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 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

Methodical Problems in Organic Farming Research

Workshop presentation with particular focus on values, transferability and praxis relevance of organic farming research. Examples from agricultural engineering lead to the conclusion, that prototype farming, goal oriented project management, participative decision making and funding, coaching of co-operation, and coaching of conflict management may enhance long term, holistic and interdisciplinary research

Biogas on-farm: energy and material flow

Objectives: European countries are committed to reduce CO2 emission originating from fossil fuels. On-farm produced biogas may replace energy produced from fossil fuels and so contribute to achieve the target. Up to now only in Germany a greater number of on-farm biogas plants has been established. The data of these plants can be used to evaluate cost and benefit of on-farm biogas production in other European countries. This paper concerns the following questions: Which parameters of biogas plant construction and operation have an influence on profit and sustainability of biogas production on-farm? Hypothesis: A biogas plant integrated within a self-contained farm organism is economically more competitive and more sustainable than an industrial biogas production unit of a mainstream farm. Method: First, a model is established that describes energy and material flow of two farm types. Farm type one produces biogas from slurry of 100 adult bovine units (ABU) and 10% co-ferment. Biogas powers a diesel engine of 26 kW electric power capacity using 10% ignition diesel fuel. Electric power production covers farm consumption and the surplus is supplied to the main grid. Heat is used for the farm estate surplus remains unused. Farm type two produces the same amount of biogas, but uses a gas motor. Additionally the farm includes a glasshouse of 1000 m2 to make use of electric power surplus and heat surplus. Further, the exhaust of the gas motor substitutes CO2 fertiliser procurement to the glasshouse. Second, cost and benefit analysis of biogas production and application is done using empirical data of the most recent biogas plant survey in Germany. These data are adjusted to Finnish conditions where necessary. Third, parameter variation is employed to find out the sensibility of the most important variables in terms of marginal profit and interest yield of investment for the biogas plant. Results: Farm type one delivers a positive interest yield of 2,6 % under German conditions. Under Finnish conditions there is no profit possible. Concerning methane production the marginal profit sensibility decreases in the following order: dry matter of slurry > quantity of co-substrate > reactor efficiency in terms of CH4 kg-1 organic dry matter (oDM) > fermentation period > number of ABU. Concerning electric power and heat production the marginal profit sensibility decreases in the following order: Level of electric power compensation > efficiency of energy conversion methane to electric power > price level of fuel oil and electric power. Farm type two delivers a positive interest yield of 8 % under Finnish conditions. Concerning methane production the marginal profit sensibility does not differ from farm type one except with regard to CO2 fertiliser costs. Concerning electric power and heat production the marginal profit sensibility decreases in the following order: price level of light and heavy fuel oil and electric power > efficiency of energy conversion of methane to electric power > process energy > heating energy and heating period of the farm estate > operating time in h d-1 of the gas motor. Discussion: The better economic performance of farm type two under Finnish conditions mainly bases on substitution of CO2 fertiliser by the gas motor exhaust gas. The interest yield is very sensitive on energy input prices; however less sensitive than the interest yield of farm type one in respect of electric power compensation level. Further use of reactor digestion residues as organic fertiliser may improve sustainability of farm type two

Solid compost from biogas plant digestion residues - a new product

Here is presented the nitrogen content of dairy cattle solid manure treated anaerobically and aerobically

Inclufar Inklusiivinen maatalous

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LIVING ON FARM – A NEW APPROACH OF COMMUNITY SUPPORTED AGRICULTURE (CSA)

The development of living on farm is described from an agricultural engineer's point of view focussing on opportunities for elderly in Finland. There are three main groups: Anthroposophical social farms, farms governed by a strict ecological philosophy of life, and farms looking for diversifi­cation concerning ecology, business and on-farm living communities. However, the boundaries between these groups are fluid. The farms may create additional income by offering accommodation, janitorial and transport services, basic and other services to people, who want to live on the farm. Thus, the traditional target of community supported farms - processing and selling the farm products to a community of customers - is considerably extended. In the long run, the increasing number and the aging of the dwellers may create new working places for nursing services personnel, which in turn may recreate doing com­pensating work on the farm. Creating facilities for living on farm requires some convincing in respect of authorities as well as new technical solutions in renewable energy supply, water supply, waste processing and nutrient recycling. Living on farm for elderly requires new skills in both disciplines: agriculture and geriatric care. Industrial farming and food processing do not coincide with salutogenetic aims. Therefore living on farm is a domain of organic farms