Biogas plants in Denmark: technological and economic developments

Biogas plants are one of the important elements in the Danish energy-policy of having reduced CO₂ emissions by 20% by 2005. Since 1984, development efforts concerning centralised biogas plants in Denmark have been carried out, and Denmark now has approximately 20 large centralised biogas plants. All Danish biogas plants have increased gas production as a result of admixing industrial organic wastes with manure. This is predominantly regarded as a great advantage for both biogas plants and waste suppliers. The paper will describe the technological development of this renewable energy source in terms of biogas production prices. The price has dropped dramatically during the last 15 years. Based on this analysis, the paper discusses the socio-economic costs of technology development including state budget and employment effects. Also the paper refers to socio-economic feasibility studies from the early 1990s, when biogas production prices were much higher than natural gas. Still, employment effects made the development feasible in socio-economic terms.     

Biogas as a potential renewable energy source: A Ghanaian case study

The associated harmful environmental, health and social effects with the use of traditional biomass and fossil fuel has enhanced the growing interest in the search for alternate cleaner source of energy globally. Ghana, a developing country depends heavy on woodfuel as a source of fuel contributing about 72% of the primary energy supply with crude oil and hydro making up the rest. Biogas generation has simply been seen as a by-product of anaerobic digestion of organic waste. Having proven to be a practicable and promising technology, it has been very successful and a very reliable and clean source of energy when proper management programmes are followed. There are vast biomass resources including organic waste in Ghana that have the potential for use as feedstock for biogas production to reduce the over reliance of woodfuel and fossil fuel, and to help reduce the it would reduce greenhouse gas emissions which may be affecting climate change. Ghana having the technical potential of constructing about 278,000 biogas plants, only a little over 100 biogas plants has so far been established. This paper presents the energy situation and the status of the biogas technology and utilization in Ghana. It also presents the potential benefits, prospects and challenges of the biogas technology.     

Status of biogas technologies and policies in South Korea

To date, there are about 49 biogas plants in South Korea that are generally recognized as economically and technically unsuccessful due to lack of knowhow, deficient technologies and policies. There is a need to analyze the status of biogas technology and policy in South Korea from the point of view of an external biogas expert, since biogas technology in South Korea has not yet been analyzed by foreign biogas experts so far. For analyzing site investigation, literature research and interviews are performed. It was found that there are several lacks of conceptual design of biogas technology, such as plant dimension, energy balance, operation knowhow. Technical and financial support for the development of biogas technology was insufficient so far. There are some policies to support biogas technologies, however financial support from different ministries seemed not to have been used efficiently. Some policies are planned excessively so that they cannot be realized on time. Based on the general policy called “Green Growth”, the Korean government plans to establish a biogas market in South Korea in order to recover energy from organic waste. For this purpose, R&D efforts should be intensified for consulting and education in national and international networks for the transfer of knowhow and technologies. Definition of the existing restrictions on the development of biogas technology is required. By developing a biogas roadmap, the creation of a biogas market could be promoted efficiently in South Korea.     

Use of waste for heat,electricity and transport—Challenges when performing energy system analysis

This paper presents a comparative energy system analysis of different technologies utilising organic waste for heat and power production as well as fuel for transport. Technologies included in the analysis are second-generation biofuel production, gasification, fermentation (biogas production) and improved incineration. It is argued that energy technologies should be assessed together with the energy systems of which they form part and influence. The energy system analysis is performed by use of the EnergyPLAN model, which simulates the Danish energy system hour by hour. The analysis shows that most fossil fuel is saved by gasifying the organic waste and using the syngas for combined heat and power production. On the other hand, least greenhouse gases are emitted if biogas is produced from organic waste and used for combined heat and power production; assuming that the use of organic waste for biogas production facilitates the use of manure for biogas production. The technology which provides the cheapest CO₂ reduction is gasification of waste with the subsequent conversion of gas into transport fuel.     

Land application of organic waste – Effects on the soil ecosystem

Growing populations and the increasing use of existing resources has led to growth in organic waste emissions. Therefore, a sustainable approach to managing this waste has become a major concern in densely populated areas. Biological treatment is an efficient method for reducing the amount of organic waste, and for producing energy. A large number of biogas plants and compost facilities that use organic waste as a substrate for electricity and fuel production are being built around the world. The biological treatment process in these plants produces large amounts of organic waste, and there is therefore a growing need to find a sustainable use for this material. Organic waste, such as biogas residues and compost can be a valuable fertilizer for agricultural soils. They can serve as a source of plant nutrients and can also improve soil structure and water holding capacity. However, as organic residues are known to contain both heavy metals and organic contaminants there is a need for long term field experiments to ensure that soil and plant quality is maintained. In order to investigate the potential risks and benefits of using organic waste in agriculture, an 8 year field experiment was established in central Sweden. Under realistic conditions, compost and biogas residues from source-separated household waste were compared with traditional mineral fertilizer. We examined crop yield and soil chemical and microbiological properties. The main conclusion from the field experiment was that biogas residues resulted in crop yields almost as high as the mineral fertilizer NPS. In addition, several important soil microbiological properties, such as substrate induced respiration, potential ammonium oxidation and nitrogen mineralization were improved after application of both biogas residues and compost. Moreover, no negative effects could be detected from using either of the organic wastes. In particular the genetic structure of the soil bacterial community appeared to resist changes caused by addition of organic waste.     

Residential energy use and conservation in Denmark, 1965–1980

New data have been assembled to quantify patterns of residential energy use in Denmark from 1965 to 1980 by fuel and end use. Indicators of the structure and intensity of energy use are developed from basic data and reviewed. Changes since 1972 are quantified and compared with those observed in other countries. The reduction in oil use in oil-heated dwellings is shown to be the largest among OECD countries. Elements of past, present and future Danish conservation policies are reviewed. While many of these are unique and far reaching, the predominant cause of conservation up until 1980 has been short-term measures stimulated primarily by higher energy prices.     

Prospective application of farm cattle manure for bioenergy production in Portugal

Biogas is a promising renewable fuel, which can be produced from a variety of organic raw materials and used for various energetic purposes, such as heat, combined heat and power or as a vehicle fuel. Biogas systems implementation are, therefore, subjected to several support measures but also to several constraints, related with policy measures on energy, waste treatment and agriculture. In this work, different policies and policy instruments, as well as other factors, which influence a potential expansion of Portuguese biogas systems are identified and evaluated. The result of this analysis shows that the use of the cattle manure for biogas production is still far from its potential. The main reason is the reduced dimension of the Portuguese farms, which makes biogas production unfeasible. Various options are suggested to increase or improve biogas production such as co-digestion, centralized plants and modular plants. Horizontal digesters are the most suitable for the typical Portuguese plant size and have the advantage of being also suitable for co-digestion due to the very good mixing conditions. Mesophilic anaerobic digestion due to a more robustness, stability and lower energy consumption should be the choice. The recent increase in the feed-in tariffs for the electricity production based on anaerobic digestion biogas is seen as a political push to this sector.     

Can slurry biogas systems be cost effective without subsidy in Mexico?

Biogas from pig slurry in Mexico has potential to produce 21 PJ per year, equivalent to 3.5% of natural gas consumption in 2013. In this paper, three different scenarios are analysed: mono-digestion of pig slurry in a finisher farm (scenario 1); co-digestion of pig slurry and elephant grass in a finisher farm in situ (scenario 2) and co-digestion of pig slurry and elephant grass in centralised biogas plants (scenario 3). The digesters proposed are anaerobic high density polyurethane (HDPE) covered lagoons. HDPE centralised plants can have capital costs 5 times cheaper than European biogas plants. The economics of utilisation of biogas for electricity generation and as biomethane (a natural gas substitute) were investigated. Economic evaluations for on-site slurry digestion (Scenario 1) and on-site co-digestion of elephant grass and pig slurry (Scenario 2) showed potential for profitability with tariffs less than $US 0.12/kWh_e. For centralised systems (Scenario 3) tariffs of $US 0.161/kWh_e to $US 0.195/kWh_e are required. Slurry transportation, energy use and harvest and ensiling account for 65% of the operational costs in centralised plants (Scenario 3). Biomethane production could compete with natural gas if a subsidy of 4.5 c/L diesel (1 m³ of biomethane) equivalent was available.     

A review of the biogas industry in China

This article presents an overview of the development and future perspectives of the Chinese biogas industry. The development of the industry has the potential to improve the rural environment and produce significant amounts of sustainable energy for China. Barriers to the development are the relatively weak environmental policies, imperfect financial policies and lack of long-term follow-up services. The rapid economic development of China has also seen a development in the scales of biogas plants constructed. Although the technology has been improved, this review has identified problems in the construction and operation of Chinese biogas plants, particularly in the efficiency of household systems. All levels of China's government acknowledge this and recent biogas projects have more focus on quality and less on the quantity. The intention is to gradually introduce stricter environmental policies, to provide better service systems, improve the financial policies that support the construction and follow-up service of biogas projects, promote the use of standardized engineering equipment and materials and standards for plant construction and production. This will promote the development of biogas projects at various scales further, and reduce the dependency on fossil fuels and emissions of greenhouse gases.     

Looking into the Danish energy system: Lesson to be learned by other communities

Industrialization, development and social transformation has brought together issues of over exploitation of limited energy resource base (e.g. fossil fuel), accelerated threats of energy insecurity, and liberation of greenhouse gas emissions across the continents. The global challenge for the 21st century and way ahead is to find other means of satisfying energy needs, diversifying the energy supply, up-scaling the make-up of renewable energy to a greater extent, optimization of energy consumption and supply system. Denmark has been continuously moving towards optimization of energy production, usage and its overall management, during and even after the first global oil crisis. The country has been delivering its priority in the development of renewable energy and standing the country an energy self sufficient from last three decades. Country's overall consumption of energy has decreased than that of the decades of 1980 and 1990s, with wider range of energy mix and saving options. The Danish government has strategized to make the country fossil fuel free by 2050, where special attention and interventions is required to boost up its development of renewable energy in the country. The past efforts of the Danish government in the energy development has helped not only making the country ‘energy self sufficient’, but also lowering the level of carbon dioxide in the atmosphere. Danish energy policy and strategies have been found more conducive and reflective of the joint EU priorities on the matter of dealing with climate change and energy security. All the past progress and its allied policies seem to be quite supportive in fulfilling its strategies for greener future. This review paper will discuss on the past efforts of Danish government in energy management and highlights on some political initiatives, which have been realised to support the country moving towards clean and green energy future.     

Employment of Anaerobic Digestion Process of Municipal Solid Waste for Energy

Abstract

Jordan is a country with a population of about five million people. It is considered a developing country that is deficient in generating its own energy source, and it relies significantly on imports of fuels from other countries, which plays an important role in various environmental related problems and issues. Jordan is distinguished among the developing countries by its reasonable industrialization and significant agricultural activities. The amount of waste generated is on the increase due to a continuing significant increase in population and it currently faces pollution of its limited fresh water sources. To mitigate the current and future environmental problems facing Jordan due to fossil fuel use and associated environment problems, Jordan is taking into consideration steps including the utilization of the biogas technology to replace fossil fuel, since Jordan is a nation striving to meet the expected energy demand that grows annually by 6%. Studies of quantity per capita estimates Jordan's generated daily waste as 8,000 tons, which is comparable to that of most semi-industrialized nations. Of that, 3,200 tons is household waste and the rest of it is waste related to industry or agricultural. Much of the total waste is organic, which could be utilized through a process of anaerobic digestion and already has been in use for decades in industrialized nations to produce clean burning methane gas, electricity, fuel, and fertilizers. Anaerobic digestion process releases no greenhouse gases to the atmosphere. Jordan's generated daily waste is estimated around the same as that of most moderately developing nations. Most of the total waste is organic, which could be utilized through a process of anaerobic digestion that does not release greenhouse gases to the atmosphere. Renewable energy and energy conservation, if efficiently utilized, might help to meet the expected increase demand on energy that is growing rapidly. A combined facility (landfill operation and biogas plant) that is established in the capital of Jordan could help reduce the disposal and accumulation of biodegradable solid waste significantly; by 90%. This will help reduce emissions of green house gases (CO₂), reduce the dependency of foreign fossil fuel and would improve issues related to the general environment. This project would be self-supported. This project, if proved to be successful, would be an example that others will follow throughout.     

Alternative policies to subsidize rural household biogas digesters

Existing policies of household biogas projects focus mainly on supports on construction, but less consider management and maintenance, resulting in high scrap rate and waste of resources. Alternative policies must be explored to balance construction and operation. Taking the costs and benefits from a typical rural household biogas project, this paper assesses the economic performance at three different subsidy levels, i.e., no subsidy, existing standard and positive externality based standard. Furthermore three subsidy alternatives, one-time, annual and combined option are applied to the externality based standard. The results show that household biogas digesters have unsatisfactory economic performance without any subsidy and even in current subsidy policies. Environmental benefits of the digester were estimated as 2732 Chinese Yuan, significantly larger than existing subsidy standard. To keep continuous work during the 20-year lifespans of digesters, the income disparity of farmers among regions must be considered for policy application. With the increasing of labor costs, the ratio of initial subsidies must be reduced. These results provide policy implications to the future development of biogas projects in terms of both their construction and follow-up management, reuse of the abandoned digesters as well as the exploitation of other emerging renewable energy projects.     

The prospects for an expansion of biogas systems in Sweden—Incentives,barriers and potentials

Biogas is a renewable, high-quality fuel, currently produced at more than 200 locations in Sweden. The present production is some 5 PJ/year but the potential is approximately 10 times higher. Biogas can be produced from a wide range of raw materials, from organic waste to dedicated energy crops, and can be utilised for various energy services such as heat, combined heat and power or as a vehicle fuel. Biogas systems are therefore affected by a number of different incentives and barriers, including energy-, waste treatment- and agricultural policies. In this paper, different policies and policy instruments, as well as other factors, which influence a potential expansion of Swedish biogas systems, are identified and evaluated. Existing incentives and barriers can be divided into those affecting the production of biogas, and those affecting the utilisation of the biogas. Only a few types of biogas systems are competitive in Sweden today, while the majority needs increased incentives of different kinds to reach profitability. Such incentives are often motivated from an energy and environmental point of view. Due to the complexity of the biogas systems and the many actors involved, all with different interests, the process of implementing adequate policy instruments will require concerted efforts.     

Biomass energy in organic farming—the potential role of short rotation coppice

One of the aims of organic farming is to “reduce the use of non-renewable resources (e.g. fossil fuels) to a minimum”. So far, however, only very little progress has been made to introduce renewable energy in organic farming. This paper presents energy balances of Danish organic farming compared with energy balances of conventional farming. In general, the conversion to organic farming leads to a lower energy use (approximately 10% per unit of product). But the production of energy in organic farming is very low compared with the extensive utilisation of straw from conventional farming in Denmark (energy content of straw used for energy production was equivalent to 18% of total energy input in Danish agriculture in 1996).Biomass is a key energy carrier with a good potential for on-farm development. Apart from utilising farm manure and crop residues for biogas production, the production of nutrient efficient short rotation coppice (SRC) is an option in organic farming. Alder (Alnus spp.) is an interesting crop due to its symbiosis with the actinomycete Frankia, which has the ability to fix up to 185 kg/ha nitrogen (N₂) from the air. Yields obtained at different European sites are presented and the R&D needed to implement energy cropping in organic farming is discussed.Possible win–win solutions for SRC production in organic farming that may facilitate its implementation are; the protection of ground water quality in intensively farmed areas, utilisation of wastewater for irrigation, or combination with outdoor animal husbandry such as pigs or poultry.     

Energy analysis of the system of two-stage anaerobic processing of liquid organic waste with production of hydrogen- and methane-containing biogases

In recent years, public attention has been increasingly attracted to solving two inextricably linked problems - preventing the depletion of natural resources and protecting the environment from anthropogenic pollution. The annual consumption of livestock waste for biogas production is about 240 thousand m³ per year, which is 0.17% of the total manure produced at Russian agricultural enterprises. At present, the actual use of organic waste potentially suitable for biogas production is 2–3 orders of magnitude lower than the existing potential for organic waste. Currently, hydrogen energy is gaining immense popularity in the world due to the problem of depletion of non-renewable energy sources - hydrocarbons, and environmental pollution caused by their increasing consumption. Of particular interest is the dark process of producing hydrogen-containing biogas in the processing of organic waste under anaerobic conditions, which allows you to take advantage of both energy production and solving the problem of organic waste disposal. An energy analysis of a two-stage anaerobic liquid organic waste processing system with the production of hydrogen- and methane-containing biogases based on experimental data obtained in a laboratory plant with increased volume reactors was performed. The energy efficiency of the system is in the range of 1.91–2.74. Maximum energy efficiency was observed with a hydraulic retention time of 2.5 days in a dark fermentation reactor. The cost of electricity to produce 1 m³ of hydrogen was 1.093 kW·h with a hydraulic retention time of 2.5 days in the dark fermentation reactor. When the hydraulic retention time in the dark fermentation reactor was 1 day, the specific (in ratio to the processing rate of organic waste) energy costs to produce of 1 m³ of hydrogen were minimal in the considered hrt range, and amounted to 26 (W/m³ of hydrogen)/(m³ of waste/day). Thus, the system of two-stage anaerobic processing of liquid organic waste to produce hydrogen and methane-containing biogases is an energy-efficient way to both produce hydrogen and process organic waste.     

Life cycle assessment (LCA) of waste management strategies: Landfilling,sorting plant and incineration

This paper focuses on a Life Cycle Assessment (LCA) of four waste management strategies: landfill without biogas utilization; landfill with biogas combustion to generate electricity; sorting plant which splits the inorganic waste fraction (used to produce electricity via Refuse Derived Fuels, RDF) from the organic waste fraction (used to produce biogas via anaerobic digestion); direct incineration of waste. These scenarios are applied to the waste amount and composition of the Municipality of Roma (Italy) and are evaluated under different points of view: global and local emissions, total material demands, total energy requirements and ecological footprints. Results, reliable for most of the European big cities, show landfill systems as the worst waste management options and significant environmental savings at global scale are achieved from undertaking energy recycling. Furthermore, waste treatments finalized to energy recovery provide an energy output that, in the best case, is able to meet the 15% of Roma electricity consumption.     

Sustainable biogas energy in Poland: Prospects and challenges

The article investigates prospects and challenges for expanding of sustainable biogas energy in Poland. The number of Polish biogas fuelled power plants and installed electrical power during the 2001-2010 decade is presented. Current economical incentives for biogas energy are discussed. It is emphasized that some revisions to the Polish tradable certificate system are urgently needed in order to encourage energy crop cultivation and the use of best available power technologies. Further, promising, but mostly unexplored feedstocks, such as energy crops, grasses and sorted municipal organic wastes are analyzed. It is also revealed that agrobiogas is characterized by a unique feature of ‘negative net’ CO₂ atmospheric emissions and thus the role of agrobiogas in solving Polish CCS dilemmas is discussed. In regard to biogas energy systems it is stressed, that the cost of electricity from biogas is almost independent on the size of agrobiogas CHP power plants in the range of 0.2-5 MW_e. Therefore agrobiogas energy is well suited for distributed energy systems involving small-scale agrobiogas power plants offering more green jobs and improved local waste management characteristics. Finally, reliable technologies suitable for biogas energy conversion and upgrading of biogas fuel to marketable gaseous fuels are briefly characterized.     

Production and use of biogas in agriculture

Anaerobic digestion, a process used in municipal waste water treatment since the late 19th century, was originally suggested as a method of controlling pollution from large, intensive, farms. With changes in prices of conventional energy sources and possible future shortages of these, the production of biogas for farm use has become an economic possibility, with the bonus of pollution control.The process uses naturally-occurring bacteria which form a complex, but self-stabilising, mixed flora and this flora and its reactions are briefly described. Laboratory, pilot-plant and full scale tests have shown that agricultural wastes can be digested with production of useful amounts of biogas and that this biogas can be used in boilers or engines. Full-scale plants are, however, only in the developmental stage, and while problems in building and running large-scale farm digesters can be discussed, there is little, if any, information on long-term running of digesters and ancillary equipment.Economics dictate that use should be made of all products of digestion, but, again, while the results of small-scale tests can be discussed there is little information on large-scale uses of digested sludges.Large-farm, automated digesters are still developmental and test plants; the next two years or so should see existing problems overcome, as well as more plants being installed.     

Energy development in China: The need for a coherent policy

China, the world's third largest consumer of primary energy, remains in relative terms a poor developing country. Ambitious modernization plans, exemplified by the goal of quadrupling per capita GNP by the year 2000, will require considerable attention to long-range energy planning. Yet the past developments, including the most recent guidelines, have been marked by abrupt changes and outright reversals leaving China without any coherent energy policy. The most durable strategies which emerged during the late 1970s are: the stress on coal as the principal fuel; building of mine-mouth power plants; accelerated construction of large hydro stations; massive diffusion of small biogas digesters; and widespread energy conservation measures.     

Biogas production and its application in compressed gas

Nowadays, the world is facing critical problem of energy deficit, global warming, and deterioration of the environment. Under the current scenario, the biogas energy source is the most challenging one to cope up with the scarcity of energy. Biogas is a renewable energy source which can be obtained by fermentation of organic matter also known as biomass. The biomass includes livestock waste (cow dung, manure, and uneaten food), food waste, and residues from meat, fish and dairy processing. The present study is to explore the potential of biogas production from cow dung and its usage through compressed form in a cylinder. This stored biogas can be put in use to the extent where it is required and it also reduces transportation costs, which is a major hurdle in the biogas usage. This paper summarizes an idea that can be carried out for effective biogas production, scrubbing, compression, and bottling process.