Residential use of firewood in Northern Sweden and its influence on forest biomass resources

Firewood is society’s oldest source of household energy and is still extensively used around the world. However, little is known about firewood usage in technologically advanced countries with high energy consumption. Some key issues include quantities of firewood currently used and future trends, as well as the influence of this usage on available biomass resources. This study addresses those issues through a postal questionnaire to 1500 of the firewood using households in a region in Northern Sweden. One-third of households produced 11-20 solid m³ of firewood per year. Three-fourths expected their production to be unchanged or increase during the coming five years. A large proportion of young producers indicated long-term continuation of firewood usage. Half (53%) of the firewood producing households owned forest and thereby had free access to wood. Produced firewood volume corresponded to 4-8% of the region’s roundwood volume harvested for industrial purposes. The use of firewood is suggested to influence decisions of private forest owners about management and harvest of forest biomass, and, thus, affect supply for bioenergy and other uses. With further incorporation of firewood usage into forest biomass management regimes, larger biomass quantities are likely to be available for industrial uses.     

Resource analysis of the Chinese society 1980–2002 based on exergy—Part 1: Fossil fuels and energy minerals

The resource inflow to the Chinese society from 1980 to 2002 is investigated based on exergy as a unified quantifier of natural resources. The major resources entering the society are divided into 17 sectors, with the annual policy for the individual group is analyzed corresponding to the exergy resource inflow. This study is divided into five consequential parts. This paper as the first part introduces the fossil fuels and energy materials entering the society, including coal, crude oil, natural gas, iron ores, nonferrous metal ores and nuclear power. The coal production, which comes form unified central planning, collective and individual parts, is analyzed according to the administrative institutions associated with variable policies. The consumption of coal is also described concerning thermal power generation, coking, heating, private consumption and gasification. The storage capacity, investment and import in crude oil production, which is imperative for the rapid economic development, are depicted. The natural gas production, slowly expanding during the study period, is illustrated according to the discovered and operating gas fields. Production of iron ores and nonferrous metal ores and nuclear power produced from uranium ores are represented in this paper.     

Thermochemical conversion of brown coal and biomass in a pressurised fluidised bed gasifier with hot gas filtration using ceramic channel filters: measurements and gasifier modelling

Biomass (wood and Miscanthus pellets) and Rhenish brown-coal were gasified using a 1.5 MW_th (max.) pressurised fluidised bed gasification (PFBG) installation. NO_x precursor and tar emissions were studied by varying process parameters like the fuel type, pressure, temperature and air factor. Carbon conversions were well above 80%. Fuel-nitrogen conversion into NH₃ was mostly above ca. 50%. Fuel-nitrogen conversion into HCN was significantly lower. Results were in-line with comparable investigations with bottom feeding. Measurements of the gas composition for Miscanthus gasification were compared with a steady-state model based on elementary reaction chemistry and heterogeneous gas–char reactions related to the emission of nitrogen species. A flash pyrolysis model (FG-DVC-biomass version) was applied to determine the initial yields. Measurements and model simulation results were in reasonably good agreement.     

Management of natural gas resources and search for alternative renewable energy resources: A case study of Pakistan

Energy usage in Pakistan has increased rapidly in past few years due to increase in economic growth. Inadequate and inconsistent supply of energy has created pressure on the industrial and commercial sectors of Pakistan and has also affected environment. Demand has already exceeded supply and load shedding has become common phenomenon. Due to excessive consumption of energy resources it would become difficult to meet future energy demands. This necessitates proper management of existing and exploration of new energy resources. Energy resource management is highly dependent on the supply and demand pattern. This paper highlights the future demands, production and supply of energy produced from natural gas based on economic and environmental constraints in Pakistan with special emphasis on management of natural gas. An attempt has been made by proposing a suitable course of action to meet the rising gas demand. A mechanism has been proposed to evaluate Pakistan's future gas demand through quantitative analysis of base, worst and best/chosen option. CO₂ emission for all cases has also been evaluated. The potential, constraints and possible solutions to develop alternative renewable energy resources in the country have also been discussed. This work will be fruitful for the decision makers responsible for energy planning of the country. This work is not only helpful for Pakistan but is equally important to other developing countries to manage their energy resources.     

Some aspects of the formation of nitric oxide during the combustion of biomass fuels in a laboratory furnace

The influence of bed-region stoichiometric ratio and fuel nitrogen content on the formation of gaseous species formed during grate combustion of biomass fuels is reported based on gas measurements made within the fuel bed. Three fuels were studied: two mixtures of pelletized bark and wood chips and one of pelletized straw. Experiments were performed in a vertical, cylindrical, laboratory-scale grate-furnace with 0.245 m i.d. and 1.8 m height. Primary air was supplied through a grate consisting of a steel plate with 340 holes of 3.7 mm diameter. Secondary air was supplied 0.66 m above the grate. Gas analysis was performed for O₂, CO₂, CO, H₂ and NO. Results were compared with values calculated using a computer program for thermochemical equilibrium conditions. The measured contents of O₂, CO₂, CO and H₂ show good agreement with calculated equilibrium conditions at all bed region stoichiometries. A higher formation of NO was found for the straw fuel (0.58% fuel nitrogen) than for the bark/wood chip fuels (≈0.25% fuel nitrogen). This is not in accordance with the thermochemical equilibrium calculations indicating that the formation of nitric oxide does not attain thermochemical equilibrium and that the nitrogen content of the fuel has an influence on the amount of NO that is formed. The fuel nitrogen conversion to NO ranged from 3 to 20% at reducing conditions and from 20 to 40% at bed region stoichiometries between 1.00 and 1.25.     

An economic assessment of the use of short-rotation coppice woody biomass to heat greenhouses in southern Canada

This study explores the economic feasibility of fossil fuel substitution with biomass from short-rotation willow plantations as an option for greenhouse heating in southern Ontario, Canada. We assess the net displacement value of fossil fuel biomass combustion systems with an integrated purpose-grown biomass production enterprise. Key project parameters include greenhouse size, heating requirements, boiler capital costs and biomass establishment and management costs. Several metrics have been used to examine feasibility including net present value, internal rate of return, payback period, and the minimum or break-even prices for natural gas and heating oil for which the biomass substitution operations become financially attractive. Depending on certain key assumptions, internal rates of return ranged from 11-14% for displacing heating oil to 0-4% for displacing natural gas with woody biomass. The biomass heating projects have payback periods of 10 to >22 years for substituting heating oil and 18 to >22 years for replacing a natural gas. Sensitivity analyses indicate that fossil fuel price and efficiency of the boiler heating system are critical elements in the analyses and research on methods to improve growth and yield and reduce silviculture costs could have a large beneficial impact on the feasibility of this type of bioenergy enterprise.     

Effect of gasification agent on the performance of solid oxide fuel cell and biomass gasification systems

In this paper, an integrated solid oxide fuel cell (SOFC) and biomass gasification system is modeled to study the effect of gasification agent (air, enriched oxygen and steam) on its performance. In the present modeling, a heat transfer model for SOFC and thermodynamic models for the rest of the components are used. In addition, exergy balances are written for the system components. The results show that using steam as the gasification agent yields the highest electrical efficiency (41.8%), power-to-heat ratio (4.649), and exergetic efficiency (39.1%), but the lowest fuel utilization efficiency (50.8%). In addition, the exergy destruction is found to be the highest at the gasifier for the air and enriched oxygen gasification cases and the heat exchanger that supplies heat to the air entering the SOFC for the steam gasification case.     

Bioenergy in the United States: progress and possibilities

Concerns about global climate change and air quality have increased interest in biomass and other energy sources that are potentially CO₂-neutral and less polluting. Large-scale bioenergy development could indeed bring significant ecological benefits — or equally significant damage — depending on the specific paths taken. In particular, the land requirements for biomass production are potentially immense.

Various entities in the United States have performed research; prepared cost–supply assessments, environmental impact assessments, life cycle analyses and externality impact assessments; and engaged in demonstration and development regarding biomass crops and other potential biomass energy feedstocks. These efforts have focused on various biomass wastes, forest management issues, and biomass crops, including both perennial herbaceous crops and fast-growing woody crops. Simultaneously, several regional and national groups of bioenergy stakeholders have issued consensus recommendations and guidelines for sustainable bioenergy development.

It is a consistent conclusion from these efforts that displacing annual agricultural crops with native perennial biomass crops could — in addition to reducing fossil fuel use and ameliorating associated ecological problems — also help restore natural ecosystem functions in worked landscapes, and thereby preserve natural biodiversity.

Conversely, if forests are managed and harvested more intensively — and/or if biomass crops displace more natural land cover such as forests and wetlands — it is likely that ecosystem functions would be impaired and biodiversity lost.     

Use of material flow accounting for assessment of energy savings: A case of biomass in Slovakia and the Czech Republic

Anthropogenic material and energy flows are considered to be the major cause of many environmental problems humans face today. In order to measure material and energy flows, and to mitigate related problems, the technique of material flow and energy flow analysis has been conceived. The aim of this article is to use material and energy flow accounting approaches to quantify the amount of biomass that is available, but that so far has not been used for energy purposes in Slovakia and the Czech Republic and to calculate how much consumed fossil fuels and corresponding CO₂ emissions can be saved by utilising this biomass. Based on the findings presented, 3544 kt/yr of the total unused biomass in Slovakia could replace 53 PJ/yr of energy from fossil fuels and 6294 kt/yr of the total unused biomass in the Czech Republic could replace 91 PJ/yr of energy. Such replacement could contribute to a decrease in total CO₂ emissions by 9.2% in Slovakia and by 5.4% in the Czech Republic and thus contribute to an environmental improvement with respect to climate change.     

Geographic distribution of economic potential of agricultural and forest biomass residual for energy use: Case study Croatia

This paper provides methodology for regional analysis of biomass energy potential and for assessing the cost of the biomass at the power plant (PP) location considering transport distance, transport costs and size of the power plants. Also, methodology for determination of an upper-level price of the biomass which energy plant can pay to the external suppliers has been proposed. The methodology was applied on the case of Croatia and energy potential of biomass in the Croatian counties was calculated, using different methodologies, for wheat straw, corn stover and forestry residues, types of biomass considered economically viable at the moment. Results indicate that the average energy potential of wheat straw is 8.5 PJ, corn stover 7.2 PJ and forestry residues 5.9 PJ.     

Energetic recovery of biomass in the region of Rabat,Morocco

Morocco has a potential of considerable biomass with a forest estate around nine million of hectares, and a herd around seven million units of large cattle. In particular, in the Rabat region, the amount of waste is about 714 350 Kg in 2014, who is equivalent to 0.96 Kg/inhabitant/day. In this document, we present, in the case of the Rabat, the Current situation of the electricity production from waste incineration. The data will be processed by statistical methods (Environmental Protection Agency (EPA) model and Solid Waste Association of North America (SWANA) model). The objective behind using these models is to introduce data for future years' estimates. We will show that the amount of electricity generated by incineration of waste in Rabat is in the order of more hundreds of Giga-watt-hours. This alternative allows a reduction in tonnage of accumulated waste and avoids its negative impact on the environment. It also provides energy independence. This involves, necessarily, construction of landfills and integration of neighbourhoods' population.     

Cogeneration of power and substitute of natural gas using electrolytic hydrogen,biomass and high temperature fuel cells

Energy storage from renewable sources is one of the main current goals for the energy sector, and the production of a substitute of natural gas could be a good solution to solve the problem in the short term, helping the transition to hydrogen in the long term.Renewable energy sources usually generate variable electric power or medium/low energy content gas. This paper proposes a way to upgrade these products through the use of electrolytic hydrogen. By using electrolytic oxygen as an oxidant for biomass partial oxidation and for high temperature fuel cells, the exhaust gas after post-combustion is an almost pure mixture of water and carbon dioxide. Once such a gas is dehydrated, the carbon dioxide can be mixed with electrolytic hydrogen to obtain methane through the Sabatier process.Four layouts based on molten carbonate fuel cells and solid oxide fuel cells has been investigated. The results obtained are very similar: the conversion efficiency is close to 60% and the mix of energy output consist of fuel for about 75% and electric power for about 25%.     

Detailed study of the impact of co-utilization of biomass in a natural gas combined cycle power plant through perturbation analysis

Co-utilization of fossil fuels and biomass is a successful way to make efficient use of biomass for power production. When replacing only a limited amount of fossil fuel by biomass, measurements of net output power and input fuel rates will however not suffice to accurately determine the marginal efficiency of the newly introduced alternative fuel. The present paper therefore proposes a technique to determine the marginal biomass efficiency with more accuracy. The process simulation model for co-utilization of natural gas and a small perturbing fraction of biomass in an existing combined cycle plant (500 MW_th Drogenbos, Belgium) is taken as case study. In this particular plant, biomass is introduced into the cycle as fuel for a primary steam reforming process of the input natural gas.     

The short- and long-run efficiency of energy,precious metals,and base metals markets: Evidence from the exponential smooth transition autoregressive models

The aim of this paper is to investigate the long and short-run relationship between spot and futures prices of the energy, precious metals, and base metals markets. We analyze daily data from January 1985 to February 2019. The empirical findings based on the cointegration test, which follows a nonlinear process, suggest that the spot prices of energy and metals assets have long-run relationships with their futures prices. Nonparametric Granger causality test results also indicate bi-directional causality among futures and spot prices. These findings indicate that the energy and metals markets are informationally efficient in the sense of Fama (1970).     

Assessment of forest biomass for use as energy. GIS-based analysis of geographical availability and locations of wood-fired power plants in Portugal

Following the European Union strategy concerning renewable energy (RE), Portugal established in their national policy programmes that the production of electrical energy from RE should reach 45% of the total supply by 2010. Since Portugal has large forest biomass resources, a significant part of this energy will be obtained from this source. In addition to the two existing electric power plants, with 22 MW of power capacity, 13 new power plants having a total of 86.4 MW capacity are in construction. Together these could generate a combination of electrical and thermal energy, known as combined heat and power (CHP) production. As these power plants will significantly increase the exploitation of forests resources, this article evaluates the potential quantities of available forest biomass residue for that purpose. In addition to examining the feasibility of producing both types of energy, we also examine the potential for producing only electric energy. Results show that if only electricity is generated some regions will need to have alternative fuel sources to fulfil the demand. However, if cogeneration is implemented the wood fuel resource will be sufficient to fulfill the required capacity demand.     

GIS-based assessment of the biomass potential from phytoremediation of contaminated agricultural land in the Campine region in Belgium

Dedicated energy crop cultivation is expected to be the prevalent form of biomass production for reaching renewable energy targets set by the European Union. However, there are some concerns with regard to its sustainability. This study demonstrates how this problem can be evaded by applying phytoremediation, i.e. the use of plants to remove pollutants from moderately contaminated soils. By selecting the appropriate plants a considerable biomass flow is produced without taking in scarce agricultural land, while simultaneously remediating the soil to levels of contamination below threshold values. Since phytoremediation is only applicable within a limited range of soil pollutant concentrations, the outer values of this range have to be determined at first. Subsequently, a Geographic Information System (GIS) is needed to perform further analyses. The contamination in the region is predicted using GIS, after which the agricultural area is determined that can be committed to energy crop cultivation. This way, the biomass potential and the resulting bioenergy potential from phytoremediation can be assessed. In this paper the Campine region in Belgium, a region diffusely contaminated with heavy metals like cadmium (Cd), is examined. It is illustrated that more than 2000 ha of agricultural land hold Cd concentrations exceeding guide values set by the Flemish Government. However, a large majority of these soils can be remediated by phytoremediation within a reasonable time span of 42 years. Concurrently, a significant amount of biomass is supplied for renewable energy production.     

Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 2: Gasification systems

Gasification as a thermo-chemical process is defined and limited to combustion and pyrolysis. The gasification of biomass is a thermal treatment, which results in a high production of gaseous products and small quantities of char and ash. The solid phase usually presents a carbon content higher than 76%, which makes it possible to use it directly for industrial purposes. The gaseous products can be burned to generate heat or electricity, or they can potentially be used in the synthesis of liquid transportation fuels, H₂, or chemicals. On the other hand, the liquid phase can be used as fuel in boilers, gas turbines or diesel engines, both for heat or electric power generation. However, the main purpose of biomass gasification is the production of low- or medium heating value gas which can be used as fuel gas in an internal combustion engine for power production. In addition to limiting applications and often compounding environmental problems, these technologies are an inefficient source of usable energy.     

Uncertainties in the design and operation of distributed energy resources: The case of micro-CHP systems

Large-scale diffusion of distributed energy resources (DERs) will have a profound impact on electricity infrastructure functioning: it will bring radical changes to the traditional model of generation and supply as well as to the business model of the energy industry. DERs comprise distributed power generators, distributed energy storages and controllable loads. There are, however, many uncertainties that influence the design and operation of DERs. This paper clarifies these uncertainties by proposing and applying a comprehensive framework for uncertainty analysis. We thereby adopt an integrated approach that considers not only the technical, but also the economic and institutional uncertainties. A delineation of the work is a focus on residential DERs and on micro-CHP systems specifically. After the proposed framework for uncertainty analysis is explained the uncertainties pertaining to the design and operation of residential DERs and micro-CHP systems are identified. In a case study system a selection of the uncertainties are quantitatively analysed. The case study system consists of a household that intelligently applies a micro-CHP unit in conjunction with energy storages and that interacts with its energy supplier. With a sensitivity analysis of the system model the salient impacts of the uncertainties on system behaviour and performance are enunciated.     

Competition between biomass and food production in the presence of energy policies: a partial equilibrium analysis

Bioenergy has several advantages over fossil fuels. For example, it delivers energy at low net CO₂ emission levels and contributes to sustaining future energy supplies. The concern, however, is that an increase in biomass plantations will reduce the land available for agricultural production. The aim of this study is to investigate the effect of taxing conventional electricity production or carbon use in combination with subsidizing biomass or bioelectricity production on the production of biomass and agricultural commodities and on the share of bioelectricity in total electricity production. We develop a partial equilibrium model to illustrate some of the potential impacts of these policies on greenhouse gas emissions, land reallocation and food and electricity prices. As a case study, we use data for Poland, which has a large potential for biomass production. Results show that combining a conventional electricity tax of 10% with a 25% subsidy on bioelectricity production increases the share of bioelectricity to 7.5%. Under this policy regime, biomass as well as agricultural production increase. A carbon tax that gives equal net tax yields, has better environmental results, however, at higher welfare costs and resulting in 1% to 4% reduction of agricultural production.     

How to analyse and maximise the forest fuel supply availability to power plants in Eastern Finland

The annual use of forest fuels has grown rapidly in Finland during the 21st century. In 2007 the annual use was 5.3 TWh (firewood use excluded), whereas the targeted growth by the year 2010 is 10.6 TWh, i.e. some 5 million m³. The purpose of this work was to evaluate the maximum availability of forest fuels to CHP plants in Eastern Finland. The total availability to the selected CHP plant population was 7 TWh at the maximum transport distance of 100 km. The main share came from logging residues, 3.3 TWh, and the rest from stumps, 1.8 TWh, and small diameter energy wood, 1.9 TWh. The highest plant-specific availability reached the level of 1.7-1.8 TWh, but the overlapping procurement areas reduced the availability for most plants to a level less than 1 TWh. In all plant sites peat fuel could be partially compensated with forest fuels according to availability, but not completely due to the boiler technology. Increasing the targeted national forest fuel use presupposes the use of new logistics supply solutions, such as other transport modes and regional buffer storage networks. This makes it possible to widen the traditional procurement area-based on truck transportation, which is less than 60 km because of a dense plant network.