Zoekresultaten

Tourism and climate change mitigation : methods, greenhouse gas reductions and policies

Targeting Energy Management

Energiebeheer gericht aanpakken, Het analyseren van doelstellingen, resultaten en impacts van energie- en broeikasgasbeheersprogramma’s in bedrijven (met een samenvatting in het Nederlands): De wereldwijde uitstoot van broeikasgassen moet drastisch worden teruggebracht om de mondiale stijging van de temperatuur tot het relatief veilige niveau van maximaal 2 graden Celsius te beperken. In de komende decennia zal de verbetering van de energie-efficiëntie de belangrijkste strategie zijn voor het verminderen van de energiegerelateerde uitstoot van broeikasgassen. Hoewel er een enorm potentieel is voor verbetering van de energie-efficiëntie, wordt een groot deel daarvan nog niet benut. Dit wordt veroorzaakt door diverse investeringsbarrières die de invoering van maatregelen voor energie-efficiëntie verbetering verhinderen. De invoering van energiemanagement wordt vaak beschouwd als een manier om dergelijke barrières voor energiebesparing te overwinnen. De invoering van energiemanagement in bedrijven kan worden gestimuleerd door de introductie van programma's voor energie-efficiëntie verbetering en vermindering van de uitstoot van broeikasgassen. Deze programma's zijn vaak een combinatie van verschillende elementen zoals verplichtingen voor energiemanagement; (ambitieuze) doelstellingen voor energiebesparing of beperking van de uitstoot van broeikasgassen; de beschikbaarheid van regelingen voor stimulering, ondersteuning en naleving; en andere verplichtingen, zoals openbare rapportages, certificering en verificatie. Tot nu toe is er echter beperkt inzicht in het proces van het formuleren van ambitieuze doelstellingen voor energie-efficiëntie verbetering of het terugdringen van de uitstoot van broeikasgassen binnen deze programma's, in de gevolgen van de invoering van dergelijke programma's op de verbetering van het energiemanagement, en in de impact van deze programma's op energiebesparing of de vermindering van de uitstoot van broeikasgassen. De centrale onderzoeksvraag van dit proefschrift is als volgt geformuleerd: "Wat is de impact van energie- en broeikasgasmanagement programma’s op het verbeteren van het energiemanagement in de praktijk, het versnellen van de energieefficiëntie verbetering en het beperken van de uitstoot van broeikasgassen in bedrijven?".

Operational modeling of a sustainable gas supply chain

Biogas production from codigestion of cattle manure and biomass can have a significant contribution to a sustainable gas supply when this gas is upgraded to specifications prescribed for injection into the national gas grid and injected into this grid. In this study, we analyzed such a gas supply chain in a Dutch situation. A model was developed with which the cost price per m n3 was presented as a function of scale level (m n3/hr). The hypothesis that transport costs increase with increasing scale level was confirmed although this is not the main factor influencing the cost price for the considered production scales. For farm-scale gas supply chains (approximately 150-250 m n3/h green gas), a significant improvement is expected from decreasing costs of digesters and upgrading installations, and efficiency improvement of digesters. In this study also practical sustainability criteria for such a supply chain were investigated. For this reason, the digestate from the digester should be used as a fertilizer. For larger scale levels, the number of transport movements and energy use in the supply chain seem to become a limiting factor with respect to sustainability. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Designing a green gas supply to meet regional seasonal demand

One of the issues concerning the replacement of natural gas by green gas is the seasonal pattern of the gas demand. When constant production is assumed, this may limit the injected quantity of green gas into a gas grid to the level of the minimum gas demand in summer. A procedure was proposed to increase thegas demand coverage in a geographical region, i.e., the extent to which natural gas demand is replaced by green gas. This was done by modeling flexibility into farm-scale green gas supply chains. The procedure comprises two steps. In the first step, the types and number of green gas production units are determined,based on a desired gas demand coverage. The production types comprise time-varying biogas production, non-continuous biogas production (only in winter periods with each digester having a specified production time) and constant production including seasonal gas storage. In the second step locations of production units and injection stations are calculated, using mixed integer linear programming with cost price minimization being the objective. Five scenarios were defined with increasing gas demand coverage, representing a possible future development in natural gas replacement. The results show that production locations differ for each scenario, but are connected to a selection of injection stations, at least in the considered geographical region under the assumed preconditions. The cost price is mainly determined by the type of digesters needed. Increasing gas demand coverage does not necessarily mean a much higher cost price.

Advances in gas-to-liquid technology for environmentally friendly fuel synthesis

Problems of energy security, diversification of energy sources, and improvement of technologies (including alternatives) for obtaining motor fuels have become a priority of science and practice today. Many scientists devote their scientific research to the problems of obtaining effective brands of alternative (reformulated) motor fuels. Our scientific school also deals with the problems of the rational use of traditional and alternative motor fuels.This article focused on advances in motor fuel synthesis using natural, associated, or biogas. Different raw materials are used for GTL technology: biomass, natural and associated petroleum gases. Modern approaches to feed gas purification, development of Gas-to-Liquid-technology based on Fischer–Tropsch synthesis, and liquid hydrocarbon mixture reforming are considered.Biological gas is produced in the process of decomposition of waste (manure, straw, grain, sawdust waste), sludge, and organic household waste by cellulosic anaerobic organisms with the participation of methane fermentation bacteria. When 1 tonne of organic matter decomposes, 250 to 500–600 cubic meters of biogas is produced. Experts of the Bioenergy Association of Ukraine estimate the volume of its production at 7.8 billion cubic meters per year. This is 25% of the total consumption of natural gas in Ukraine. This is a significant raw material potential for obtaining liquid hydrocarbons for components of motor fuels.We believe that the potential for gas-to-liquid synthetic motor fuels is associated with shale and coalfield gases (e.g. mine methane), methane hydrate, and biogas from biomass and household waste gases.

Will implementation of green gas into the gas supply be feasible in the future?

Energy efficiency, greenhouse gas reduction and cost price of a green gas supply chain were evaluated. This supply chain is based on co-digestion of dairy cattle manure and maize, biogas upgrading and injection into a distribution gas grid. A defined reference scenario reflects the current state of practice, assuming that input energy is from fossil origin. Possible improvements of this reference scenario were investigated. For this analysis two new definitions for energy input-output ratio were introduced; one based on input of primary energy from all origin, and one related to energy from fossil origin only. Switching from fossil to green electricity significantly improves the energy efficiency (both definitions) and greenhouse gas reduction. Preventing methane leakage during digestion and upgrading, and re-using heat within the supply chain show smaller improvements on these parameters as well as on cost price. A greenhouse gas reduction of more than 80 % is possible with current technology. To meet this high sustainability level, multiple improvement options will have to be implemented in the green gas supply chain. This will result in a modest decrease of the green gas cost price.