Suchergebnisse

Anaerobic Digestion (AD) is a natural process of decomposition and decay that takes place in the absence of oxygen and by which organic matter is broken down to its simpler chemical components. AD plants could help Ireland meet its requirements under a number of EU Directives as landfills release far more greenhouse gas emissions than other forms of waste treatment. It is estimated that 37 million tonnes per year of animal manure are stored on farms before disposal. There are also 676,000 tonnes of municipal food and garden waste produced annually. This waste could be used in AD plants to produce electricity which would be considered to be a renewable technology. The objective of this study is to determine if cooperatives for anaerobic digestion (AD) could be developed. The study will address the feasibility of an anaerobic digestion cooperative using the following influencing factors: economical, financial, logistical, participation of farmers and local communities, sizing perspective, waste material required, assistance from government and related agencies and national and EU legal requirements. The impact anaerobic digestion plants could have on the rural domestic electricity network will be discussed. A model will be proposed addressing the above. There is no cooperative such as this in Ireland; therefore the ideas behind cooperatives for AD in Europe will be examined.

The introduction of Feed-in tariffs in the German Renewable Energy Act (EEG) fuelled the growth of anaerobic digestion (AD) industry making Germany the country with highest number of operational AD plants. However, the rapid expansion of AD industry resulted in some unwanted side-effects such as food vs fuel debate, increased prices for electricity and the temporal mismatch between supply and demand of electricity grid. Subsequent amendments in EEG has tried to address some of these issues by reduction in Feed-in tariffs, introduction of a cap on cereal based feedstocks and providing premium for energy production in accordance with market demand. Furthermore, the Feed-in tariffs which were introduced for 20 years are soon going to expire. The changes in legal and political discourse is soon going to introduce some new challanges to the AD industry. This paper has discussed some of these challanges and their potential solutions.

1. Introduction to anaerobic digestion and biogas -- 2. A history of anaerobic digestion and biogas -- 3. Digester feedstock/substrate -- 4. AD plant types and processes -- 5. Inputs and outputs -- 6. Plant scale -- 7. AD plant economics -- 8. Legislation, permits and regulation -- 9. AD and local communities -- 10. The market for digestate -- 11. Case studies -- 12. AD around the world.

Nowadays, the climate mitigation policies of EU promote the energy production based on renewable resources. Anaerobic digestion (AD) constitutes a biochemical process that can convert lignocellulosic materials into biogas, used for chemical products isolation or energy production, in the form of electricity, heat or fuels. Such practices are accompanied by several economic, environmental and climatic benefits. The method of AD is an effective method of utilization of several different low-value and negative-cost highly available materials of residual character, such as the lignocellulosic wastes coming from forest, agricultural or marine biomass utilization processes, in order to convert them into directly usable energy. Lignin depolymerization remains a great challenge for the establishment of a full scale process for AD of lignin waste. This review analyzes the method of anaerobic digestion (biomethanation), summarizes the technology and standards involved, the progress achieved so far on the depolymerization/pre-treatment methods of lignocellulosic bio-wastes and the respective residual byproducts coming from industrial processes, aiming to their conversion into energy and the current attempts concerning the utilization of the produced biogas. Substrates' mechanical, physical, thermal, chemical, and biological pretreatments or a combination of those before biogas production enhance the hydrolysis stage efficiency and, therefore, biogas generation. AD systems are immensely expanding globally, especially in Europe, meeting the high demands of humans for clean energy.

AbstractThe objectives of sludge stabilization include (a) the degradation of organic matter, (b) a reduction of solid matter, (c) a decrease in the number of pathogenic organisms, (d) an improvement of dewaterability, and (e) the production of biogas.The anaerobic digestion of organic substances normally proceeds in four stages, and the various microorganisms which are involved in microbial metabolism have different ambient conditions for their optimum mode of operation. This can be achieved, for example, by splitting the process technique into two stages.In order to achieve disinfection, a primary thermophilic stage with 1–3 days'retention is followed by anaerobic degradation under mesophilic conditions having a retention period of 10–15 days.The combined retention period of about 15 days for this two‐stage combined sludge stabilization process is compared with the results of single‐stage mesophilic digestion with a retention period of 20 to 30 days.