The over growth of world’s human population needs effective and sufficient mechanism to realize sustainable development and availability of renewable resources through promoting the attentions and upgrading the amount of studies which improves both environmental and economic benefits (Vardanega et al., 2015). It is long since the significance of the role of energy in sustainable development is well recognized by the global community. One way of looking at human development is in terms of choices and opportunities available to individuals.
Energy can dramatically widen these choices (UNDP, 2000). Access to inexpensive energy services is essential to human activities, development and economic growth (UNDP, 2004).However currently the dominant sources of energy in the world are fossil fuels that include coal, oil and natural gas, which result emission of greenhouse gases which are the main causes of increasing global warming, In addition such resources are limited and are not renewable. And an increasing in demand of heat and power for cooking, construction, manufacturing, communications, transportation, lighting and other utility have led to the great consumption and depilation of these energy sources and the subsequently price increments over years.
This high demand is a good indication in the growth and development of economies especially in the developing countries (Okure et al., 2006). And also accessing locally available and affordable energy services is an essential determining factor to human activities, development and economic growth (Mussatto et al., 2011).
The energy sector of Ethiopia, like other developing countries of sub-Saharan Africa, is dominated by traditional biomass energy. 94% of the national energy consumption is based on biomass resources. Modern energy, which is mainly based on petroleum products and electricity from hydroelectric power, and infrastructure for energy supply is only available in urban areas.
Majority of the population live in rural areas and have little access to modern energy. The country has got considerable potential of renewable energy resources including hydropower which is the major source of the electricity, solar, wind, geothermal and biomass which may be exploited to ensure sustainable energy supply (Melis, 2006).The none_ renewable nature of fossil fuels and global warming are the reasons for growing up interests for biomass utilization as a source of heat and power production. Renewable energy sources that use indigenous resources have considerable potential to provide sustainable solution to this situation. Especially, modern distributed forms of biomass seem particularly promising for their potential to provide rural areas with clean forms of energy (UNDP, 2000).However the major factor that limits the utilization of biomass for heat and power production is its low bulk density and inhomogeneous structure.
As a result of these problems Preparation of Briquettes from biomass is needed to increases its bulk density and offers several other benefits, such as a homogeneous shape and structure to the final products (Stelte et al., 2012). Biomass is locally available source energy that has huge potential to reduce green gas emissions resulting from the excessive use of petrol fuels. However the direct use of biomass as sources of energy is very difficult to handle, transport, store and utilize, due to factors include high moisture content, irregular shape and sizes, and low bulk density. But Briquetting of this biomass can produce densified products with uniform shape and sizes that can be more easily handled using existing handling and storage equipment and thereby reduce cost associated with transportation, handling, and storage.Agricultural bio waste is one of the sources of biomass which is mostly under- utilized worldwide.
Currently, there is rapid increase in volume and types of waste agricultural biomass produced due to intensive agricultural activities in the wake of population growth and improved living standards. In Ethiopia, with human population of more than 85 million, agriculture is the dominant activity and source of GDP for the country. According to ECRGE, Ethiopia’s climate-resilient green economy strategic document (2011), among other, the country’s ambition to build green economy focuses on increased greenhouse gas (GHG) sequestration and development of renewable and clean power generation Ethiopia, as origin of coffee Arabica, huge amount of coffee and bio products such as residues of coffee husk and pulp are produced every year. However these products have been improperly utilized and managed or are simply left to decompose or burned (Seboka, 2009) or accumulated in the environment including water bodies (Haddis and Devi, 2008). So far these result facilitating pollution of air and water (Beyene et al.
, 2011). Previous studies suggest that, the use of coffee husk as energy sources is an alternative option to diminish these problems (Kebede et al., 2010).In addition, the conversion of coffee husks in to briquette will increase the capacity of carbon sequestration through reducing the deforestation rate and also provides renewable, clean and sustainable energy as substitute for fuel wood and charcoal (Merete et al., 2014). If the resource is utilized properly, it has potential to aspire the country’s longer-term vision of reaching middle-income status by 2025Coffee husk is obtained as a waste from coffee processing facilities.
There are three coffee processing methods, namely: wet, semi-dry and dry processes. The husk constitutes the crumbly parchment skin for wet-processed coffee, the parchment skin and dried mucilage for semi-dry-processed coffee, and the entire dry leathery fruit covering for the dry-processed coffee (Wikipedia, 2010). This indicates that the husk yield and particle size is considerably bigger for dry process than the other two methods. Ethiopia exports 80-85% sun-dried (natural) coffee and 15-20% wet processed coffee (Sustainable Tree Crops Program (STCP), 2010).
Hence, it can be seen that huge amount of this resource is available in the country. Thus, studying its properties and looking for a means to utilize it properly is important.