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Biomass, as a renewable energy source, has started to look much more favourable again in recent years. There are many reasons for this trend, ranging from increased socio-political discussion on our future energy supply to technological progress. The latter, in particular, has helped change the image of biomass: while fewer regard it as old fashioned, expensive or even dirty, today biomass raise its profile as a renewable and profitable energy carrier. New processing methods have even improved the fuel and handling characteristics of biogenic fuels. Those that have made the biggest difference are briquetting and pelletization, from the solid fuel industry. Both of these techniques are based on compacting the original loose material to yield one basic advantage: a higher energy densification. Hereinafter the term briquetting will be used for both products briquettes and pellets. To understand the difference, see following chapter “Why to briquette”.
The advantages of biomass briquetting are by no means limited to its use in modern industrial plants or solid fuel boilers. Indeed, in developing countries a far bigger percentage of the population cover their energy needs with biomass alone, where their primary need is for heat energy for cooking and heating. International development cooperation has accordingly long been focussed on improving the basic energy supply in many countries around the world. It is notable that biomass briquettes have played a bigger part in many projects over recent years, such as those for distributing better stove technologies, for example. Next to adapted cooking behaviours and improved cooking appliances, the fuel can play one important role in improving the overall situation of households. Biomass briquettes can be produced out of many field or process residues and burning them in cooking appliances instead of traditional fuels as logged and collected wood or charcoal can be an interesting alternative for business makers but also for fuel clients. However, like for most new technologies, many technological but also economical questions may arise. This article will not answer to all questions but should rather help to ask the right ones. The following pages address persons who are interested in the theme of briquetting and who might have thought about: what to concern when starting a business or support business development with biomass briquettes? The aim is to provide an overview of the main findings about biomass briquettes as fuel. But, this article should not be a final version but rather a “living document”: everybody who posses experiences with biomass briquetting is welcome to add information and to share discussion with other readers of this article.
Why to briquette biomass?
“In order to understand where we are with our energy resources and consumption patterns today, it's worth taking a look back at how human energy use has changed over time.”
Let’s start with a short look back: the history of human energy use is shaped by energy densification! For thousands of years, biomass was almost the only constant available and controllable energy source. Wood served as the preeminent form of energy until the mid- to late-1800s, even though water and wind mills were important to some early industrial growth. Coal became dominant in the late 19th century before being overtaken by petroleum products in the middle of the last century, a time when natural gas usage also raised quickly. Thus, the energy content per unit (mass or volume) of the resources increased steadily.
Almost all forms of energy, fossil fuels, wind or biomass, were or are driven by solar energy. When managed sustainable, i.e. harvest does not exceed growth, biomass is a renewable energy. Through the mechanism of photosynthesis solar energy is bound into chemical energy in the plants. Thereby it gets usable for humans in form of eating or burning.
Briquetting or pelletizing is the process to improve the characteristics of biomass as a renewable energy resource by densification. Densification means less volume needed for the same amount of energy output. Figure 1 visualises the magnitude of the differences of bulk density. Each column has the same energy content and represents the volume needed to obtain the equivalent energy of one litre of fossil heating oil. Wood pellets have the highest energy content per volume within the solid biomass examples here listed.
Figure 1: Energy per volume of renewable resources compared to fossil oil and coal
Energy per volume of renewable resources compared to fossil oil and coal
The advantages of processing and densifying of biomass are not only limited to the higher energy content.Both of the techniques, briquetting and pelletizing, are based on compacting the raw material to yield certain advantages
- High volumetric energy density
- Favourable dosing characteristics
- Lower water content in the fuel and therefore greater storage stability (less biodegradation)
- Option to use additives to change the chemical/material properties
- Less dust produced when handling
- High homogeneity of the fuel
For the European market, the differences of briquettes and pellets is listed in the European classification standard CEN/TS 14 961. For both products, different parameters as shapes and sizes are exactly predefined. In the context of developing countries these definitions might be much too strict. Pellets are small round rods whereas briquettes are bigger and can show different forms. So in a broader context, pellets might be described as a bulk material whereas briquettes can be stacked.
Figure 2: Pellets and briquettes
Keep in mind!
- Briquettes and pellets are both products deriving from the densification of a raw material.
- Biomass briquettes and pellets for fuel use are a product which aims to improve the characteristics of a certain raw material.
- The main reason for the densification is to increase their energy content per volume.
A comparison of mass and volumetric energy contents of different fuels can be found here
. (accessed 16/02/2014).-> The factsheet “Biomass Densification for Energy Production” by S. Clarke, P. Eng, and F. Preto (2001) gives a good illustrated overview for the reason why to briquette.
The Raw Material
„If you can shovel it then you can briquette it”
The raw material is always the beginning of each value chain for processed products. Therefore, before starting to briquette, the main questions are: what to briquette and how to get the raw material. Basically, each kind of biomass might be used for the production of biomass briquettes as a fuel. The mentioned quotation above from S. Eriksson and Michael Prior illustrates in a very simple way the huge theoretical potential of raw material. However, it also contains an important requirement for the biomass: it should be dry!
It is rare that energy plants are cultivated and grown for the only purpose of a later briquetting. Moreover, briquetting is applied to improve the quality of an original fuel material and thereby add value to a poor quality product, mainly agro-residues. Briquetting biomass-residues is one way to solve a problem: how to put the huge volume of wastes from agricultural and agro-processing to some useful purpose. The following picture illustrates the wide range of raw material used for briquetting.
Figure 3: Samples of biomass briquettes from all over the world
Samples of biomass briquettes from all over the world
It is sometimes assumed that residues are wastes and therefore “free” almost by definition. In practice,it is unwise to assume that any residue is “free” in the sense that it has no alternative use of some value. Thus inevitably in a monetized economy, everything which has a use acquires a monetary value. This is most obvious in the case of fully commercial briquetting plants based upon processing residues or wood-wastes. It is difficult to find examples of operating briquetting plants which do not have to pay something for the residues they use. Such payments may arise because there are competing uses for the “waste” but it may also arise simply because a residue provider is unwilling to allow someone else to make profit from their wastes without asking for a share in the form of payment for the raw material. In general we can distinguish field or processed residues.
International and regional statistics (see: faosta.org) often demonstrate the immense quantities of field residues. Most residues are dry at the moment of harvesting and therefore a high potential raw material for briquetting. The volume of residues produced per unit of cultivation is within a wide range, depending strongly on the crop, the intensity of agriculture and climate. However, the recovery rate would be lowered by alternative uses for the residue, though important, uses by local people. These could include animal feed and bedding, direct use as fuel and various building material. In addition, the ploughing in or burning of residues play an important part in promoting soil fertility.
Apart of these alternative uses, some additional economical issues should be considered, especially when thinking of briquetting of field residues:
- The access to a sufficient quantity of raw material to run the briquetting machine economically.
- Seasonal transport and storage capacities.
The following two example calculations help to understand the importance of these aspects for briquetting of field residues:
To demonstrate the important role of the volume of residues for a briquetting plant, a very simple calculation might help: assuming a specific recovered residue value of 3 tons per hectare, as well as a briquetting machine with a production capacity of 300 kg per hour; furthermore for an economical output of the briquetting machine we assume that it will run for 8 hours a day for half a year. These presumptions result in a necessary access to 146 hectares of cultivated land!
Transport and storage
In general, field residues are bulky; baled wheat straw has been put at around 100 kg/m3 and stacked cotton residues at 55 kg/m3. Even when chipped, cotton residues only have a bulk density of 130 kg/m3. By contrast, stacked wood has a bulk density above 500 kg/m3. This means that the transport of residues to a briquetting plant can become increasingly expensive as the distance from the site of the residues to the plant increases. In addition, most field residues appear only for a given period in the year requiring seasonal transport capacities (tractors, trailers etc.) and storage capacities. Coming back to the above mentioned example calculation: there would be the need to transport almost 440 tons of raw material in few days and, assuming baled straw wheat, a storage room of 4400 m3, which could be a building with an outline of 30 x 30 meters and 5 meters of height.
In this category, all residues obtained from the processing of a crop or wood are included, for example: coffee husks, groundnut shells, rice husks, coir dust, sawdust, furniture waste etc. In principle, the briquetting process works quite well for a wide range of feedstocks provided they are homogeneous and contain moisture below 15 %.
In general, the evaluation of a plant based upon process residues is less complex than for one based on field wastes. The main problem is to establish the quantitative availability of material from a limited number of point sources, possibly only one. This is inherently simpler than to establish the potential residue yields from shifting agricultural patterns of several outside farms. In effect, the transport costs of gathering, which can be the main barrier to utilization of crop residues, have been absorbed by the transport of the valuable food-component of the crop.
At the other extreme, a briquettor tied to a particular process residue from a single plant may find itself stranded if the supply of residues fails to meet expectations as the plant itself fails to find any raw material. Changes in agricultural practices or simple miscalculation can lead to that the feed-plants simply cannot deliver enough residues. The small value of the briquettes relative to the total value of the crop means that the issue of providing briquetting raw-material was irrelevant to the wider agricultural changes going on.
Keep in mind!
- It is unwise to assume that any residue is “free” in the sense that it has no alternative use of some value.
- Briquetting raw material should have the goal to give a higher value to an existing product. This might be to lower transportation costs or to enable the use of a material as fuel.
- The access to raw material is a crucial factor for transportation (distance) and investment costs (buildings, transportation equipment, storage).
Production of Biomass Briquettes
► See Biomass Briquette - Production
Markets and Users for Briquettes
► See Biomass Briquettes - Marketing
The following examples of biomass briquetting projects are by far not a complete list of biomass briquetting projects in developing countries all over the world. The mentioned examples were chosen during the research for this article. Everybody is welcome to add other or new projects. The goal is to enable interested persons who are thinking about briquetting of biomass to quickly find projects with similar conditions and so to enable an exchange.
Cambodia – Sustainable Green Fuel Enterprise (SGFE)
SGFE (Sustainable Green Fuel Enterprise) was created in 2008 with the aim of alleviating poverty and reducing deforestation in Cambodia, as well as improving waste management in urban areas, by developing a local economic activity: manufacturing charcoal using organic waste, mostly coconut. SGFE was initiated by the NGOs GERES Cambodia and PSE (Pour un Sourire d’Enfant) through a joint project: PSE added its social commitment to GERES’s environmental and technical expertise. The goal of SGFE as a real social business is to provide long-term employment to its workers so that they can get a regular, secure and fair income. Thus, the economic viability of the business is crucial, and profits are to be shared among the stakeholders and employees, and reinvested in the company’s development. Currently, SGFE employs 16 people who used to work as waste pickers on Phnom Penh’s municipal landfill.
SGFE charbriquette manufacturing begins with the collection of organic waste in and around Phnom Penh through a network of dedicated suppliers. After drying and sifting coconuts and other raw materials, they are efficiently carbonized, crushed and mixed, then shaped into a convenient and efficient size, and finally dried to guarantee high performance. Furthermore, the production process has been modified to be as energy efficient as possible: the kilns used to carbonize the coconut and biomass ensure efficient combustion, reducing the emission of harmful gases and air pollution; and, the energy generated by the carbonization process is recovered and used to increase efficiency.
Sustainable Green Fuel Enterprise is manufacturing two types of products : Premium and Diamond briquettes. Their tubular shape provides better heating properties compared with traditional charcoal, and is perfectly adapted to cookstoves and barbecues.
All char-briquettes are sold on the local market to shops (retailers who further sell them to households) and food businesses (restaurants and street food vendors). Shops and restaurants tend to prefer premium, while interestingly street food vendors choose the higher quality product (diamond) which has a duration of up to 5 hours. This is because households don't need to cook for long time and restaurants, which use a high amount of char-briquettes, prefer the cheaper product, while street food vendors, cook all day with small quantities of char-briquettes and therefore even though the diamond is more expensive, at last it is financially more convenient for them.
The current production rate is at about 40 tons/month (with a growing trend). Regarding our sales capacity, SGFE currently sell the entire production (the demand is higher than what they can produce) and therefore they are planning to expand the production capacity this year.
For further information see:
Kenya – Chardust Ltd.
Chardust Ltd. was founded in 2000 to produce substitutes for charcoal on a commercially sustainable basis. Chardust making use of low-priced raw materials, ample labour supply and a good measure of innovation, set out to produce fuels that could sell directly into traditional charcoal markets and compete head-to-head on both price and quality.
Today, daily sales are in excess 7 tonnes.
Chardust's centre of operations is a 2 acre plot in the Lang'ata area of Nairobi. This is the company head office and home of the briquetting operation and Chardust's programme of research and development. Chardust's main product is the Vendor's Waste Briquette - 'VWB'. It is made from charcoal dust and fines that are salvaged from charcoal traders
across the city of Nairobi. These briquettes are for space heating and water heating applications, as well as cooking and roasting. VWB is sold to institutional customers such as poultry farms, hotels, lodges and restaurants, as well as to charcoal dealers and individuals for direct sales into the domestic market.
Chardust also produces a premium charcoal briquette made from selected vendors' waste and natural binders. This lower ash product is designed for the domestic barbecue market and is sold mainly through supermarkets within the city of Nairobi.
Finally, in 2010 chardust introduced agglomeration machinery to their production line for the fabrication of spherical briquettes which are called FireBalls. These are also aimed at the urban mid-scale market.
For further information see:
India – Biomass Urja Kotdwar
This international carbon offset project was initiated by myclimate in 2009. Previously coal was used in the Indian province Uttarakhand as fuel in the brick and iron production. The carbon offset project by myclimate promotes the use of briquettes made of renewable biomass from forest and agricultural waste. In addition, restaurants, temples, schools, and hospitals are supplied with efficient, smokeless cookers.
In India, many millions of tons of biomass waste accumulate annually from forestry and agriculture as well as from industrial production. Due to its low density and the high water content, this waste material cannot be directly processed. The local organization Rural Renewable Urja Solutions Pvt. Ltd. (RRUSPL) now utilizes this waste raw material as fuel. Biomass briquettes are produced, which are then delivered to companies producing brick kiln and rod iron in the states of Uttarakhand and Uttar Pradesh in the north of India. The climate-friendly energy supply is thus replacing coal, a greenhouse gas-intensive fuel, in the kiln and iron production. The briquette machine is already successfully used in many of India and reduces the local population's dependence on fossil fuels.
However, the project not only includes the manufacture of renewable, clean fuel, but also the distribution of an efficient and smokeless cooker (chulha) for restaurants, temple complexes, day schools and hospitals. These rural institutions in India were previously very dependent on liquefied petroleum gas for cooking. The new efficient gas cookers were developed by the Indian Energy and Resource Institute (TERI).
For more information see:
Zambia – Emerging Cooking Solutions (ECS)
Emerging Cooking Solutions is combining the sales of clean cooking stoves with pellets as fuel. ECS introduces to the market a unique cooking-system using an inexpensive, abundant and largely untapped source of energy for cooking:they are (at the moment) using a mix of pine and eucalyptus sawdust and peanutshells
. The sawdust is a waste product from local sawmills that get their wood from state owned plantations, no virgin or indigenous trees are touched. ECS has also experimented with a variety of biomass, ricehusks, maize and straw to name a few and will use these at a later stage, but the reason they use sawdust is that it is there, in one place, and is waste. They only wish to use agro- and forestry waste so original forests can be spared, that's their vision. These wastes will be made into pellets. Together with clean-burning, micro-gasifying stoves
for homes and restaurants, ECS sells pellets at below market price of the equivalent in charcoal
, leading to substantial savings. Today focusing on the Philips stove, but the company is stove-neutral: ECS will provide the best stove for a particular user-group. This can be done at favorable financial terms for the company due to the new product concept and industrialized production and distribution systems. Starting modestly in 2010 with 40 households, ECS, by their own admission, now has the capacity to produce clean, renewable cooking fuel for thousands of households.During the fall 2013 they made about 30 tons per month. Their equipment can make 5-600 kg per hour, but they haven't had the need to run it full speed yet, since they are a start-up and building a customer base. Their clients are BOP citizens who today use charcoal for cooking, people in townships in Lusaka and Kitwe, and who have no alternative until now.
- ↑ Brandi Robinson (2014), Lecturer, College of Earth and Mineral Sciences, The Pennsylvania State University: http://bit.ly/1dHM3Li (accessed 16/02/2014)
- ↑ http://www.eia.gov/todayinenergy/detail.cfm?id=10 (accessed 16/02/2014)
- ↑ Picture: TFZ (2013): Die Energiedichte biogener Energieträger im Vergleich zu Heizöl und Steinkohle. A German comparison of the energy density of different biomass fuels compared to heating oil and fossil coal. http://www.tfz.bayern.de/mam/cms08/festbrennstoffe/dateien/poster_brennstofforgel.pdf (accessed 16/02/2014)
- ↑ The original German version: Kaltschmitt, M.; Hartmann, H. und Hofbauer, H. (2009): Energie aus Biomasse. Grundlagen, Techniken und Verfahren; Springer-Verlag Berlin Heidelberg 2001, 2009, korrigierter Nachdruck 2009
- ↑ Eriksson, S. and Prior, M. (1990): The briquetting of agricultural wastes for fuel, FAO Environment and Energy Paper 11, FAO of the UN, Rome, 1990
- ↑ Picture: http://www.legacyfound.org/images/photoGallery/briquettesResources/pages/05.html (accessed 16/02/2014)
- ↑ 7.0 7.1 ---. 2014. "Various e-mail conversations with Carlo Figà Talamanca, SGFE Cambodia, in February 2014"