Posts Tagged ‘ecological sustainability’
Biomass Energy – Sustainable Solution to Livestock Wastes?
Submitted by: Karl Ramjohn
Livestock production is an important food supply and economic activity, the primary goal of which is to supply high-quality protein (meat, eggs, dairy products, etc) for the needs of human populations. The animals serve as concentrated sources of typically dispersed nutrients. Subsidiary products may include leather, fertilizers, inputs to animal feeds, and energy sources (biofuels). The challenge of sustainable livestock production systems is to promote food security in a manner which is economically viable and socially acceptable without causing land degradation or irreversibly affecting ecological resilience. As such, sustainability must promote a favourable cost – benefit ratio, and as far as possible avoid reducing the set of options available to future generations. This has very significant social considerations, as seemingly obvious solutions may be difficult to implement, as they may be biologically but not economically sustainable.
The recycling of materials, and thus minimizing the generation of wastes is a basic process which must be implemented to meet the demands of sustainability in developed and developing countries alike. Systems which utilize energy produced from biomass are examples of energy-recycling systems. All biomass originates through carbon dioxide fixation by photosynthesis. Consequently, biomass utilization may be regarded as a critical component of the global carbon cycle of the biosphere.
Most biomass cannot be directly utilized, and must undergo some sort of transformation before being converted to fuel. Biological processes for the conversion of biomass to fuels include ethanol fermentation by yeast or bacteria, and methane production by microbial consortia under anaerobic conditions. Unlike ethanol fermentation, anaerobic digestion for methane production utilizes organic materials containing carbohydrates, lipids and proteins. Waste materials from livestock production are applicable to anaerobic digestion, with the added advantage of reducing environmental impacts, such as unpleasant odours and water pollution.
Methane fermentation is therefore a versatile biotechnology, which can convert almost all types of polymeric materials to methane and carbon dioxide under anaerobic conditions. It converts the waste products of livestock systems into useful products of commercial value, while reducing the environmental costs associated with other methods of livestock waste disposal. As such, it offers an effective means of pollution reduction, superior to that achieved by conventional aerobic processes. It is also an efficient method of converting unused biomass resources (crop residues, forestry, industrial/municipal and livestock wastes) into biofuels and fertilizers.
The digested slurry (by-product of methane production) retains the nitrogen and other mineral nutrients which are lost when biomass wastes are directly burned, while reducing BOD/COD. Methane is a principal constituent of natural gas, and extraction of this resource from livestock waste is a small-scale but useful method of supplementing extraction from geologic deposits. It also mitigates the problems associated with slow decomposition on the land surface, in the context of the large “greenhouse effect” of methane – up to 25 times that of carbon dioxide. The pathogens are also destroyed, reducing the health effects of the digested biomass, which also does not attract flies or rodents.
Biomass conversion is economically feasible within the constraints of scale and location. The main problems associated with biomass digestors is the relatively high price of implementation, the fact that the technology is still somewhat experimental, and the high standard of management and maintenance required.
Overriding issues in the future of biological energy systems are the overall efficiency of converting biomass to fuels, the economics of such processes, their environmental impacts, their competitiveness with thermochemical processes for biomass, and their compatibility with evolving economic and political structures.
Related:
http://tropicalenv.conforums.com/index.cgi?board=landuse04&action=display&num=1218573241
Integrated Food–Energy Systems (IFES)
Submitted by: Karl Ramjohn
Our life on Earth depends on a dynamic complex of linkages, synergies and interactions among the processes, components and sub-systems of the atmosphere, hydrosphere, lithosphere and biosphere. The ecological view of sustainability focuses on the stability of biological and physical systems. Of particular importance is the viability of sub-systems that are crucial to the global stability of the overall ecosystem. Protection of biodiversity is a key aspect. Furthermore “natural” ecosystems may be interpreted to include all aspects of the biosphere, including man-made environments like intensive agriculture, cities and industrial estates. The emphasis is on preserving the resilience and dynamic ability of the totality of systems to adapt to change, rather than conservation of some “ideal” static state of the environment. Therefore, expansion of renewable bio-energy will require not only advances in technology, but also tangible economic accounting of their environmental and social benefits, compared to fossil fuels.
The development of sustainable, multi-purpose, integrated biomass conversion systems, is based on highly efficient photosynthesis and microbial processes, generating a number of products including energy resources (biofuels). Such systems have the potential for reducing the adverse impacts of agriculture and forestry, while providing food, fibre, pharmaceuticals and supplementary biofuels, to enhance the requirements for an acceptable standard of living. Energy production via biomass conversion of agricultural wastes reduces the environmental costs of food production systems, and provides economic benefit for the farmer, as well as reducing social impacts. As such, it provides a platform for integrating food and energy production in a sustainable manner.
The major social aims of Integrated Food – Energy Systems (IFES) is to maximize synergies between food crops, livestock, fish production and sources of renewable energy (e.g. biodigestion of wastes). This is achieved by adoption of agro-industrial technology that allows maximum utilization of by-products, diversification of raw materials, waste production on a smaller scale, and encouraging recycling and economic utilization of residues, for harmonization of energy and food production.
The essential features of IFES include:
• Using technology mix to provide a minimum cost alternative;
• Meeting energy needs not only for agriculture, but also other social needs (e.g. domestic, commercial, industrial);
• Maximizing utilization of available bio-resources with minimum environmental impact;
• Benefiting all classes of the community;
• Increasing food productivity;
• Generating additional income and employment opportunities; and
• Requirement of minimum maintenance to integrate community participation in management.
The design of IFES requires a simultaneous consideration of:
• The bio-physical components of resource management;
• The social and ecological impacts of technologies used; and
• The institutional settings involved
For each site-specific configuration of climatic and environmental conditions, several socially desirable, ecologically sustainable and economically efficient production systems are conceivable, differing in output mix, forms of social organization and community participation, size of operation, complexity of design and technical sophistication. Ideally, they should have a modular structure, allowing progressive implementation by adding new modules to the initial structure. While, in practice, these systems are often implemented as private enterprises, they can provide a template for the design and adoption of IFES technology at the community level in other circumstances, with appropriate modification, to mitigate environmental impacts and supply other benefits, towards improving the sustainability of food and energy production systems.
Related Posts:
http://tropicalenv.conforums.com/index.cgi?board=energy03&action=display&num=1217141112
http://213.238.59.20/app/forum?op=showarticles;id=8635448;articleid=8635448
http://www.theenvironmentsite.org/forum/biofuel-forum/11964-integrated-food-energy-systems-ifes.html
http://discuss.greenoptions.com/viewtopic.php?f=40&t=500
http://www.unu.edu/unupress/unupbooks/80757e/80757E03.htm
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