Sustainability, overall and process efficiency of energy crops

A method to calculate efficiency of energy crop production including sun energy, direct and indirect energy for cultivation, processing, and conversion into fuel is demonstrated using rape and derived fuels as an example. Every production and conversion step is a process and calculated separately. The overall efficiency includes energy input and output of all processes. The process efficiency of rape cultivation reaches in Finland up to 1100 %. However, the overall energy efficiency of rape methyl ester (RME) is 1 to 2 ‰ only. The production of biogas from manure of dairy fed by rape meal results in a process energy efficiency of 33 to 41 %, but the overall energy efficiency of RME and biogas together is only 1.2 to 2.5 ‰. In contrast, thermal or photovoltaic solar collectors improve overall efficiency 1 to 3 orders of magnitude compared to fuel production from rape. Competition for cultivation area and the low photosynthetic efficiency limit the feasibility of fuel production from energy crops. As a measure for sustainability of renewable fuel production, the energy surplus of energy conversion from insolation to fuel per resident and square meter is proposed

"The German language and literature special collections at the University library of Frankfurt am Main and the work of the subject specialist" : paper delivered in Göttingen, 4. 9. 2007, at the annual conference of the German Studies Library Group (GSLG)

Contents - BIX: pole position and runner-up - Frankfurt University Library: its responsibilities, its collections, its databases, its supra-regional collecting responsibilities – and some statistics - The "Sondersammelgebiet" Germanistik: its scope and contents, its principal strengths, present situation, and budget - Sammlung Deutscher Drucke: the 1801-1870 segment of the "Distributed National Library" - Information Services: Bibliographie der deutschen Sprach- und Literaturwissenschaft (BDSL), Neuerwerbungsliste Germanistik, Bibliographie germanistischer Bibliographien (BgB), DigiZeitschriften, information bulletins - Work of the Subject Specialist: exhibitions, publicity material"Das Sondersammelgebiet und Fachreferat Germanistik an der Universitätsbibliothek Frankfurt am Main" : Vortrag am 4. 9. 2007 in Göttingen ; Ort: Niedersächsische Staats- und Universitätsbibliothek Göttingen ; Anlass: Annual conference of the German Studies Library Group (GSLG) Inhalt - BIX: Pole position and Runner-up - UB Frankfurt: Funktionen, Zahlen, Sammlungen, Datenbanken, Sondersammelgebiete - SSG Germanistik: Bestand, Schwerpunkte, Gegenwart, Budget, Sammelauftrag - Sammlung Deutscher Drucke: "Verteilte Nationalbibliothek", Zeitsegment 1801-1870 - Informationsdienste: Bibliographie der deutschen Sprach- und Literaturwissenschaft (BDSL), Neuerwerbungsliste Germanistik, Bibliographie germanistischer Bibliographien (BgB), DigiZeitschriften, Flyer - Fachreferat: Literaturausstellungen, Begleithef

The role of engineering in organic farming – case energy crops

Energy self-reliance and a closed nutrient cycle are basic principles of organic farming ever since. Engineering sciences methods in energy accounting may support efforts to introduce these principles into praxis. A method to calculate efficiency of energy crop production including sun energy, direct and indirect energy for cultivation, processing, and conversion into fuel is demonstrated using rape and derived fuels as an example. Every production and conversion step is a process and calculated separately. The overall efficiency includes energy input and output of all processes. The process effi-ciency of rape cultivation reaches in Finland up to 1100%. However, the overall en-ergy efficiency of rape methyl ester (RME) is 1 to 2 ‰ only. The production of biogas from manure of dairy fed by rape meal results in a process energy efficiency of 33 to 41%, but the overall energy efficiency of RME and biogas together is only 1.2 to 2.5 ‰. In contrast, thermal or photovoltaic solar collectors improve overall efficiency 1 to 3 orders of magnitude compared to fuel production from rape, because the process efficiency of photosynthesis attains about 0.6% whereas solar collector’s efficiency reaches about 90%. However, for the time being solar energy based techniques are more expensive than the use of fossil energy sources since environmental benefits in terms of GHG mitigation, reduction of nutrient run off and use of renewable energy do not create cash income in both organic and main stream production. This and the low photosynthesis efficiency in Finland encourage bio-refinery enterprises to purchase energy crop produce for fuel production from the tropics. Mineral fertilisers as well as genetic modification increase the technical efficiency of photosynthesis. Thus, envi-ronmental pollution of mainstream agriculture is exported to developing countries in the tropics

Energy crops and renewable energy: overall and process efficiency

Here are compared efficiencies of energy crops with technical alternatives of renewable energy production. Production of rape as energy crop is presented

Technique of pneumatic pest control – analyses and a new device

Pest control in organic production of berries, potatoes and vegetables usually employs spreading technique of registered phytopharmaceutical agents. This technique may be supported or even replaced by pneumatic pest control. Pneumatic pest control means suction of pest using a vacuum device similar to a home vacuum cleaner. Up to now there is no evaluation of pneumatic pest control available from an agricultural engineering point of view. This paper concerns the following questions: Which techniques of pneumatic pest control are available and how may these techniques be improved in terms of technical and physical parameters? Based on the answers a new device design is presented

Entropy of energy crops and GHG mitigation

The photosynthesis process generates beside carbon hydrates also complex chemical compounds. The artificial synthesis of such compounds is often impossible or may require high energy input compared to their heat value. In other words, the entropy of energy crops is low compared to fossil fuels. This fact is usually neglected in energy analysis of bio fuels resulting in questionable political decisions concerning renewable energy. The objective of this paper is to demonstrate that the GHG mitigation potential of e.g. fibre crops may be enhanced using them first as raw material for commercial products before processing to fuel at the end of their lifetime. For example, reed canary grass may be used for paper production and after recycling, the used paper can be processed to insulation material in buildings before thermal use. Such a chain of usage trades off both, the low entropy as raw material for pulp and the heat value of the carbon hydrates. A calculation model is used to estimate the reduction of CO2 equivalents of two options: Alternative A: Production of reed canary grass + processing to fuel for heating. Alternative B: Production of reed canary grass + processing to paper + recycling of paper + processing to insulation material + installation of insulation material in buildings + recycling of insulation material + processing for heating. The results show, that alternative B is outclassing alternative A. However, fossil fuels render a higher energy return of investment and are for the time being more competitive than both options

Forgetting the starting distribution in finite interacting tempering

Markov chain Monte Carlo (MCMC) methods are frequently used to approximately simulate high-dimensional, multimodal probability distributions. In adaptive MCMC methods, the transition kernel is changed "on the fly" in the hope to speed up convergence. We study interacting tempering, an adaptive MCMC algorithm based on interacting Markov chains, that can be seen as a simplified version of the equi-energy sampler. Using a coupling argument, we show that under easy to verify assumptions on the target distribution (on a finite space), the interacting tempering process rapidly forgets its starting distribution. The result applies, among others, to exponential random graph models, the Ising and Potts models (in mean field or on a bounded degree graph), as well as (Edwards-Anderson) Ising spin glasses. As a cautionary note, we also exhibit an example of a target distribution for which the interacting tempering process rapidly forgets its starting distribution, but takes an exponential number of steps (in the dimension of the state space) to converge to its limiting distribution. As a consequence, we argue that convergence diagnostics that are based on demonstrating that the process has forgotten its starting distribution might be of limited use for adaptive MCMC algorithms like interacting tempering