Optimal running and planning of a biomass-based energy production process

We propose mathematical programming models for solving problems arising from planning and running an energy production process based on burning biomasses. The models take into account different aspects of the problem: determination of the biomasses to produce and/or buy, transportation decisions to convey the materials to the respective plants, and plant site locations. Whereas the “running model” is linear, we propose two “planning models”, both of which are mixed-integer nonlinear programming problems. We show that a spatial branch-and-bound type algorithm applied to them is guaranteed to converge to an exact optimum in a finite number of steps.     

A regional decision support system for onsite renewable hydrogen production from solar and wind energy sources

Hydrogen technologies driven by renewable energy sources (RES) represent an attractive energy solution to ensure environmental sustainability. In this paper, a decision support system for the hydrogen exploitation is presented, focusing on some specific planning aspects. In particular, the planning aspects regard the selection of locations with high hydrogen production mainly based on the use of solar and wind energy sources. Four modules were considered namely, the evaluation of the wind and solar potentials, the analysis of the hydrogen potential, the development of a regional decision support module and a last module that regards the modelling of a hybrid onsite hydrogen production system. The overall approach was applied to a specific case study in Liguria region, in the north of Italy.     

A decision support system for strategic maintenance planning in offshore wind farms

This paper presents a Decision Support System (DSS) for maintenance cost optimisation at an Offshore Wind Farm (OWF). The DSS is designed for use by multiple stakeholders in the OWF sector with the overall goal of informing maintenance strategy and hence reducing overall lifecycle maintenance costs at the OWF. Two optimisation models underpin the DSS. The first is a deterministic model that is intended for use by stakeholders with access to accurate failure rate data. The second is a stochastic model that is intended for use by stakeholders who have less certainty about failure rates. Solutions of both models are presented using a UK OWF that is in construction as an example. Conclusions as to the value of failure rate data are drawn by comparing the results of the two models. Sensitivity analysis is undertaken with respect to the turbine failure rate frequency and number of turbines at the site, with near linear trends observed for both factors. Finally, overall conclusions are drawn in the context of maintenance planning in the OWF sector.     

Decision support system for exploiting local renewable energy sources: A case study of the Chigu area of southwestern Taiwan

The topic of climate and energy policy has drawn new attention since the Kyoto Protocol has now come into force. It is hoped that strengthened use of renewable energy sources can meet new international environmental requirements and provide self-sufficient domestic energy supplies. The decision support system established in this study integrates potential evaluations, cost analyses, legal incentives, and analysis of returns on investments with the aid of a geographic information system (GIS). This system can provide insights for policymakers into where and the extent of the potentials, for lawmakers into whether the current legal incentives are sufficient to encourage private investment, and for investors into whether investments in exploiting local renewable energy sources are economically feasible. Under the current incentive framework in Taiwan, the amortization periods of investment on renewable energy are generally longer than the period over which the investment is to be recovered. This presents an unfavorable condition for attracting investments to and for developing renewable energy. An increase in remuneration through legal revisions is needed before domestic investment in renewable energy will actively expand.     

Biomass energy production in agriculture: A weighted goal programming analysis

Energy production from biomasses can be an important resource that, when combined with other green energies such as wind power and solar plants, can contribute to reduce dependency on fossil fuels. The aim of this study is to assess how agriculture could contribute to the production of bio-energy. A multi-period Weighted Goal Programming model (MpWGP) has been applied to identify the optimal land use combinations that simultaneously maximise farmers' income and biomass energy production under three concurrent constraints: water, labour and soil availability. Alternative scenarios are considered that take into account the effect of climate change and social change. The MpWGP model was tested with data from the Rovigo county area (Italy) over a 15-year time period.     

Decarbonization synergies from joint planning of electricity and hydrogen production: A Texas case study

Hydrogen (H₂) shows promise as an energy carrier in contributing to emissions reductions from sectors which have been difficult to decarbonize, like industry and transportation. At the same time, flexible H₂ production via electrolysis can also support cost-effective integration of high shares of variable renewable energy (VRE) in the power system. In this work, we develop a least-cost investment planning model to co-optimize investments in electricity and H₂ infrastructure to serve electricity and H₂ demands under various low-carbon scenarios. Applying the model to a case study of Texas in 2050, we find that H₂ is produced in approximately equal amounts from electricity and natural gas under the least-cost expansion plan with a CO₂ price of $30–60/tonne. An increasing CO₂ price favors electrolysis, while increasing H₂ demand favors H₂ production from Steam Methane Reforming (SMR) of natural gas. H₂ production is found to be a cost effective solution to reduce emissions in the electric power system as it provides flexibility otherwise provided by natural gas power plants and enables high shares of VRE with less battery storage. Additionally, the availability of flexible electricity demand via electrolysis makes carbon capture and storage (CCS) deployment for SMR cost-effective at lower CO₂ prices ($90/tonne CO₂) than for power generation ($180/tonne CO₂). The total emissions attributable to H₂ production is found to be dependent on the H₂ demand. The marginal emissions from H₂ production increase with the H₂ demand for CO₂ prices less than $90/tonne CO₂, due to shift in supply from electrolysis to SMR. For a CO₂ price of $60/tonne we estimate the production weighted-average H₂ price to be between $1.30–1.66/kg across three H₂ demand scenarios. These findings indicate the importance of joint planning of electricity and H₂ infrastructure for cost-effective energy system decarbonization.     

Potential of renewable hydrogen production for energy supply in Hong Kong

Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.     

A superstructure model of an isolated power supply system using renewable energy: Development and application to Jeju Island,Korea

In this study, we aim to develop a superstructure-based optimization model using mixed integer linear programming (MILP) to determine the optimal combination and sizing for a hybrid renewable energy system to be used in an isolated area. The developed model has a three-layered energy structure to reflect the current reality in which energy production and consumption sites are generally separate. A variety of economic factors, including distance between facilities and an installation area, are considered for a more accurate estimation of the total annualized cost. Two types of optimization models, i.e., with and without a battery, are proposed to evaluate the economic and technical effects of a storage device to resolve operation issues caused by intermittent resources. An application case study on Jeju Island, Korea, confirms that the proposed model is suitable for decision making at the planning stage of a renewable energy system.     

On developing a prospecting tool for wind industry and policy decision support

This paper presents the rudiments of a Wind Prospecting Tool designed to inform private and public decision makers involved in wind industry development in reducing transaction costs associated with identifying areas of mutual focus within a state. The multiple layer decision support framework has proven to be valuable to industry, state government and local decision makers. Information on wind resources, land availability, potential land costs, potential NIMBYism concerns and economic development potential were integrated to develop a framework for decision support. The paper also highlights implications for decision support research and the role of higher education in providing anticipatory science to enhance private and public choices in economic development.     

Optimization of energy production system in the Dodecanese Islands

The ongoing depletion of the fossil fuels and the dependency of the economies on them have made the need for new sources of energy more obvious. Renewable energy sources (RES) can ensure the sustainable development of the communities, and especially of those in which RES are in abundance. This study deals with the exploitation of RES in the Dodecanese Islands. Specifically, it is examined the optimum percentage by which the renewable sources can participate in the energy production system. Three different scenarios are examined. The first scenario considers that the existent system should be used less than 75% for environmental reasons, in the second scenario, a minimization of the electricity production cost is sought without any environmental constraints, while in the third scenario, it is considered that the RES’ participation in the electricity production would be 30% at most according to the current legislation. The environmental impacts from the energy production are quantified and a comparison is made between the impacts resulting from the existing system and the system found from the first scenario, because this is the scenario with the highest penetration of the RES to the energy production system.     

UK renewable energy strategy The need for longer-term support

The UK renewable energy R&D programme is currently being cut back. The ‘near market’ technologies that it has identified are expected to be taken over by the private sector, with the support of the NFFO cross-subsidy. This paper explores the implication of this strategy for the more novel, less developed, renewables, which are unlikely to benefit from the NFFO. It argues that, as longer-term environmental costings are factored into the assessment, the currently less economically attractive technologies could become strategically important. In this situation, it is suggested, the cut backs in research would seem unwise.     

Economic assessment and comparison of acacia energy crop with annual traditional crops in Southern Europe

In several policy documents bioenergy is recognized as an important renewable energy source in Italy. The increase in energy prices represents an opportunity for lignocellulosic energy crops such as acacia and poplar.     

Wind park reliable energy production based on a hydrogen compensation system. Part I: Technical viability

Power production from renewable energy resources is increasing day by day. In the case of Spain, in 2009, it represents the 26.9% of installed power and 20.1% of energy production. Wind energy has the most important contribution of this production. Wind generators are greatly affected by the restrictive operating rules of electricity markets because, as wind is naturally variable, wind generators may have serious difficulties on submitting accurate generation schedules on a day ahead basis, and on complying with scheduled obligations. Weather forecast systems have errors in their predictions depending on wind speed. Thus, if wind energy becomes an important actor in the energy production system, these fluctuations could compromise grid stability. In this study technical and economical viability of a large scale compensation system based on hydrogen is investigated, combining wind energy production with a biomass gasification system. Combination of two systems has synergies that improve final results. In the economical study, it is considered that all hydrogen production that is not used to compensate wind energy could be sold to supply the transportation sector.     

Wind park reliable energy production based on a hydrogen compensation system. Part II: Economic study

Power production from renewable energy resources is increasing day by day. In the case of Spain, in 2009 it represented 26.9% of installed power and 20.1% of energy production. Wind energy makes the most important contribution to this production. Wind generators are greatly affected by the restrictive operating rules of electricity markets because, as wind is naturally variable, wind generators may have serious difficulties in submitting accurate generation schedules on a day-ahead basis, and in complying with scheduled obligations. Weather forecast systems have errors in their predictions depending on wind speed. Therefore, if wind energy becomes an important actor in the energy production system, these fluctuations could compromise grid stability. In the previous paper in this brief series [1], the authors showed technical results of the proposed solution, which consists of combining wind energy production with a biomass gasification system and a hydrogen generation system based on these two sources. In the present paper it is shown the economic results of the study, considering the most profitable technical configurations and three possible economic scenarios.     

Power management control for off-grid solar hydrogen production and utilisation system

Climate change concerns, increasing global energy demand, coupled with pending peak supply of fossil fuels, calls for development of new power source. The rapid price drops for solar technologies and combined with international and national policy changes makes solar energy more affordable and accessible for widespread adoption. Solar energy also contributes towards the reduction of greenhouse gas emissions. The combination of electrolysis of water and fuel cells, which use hydrogen as an energy carrier extends the utility of the solar energy. For an integrated solar powered hydrogen production, storage and utilisation system, one of the elements that needs to be designed carefully is the power management system. Power management strategy has a complex function in this type of solar hydrogen system. This paper presents a power management strategy based on fuzzy logic technology to address the problems.     

A hybrid model for the optimum integration of renewable technologies in power generation systems

The main purpose of this work is to assess the unavoidable increase in the cost of electricity of a generation system by the integration of the necessary renewable energy sources for power generation (RES-E) technologies in order for the European Union Member States to achieve their national RES energy target. The optimization model developed uses a genetic algorithm (GA) technique for the calculation of both the additional cost of electricity due to the penetration of RES-E technologies as well as the required RES-E levy in the electricity bills in order to fund this RES-E penetration. Also, the procedure enables the estimation of the optimum feed-in-tariff to be offered to future RES-E systems. Also, the overall cost increase in the electricity sector for the promotion of RES-E technologies, for the period 2010–2020, is analyzed taking into account factors, such as, the fuel avoidance cost, the carbon dioxide emissions avoidance cost, the conventional power system increased operation cost, etc. The overall results indicate that in the case of RES-E investments with internal rate of return (IRR) of 10% the cost of integration is higher, compared to RES-E investments with no profit, (i.e., IRR at 0%) by 0.3–0.5 €c/kWh (in real prices), depending on the RES-E penetration level.     

Optimal design of the distributed H2 production system with cost and safety considerations

H₂ is an important commodity chemical that can also be used as an alternative fuel. The way how H₂ is currently produced and distributed, however, is not compatible with this usage. This is primarily due to the high costs associated with storing and delivering H₂ from the centralized production facilities to the end-use sites like H₂ stations that will be distributed throughout a region. Here, we propose a methodology for configuring the distributed H₂ production system that minimizes the overall cost in delivering H₂ to demand sites while meeting the safety requirements. The methodology also takes into account changes in costs with respect to production volume by applying the concept of economy of scale. The proposed methodology is applied to a hypothetical case involving H₂ supply to three stations. The results demonstrate significant reduction in the overall cost when adopting the optimal solution found by our methodology compared to the traditional, centralized production system. Insights on the cost structures associated with producing and delivering H₂ are provided, as well as specific improvements required to make H₂ affordable at the level defined by the international society.     

Hydrogen supply scenarios for a climate neutral energy system in Germany

A climate neutral energy system in Germany will most likely require green hydrogen. Two important factors, that determine whether the hydrogen will be imported or produced locally from renewable energy are still uncertain though - the import price for green hydrogen and the upper limit for photovoltaic installations. To investigate the impact of these two factors, the authors calculate cost optimized climate neutral energy systems while varying the import price from 1.25 €/kg to 5 €/kg with unlimited import volume and the photovoltaic limit from 300 GW to unlimited. In all scenarios, hydrogen plays a significant role. At a medium import price of 3.75 €/kg and photovoltaic limits of 300–900 GW the hydrogen supply is around 1200 to 1300 TWh with import shares varying from 60 to 85%. In most scenarios the electrolysis profile is highly correlated with the photovoltaic power, which leads to full load hours of 1870 h–2770 h.     

Performance evaluation of renewable energy support policies,applied on Flanders’ tradable certificates system

The article is composed as a diptych. First, a general framework of criteria to evaluate the performance of renewable energy support systems is elaborated. It is built around the main criteria effectiveness, efficiency and equity. All three are multi-layered and specifying the contents of the various layers is case dependent. Second, the framework is applied on detailed data about the Flemish tradable certificates support system.     

Exploring the feasibility of green hydrogen production using excess energy from a country-scale 100% solar-wind renewable energy system

When planning large-scale 100% renewable energy systems (RES) for the year 2050, the system capacity is usually oversized for better supply-demand matching of electrical energy since solar and wind resources are highly intermittent. This causes excessive excess energy that is typically dissipated, curtailed, or sold directly. The public literature shows a lack of studies on the feasibility of using this excess for country-scale co-generation. This study presents the first investigation of utilizing this excess to generate green hydrogen gas. The concept is demonstrated for Jordan using three solar photovoltaic (PV), wind, and hybrid PV-wind RESs, all equipped with Lithium-Ion battery energy storage systems (ESSs), for hydrogen production using a polymer electrolyte membrane (PEM) system. The results show that the PV-based system has the highest demand-supply fraction (>99%). However, the wind-based system is more favorable economically, with installed RES, ESS, and PEM capacities of only 23.88 GW, 2542 GWh, and 20.66 GW. It also shows the highest hydrogen annual production rate (172.1 × 10³ tons) and the lowest hydrogen cost (1.082 USD/kg). The three systems were a better option than selling excess energy directly, where they ensure annual incomes up to 2.68 billion USD while having payback periods of as low as 1.78 years. Furthermore, the hydrogen cost does not exceed 2.03 USD/kg, which is significantly lower than the expected cost of hydrogen (3 USD/kg) produced using energy from fossil fuel-based systems in 2050.