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Recent News on Energy and the Environment 12.12.08

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Recent News on Energy and the Environment 05.12.08

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Sustainable Energy (Video)

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Posted by: Karl Ramjohn

Sustainable Energy

This might not add much to the debate and discussion on “Sustainable Energy”, but it has a somewhat different presentation format: 

More videos on sustainable energy, climate and related: Geo Energy Network Media

Modelling civilization as “heat engine” could improve climate predictions

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Posted by: Karl Ramjohn

An interesting article from Environmental Research Web  (November 27, 2008)  on a possible conceptual approach to modelling human activities (and the built environment) and how they interact with climate systems (and the natural environment).

—>  Modelling civilization as ‘heat engine’ could improve climate predictions – environmentalresearchweb

The extremely complex process of projecting future emissions of carbon dioxide could be simplified dramatically by modelling civilization as a heat engine. That is the conclusion of an atmospheric physicist in the US, who has shown that changes in global population and standard of living correlate to variations in energy efficiency. This discovery halves the number of variables needed to make emissions forecasts and therefore should considerably improve climate predictions, he claims. 

Computer models used to predict how the Earth’s climate will change over the next century take as their input projections of future manmade emissions of carbon dioxide. These projections rely on the evolution of four variables: population; standard of living; energy productivity (or efficiency); and the “carbonization” of energy sources. When multiplied together, these tell us how much carbon dioxide will be produced at a given point in the future for a certain global population. However, the ranges of values for each of the four variables combined leads to an extremely broad spectrum of carbon dioxide-emission scenarios, which is a major source of uncertainty in climate models. 

Timothy Garrett of the University of Utah in the US believes that much of this uncertainty can be eliminated by considering humanity as if it were a heat engine (arXiv:0811.1855). Garrett’s model heat engine consists of an entity and its environment, with the two separated by a step in potential energy that enables energy to be transferred between the two. Some fraction of this transferred energy is converted into work, with the rest released beyond the environment in the form of waste heat, as required by the second law of thermodynamics.

However, the work is not done on some external task, such as moving a piston, but instead goes back to boosting the potential across the boundary separating the entity from the environment. In this way, says Garrett, the boundary “bootstraps” itself so that it can get progressively bigger and bigger, resulting in higher and higher levels of energy consumption by the entity.

…continues…

Recent News on Energy and the Environment 09.11.08

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Recent News on Energy and the Environment 26.10.08

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Biomass Energy – Sustainable Solution to Livestock Wastes?

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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