Factors affecting households' decisions in biogas technology adoption,the case of Ofla and Mecha Districts,northern Ethiopia

This study examined the factors that influence households' decisions on adoption of biogas technology in northern Ethiopia. It involved 179 biogas-user and 179 non-user sample households. They were selected using proportionate simple random and purposive sampling techniques, respectively. Data were collected mainly using semi-structured questionnaires. Data analyses employed logistic regression model. The results of the study showed that male-headed households are more likely to adopt the technology than female-headed ones. Educational level, heads of cattle, income level, access to credit, distance to the main fuelwood source, and number of planted trees have significant (p < 0.01) positive influences on adoption of biogas technology. Significant (p < 0.01) spatial variations are also obtained between the two study sites. Furthermore, the interaction effects of a few pairs of explanatory variables were found significant (p < 0.1). Empowering females and female-headed households, improving educational levels of the household heads, increasing cattle size, raising income levels, improving access to credit, and encouraging households to plant more trees are likely to be some of the way forward to increase the adoption of the technology. Considering the spatial variations, ensuring the creation of satisfied biogas-users, upgrading the existing biogas model through addition of ‘injera’ stove can also enhance adoption of biogas technology.     

Economics and greenhouse gas balance of biogas use systems in the Finnish transportation sector

Energy decisions play an essential role in reducing greenhouse gas (GHG) emissions in the transportation sector. Biogas is a renewable energy source and can be used as an energy source for gas-operated cars or for electric cars. This paper compares different ways to use biogas, which is produced on a medium scale anaerobic digestion plants, as an energy source for transportation. The research is conducted from an economic and environmental point of view, and the option to deliver upgraded biogas via a natural gas grid is taken into account. Different processes for the use of biogas for transportation purposes are compared using life cycle assessment (LCA) methods in the Finnish operational environment. It seems that the most economical way is to use biogas in gas-operated cars due to the high price of methane for vehicle fuel use. A new feed-in tariff for electricity produced with biogas will, however, have highly positive economic effects on electricity production from biogas. From the environmental point of view, the highest CO₂ reductions are gained when biogas is used in gas-operated cars or in CHP plants for power and heat production. During the transition stage, it might be reasonable to use biogas in gas-operated cars and most importantly in heavy vehicles to reduce GHG and local pollutants rapidly. If biogas production is located near a natural gas grid, the biogas can be delivered effectively via the natural gas grid. The use of biogas in gas-operated cars is an effective way to reduce carbon dioxide significantly in the transportation sector.     

Primary energy and greenhouse gas implications of increasing biomass production through forest fertilization

In this study we analyze the primary energy and greenhouse gas (GHG) implications of increasing biomass production by fertilizing 10% of Swedish forest land. We estimate the primary energy use and GHG emissions from forest management including production and application of N and NPK fertilizers. Based on modelled growth response, we then estimate the net primary energy and GHG benefits of using biomaterials and biofuels obtained from the increased forest biomass production. The results show an increased annual biomass harvest of 7.4 million t dry matter, of which 41% is large-diameter stemwood. About 6.9 PJ/year of additional primary energy input is needed for fertilizer production and forest management. Using the additional biomass for fuel and material substitution can reduce fossil primary energy use by 150 or 164 PJ/year if the reference fossil fuel is fossil gas or coal, respectively. About 22% of the reduced fossil energy use is due to material substitution and the remainder is due to fuel substitution. The net annual primary energy benefit corresponds to about 7% of Sweden's total primary energy use. The resulting annual net GHG emission reduction is 11.9 million or 18.1 million tCO_2equiv if the reference fossil fuel is fossil gas or coal, respectively, corresponding to 18% or 28% of the total Swedish GHG emissions in 2007. A significant one-time carbon stock increase also occurs in wood products and forest tree biomass. These results suggest that forest fertilization is an attractive option for increasing energy security and reducing net GHG emission.     

Popularizing household-scale biogas digesters for rural sustainable energy development and greenhouse gas mitigation

Biogas utilization has undergone great development in rural China since the government systematically popularized household-scale biogas digesters for meeting the rural energy needs in the 1970s. In order to comprehensively estimate the significance of biogas utilization on rural energy development and greenhouse gas emission reduction, all types of energy sources, including straw, fuelwood, coal, refined oil, electricity, LPG, natural gas, and coal gas, which were substituted by biogas, were analyzed based on the amount of consumption for the years from 1991 to 2005. It was found that biogas provided 832749.13 TJ of energy for millions of households. By the employment of biogas digesters, reduction of greenhouse gases (GHG) was estimated to be 73157.59 Gg CO₂ equivalents (CO₂-eq), and the emission by the biogas combustion was only 36372.75 Gg CO₂-eq of GHG. Energy substitution and manure management, working in combination, had reduced the GHG emission efficiently. The majority of the emission reduction was achieved by energy substitution that reduced 84243.94 Gg CO₂, 3560.01 Gg CO₂-eq of CH₄ and 260.08 Gg CO₂-eq of N₂O emission. It was also predicted that the total production of biogas would reach to 15.6 billion m³ in the year 2010 and 38.5 billion m³ in the year 2020, respectively. As a result, the GHG emission reductions are expected to reach 28991.04 and 46794.90 Gg CO₂-eq, respectively.     

Biogas: A promising renewable technology and its impact on rural households in Nepal

Nepal, one of the least developed countries, is characterized by very low per capita energy consumption. Because of a lack of other commercial sources of energy, the country relies heavily on traditional fuel source, especially firewood. In order to solve the energy problem in rural areas, the country initiated production and distribution of several renewable energy technologies. Among several technologies, biogas has been proved to be viable and emerged as a promising technology. It has been one of the most successful models for the production of clean, environmental friendly, cost effective source of energy and has multiple benefits. In this paper we present the current state and discuss benefits of the biogas technology in Nepal. Improved health, increased crop productivity, saved time for women are some of the major benefits to the users. It provides economic benefit to the country through reduced deforestation and carbon trading. In addition, by reducing green house gas emission, the technology helps in mitigating global warming and climate change. Thus biogas is a renewable, sustainable and clean source of energy that provides multiple benefits; locally and globally. With some exception, cattle dung has been used primarily as an input and the technology is limited to households only. More systematic and comprehensive study supported by research and development is required to use other degradable waste such as municipal waste to produce biogas on a large scale.     

Dairy farming and biogas use in Rungwe district, South-west Tanzania: A study of opportunities and constraints

This study examined the opportunities and constraints of biogas use in Rungwe district, South-west Tanzania. Two hundred households with and without biogas facilities were selected randomly from four villages. Structured, semi-structured and open-ended discussion was used to gather information. Findings show a number of opportunities for biogas technology adoption including large numbers of indoor-fed cattle and inadequate firewood in the district, which has increased its cost of such commodity. Households generally spend an average of TShs. 20,656.50 per month or TShs. 247,876.8 per annum for energy. The demand for biogas (90%) among respondents is high and the energy policy as well as donor community favour the promotion of energy efficient technologies such as biogas. Constraints encountered in establishing biogas plants were found to include unaffordability (75%) and water scarcity. Also there is inadequate expertise where some of the biogas plants have been poorly constructed leading to ineffective performance. There is also a small proportion of the respondents who admitted that they had heard nothing about biogas technology. It is being suggested that credit should be available as well as developing affordable biodigestors. Communal biogas should be encouraged to reduce the cost per unit and the government should undertake the improvement of water services.     

Energy and environmental balance of biogas for dual-fuel mobile applications

Considerable research is currently being devoted to seeking alternative fuels to comply with transportation needs while reducing the environmental impact of this sector. Within the transport activity sector, on road vehicles and agricultural machinery require around 2 Mtoe energy in France. The anaerobic digestion of farm waste could roughly cover these needs. This paper aims to study the environmental and energy interest of this short power supply path. An ideal biogas production system has been built up from the average characteristics of current rural biogas plants in France. Pollutant emissions, energy demands and production are assessed for various scenarios in order to produce methane for dual fuel engines. Life cycle assessment (LCA) is used to evaluate the environmental impact of dual fuel agricultural machines, compared to diesel engines. The energy balance is always in disfavour of biogas fuel, whereas LCA energy indicators indicate a benefit for biogas production. This gap is related to the way in which the input of biomass energy is handled: in conventional biofuel LCA, this energy is not taken into account. A carbon balance is then presented to discuss the impact of biogas on climate change. Dual fuel engines were found to be interesting for their small impact. We also show, however, how the biogenic carbon assumption and the choice of allocation for the avoided methane emissions of anaerobic digestion are crucial in quantifying CO₂ savings. Other environmental issues of biogas fuel were examined. Results indicate that are management and green electricity are the key points for a sustainable biogas fuel. It is concluded that biofuel environmental damage is reduced if energy needs during biofuel production are covered by the production process itself. As agricultural equipment is used during the biofuel production process, this implies that a high substitution rate should be used for this equipment.     

沼气发酵猪粪管理系统对温室气体排放的影响

基于生命周期清单分析以及清洁发展机制,引入"碳足迹"概念,对我国散养猪以及规模化养猪场引入沼气发酵系统后猪粪管理系统温室气体排放及减排进行了估算。农户散养猪粪处理系统中,12 m3沼气池厌氧发酵过程碳足迹为223.40 kg CO2e/a,沼气代替原煤燃烧减少444.33 kg CO2e/a温室气体,沼气发酵净减少220.93 kg CO2e/a温室气体,我国散养生猪产生的猪粪以此沼气池发酵可减少温室气体20 984.62 Gg CO2e/a;分析运行规模约1 000 m3大型沼气工程的碳足迹,保守估计为2 835.32 t CO2e/a,运行沼气工程替代煤炭以及减少猪粪排放的温室气体共约2 914.23 t CO2e/a,故沼气工程年减少温室气体78.91 t CO2e,该项目共可减排1 578.20 t CO2e。在猪粪管理系统中采用沼气发酵系统可以更好地促进温室气体减排的进行。     

Estimating GHG emission mitigation supply curves of large-scale biomass use on a country level

This study evaluates the possible influences of a large-scale introduction of biomass material and energy systems and their market volumes on land, material and energy market prices and their feedback to greenhouse gas (GHG) emission mitigation costs. GHG emission mitigation supply curves for large-scale biomass use were compiled using a methodology that combines a bottom-up analysis of biomass applications, biomass cost supply curves and market prices of land, biomaterials and bioenergy carriers. These market prices depend on the scale of biomass use and the market volume of materials and energy carriers and were estimated using own-price elasticities of demand. The methodology was demonstrated for a case study of Poland in the year 2015 applying different scenarios on economic development and trade in Europe. For the key technologies considered, i.e. medium density fibreboard, poly lactic acid, electricity and methanol production, GHG emission mitigation costs increase strongly with the scale of biomass production. Large-scale introduction of biomass use decreases the GHG emission reduction potential at costs below 50 €/Mg CO_2eq with about 13–70% depending on the scenario. Biomaterial production accounts for only a small part of this GHG emission reduction potential due to relatively small material markets and the subsequent strong decrease of biomaterial market prices at large scale of production. GHG emission mitigation costs depend strongly on biomass supply curves, own-price elasticity of land and market volumes of bioenergy carriers. The analysis shows that these influences should be taken into account for developing biomass implementations strategies.     

Trade-linked Canada–United States household environmental impact analysis of energy use and greenhouse gas emissions

We compare energy use and greenhouse gas (GHG) emissions associated with total household expenditures and activities in Canada and US in 1997, the first detailed estimate of environmental burdens for Canadian households. We estimate direct burdens from published government data and indirect burdens using an industry-by-commodity, bi-national economic input–output life cycle assessment model developed in this study. Comparing 30 expenditure and two activity categories, per capita US household expenditures were 70% higher, while per capita household energy use and GHG emissions were only 10% and 44% higher, respectively. Energy use/dollar of expenditure was higher in most Canadian categories, while the average ratio of GHG emissions/energy use was higher in the US (65 vs 50 kg Eq. CO₂/GJ) due largely to a higher proportion of electricity from nonrenewable sources. Indirect environmental burdens represented 63–69% of total burdens and 62–70% of total burdens were associated with household operation and transportation. Key drivers of differences between energy profiles were: higher per capita electricity use by Canadian households, and higher US household private health care expenditures and motor fuel use. Energy-intensive production for export represented a higher proportion of Canadian production, resulting in less agreement between consumption and production-based analyses for Canada than US.     

The impact of household behavioral changes on GHG emission reduction in Lithuania

It is commonly understood that households must change their behavior to reduce problems related increased energy consumption and climate change therefore in the search of cheap GHG emission reduction measures households are an important target group because they are responsible for more than 20% of total energy consumption in developed countries. In addition waste management and responsible consumption of products are the key issues in GHG emission reduction.The aim of the paper is to assess GHG emission reduction potential in households in terms of behavioral changes towards sustainable consumption. The review of literature on analysis of households behavioral changes impact on GHG emission reduction was performed; the daily survey of household agenda and energy use records were performed in Lithuania for two scenarios – baseline and GHG emission reduction scenario including energy saving. GHG emission reduction potential in household was assessed based on daily survey data and energy consumption records by applying carbon calculator based on modified coefficients. Evaluated GHG emission reduction potential in households was compared with GHG emission reduction potentials in other sectors of Lithuania. Based on analysis performed in the paper the tools to promote household behavioral changes towards sustainable consumption were proposed.     

Productive use of bioenergy for rural household in ecological fragile area,Panam County,Tibet in China: The case of the residential biogas model

Bioenergy is the major domestic energy for rural households in developing countries due to its cheap or easy-getting characteristics. Productive use of bioenergy is an important strategy for rural households to improve not only their income, but also their health, living environment and so on. In Tibet of China, which is rich in cattle dung and firewood as the major energy sources for rural households, the efficiency of energy utilization is just about 10%. In order to improve energy utilization efficiency and the living conditions for rural residents, the Tibet Autonomous Region government introduced residential biogas model (RBM) to local households, which was a comprehensive utilization system of energy integrated with residential biogas digester, vegetable greenhouse and livestock shed. This paper aims to show the productive use of the bioenergy by the RBM, which could be depicted as the feasibility and the benefits on economic, eco-environmental and social aspects of biogas utilization, based on household questionnaires in Panam County. In RBM, biogas digester works as the biomass material supplement loop to transform originally biomass flow from single-direction to recycling-direction. The results indicate that the output of unit biogas digester could replace 1.44 t of firewood, 1.65 t of agricultural residues and 1.75 t of cattle dung, respectively. The net incremental benefit of RBM could reach 5550.72 Yuan in 15 years. The reduced amount of CO₂ emission when substituted by biogas in other agricultural areas and the areas of semi-agricultural and semi-husbandry in Tibet could be (76.66–79.89) × 10⁴ t/year and the capability for nitrogen storage could achieve (0.39–0.99) × 10⁴ t/year. The amount of cattle dung replaced by biogas could reach 78.29 × 10⁴ t/year; this means that the saved cattle dung, 3.51 t/hm², could be reallocated back to cultivated land to improve the soil fertility and to keep the balance of nutrient elements in cultivated land. Biogas utilization reduces the labor opportunity costs of women compared to use of traditional bioenergy sources. It could be concluded that the productive use of bioenergy through RBM in this area has its capability to release the current pressures on biomass sources by adjusting patterns of rural energy consumption, and to improve the conditions of health, environment, economy and energy conservation.     

Economic and greenhouse gas emission analysis of bioenergy production using multi-product crops—case studies for the Netherlands and Poland

In the face of climate change that may result from greenhouse gas (GHG) emissions, the scarcity of agricultural land and limited competitiveness of biomass energy on the market, it is desirable to increase the performance of bioenergy systems. Multi-product crops, i.e. using a crop partially for energy and partially for material purposes can possibly create additional incomes as well as additional GHG emission reductions. In this study, the performance of several multi-product crop systems is compared to energy crop systems, focused on the costs of primary biomass fuel costs and GHG emission reductions per hectare of biomass production. The sensitivity of the results is studied by means of a Monte-Carlo analysis. The multi-product crops studied are wheat, hemp and poplar in the Netherlands and Poland. GHG emission reductions of these multi-product crop systems are found to be between 0.2 and 2.4 Mg CO_2eq/(ha yr) in Poland and 0.9 and 7.8 Mg CO_2eq/(ha yr) in the Netherlands, while primary biomass fuel costs range from −4.1 to −1.7 €/GJ in the Netherlands and from 0.1 to 9.8 €/GJ in Poland. Results show that the economic attractiveness of multi-product crops depends strongly on material market prices, crop production costs and crop yields. Net annual GHG emission reductions per hectare are influenced strongly by the specific GHG emission reduction of material use, reference energy systems and GHG emissions of crop production. Multi-product use of crops can significantly decrease primary biomass fuel costs. However, this does not apply in general, but depends on the kind of crops and material uses. For the examples analysed here, net annual GHG emission reductions per hectare are not lowered by multi-product use of crops. Consequently, multi-product crops are not for granted an option to increase the performance of bioenergy systems. Further research on the feasibility of large-scale multi-product crop systems and their impact on land and material markets is desirable.     

GHG reduction potential of changes in consumption patterns and higher quality levels: Evidence from Swiss household consumption survey

An effective consumer-oriented climate policy requires knowing the GHG reduction potential of sustainable consumption. The aim of this study is to draw lessons from differences in consumption between households with high and low GHG emissions. We evaluate a survey of 14,500 households and use a method that allows measuring changes in price level of consumption. Comparing the 10% of households with the highest GHG emissions per capita with the lowest 10% – controlling for differences in expenditure level and household structure – we find a range 5–17 tons of CO₂-equivalent per capita and year. The observed differences stem mainly from heating, electricity use, car use, and travel by aircraft. Consumption patterns with low GHG emissions are characterized by less spending on mobility, but more on leisure and quality oriented consumption (leading to higher prices per unit). Further characteristics are: a higher share of organic food, low meat consumption and fewer detached single family houses. Our findings imply that a significant reduction in GHG emissions would be possible by adopting real-world consumption patterns observable in society. The twin challenge is to shift consumption towards more climate friendly patterns, and to prevent any trend towards high emitting consumption patterns.     

Determinants for adoption decision of small scale biogas technology by rural households in Tigray,Ethiopia

The deployment of biogas energy as alternative energy source can have the potential to fill the gap in the energy needs of the rural community if it is effectively managed and appropriately utilized. Using a logistic regression analysis of cross sectional data, the driving forces for adoption decision of biogas technology by rural households in the Tigray region, Ethiopia, were examined. The study found that the factors that significantly affect biogas adoption decision of rural households were for the most part socio-demographic factors and access to basic infrastructures. Besides, some environmental, institutional and economic attributes were significantly associated with diffusion of biogas technology. From among the variables included in the model, age of household head, family size, level of education, cattle size owned, distance to firewood collection site, access to electricity, access to credit and access to all weather roads were found to positively affect biogas adoption decision of households. On the other hand, distance to the nearest market negatively affected the adoption decision of the households. Female headed households tend more to adopt the biogas technology as compared to their male counterparts. As socio-economic attributes of households and environmental factors are mostly varied contextually and spatially, the policy of biogas technology promotion should be tailored based on the principle of fit for the purpose instead of the existing unimodal approach for all settings.     

Energy and greenhouse gas balance of the use of forest residues for bioenergy production in the UK

Life cycle analysis is used to assess the energy requirements and greenhouse gas (GHG) emissions associated with extracting UK forest harvesting residues for use as a biomass resource. Three forest harvesting residues were examined (whole tree thinnings, roundwood and brash bales), and each have their own energy and emission profile. The whole forest rotation was examined, including original site establishment, forest road construction, biomass harvesting during thinning and final clear-fell events, chipping and transportation. Generally, higher yielding sites give lower GHG emissions per ‘oven dried tonne’ (ODT) forest residues, but GHG emissions ‘per hectare’ are higher as more biomass is extracted. Greater quantities of biomass, however, ultimately mean greater displacement of conventional fuels and therefore greater potential for GHG emission mitigation. Although forest road construction and site establishment are “one off” events they are highly energy-intensive operations associated with high diesel fuel consumption, when placed in context with the full forest rotation, however, their relative contributions to the overall energy requirements and GHG emissions are small. The lower bulk density of wood chips means that transportation energy requirements and GHG emissions are higher compared with roundwood logs and brash bales, suggesting that chipping should occur near the end-user of application.     

Climate consequences of low-carbon fuels: The United States Renewable Fuel Standard

A common strategy for reducing greenhouse gas (GHG) emissions from energy use is to increase the supply of low-carbon alternatives. However, increasing supply tends to lower energy prices, which encourages additional fuel consumption. This “fuel market rebound effect” can undermine climate change mitigation strategies, even to the point where efforts to reduce GHG emissions by increasing the supply of low-carbon fuels may actually result in increased GHG emissions. Here, we explore how policies that encourage the production of low-carbon fuels may result in increased GHG emissions because the resulting increase in energy use overwhelms the benefits of reduced carbon intensity. We describe how climate change mitigation strategies should follow a simple rule: a low-carbon fuel with a carbon intensity of X% that of a fossil fuel must displace at least X% of that fossil fuel to reduce overall GHG emissions. We apply this rule to the United States Renewable Fuel Standard (RFS2). We show that absent consideration of the fuel market rebound effect, RFS2 appears to reduce GHG emissions, but once the fuel market rebound effect is factored in, RFS2 actually increases GHG emissions when all fuel GHG intensity targets are met.     

New power generation technology options under the greenhouse gases mitigation scenario in China

Climate change has become a global issue. Almost all countries, including China, are now considering adopting policies and measures to reduce greenhouse gas (GHG) emissions. The power generation sector, as a key source of GHG emissions, will also have significant potential for GHG mitigation. One of the key options is to use new energy technologies with higher energy efficiencies and lower carbon emissions. In this article, we use an energy technology model, MESSAGE-China, to analyze the trend of key new power generation technologies and their contributions to GHG mitigation in China. We expect that the traditional renewable technologies, high-efficiency coal power generation and nuclear power will contribute substantially to GHG mitigation in the short term, and that solar power, biomass energy and carbon capture and storage (CCS) will become more important in the middle and long term. In the meantime, in order to fully bring the role of technology progress into play, China needs to enhance the transfer and absorption of international advanced technologies and independently strengthen her ability in research, demonstration and application of new power generation technologies.     

Optimization of biogas production by anaerobic digestion for sustainable energy development in Zimbabwe

There is increasing international interest in developing low carbon renewable energy technologies. Biomass is increasingly being utilized as an energy source throughout the world. Several modern technologies have been developed that convert biomass to bioenergy. Anaerobic digestion is a mature energy technology for converting biomass to biogas, which is a renewable primary energy source. Biogas is a robust fuel that can be used to supply heat, electricity, process steam and methanol. There are vast biomass resources in Zimbabwe that have good potential for biogas production by anaerobic digestion. However, anaerobic digestion is not being optimally used as a biomass conversion technology in the country. This paper presents an overview of biogas production in Zimbabwe and outlines technical options that can be utilized to optimize biogas production by anaerobic digestion in the country.     

Green hydrogen-based E-fuels (E-methane,E-methanol,E-ammonia) to support clean energy transition: A literature review

Renewable power-to-fuel (PtF) is a key technology for the transition towards fossil-free energy systems. The production of carbon neutral synthetic fuels is primarily driven by the need to decouple the energy sector from fossil fuels dependance which are the main source of environmental issues. Hydrogen (H₂) produced from water electrolysis powered by renewable electricity and direct carbon dioxide (CO₂) captured from the flue gas generated by power plants, industry, transportation, and biogas production from anaerobic digestion, are used to convert electricity into carbon-neutral synthetic fuels. These fuels function as effective energy carriers that can be stored, transported, and used in other energy sectors (transport and industry). In addition, the PtF concept is an energy transformation that is capable of providing services for the balancing of the electricity grid thanks to its adaptable operation and long-term storage capacities for renewable energy surplus. As a consequence, it helps to potentially decarbonize the energy sector by reducing the carbon footprint and GHG emissions. This paper gives an overview on recent advances of renewable PtF technology for the e-production of three main hydrogen-based synthetic fuels that could substitute fossil fuels such as power-to-methane (PtCH₄), power-to-methanol (PtCH₃OH) and power-to-ammonia (PtNH₃). The first objective is to thoroughly define in a clear manner the framework which includes the PtF technologies. Attention is given to green H₂ production by water electrolysis, carbon capture & storage (CCS), CO₂ hydrogenation, Sabatier, and Haber Bosch processes. The second objective is to gather and classify some existing projects which deal with this technology depending on the e-fuel produced (energy input, conversion process, efficiency, fuel produced, and application). Furthermore, the challenges and future prospects of achieving sustainable large-scale PtF applications are discussed.