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Recent News on Energy and the Environment 05.12.08

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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.


Recent News on Energy and the Environment 02.11.08

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Integrated Food–Energy Systems (IFES)

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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.

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