such development in mind and according to the company’s corporate strategy, the company has planned to go with maximum use of renewable energy for their printing operations under the green concepts. According to that, the Company have also been using natural lights in their operations at the day times. On the other hand, the management of the WNL is looking to accumulate more carbon credits to their business by utilizing renewable energy technologies in the fac-tory operations. Therefore, Wijeya Newspapers Ltd. is interested in building a 2 MW net biomass power generation project with annual generation capacity of 10,500 MWh
(2MW*24*365*0.6=10,512 with 0.6 plant factor) year to sell the electricity to the national grid and take back only required power from national grid to their factory energy needs. The Wijeya Group has their own coconut and tea plantations in which they plan to grow SRC to generate adequate biomass in a sustainable manner to meet the demands of power plants. A 2 MW power plant would require 72 tonnes of wet wood per day or 21,000 [72*365*0.8=21024] tonnes per year. To obtain this on a sustainable manner; 6.4 million trees would be required. At an estimated yield of 30 tonnes per hectare [2], approximately 700 hectare of dedicated Gliricidia plantation would be needed (21000/30=700). Essential-ly, this facility consists of a biomass-operated steam boiler generating high-pressure steam at superheated temperature and a steam turbine driven electricity generator. The facility will also include all auxiliary associated equipment such as water treatment plant, condenser cooling system and electrical switchgear to export electricity generated to the national grid. The capacity of power exported will be 2 MW.
1.3 Problem Statem ent
One of the main drawbacks of national supply of electricity (CEB) in the country is that still over 80% of the energy contribution in the country is generated from non-renewable energy sources like coal and thermal power plants. Being a leading newspaper company in Sri Lanka, the energy demand of Wijeya Newspapers Ltd. has been on the rise due to the company’s increased development in the last decade. The company energy consumption is also projected to increase by a significant amount over the years to come. As a result, the carbon footprint of the company is increased and the company’s energy security is also in a risk. Therefore, it is proposed to establish a biomass based power-generating facility within the premises of Wijeya Group’s plantation to cater to the energy need of the company in a sustainable and an environmentally friendly way. This project is carried out to assess the feasibility of the proposed Dendro power generation plant. Mainly, the technical and eco-nomic feasibility will be studied.
1.4 Objectives
1. To assess the present situation of Dendro power generation and its applications to the country.
2. To evaluate the feasibility of utilizing Dendro power to meet the power requirement of the printing industry.
1.5 Method olog y
This study is qualitative in nature and is mainly based on secondary data. Well-reputed books and magazines related to the sustainable energy engineering were referred to in order to study about Dendro, Dendro potential, cost of Biomass, Dendro power generation and plantation. Studies of available biomass technologies in Sri Lanka, success stories, and Dendro power gasification technology and their application in the country were taken into consideration
To evaluate the feasibility of utilizing Dendro power to meet the power requirement of the printing industry, following steps were taken:
• Estimating of the power requirement of the printing presses and matching the en-ergy requirement with renewable biomass power generation called.
• Studying about biomass power generation technologies and selecting the most ap-propriate equipment such as the turbine and related accessories to design the Dendro power generation plant.
• Determining the specification of steam turbine and related accessories to match the power requirement.
• Determining the biomass requirement to supply the fuel to the designed Dendro power plant
• Carrying out risk and scenario analysis and estimation about project cost and con-ducting the economic analysis to investigate the economic benefits of the project.
1.6 S ig nificance of the Stud y
Introduction and demonstration of modern, environmentally friendly power generation techniques at commercial scale are the major objectives of this project. The project will demonstrate the practical aspects of emission reductions resulting from utilization of re-newable resources for electrical energy production in place of conventional fuels and ways of earning additional income to rural people, which will contribute to the company corpo-rate social responsibility as well. Since Sri Lanka has a wealth of Sustainably Grown Fuel-wood (SGF) varieties that can be productively converted into other forms of energy, this project will be feasible to be implemented while ensuring that the environment is secured and without depleting the sources of supply. Dendro power will serve as a viable alternative to expensive oil imports and fuel wood-based energy production can also be a useful source of income to farmers and commercial growers. Therefore, biomass power genera-tion will lead to the betterment of socio economic condigenera-tions of the woodland dependent community in Sri Lanka.
2
Literature Survey
An extensive literature survey on Dendro, Dendro potential in Sri Lanka, Dendro Tech-nologies, Dendro Retrofit Gasification in Sri Lanka, Dendro Power for Electrification was conducted.
2.1 D end ro / B iom ass Energy
2 . 1 . 1 D e n d r o P o w e r
Denro power is known as renewable energy harvesting technology from energy crop that is called Gliricidia. The scientific name of this crop is Gliricidia sepium and it is widely known as Ginisiriya, with other many local names such as Wetamara, Nanchi, Albesia and Ladap-pa. Gliricidia has been considered as a multipurpose crop that is also used as boundary fences in rural areas and variety of uses in coconut and tea plantations. It is hardly fast growing tree that can withstand even the most adverse weather conditions, and it also grows in a variety of soil conditions. On the other hand, it is free from disease and pests. Further, it is used as supports for vegetable cultivation and pepper vines. Not only that but also it is a legume that can greatly enrich the soil and its green matter forms an ideal base for organic fertilizer. The leaves are an attractive fodder for cattle and goats. Gliricidia is an energy crop in its own right sticks, which can be harvested every eight months and be used as a Dendro fuel. Only mature branches of Gliricidia trees will be harvested maintaining appropriate foliage canopy cover right through the year. Energy plantations based on Gliri-cidia trees has been declared as the 4th plantation crop by the Government of Sri Lanka.
2 . 1 . 2 D e n d r o / B i o m a s s P o w e r G e n e r a t i o n T e c h n o l o g i e s
2 . 1 . 2 . 1 S t e a m Tu r b i n e Te c h n o l o g y
Steam turbine technology is the almost all of electricity generation power plants from bio-mass used power generation in the world at present. This technology is well established due to availability of cheap or waste biomass in the world. As an example, USA has the installed capacity of electricity generation from biomass around 7000 MW with efficiency of 20 to 25 percent [14].
The biomass Boiler steam turbine systems are expected to find more applications for elec-tricity generation in the future, particularly in situations where cheap biomass, e.g. agro in-dustrial residues, and waste wood, are available. On the technology side, the efficiency of these systems is expected to improve through incorporation of biomass dryers, where ap-plicable, and larger plant sizes as well as higher steam conditions.
The steam boiler turbine arrangement, woody biomass is combusted in a furnace of a steam boiler with fluidized bed combustion. Heat released during combustion is utilized for raising the pressure and the temperature of the steam. This steam is expanded through the
steam turbine, which in turn drives an electric alternator. Exhaust steam from the turbine is condensed and returned to the boiler.
Wood fuel is usually shredded to appropriate size and dried utilizing a part of the flue gas, before the fuel introduced into the furnace. This technology has been in existence in many parts of the world, specifically to produce electricity and motive power in the sugar industry utilising bagasse (residue produced after crushing sugar cane) as the fuel.
In this modern version of this technology, wood fuel is shredded into very small pieces and combustion is carried out in a fluidised state. Although this improvement increases the cost of fuel preparation and air supply, it improves the combustion efficiency, thus reducing the operational costs and also reducing stack emission levels. A fluidized bed boiler could ac-cept not only chipped wood but also residues such as rice husk, sawdust etc.
This technology is widely used all over the world to generate electrical and motive power from solid fuel. The modern versions have incorporated many new features to improve operational efficiency, thus reducing cost of operation and to reduce emission levels. Some of these improvements are increasing the pressure of boiler, increasing the vacuum in the condenser, combustion air pre heating and steam reheating. Figure 01 schematically shows the principle of this conventional system.
Figure 01: Boiler-steam turbine system [15]
2 . 1 . 2 . 2 C o g e n e r a t i o n
Cogeneration is the process of producing two useful forms of energy, normally electricity and heat, utilizing the same fuel source in an industrial plant where both heat/steam and electricity are needed, these requirements are normally met by using either;
1) Plant-made steam and purchased electricity, or
2) Steam and electricity produced in the plant in a cogeneration system.
The second option results in significantly less overall fuel requirement. Steam turbine based cogeneration is normally feasible if electricity requirement is above 500 kW. Biomass based
Condenser Flue Gas
cogeneration is often employed for industrial and district heating applications; however, the district heating option would not be applicable in the tropical countries. A number of stud-ies have been carried out on cogeneration in different agro industrstud-ies, particularly, sugar mills and rice mills. These show that biomass based cogeneration technology is well estab-lished in the pulp and paper industry, plywood industry as well as a number of agro-industries, for example, sugar mills and palm oil mills. Normally, there is substantial scope for efficiency improvements in such cases. For example, bagasse is burnt inefficiently in sugar mills in most developing countries because of a number of reasons, e.g., old and ob-solete machinery, disposal problems created by surplus bagasse, lack of incentive for effi-cient operation etc. Improving the efficiency of biomass-based cogeneration can result in significant surplus power generation capacity in wood- and agro-processing industries; in turn, this can play an important role in meeting the growing electricity demand in develop-ing countries. India has launched an ambitious biomass based cogeneration programme. A surplus power generating capacity of 222 MW was already commissioned by the end of 1999, while a number of projects of total capacity 218 MW were under construction. The total potential of surplus power generation in the 430 sugar mills of the country has been estimated to be 3500 MW [15].
2 . 1 . 2 . 3 C o - f i r i n g
Co-firing is set up as an auxiliary firing with biomass energy source in coal fired boilers. The co-firing has been tested in pulverized coal (PC) boilers, coal-fired cyclone boilers, flu-idized-bed boilers, and spreader stokers. Due to fuel flexibility of fluidized bed combustion technology, it is currently the dominant technology for co-firing biomass with coal. Co-firing can be done either by blending biomass with coal or by feeding coal and biomass separately and is a near term low-cost option for the efficient use of biomass. Co-firing has been extensively demonstrated in several utility plants, particularly in USA and Europe. Co-firing represents a relatively easy option for introducing biomass energy in large energy sys-tems. Besides low cost, the overall efficiency with which biomass is utilized in co-firing in large high pressure boilers is also high. Current wood production systems in most countries are dispersed and normally can only support relatively small energy plants of capacity up to 5-20 MWe, although dedicated plantations can probably support much bigger plants in the future. Thus, biomass supply constraint also favour co-firing biomass with coal (with only a part of the total energy coming from biomass) in existing co-fired plants in the short term
[15].
2 . 1 . 2 . 4 W h o l e Tr e e E n e r g y ( W T E ) s y s t e m
The Whole Tree Energy (WTE) system is a special type of wood fired system, in which whole tree trunks, cut to about 25 ft long pieces, are utilized in the process of power gener-ation in an innovative steam turbine technology that uses an integral fuel drying process. Flue gas is used to dry the wood stacked for about 30 days before it is conveyed to a boiler and burnt. Allowing the waste heat to dry the wet whole tree can result in improvement in furnace efficiency with net plant efficiency reaching comparable value of modern coal fired plants [15].
2 . 1 . 2 . 5 S t i r l i n g E n g i n e
A Stirling engine is an external combustion engine; working on the principle of the Stirling thermodynamic cycle, the engine converts external heat from any suitable source, e.g. solar energy or combustion of fuels (biomass, coal, natural gas etc.) into power. These engines may be used to produce power in the range from 100 watts to several hundred kilowatts. Stirling engines can also be used for cogeneration by utilizing the rejected heat for space or water heating, or absorption cooling. A number of research institutes and manufacturers are currently engaged in developing biomass fired Stirling engine systems. For example, the Technical University of Denmark is developing medium and large Stirling engines fuelled by biomass. For 36 kWe and 150 kWe systems, the overall efficiency is about 20 percent and 25 per cent respectively [15].
2 . 1 . 2 . 6 G a s i f i c a t i o n
Gasification is the process of converting a solid fuel to a combustible gas by supplying a re-stricted amount of oxygen, either pure or from air. The major types of biomass gasifiers are; fixed bed gasifier, Fluidized bed gasifier, and Biomass integrated gasification combined cycles (BIGCC).
2 . 1 . 2 . 7 F i xe d B e d G a s i f i c a t i o n
Fixed bed gasification technology is more than a century old and use of such gasifiers for operating engines was established by 1900. During World War II, more than one million gasifiers were in use for operating trucks, buses, taxis, boats, trains etc in different parts of the world. Currently, fixed bed gasification shows for the most part possible selection into biomass based power generation with capacity up to 500 kW. Although charcoal gasifica-tion presents no particular operagasifica-tional problem, the actual acceptance of the technology by potential users is rather insignificant at present, mostly because of low or no cost benefit that it offers. Also, producer gas is less convenient as an engine fuel compared with gaso-line or diesel and the user has to have time and skill for maintaining the gasifiers-engine system. However in situations of chronic scarcity of liquid fuels, charcoal Gasifier-engine systems appear to be acceptable for generating power for vital applications. Thus, several gasoline-fueled passenger buses converted to operate with charcoal gasifiers were reported to be in use in at least one province of Vietnam in early 1990s. As reported by Stassen (1993), a number of commercial charcoal Gasifier-engine systems have been installed since early eighties in the South American countries. Wood gasification for industrial heat appli-cations, although not practiced widely, is normally economically viable if cheap wood/wood waste is available. On the other hand, wood gasifiers-engine systems, if not designed properly, may face a wide range of technical problems and may not be commer-cially viable. Research and development efforts of recent years have been directed towards developing reliable gasifier-engine systems and the technology appears to be maturing fast. Although the demand for wood gasifiers is rather limited at present, a number of gasifier manufacturers appear to have products to offer in the international market. Gasification of rice husk, which is generated in rice mills where a demand for mechanical/electrical power also exists, has attracted a great deal of interest in recent years. The rice husk gasifier design that has found quite wide acceptance is the so-called Open Core design that originated in
China; this is basically a constant diameter, (i.e. throttles) downdraft design with air enter-ing from the top. The main components of the gasifier are an inner chamber over a rotat-ing grate, a water-jacketed outer chamber and a water seal-cum ash-settlrotat-ing tank. Gasifica-tion takes place inside the inner chamber. The char removed by the grate from inside the gasifier settles at the bottom of the water tank. At present, 120 to 150 rice husk gasifiers appear to be in operation in China. A third of the gasifiers are in Jiangsu Province; these include about thirty 160 kW systems and about ten 200 kW systems. A number of rice husk gasifier systems have been shipped to other countries namely, Mali, Suriname, and Myan-mar. A husk gasifier system of capacity 60 kW was developed in 1980s to use in smaller mills in the developing countries. This prototype was successfully used in a mill in China, although no other such unit appears to have been built or used. Beside rice husk gasifiers, several other gasifier models have also been developed in China. Presently, more than 700 gasification plants are operating in China (Qingyu and Yuan Bin, 1997). As a result of sev-eral promotional incentives and R&D support provided by the government, gasification technology has made significant progress in India in the recent years. Up to 1995-96 about 1750 gasifier systems (Khandelwal, 1996) of various models were installed in the different parts of India. The total installed capacity of biomass gasifier system in India by 1999 is es-timated to be 34 MW. Besides generating electricity for the local community, it is eses-timated that the project has also benefited about 11,000 people directly or indirectly [15].
2 . 1 . 2 . 8 F l u i d i z e d B e d G a s i f i c a t i o n
Fluidized bed gasifiers are flexible in terms of fuel requirements, i.e. these can operate on a wide range of fuels so long as these are sized suitably. However, because of complexity in terms of manufacturing, controls, fuel preparation and operation, these gasifiers can only be used for applications of larger capacities compared with fixed bed gasifiers, typically above 2.5 MW [15].
2 . 1 . 2 . 9 B i o m a s s i n t e g r a t e d g a s i f i c a t i o n c o m b i n e d c y c l e
( B I G C C ) t e c h n o l o g y
In the gasification - gas turbine technology described above, an overall maximum efficiency attainable is 20%. This could be substantially improved, by raising steam utilizing the gas turbine exhaust and driving a steam turbine. A number of BIGCC power plants are in op-eration in countries such as Sweden and Finland [15].
2 . 1 . 2 . 1 0 G a s i f i e r- i n t e r n a l c o m b u s t i o n ( I C ) e n g i n e
t e ch n o l o g y
In this arrangement, solid wood is first dried and shredded into appropriate size and then converted into a combustible gas in a gasifier. Gasifier is a cylindrical reactor with a throat section, which is narrower than the rest of the reactor. In this throat section, air is intro-duced through a set of tubes. Wood dried to a maximum of 20% moisture level and shred-ded into appropriate sizes is introduced at the top of the reactor through an air lock. Up draught gasifiers are widely used for heat applications as they are easier to construct and are more energetically efficient. Such gasifiers are rarely used for motive power or electricity
generation purposes due high tar levels in the gas stream [15]. Figure 02 displays the basic
steps of internal combustion engine.
Figure 02: Gasifier-Gas Cleaning-Engine System [15]
As the material slowly passes through the reactor, it undergoes physical and chemical changes in the many overlapping zones. First the material is dried in the drying zone, losing all the remaining water. Then the material is pyrolysed into solid char and volatiles. In the next zone - the combustion or oxidation zone at the throat of the gasifier, all the volatiles get combusted into carbon dioxide and water. This section liberates all the heat required for the gasification process. In the expanding section below the throat section known as the reduction zone carbon dioxide and steam produced in the upper sections are made to react with carbon, which has reached red-hot stage. In this reduction zone, carbon dioxide and water reacts with carbon to form carbon monoxide, hydrogen, methane and other hy-drocarbon mixtures.
The oxidation is essentially an exothermic process liberating heat in the action, whereas the reduction zone is an endothermic process making use of heat. The gas mixture so pro-duced is called producer gas.
Un-burnt materials in the wood end up as ash and are collected and periodically removed from the bottom. Hot producer gas leaves the gasifier at the bottom of the gasifier under the action of an induced draft fan. Air for combustion in the combustion zone is drawn in-to the section due in-to low pressure created under the action of the induced draft fan.
Producer gas leaving the gasifier, if mixed with air can form a combustible mixture. It can be used as a fuel in internal combustion (IC) engines or in furnaces or boilers. To be used in IC engines, the gas needs to be treated further. First it must be cooled to improve the volumetric efficiency (to facilitate the introduction of maximum quantity of fuel into the cylinders of the engine). This is done by a jet of water. The water jet also washes away a part of the tar and particulates in the gas. Then the gas needs to be thoroughly cleaned of all traces of tar and particulate matter. This is achieved by passing the gas through a series of filters. Wood Gasifier Gas Cleaning IC Engine Generator Gas Gas Exhaust Electricity
If the gas is to be used as fuel in a furnace or a boiler, the cooling and filtering operations may be omitted.
If the gas is to be used as fuel for IC engine, then the gas mixed in the correct proportion of air is admitted to inlet manifold. In respect of spark ignition type of IC engines (petrol or natural gas engines), producer gas alone can operate such engines. For compression- ig-nition type of engines (diesel engines), it is necessary to utilise a minimum quantity (less than 5%) diesel fuel as the ignition source in a well optimised engine.
When standard IC engines are fuelled with producer gas, the maximum output of the en-gine gets de-rated. In respect of spark ignition enen-gines, this de-rating is about 50% (i.e. the new output is 50% of the name plate output). In respect of compression ignition engines, it is insignificant if 30% diesel fuel is used as pilot fuel.
This technology to use producer gas from biomass fuel was popularised during the Second World War in the 1940s. During this war, distribution of petroleum fuel was disrupted and was in short supply. Many countries, particularly, USA and Sweden utilised this technology for transport vehicles. With the end of the war, the supply of petroleum was restored and this technology was discontinued.
With the increase in cost of petroleum in the 1970s with the formation of OPEC, this technology has once again gained popularity, particularly for off-grid application for decen-tralised electricity production. In many Asian countries such as India, Cambodia and Sri Lanka this technology is becoming very popular for off-grid applications.
In Sri Lanka, this technology was used prior to the introduction of Grid Electricity. In the earlier version, coconut shell charcoal was used as the fuel for the gasifiers. Producer gas from these gasifiers was used to drive slow-speed IC engines. Motive power of the engine was used to drive a single over-head shaft with multiple pulleys driving individual drives. Later, the IC engines were fuelled with furnace oil with injectors and hot bulb. When grid electricity was popularised, these devices were discontinued. At the Government Factory at Kollonnawa, near Colombo, remnants of this system are still available to see.
With the increase in oil prices in the 1970s, interests in new and renewable energy resources surfaced again. A few gasifiers with IC engines were introduced through donor-funded pro-jects. Attempts were made by many research institutions to develop this technology locally. These attempts were successful in varying degrees. With the declining oil prices in the late 1980s, the enthusiasm shown in renewable energy declined. Almost all the gasifiers system in the country became inoperative.
Three years ago, a team of officials visited India to identify gasifier-IC engine systems for local adaptation. Later a 35kWe system was introduced from India by the Ministry of Sci-ence and Technology. For the past two years, this has been operating as a demonstrating unit for off-grid electricity generation. This system will be relocated to a rural area shortly to serve an isolated village community.
The 35kWe system consumes 1.6 to 1.8 kg wood per kWh of net electricity generated. Fig-ure 03 shows a photograph of this system in operation.
Figure 03:35 kW gasifier-IC engine generator.
2 . 1 . 2 . 1 1 G a s i f i e r- g a s Tu r b i n e Te c h n o l o g y
The gasifier-IC engine system described in the previous section is more suitable for outputs in the kW to say 1 MW range. To use gasifier system for larger applications in the multiple MW range, gas turbine technology is generally more suitable. A schematic diagram of this technology is shown in Figure 04.
Figure 04: Gasifier - gas turbine technology [15]
2 . 1 . 2 . 1 2 B i o m a s s i n t e g r a t e d g a s i f i c a t i o n s t e a m i n j e c t e d
g a s t u r b i n e ( B I G / S T I G ) t e c h n o l o g y
A method of improving the efficiency and output of the above-described BIGCC technol-ogy is to inject steam into the gas turbine combustor. This increases the output of the gas turbine without consuming power at the compressor. This technology requires very strin-gent water purification system and other control measures. At this early stage of biomass technology for power generation in Sri Lanka, such complicated technologies are not con-sidered. Figure 05 illustrates this principle.
r Clean - up Flue Gas Gas Turbine Air Ash Biomass Gasifier
Figure 05: Biomass integrated gasification steam injected gas turbine technology [15].
2 . 1 . 3 C o n c l u s i o n s o f t h e T e c h n o l o g y
Table 01 illustrates a capacity evaluation of available biomass combustion technologies. Table 01: Typical capacity/efficiency/resource data for biomass power systems [16]
Sys tem Pow er kW E ner gy eff ici en cy % Biom as s dm to ne s/ yr Co m m ent s
Small down draft gasifier/IC en-gine
10 15 74 High operation & maintenance,
and/or low availability, low cost
Large down draft gasifier/IC
en-gine 100 25 442 High operation & maintenance, and/or low availability, low cost
Stirling Engine 35 20 177 Potentially good availa-bility, under develop-ment, high cost
Steam Engine 100 6 1840 Good reliability, high
cost
Indirect-fired gas turbine 200 20 1104 Not available commer-cially
Pyrolysis/IC engine 300 28 1183 Under development Rankine Organic Cycle 1000 18 6133 Commercial
Gasifier Biomass
Cleanup -
Flue Gas Steam Turbine
Condenser
Gas Turbine Air
Table 01 (cont.)
Updraft gasifier/IC engine 2000 28 7886 Commercial Fixed grate or fluid bed
boil-er/steam turbine 2000 18 12270 Commercial Fluid bed (BIG/CC) – dedicated
biomass 8,000 28 29710 Demonstrated
Fluid bed gasifier co-fired 10,000 35 31500 Commercial
The literature survey for Dendro technologies are focused on industrial power generation from direct steam turbine technologies, cogeneration, co-firing, whole tree energy system, Stirling engine, and gasification technologies.
2 . 1 . 4 D e n d r o P o w e r i n t h e w o r l d S c e n a r i o
In many parts of the world, the wood is utilized as an industrial fuel to generate electricity from Dendro power, as well as thermal and heat application. Dendro power is generating electricity using sustainably grown biomass. Since a long time period, developed countries such as Sweden, Denmark, Finland, the USA, Austria, the UK and the Netherland had been using fuel wood to generate electricity. Developing counties also have tried to use Dendro power technology, as evidenced in year 2001, Thailand has become first place by producing 1230 MW through the Dendro and China become second place by producing 800 MW, as well as India, Malaysia and Indonesia sequentially produced 273 MW, 200 MW and Indonesia 178 MW[8].
Sri Lanka also has experimented to generate power through Dendro. The country has a wealth of Sustainably Grown Fuel-wood (SGF) varieties that can be productively converted into other forms of energy while ensuring that the environment is secured and without de-pleting the sources of supply.
The main variety identified for this purpose is Gliricidia – (Gliricidia sepium) also com-monly known as wetahiriya, wetamara, ladappa, nanchi, sevana, kola pohora etc. Gliricidia is widely available particularly in rural countryside as well as in tea and coconut plantations. It is mostly used in boundary fences for private lands. It is a legume that can greatly enrich the soil. It provides shade and hence widely applied in the tea plantations. It is used as sup-ports for vegetable cultivation as well as for pepper vines. Its green matter forms an ideal base for organic fertilizer. Its leaves are an attractive fodder for goats and cattle. It is a fast growing tree that can sustain the most adverse of weather. It can grow in varying of soil conditions and it is free from deceases and pests. There are many other varieties of trees that fall into similar category. Some of them are kaha kona (cassia siamea) ipil ipil (leuceana leucocephela) and kalapu andara - mystique (prosodic).
Recently, national energy policies have seriously accepted that fuel wood based energy pro-duction can provide an economically viable alternative to expensive oil imports and that it can be a useful source of income to farmers and commercial growers. Sri Lankan
govern-ment recently took a decision to recognize the Gliricidia plantation as the fourth cash crop of the country.
Sri Lanka has already embarked on a field testing programme of the production capabilities of short-term rotation crops in a range of sites and additional studies have been conducted by the Coconut Research Institute (CRI), who are interested in a more efficient use of the site through under planting with fast growing leguminous tree species both for the produc-tion of energy crops and for green manure.
The species selection bases are categorized in following manner;
• Coppicing ability (Ability to produce new shoots when a stem is cut). • Nitrogen fixation.
• High growth rate. • Multiple uses. • Ease of propagation.
• Less susceptible for pests and diseases. • Tolerant to droughts.
• Tolerant to poor soils. • Tolerant to fire.
• Amenable for easy harvest and transport. • High bulk density.
The Ministry of Science and Technology (MOST) and the CRI carried out extensive field trials to determine the optimum set of parameters applicable for SRC energy plantations. These trials were also aimed at determining the technical financial viability of this form of plantations.
Findings of these trials are as follows:
Gliricidia sepium, Acasia auriculiformis, Cassia siamea, Leucaena leucocephala, Calliandra calothyrsus and Casuarina equisetifolia are suitable species for SRC plantations. Amongst these, Gliricidia sepium has the following outstanding qualities (and for these reasons Gliri-cidia has been selected over the other species):
• Coppicing ability: It groves freely after collecting harvest. Also both growth and pro-duction of new coppices do not decline over the year. In all other species mentioned above, there is a decline in coppice production over the years, and the trees need to be re-planted.
• Nitrogen fixation: Gliricidia sepium is called a leguminous tree which is very high rate of nitrogen fixation. The Measurements was carried out by Coconut Research Institute (CRI) and reveal that one hectare of plantation annually produces an average of 26 tonnes of fresh foliage, equivalent to 0.4 tonnes of urea [9].
• Growth rate: A one hectare of Gliricidia sepium plantation is established on degraded land in the dry zone which will produced an average of 30 tonnes of woody biomass annu-ally at the rate of 20% moisture [9].
• Multiple uses: Gliricidia sepium is used as branch wood which is used as fuel wood, as support for vegetable cultivation, as well as a support tree in pepper cultivation. Then foli-age is also used as nitrogenous green compost, and cattle and goat fodder. The plants from 1 hectare of Gliricidia sepium could maintain 6 cows [9].
• Ease of propagation: Gliricidia sepium could be spread either from seeds or from stem cuttings. The Stems with length varying from 0.1 meter to 2 meters could be used as plant-ing material. Holes created by crow bar are adequate for the stems to take roots, provided planting carried out at a time when moisture is retained in the soil. Ideally, this is done at the beginning of the monsoon rainy season. When propagated from seeds, a nursery is es-tablished and seedlings are replanted at the beginning of the monsoon rain.
• Less susceptible for pests and diseases
• Tolerant to droughts: Gliricidia sepium needs water at the initiating. And after plant gets withstand, the plant withstand severe droughts as experienced in Sri Lanka. Most of the dry zone in Sri Lanka receives an annual rainfall of over 1200 mm. Some areas receive only 1000 mm. Gliricidia sepium performs well in all these areas.
• Accepting to lower quality soils: Apart from water logged and rocky soils, Gliricidia sepium can be cultivated at all other types of soil including degraded marginal lands availa-ble in the dry zone in Sri Lanka.
• High bulk density
• Easily decomposable litter: Experiments carried out at Coconut Research Institute, Lu-nuwila in Sri Lanka have revealed that Gliricidia sepium foliage, when buried in soil, lasts for about 6 weeks. The soil retains the nutrients for about 5 to 6 months. Foliage of most of other trees takes much longer to decompose.
• Accelerate nutrient recycling process in the soil.
• Reduces Pests and Diseases to Adjoining Crops (Alloepathy): Aloepathy is the natural property of some trees to repel pests and suppress weeds. Gliricidia sepium, when planted in high density, maintains a persistent closed canopy of leaves thus preventing sunlight reaching the ground. This prevents the growth of weeds. The natural faint smell of the foli-age is responsible for repelling all insects and pests. Furthermore, roots of Gliricidia sepium exudes root chemical which would inhibit the survival of undesirable weeds and pests. However, goats and cattle relish on Gliricidia sepium foliage [9].
2.2 D end ro Plantation in S ri Lanka
2 . 2 . 1 A v a i l a b i l i t y o f L a n d f o r B i o M a s s P l a n t a t i o n
It was noted that the State owns 82% of the land within the country in terms of land that is most relevant for plantation development we have: -
• Category 1- Unutilized State-owned land -114, 093 hectares
• Category 2- Alienated State-owned land, comprising major settlement schemes - 54,213 hectares
• Category 3- Open Forest - 471,593 hectares
The prevailing crops in agriculture are paddy, tea, rubber, and coconut. Whereas the amount of land devoted to tea, coconut, and rubber remained stable in the years after inde-pendence; the Accelerated Mahaweli Program irrigation project, begun in the 1980s, opened a large amount of new land for paddy cultivation in the dry zone of the Eastern part of Sri Lanka.
Land Ownership Regime in Sri Lanka
Rural lands in Sri Lanka are subject to a complex system of public-private ownership. The 2005 report of the “Inter-Ministerial Working Committee on Dendro Thermal Technolo-gy” classified the country’s land tenure as following points;
• State lands including forest reservations and other lands that are not utilized for any spe-cific productive purpose
• Large-scale mono-cultured plantations dedicated for tea, rubber and coconuts owned by state agencies together with lands that are released to private sector companies on long term lease basis
• Large medium and small scale mono-cultured plantations owned by private companies and individuals
• Chena lands and irrigable high land crop lands particularly in dry zone areas [10].
2 . 2 . 2 C l i m a t e C o n d i t i o n f o r G l i r i c i d i a S e p i u m
Gliricidia grows best under wet and warm weather conditions, flourishing from sea level to 1300 m or even up to 1600 m elevation. High elevations probably limit the growth due to low temperatures. It grows very well in the temperature range of 22-33° C and rainfall of 800-2300 mm per year. It can tolerate prolonged dry weather and sheds leaves from the mature branches. It cannot tolerate water logged conditions. Gliricidia sepium grows very well on fertile soils however, can withstand low fertile acidic will on the eroded tea lands where many forage legumes cannot grown satisfactorily. This also can tolerate heavy dry soils [11].
2 . 2 . 3 C o s t o f b i o m a s s f u e l
Figure 06: 1 kg of Gliricidia replaces 4kg of HFO / Diesel / LPG [12]
2 . 2 . 3 . 1 Re p l a c i n g D i e s e l [ 1 2 ]
Energy calculation1 litre of diesel = 4 kg of Gliricidia biomass
Diesel burners have a combustion efficiency of about 85% Dual fuel burners have a combustion efficiency of about 70%
Diesel has a heating value of 42 MJ/kg with a density of 0.851 kg/liter To produce 1MJ of heat 33 millilitres of diesel are required
Biomass gasifiers operate at 80% thermal efficiency
Biomass fuel-wood - Gliricidia has a heating value of 13.5 MJ/kg (20% moisture) To produce 1MJ of heat 132 grams of Gliricidia are required
1 litre of diesel can be replaced by 4 kg of Gliricidia biomass Savings in energy cost
1 litre of diesel sells at Rs 95
1 kg of Gliricidia biomass sells at Rs 8.25
By switching from Diesel to Gliricidia biomass saves you Rs 62 per litre of Diesel
65% of your thermal energy cost can be reduced by switching from Diesel to Gliricidia bi-omass
2 . 2 . 3 . 2 Re p l a c i n g H F O ( H e av y F u r n a s O i l )
[ 1 2 ]
Basic energy calculation
1 litre of HFO = 4 kg of Gliricidia biomass
HFO burners have a combustion efficiency of about 85% Dual fuel burners have a combustion efficiency of about 70% HFO has a heating value of 40 MJ/kg with a density of 0.9 kg/litre To produce 1MJ of heat 33 millilitres of HFO are required
Biomass gasifiers operate at 80% thermal efficiency
Biomass fuel-wood - Gliricidia has a heating value of 13.5 MJ/kg (20% moisture) To produce 1MJ of heat 132 grams of Gliricidia are required
1 litre of HFO can be replaced by 4 kg of Gliricidia biomass Savings in energy cost
1 kg of Gliricidia biomass sells at Rs 8.25
By switching from HFO to Gliricidia biomass saves you Rs 32 per litre of HFO
49% of your thermal energy cost can be reduced by switching from HFO to Gliricidia bi-omass
2 . 2 . 3 . 3 Re p l a c i n g L P G ( L i q u i d p e t r o l e u m g a s )
[ 1 2 ]
Basic energy calculation
1 kg of LPG = 4 kg of Gliricidia biomass
LPG burners have a combustion efficiency of about 85% Dual fuel burners have a combustion efficiency of about 70% LPG has a heating value of 45 MJ/kg
To produce 1MJ of heat 26 kg of LPG are required Biomass gasifiers operate at 80% thermal efficiency
Biomass fuel-wood - Gliricidia has a heating value of 13.5 MJ/kg (20% moisture) To produce 1MJ of heat 132 grams of Gliricidia are required
1 kg of LPG can be replaced by 4 kg of Gliricidia biomass Savings in energy cost
1 kg of LPG sells at Rs 130
1 kg of Gliricidia biomass sells at Rs 8.25
By switching from LPG to Gliricidia biomass saves you Rs 96.61 per kg of LPG
74% of your thermal energy cost can be reduced by switching from LPG to Gliricidia bio-mass
2 . 2 . 4 E n v i r o n m e n t a l a s p e c t s
When used in the renewable mode, (i.e. cutting/harvesting of trees is balanced by new plantations) CO2 released to the atmosphere from combustion of biomass is reabsorbed
during growth of new plants/trees. Thus, overall, biomass energy can be regarded as CO2
-neutral. However, certain other greenhouse gases (GHGs), namely CH4 and N2O, as well as
other pollutants are also normally produced during biomass combustion; as a result, bio-mass use causes some net emission of GHGs as well as local air pollution.
2 . 2 . 4 . 1 S o c i o e c o n o m i c a n d E nv i r o n m e n t a l B e t t e r m e n t o f
D e n d r o Po we r
• The each and every Dendro power generation plant creates employment for rural community.
• People can improve their earning by shelling fuel wood which are being planted in unused and agricultural small lands to Dendro plant.
• The plant construction and maintenance employment opportunities also are gener-ated.
• The Gliricidia leaves could be used for cattle feed or as a substitute for urea fertiliz-er as a soil nutrient in coconut or any othfertiliz-er plantations in their lands.
2.3
S upply chain m anag em ent
2 . 3 . 1 R e s o u r c e s f o r D e n d r o p o w e r p l a n t s
Among 16 identified fuel wood plants, there is general agreement in Sri Lanka that Gliri-cidia is the fuel wood plant of choice three reasons are given for this,
• The natural prevalence of the plant in rural Sri Lanka;
• The value of its leaves as natural fertilizer or as feed for animals, • The ability of its tree roots to fix nitrogen in the soil.
2 . 3 . 2 P o t e n t i a l s o u r c e s o f s u p p l y
Table 02 illustrates the annual generation figures of biomass in Sri Lanka Table 02: Potential sources of supply [13]
Type MT/Year %
Rice Husk available from Commercial mills 179,149 6.2 Biomass from Coconut Plantations available for industrial 1,062,385 37
Sugar Bagasse 283,604 8.3
Bio degradable garbage 786,840 27.4
Saw Dust 52,298 1.8
Off cuts from Timber Mills 47,938 1.7
Biomass from Home Gardens such as Gliricidia 505,880 17.6
Total 2,873,880 100
2.4 Alternative fuels for G liricid ia
Biomass waste is used as part of the fuel mix in Dendro-power plants to reduce the sector’s demand for land. The most attractive sources are coconut shells and paddy rice husks. Paddy husk can be supplied by Rice mill owners during their high season, and then they stop. Even during the high season, supply is not regular: mill owners choose to mill the rice when the market price is favourable. Thus, although rice millers are willing to transport their waste to the site of Dendro power plants to get rid of an environmental problem, rice paddy husk can be a supplementary source of supply only. Sri Lanka has 60 coconut mills. Most coconut lands are less than 5 acres; total land use amounts to 720,000 acres (290,000 hectares). An average mill produces 60,000 nuts per day, works up to 180 days per year and needs 12,000 acres of planted coconuts for supply. The waste coconut shells from an aver-age plant have enough calorific value to cover the energy needs of a 12 MW power plant. Since the energy needs of coconut mills are lower, they have surplus coconut shells to sell. Some are sold to thermal applications in industries, including in cement factories, others can be sold to Dendro-power plants. Although coconut shells from coconut estates can be only a marginal source of supply for future biomass plants, they increase the plant’s security of fuel supply and are cheap.
3 Analysis and Results
3.1 Pres ent s ituation of D entro pow er in S ri Lanka
3 . 1 . 1 D e n d r o P o t e n t i a l i n S r i L a n k a
The potential of Dendro power has as a long-term power invention opportunity, for off-grid as well as off-grid-connected generation communities. Only both of village hydropower (mini or micro-hydro) and solar power have the possibility to meet the energy require-ments of approximately 15-20% of off-grid residents in Sri Lanka. Dendro power can pro-vide opportunities to off-grid villages where there are no hydropower potentials. Dendro power generation plant may be implemented as community-based electricity generating method that includes all households in a village irrespective of their income level.
3 . 1 . 2 D e n d r o p o w e r e d G a s i f i c a t i o n p r o j e c t s i n S r i L a n k a
Dendro power that have already been used for heat applications in Sri Lankan industries called Samson Industries Ltd, Lanka wall tiles PLC, Kandalama Hotel, Tea factory Hotel, Lalan Rubber Industries Ltd, Ansell Lanka (Pvt)Ltd, CIC Agree business (Pvt)Ltd. and C.W.Mackie & Company (Pvt)Ltd, were investigated.
Samson Industries Ltd is operating a thermal gasifier. A steam boiler of capacity 2 ton/hr has been retrofitted to operate on produced gas. The retrofit was done by installing a gasi-fier and replacing the Heavy Furnace Oil (HFO) burner with a produced gas burner. Be-fore the gasifier was installed, the factory used to consume over 45 litres of HFO per hour and over 25,000 litres of HFO per month. At present, the factory operates the gasifier 24 hours, replacing an equivalent of 27,000 litres with 210 ton of Gliricidia fuel wood per month.
The Lanka Wall tile PLC has installed bio wood gacifier and replaced 125 tons of LPG (Liquid Petroleum Gas) with offering biomass based fuel replacement for their gasifier. Which offer over 75% savings in fuel cost over LPG. The gasifier system uses chopped and dried Gliricidia sticks as fuel which is supplied by their own plantations and out grow-ers who are in near villages.
Gasification Project Summaries in Sri Lanka
Case Study-1: Samson Industries Ltd, a subsidiary of the DSI group
Industry : Export Quality Rubber Products
Produc-tion
Application : Boiler Retrofit
Fuel Type Replaced : HFO (Heavy Furnace Oil)
Fuel Rate Replaced : 45 litres/hour
Monthly Fuel Replacement : 27,000
Gasifier Model : WBG-350
Thermal Rating : 1050 kW
Monthly Fuel Wood (Gliricidia) Consumption : 210 ton
Steam Generation : 2 ton/hour
Figure 07: WBG 350 gasifier at Samson Industries Ltd at Galle – Sri Lanka
Case Study-2: Lanka Walltile Meepe (Pvt) Ltd.
Industry : Export Quality wall tiles Products Production
Application : Boiler Retrofit
Fuel Type Replaced : LPG (Liquid Petroleum Gas)
Energy / Fuel (Cost of Energy Accounts to 40% of the total production cost) Fuel wood Replacement : 125 Tonnes of LPG
Figure 09: Gliricidia storage Canopy at Lanka Walltile Meepe (Pvt) Ltd
Case Study-3: Kandalama Hotel
Industry : 5 Star Eco Friendly Hotel
Application : Boiler Retrofit
Fuel Type Replaced : Diesel
Capacity : 900 kW
Gasifier Model : WBG-300
Gasifier Type : Down Draft
Thermal Rating : 900 kW
Fuel Wood (Gliricidia) Consumption Rate : 225kg/h
Fuel Type : Gliricidia/ Cinnamon
Figure 11: WBG 300 gasifier at Kandalama Hotel at Dambulla – Sri Lanka
Case Study-4: CIC Agri Business (Pvt.) Limited
Replaced Fossil Fuel Type : Diesel
Gasifier Type : Gas 70
Wood Consumption : 280 kg per hour
Average Duration of Operation : 10hrs per day, 100 days per year Average Annual Wood Consumption: 280 MT (23 MT per Month)
Wood Supply : From Their Own Plantations
Savings : For CIC
Annual Saving : Rs. 3.5 Million per annum with Diesel price
of Rs.73.00 per Liter
Saving Increment : Rs. 50,000 per Annum with a increment of
1rupee per Diesel Liter
Savings: For Country
Reduction in Fuel Imports : 70,000 Liters per Annum Reduction in CO2 Emissions : 175 MT per An-num
Case Study-05: C.W. Mackie & Company (Pvt.) Limited
Location : Ceymack Rubber Factory – Natupana,
Horana
Installed for : Rubber Drier
Replaced Fossil Fuel Type : Diesel
Gasifier Type : WBG 350
Wood Consumption : 280 kg per hour
Average Duration of Operation : 16hrs per day, 300 days per year Average Annual Wood Consumption : 1,300MT (112 MT per Month)
Wood Supply : Through their own Suppliers
Savings : For C.W. Mackie
Annual Saving : Rs. 15 Million per annum with Diesel price
Saving Increment : Rs. 250,000 per Annum with a increment of 1rupee per Diesel Liter
Savings: For Country
Reduction in Fuel Imports : 336,000 Litres per Annum Reduction in CO2 Emissions : 840 MT per An-num
Figure 12: WBG 350 gasifier at C.W. Mackie & Company (Pvt.) Limited at Horana – Sri Lanka
Table 3 below displays available gasifier technologies, their models, ther-mal capacity, fuel consumption, produced gas flow rate and etc.
Table 3: Gasifiers capacities and their thermal rating, fuel wood consumption, rated gas flow rates, and equivalent diesel/HFO ratings [6].
Ga sif ie r M od el Th er ma l R at -ing Fuel W ood * Consu m pt ion
Fuel Wood* Size
Ra te d Pr o-du ced G as Fl ow R at e Bio ma ss F ee din g F re-que nc y Mi nu te E le ct ric al Powe r R e-qui re d E qu iv ale nt Die se l/ HF O Ra te Len Dia kW kg/h Mm Mm M3/h at STP kVA Liter/h WBG-5 15 4-5 10-25 10-25 125 60 <1 1.25 WBG-10 30 8-10 10-25 10-25 25 60 1-2 2.5 WBG-13 45 12-15 10-25 10-25 37.5 60 1-2 3.75 WBG-20 60 16-20 10-25 10-25 50 60 1-2 5 WBG-40 120 32-40 10-25 10-25 100 45 3-5 10 WBG-80 240 64-80 10-50 10-50 200 45 3-5 20 WBG-100 300 80-100 10-60 10-75 250 45 4-6 25
Table 3: (Cont.)
3 . 1 . 3 D e n d r o P o w e r f o r E l e c t r i f i c a t i o n
Dendro power electricity generating technology which is the most prominent renewable power generation technology is being studied in Sri Lanka.
First Dendro power electrification project was started by LTL (Lanka Transformer Lim-ited) group in Walapane with capacity of 1 MW. This has added 6647 MWh [7] to national grid annually. The Hammer International runs 2.5 MW paddy husk based plant at Pol-onnaruwa. And 10 MW paddy husk and biomass mix plant has based in Tokio Supper ce-ment plant at Trincomallee. In addition to that there are two more bagasse based power generation units in two sugar factories in Palawatte Sugar Industries Limited (PSIL) and Sevanagala Sugar Industries Limited (SSIL). One coconut cell based power generation unit has been installed at Heycarb Limited at Madampe. All of these power electrification plants use combustion technology. They use biomass as fuel to boiler and produce steam which supply to steam turbines.
3.2 Feas ibility on g enerating pow er of us ing D enro
pow er for printing press .
3 . 2 . 1 P o w e r r e q u i r e m e n t
The average monthly power consumption of the printing presses is 280000 kWh. Then an-nual average power requirement would be 3.36 GWh. In addition to that the company power demand would be increased by 30% with its capacity development in the near fu-ture. Then the total power requirement would be 5.2 GWh annually.
3 . 2 . 2 D e s i g n i n g o f P o w e r p l a n t c a p a c i t y
The company expects to produce 10 GWh power generation annually to utilize their own consumption in the printing plant and earn extra revenue by selling over generation of power to the Ceylon electricity board.
WBG-120 360 96-120 10-60 10-75 300 30 5-8 30 WBG-150 450 120-150 10-60 10-75 375 30 6-9 37.5 WBG-200 600 160-200 10-60 10-75 500 30 9-12 50 WBG-250 750 200-250 10-75 10-100 625 30 9-12 62.5 WBG-300 900 240-300 10-75 10-100 750 20 11-14 75 WBG-350 1050 280-350 10-75 10-100 875 20 13-17 87.5 WBG-400 1200 320-400 10-75 10-100 1000 20 15-20 100 WBG-500 1500 400-500 10-75 10-100 1250 20 18-24 125 WBG-600 1800 480-600 10-75 10-100 1500 15 22-29 150 WBG-700 2100 560-700 10-75 10-100 1750 15 25-35 175 WBG-850 2550 680-850 10-75 10-100 2125 15 31-41 212.5
3 . 2 . 2 . 1 E n e r g y o u t p u t a n d F u e l i n p u t o f t h e p o we r p l a n t
• Design Capacity of the power plant = 2 MW
• Energy output of the turbine
Energy output from the turbine = 2 MW x 24 x 365 x 0.6 = 10512 MWh
= 10.5 GWh
(Where; Plant Factor of the Power Plant = 0.6) • Mass flow rate to the power plant
Power output = 2 MW
= 2000 kW
Input Power to the boiler = 2000 kW / 0.92 X 0.62 = 3506.31 kW
(Where; Electrical Efficiency = 0.92 and Boiler Efficiency = 0.62)
Mass Flow rate, m = 3506.31 kW
13500 kJ/kg
m = 0.2597 kg/s
(Where; Calorific Value of the Biomass = 13500 kJ/kg from Literature) Fuel flow rate to the boiler = 0.2597 x 3600 kg/h
= 935.02 kg/h Daily Fuel flow rate to the boiler = 22440.38 kg/day
= 22.44 MT/day
3 . 2 . 3 D e n d r o f u e l h a r v e s t i n g a n d s u p p l y c h a i n
m a n a g e m e n t t o t h e p o w e r p l a n t
Dendro fuel consumption rate = 22500 kg/day
Annual fuel consumption for the power plant = 22440.38* 365/1000 tons/year = 8190.74 tons/year
= 8200 tons/year
According to the studied has been carried out on Gliricidia harvesting and plantation by Biomass Energy Association, one tree can yield 6 kg of wood per year on a sustainable ba-sis and 4700 trees can plant in one hectare of land. If this assumption is used, about 28200 kg of Gliricidia wood can produce from 1 hectare of land.
No of trees required to supply of 8200 tons per year = 8200*1000 kg/6 = 1,366,666 trees. The 4700 trees can plant in one hectare,
Then total land requirement for 1,366,666 tress is = 1,366,666/4700 = 290.78 hectares Therefore, Total land area requirement for the plant is = 290.78*2.5
= 726.95 acres = 730 acres
The main sources of supply of Gliricidia (Biomass fuel) to the power plant;
The fuel wood requirement for the plant is 22500 kg/day, which is, required about 730 acres of land. Therefore the main fuel wood supply sources are,
• The company has their own plantation is about 500 acres of coconut land which is used to plant Gliricidia trees under the coconut trees as a secondary plant and har-vesting about 50 – 60% of biomass fuel for the power plant as a primary source of supply.
• The secondary source of supply of biomass fuel wood (Gliricidia trees) is collected from communities who are living in the area close to the power plant is going to be installed.
• As an another optional potential source of supply of biomass fuel is collected from, Rice husk available from rice mills in the area
Saw dust available from timber mills in the area Off cuts from Timber mills in the area
Paddy husk from main two seasons of cultivation near to the power plant.
3 . 2 . 4 O u t p u t o f t h e P r o j e c t
The power plant produces energy at the rate of 10 GWh/year to the national grid when it is fully operational. The WNL total energy requirement can be generated from the power plant and the company can generate additional income from selling the extra energy to the CEB. There appears to be sufficient wood produced by the company own plantation and rest by community level growers. This could create sustainable employment opportunities to communities in the area. Tree farms also offer an opportunity for production of biomass fuels on traditional lands where they have very little or don’t have any financial outcomes.
3.3 T echnology As s es sm ent
It is determined that the chosen technology would have to be practical and successfully uti-lized in other similar situation in order to provide a reasonable assurance of commercial vi-ability. The selected bio mass project would have to have a reasonable chance of economic success in order to justify the investment of WNL resources. The primary techniques are utilized in the conversion of biomass fuel to power. These are:
