| 1. |
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| 2. |
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| 3. |
- Qasim, Muhammad, et al.
(författare)
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Dataset of knowledge, attitude, practices and psychological implications of healthcare workers in Pakistan during COVID-19 pandemic
- 2020
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Ingår i: Data in Brief. - : Elsevier. - 2352-3409. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has created a global health emergency and has a huge impact on the health care workers, especially on their mental health. The dataset presented was an assessment of COVID-19 related knowledge, attitude, practices and its effects on the mental health of frontline healthcare workers in Pakistan. The data were collected using a snowball sampling technique. A questionnaire was developed assessing sociodemographic characteristics (6 items), knowledge (11 items), attitude (5 items), practices (6 items), information sources (1 item) and psychological implications (12 items) and distributed using online tools. The dataset includes 476 healthcare workers in Pakistan. The dataset will help to prevent and curb the spread of COVID-19 among health workers and contribute to policymakers. Furthermore, our dataset provides detailed insights into different risk factors of psychological problems, and it may be served as the reference for various in-depth surveys.
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| 4. |
- Saqib, M. A. N., et al.
(författare)
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Effect of COVID-19 lockdown on patients with chronic diseases
- 2020
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Ingår i: Diabetes & Metabolic syndrome. - : Elsevier. - 1871-4021 .- 1878-0334. ; 14:6, s. 1621-1623
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: We sought to measure the effect of lockdown, implemented to contain COVID-19 infection, on routine living and health of patients with chronic diseases and challenges faced by them. Methods: A semi-structured online questionnaire was generated using “Google forms” and sent to the patients with chronic diseases using WhatsApp. Data were retrieved and analyzed using SPSS. Results: Out of 181 participants, 98% reported effect of lockdown on their routine living while 45% reported an effect on their health. The key challenges due to lockdown were to do daily exercise, missed routine checkup/lab testing and daily health care. Conclusion: It is important to strategize the plan for patients with chronic diseases during pandemic or lockdown.
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| 5. |
- Siddiqui, Afzal S., 1975-, et al.
(författare)
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Ambiguities and nonmonotonicities under prosumer power : Optimal distributed energy resource investment in a deregulated electricity industry
- 2022
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Ingår i: TOP - An Official Journal of the Spanish Society of Statistics and Operations Research. - : Springer Science and Business Media LLC. - 1134-5764 .- 1863-8279. ; 30:3, s. 492-532
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Tidskriftsartikel (refereegranskat)abstract
- Prosumers adopt distributed energy resources (DER) to cover part of their own consumption and to sell surplus energy. Although individual prosumers are too dispersed to exert operational market power, they may collectively hold a strategic advantage over conventional generation in selecting DER capacity via aggregators. We devise a bilevel model to examine DER capacity sizing by a collective prosumer as a Stackelberg leader in an electricity industry where conventional generation may exert market power in operations. At the upper level, the prosumer chooses DER capacity in anticipation of lower-level operations by conventional generation and DER output. We demonstrate that exertion of market power in operations by conventional generation and the marginal cost of conventional generation affect DER investment by the prosumer in a nonmonotonic manner. Intuitively, in an industry where conventional generation exerts market power in operations similar to a monopoly (MO), the prosumer invests in more DER capacity than under perfectly competitive operations (PC) to take advantage of a high market-clearing price. However, if the marginal cost of conventional generation is high enough, then this intuitive result is reversed as the prosumer adopts more DER capacity under PC than under MO. This is because the high marginal cost of conventional generation prevents the market-clearing price from decreasing, thereby allowing for higher prosumer revenues. Moreover, competition relieves the chokehold on consumption under MO, which further incentivises the prosumer to expand DER capacity to capture market share. We prove the existence of a critical threshold for the marginal cost of conventional generation that leads to this counterintuitive result. Finally, we propose a countervailing regulatory mechanism that yields welfare-enhancing DER investment even in deregulated electricity industries.
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| 6. |
- Boonman, Hettie J., et al.
(författare)
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Capacity optimization under uncertainty : The impact of operational time lags
- 2017
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 262:2, s. 660-672
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Tidskriftsartikel (refereegranskat)abstract
- Time lags in switching operational modes are typical in the manufacturing and power sectors but are not treated in most real options models. In this paper, we consider a firm that has the opportunity to suspend and to resume production infinitely many times subject to a time lag after each startup decision. We contribute to the literature by allowing the firm to determine its level of installed capacity in conjunction with its optimal investment timing. We find that an increase in the length of the time lag results in an increase in the optimal capacity level. Capacity optimization also interacts with the length of the time lag to affect investment timing and the triggers to suspend and resume production, thereby weakening the result about hysteresis from a standard real options model. Under the assumption of a fixed level of capacity, a longer lag speeds up the decision to resume operations due to a positive upside to the revenue but delays the suspension of operations. By contrast, with capacity optimization, a longer time lag results in a larger capacity choice, which can indirectly delay the investment decision and the timing to resume operations. This indirect effect dominates when the level of market uncertainty is low and the time lag is initially small.
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| 7. |
- Chen, Yihsu, et al.
(författare)
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Market Power with Tradable Performance-Based CO2 Emission Standards in the Electricity Sector
- 2018
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Ingår i: Energy Journal. - : International Association for Energy Economics (IAEE). - 0195-6574 .- 1944-9089. ; 39:6, s. 121-145
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Tidskriftsartikel (refereegranskat)abstract
- The U.S. Clean Power Plan stipulates a state-specific performance-based CO2 emission standard, delegating states with considerable flexibility for using either a tradable performance-based or a mass-based permit program. This paper analyzes these two standards under imperfect competitive. We limit our attention to (1) short-run analyses and (2) a situation in which all states are subject to the same type of standard. We show that while the cross-subsidy inherent in the performance-based standard might effectively reduce power prices, it could also inflate energy consumption. A dominant firm with a relatively clean endowment under the performance-based standard would be able to manipulate the electricity market as well as to elevate permit prices, which might worsen market outcomes compared to its mass-based counterpart. On the other hand, the "cross-subsidy" could be the dominant force leading to a higher social welfare if the leader has a relatively dirty endowment.
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| 8. |
- Chen, Yihsu, et al.
(författare)
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Tradable Performance-Based CO₂ Emissions Standards : Walking on Thin Ice?
- 2016
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Ingår i: Energy: Expectations and Uncertainty. - : International Association for Energy Economics. ; , s. 1-28
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Climate policy, like climate change itself, is subject to debate. Partially due to the political deadlock in Washington, DC, US climate policy, historically, has been driven mainly by state or regional effort until the recently introduced federal Clean Power Plan (CPP). Instead of a traditional mass-based standard, the US CPP stipulates a state-specific performance-based CO2 emission standard and delegates considerable flexibility to the states in achieving the standard. Typically, there are two sets of policy tools available: a tradable performance-based and a mass-based permit program. We analyze these two related but distinct standards when they are subject to imperfect competition in the product and/or permit markets. Stylized models are developed to produce general conclusions. Detailed models that account for heterogenous technologies and the transmission network are developed to evaluate policy efficiency. Depending on the scenarios under consideration, the resulting problem could be either a complementarity problem or a Stackelberg leaderfollower game, which is implemented as a mathematical program with equilibrium constraints (MPEC). We overcome the nonconvexity of MPECs by reformulating them as mixed integer problems. We show that while the cross-subsidy inherent in the performance-based standard that might effectively reduce power prices, it could inflate energy demand, thereby rendering permits scarce. When the leader in a Stackelberg formulation has a relatively clean endowment under the performancebased standard, its ability to manipulate the electricity market as well as to lower permit prices might worsen the market outcomes compared to its mass-based counterpart. On the other hand, when the leader has a relatively dirty endowment, the "cross-subsidy" could be the dominant force leading to a higher social welfare compared to the mass-based program. This paper contributes to the current policy debates in regulating emissions from the US power sector and highlights different incentives created by the mass- and performance-based standards.
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| 9. |
- Debia, Sebastien, et al.
(författare)
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Strategic storage use in a hydro-thermal power system with carbon constraints
- 2021
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Ingår i: Energy Economics. - : Elsevier BV. - 0140-9883 .- 1873-6181. ; 98
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Tidskriftsartikel (refereegranskat)abstract
- Several interconnected power systems worldwide have largely thermal and hydro production along with CO2 cap-and-trade (C&T) systems and variable renewable energy sources (VRES). C&T policies increase VRES generation, and socially optimal storage deployment could integrate VRES output. However, hydro reservoirs may be used strategically due to market power. We investigate these distortions and assess measures for their mitigation via a bottom-up equilibrium model of New York and Quebec. In particular, we find evidence that hydro producers shift water between seasons to manipulate electricity prices even under a net-hydro production constraint. Alternative regulation covering net imports as well as net-hydro production limits such temporal arbitrage but enables firms with both thermal generation and pumped-hydro storage to exercise spatial arbitrage. We demonstrate that these distortions will be exacerbated under more stringent C&T policies because price-taking thermal producers are less able to respond to price signals.
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| 10. |
- Debia, Sébastien, et al.
(författare)
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Strategic use of storage : The impact of carbon policy, resource availability, and technology efficiency on a renewable-thermal power system
- 2019
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Ingår i: Energy Economics. - : Elsevier BV. - 0140-9883 .- 1873-6181. ; 80, s. 100-122
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Tidskriftsartikel (refereegranskat)abstract
- Concerns about climate change have spurred governments to reduce carbon emissions by supporting adoption of renewable energy (RE) technologies. Due to the intermittent and location-specific nature of RE technologies, energy storage has become important because it could be used to smooth out temporal disparities in residual demand. Thus, carbon policy has made storage-enabled RE generation more critical to the power sector, and this enhanced position could be exploited by firms to exert market power. Using an equilibrium model, we examine the implications of policy interventions and technological change on the marginal value of energy storage in a power market with RE and thermal generation. In particular, we specify the market conditions under which RE producers with storage strategically shift deployment of their resource to the off-peak period and outline its implications for the marginal value of RE storage. Moreover, we find that even price-taking RE producers may actually increase off-peak RE production as storage efficiency increases. Consequently, the RE producer's profit decreases with storage efficiency, which conflicts with the social objective of improving storage efficiency. These private and social incentives can be better aligned via a carbon tax, however. Hence, our results may inform the regulatory process governing market design of a power sector with increasing capacities of RE generation and storage.
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| 11. |
- Egging-Bratseth, Ruud, et al.
(författare)
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Stochastic equilibria with capacity expansion: Increasing expected profit with risk aversion
- 2023
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Ingår i: Decision Analytics Journal. - 2772-6622. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Profit-maximizing firms hedge risk from uncertainty by deciding on capacity investment and production. Typically, risk-averse firms monotonically forgo expected profit in exchange for an improved risk measure, e.g., conditional value-at-risk (CVaR). However, the stochastic-equilibrium literature exhibits non-monotonicities, i.e., both CVaR and expected profit increase with risk aversion. We prove that this result arises because oligopolistic firms account for the price impacts of their own decisions but ignore those of other firms. Consequently, firms reduce capacity “too much” with risk aversion.
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| 12. |
- Hassanzadeh Moghimi, Farzad, et al.
(författare)
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Aggregator-Enabled Prosumers' Impact on Strategic Hydro-Thermal Operations
- 2023
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Ingår i: Proceedings of the Annual Hawaii International Conference on System Sciences. - 9780998133164 ; , s. 2693-2702
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Konferensbidrag (refereegranskat)abstract
- Climate packages envisage decarbonization of the power system and electrification of the wider economy via variable renewable energy (VRE). These trends facilitate the rise of aggregator-enabled prosumers and engender demand for flexibility. By exploiting conducive geography, e.g., in the Nordic region, hydro reservoirs can mitigate VRE's intermittency. Nevertheless, hydro producers may leverage this increased need for flexibility to exert market power through temporal arbitrage. Using a Nash-Cournot model, we examine how aggregator-enabled prosumers with endogenous loads and VRE capacity interact with other agents to affect market outcomes. Based on Nordic data, we find that hydro producers enhance their market power by shifting their production away from periods in which prosumers are net buyers and "dumping" their output during periods in which prosumers are net sellers. Hence, jurisdictions that rely upon (hydro) storage to integrate VRE from prosumers will need to be wary of incumbent firms' incentives to manipulate prices.
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| 13. |
- Hassanzadeh Moghimi, Farzad, 1994-, et al.
(författare)
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Climate Policy and Strategic Operations in a Hydro-Thermal Power System
- 2023
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Ingår i: Energy Journal. - : International Association for Energy Economics (IAEE). - 0195-6574 .- 1944-9089. ; 44:5, s. 67-94
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Tidskriftsartikel (refereegranskat)abstract
- Decarbonisation of the Nordic power sector entails substantial variable renewable energy (VRE) adoption. While Nordic hydropower reservoirs can mitigate VRE output's intermittency, strategic hydro producers may leverage increased flexibility requirements to exert market power. Using a Nash-Cournot model, we find that even the current Nordic power system could yield modest gains from strategic reservoir operations regardless of a prohibition on "spilling" water to increase prices. Instead, strategic hydro producers could shift generation from peak to off-peak seasons. Such temporal arbitrage becomes more attractive under a climate package with a €100/t CO2 price and doubled VRE capacity. Since the package increases generation variability, lowers average prices, and makes fossil-fuelled plants unprofitable, strategic hydro producers face lower opportunity costs in shifting output from peak to off-peak seasons and encounter muted responses from price-taking fossil-fuelled plants. Hence, a climate package that curtails CO2 emissions may also bolster strategic hydro producers' leverage.
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| 14. |
- Hassanzadeh Moghimi, Farzad, et al.
(författare)
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Flexible supply meets flexible demand : prosumer impact on strategic hydro operations
- 2023
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Ingår i: Computational Management Science. - 1619-697X .- 1619-6988. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Ambitious climate packages promote the integration of variable renewable energy (VRE) and electrification of the economy. For the power sector, such a transformation means the emergence of so-called prosumers, i.e., agents that both consume and produce electricity. Due to their inflexible VRE output and flexible demand, prosumers will potentially add endogenous net sales with seasonal patterns to the power system. With its vast hydro reservoirs and ample transmission capacity, the Nordic region is seemingly well positioned to cope with such intermittent VRE output. However, the increased requirement for flexibility may be leveraged by incumbent producers to manipulate prices. Via a Nash-Cournot model with a representation of the Nordic region’s spatio-temporal features and reservoir volumes, we examine how hydro producers’ ability to manipulate electricity prices through temporal arbitrage is affected by (i) VRE-enabled prosumers and (ii) the latter plus a high CO22 price. We find that hydro reservoirs could exploit prosumers’ patterns of net sales to conduct temporal arbitrage more effectively, viz., by targeting periods in which prosumers are net buyers (net sellers) to withhold (to “dump”) water. Meanwhile, a higher CO22 price would further enhance hydro reservoirs’ market power because flexible price-taking thermal plants would be unable to ramp up production in order to counter such producers’ strategy to target VRE’s intermittency. Hence, in spite of a flexible demand side to complement additional intermittent VRE output, strategic hydro producers may still exacerbate price manipulation in a future power sector via more tailored exercise of market power.
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| 15. |
- Heydari, S., et al.
(författare)
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Real options analysis of investment in carbon capture and sequestration technology
- 2012
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Ingår i: Computational Management Science. - : Springer Science and Business Media LLC. - 1619-697X .- 1619-6988. ; 9:1, s. 109-138
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Tidskriftsartikel (refereegranskat)abstract
- Among a comprehensive scope of mitigation measures for climate change, CO 2 capture and sequestration (CCS) plays a potentially significant role in industrialised countries. In this paper, we develop an analytical real options model that values the choice between two emissions-reduction technologies available to a coal-fired power plant. Specifically, the plant owner may decide to invest in either full CCS (FCCS) or partial CCS (PCCS) retrofits given uncertain electricity, CO 2, and coal prices. We first assess the opportunity to upgrade to each technology independently by determining the option value of installing a CCS unit as a function of CO 2 and fuel prices. Next, we value the option of investing in either FCCS or PCCS technology. If the volatilities of the prices are low enough, then the investment region is dichotomous, which implies that for a given fuel price, retrofitting to the FCCS (PCCS) technology is optimal if the CO 2 price increases (decreases) sufficiently. The numerical examples provided in this paper using current market data suggest that neither retrofit is optimal immediately. Finally, we observe that the optimal stopping boundaries are highly sensitive to CO 2 price volatility.
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| 16. |
- Kauppinen, Lauri, et al.
(författare)
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Investing in Time-to-Build Projects With Uncertain Revenues and Costs : A Real Options Approach
- 2018
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Ingår i: IEEE transactions on engineering management. - 0018-9391 .- 1558-0040. ; 65:3, s. 448-459
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Tidskriftsartikel (refereegranskat)abstract
- Lagging public-sector investment in infrastructure and the deregulation of many industries mean that the private sector has to make decisions under multiple sources of uncertainty. We analyze such investment decisions by accounting for both multiple sources of uncertainty and the time-to-build aspect. The latter feature arises in the energy and transportation sectors, because investors can decide the rate at which the project is completed. Furthermore, two explicit sources of uncertainty represent the discounted cash inflows and outflows of the completed project. We use a finite-difference scheme to solve numerically the option value and the optimal investment threshold. Somewhat counterintuitively, with a relatively long time to build, a reduction in the growth rate of the discounted operating cost may actually lower the investment threshold. This is contrary to the outcome when the stepwise aspect is ignored in a model with uncertain price and cost. Hence, research and development efforts to enhance emerging technologies may be more relevant for infrastructure projects with long lead times.
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| 17. |
- Lavrutich, Maria, et al.
(författare)
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Transmission Investment under Uncertainty : Reconciling Private and Public Incentives
- 2022
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 304:3, s. 1167-1188
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Tidskriftsartikel (refereegranskat)abstract
- Private companies (PCs) in restructured electricity industries determine facility investment timing and sizing. Such decisions maximize the PC’s expected profit (rather than social welfare) under uncertainty. By anticipating the PC’s incentives, a welfare-maximizing transmission system operator (TSO) shapes the network to align public and private objectives. Via an option-based approach, we first quantify welfare losses from the PC’s and TSO’s conflicting objectives. We show that by anticipating the optimal timing and capacity decisions of the profit-maximizing PC, the TSO is able to reduce, though not eliminate, welfare loss. Next, we exploit the dependence of the PC’s capacity on the TSO’s infrastructure design to devise a proactive transmission-investment strategy. Hence, we mitigate welfare losses arising from misaligned incentives even in relatively uncertain markets.
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| 18. |
- Maurovich-Horvat, Lajos, et al.
(författare)
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Optimal Operation of Combined Heat and Power under Uncertainty and Risk Aversion
- 2016
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 110, s. 415-425
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Tidskriftsartikel (refereegranskat)abstract
- Despite the proven benefits of combined heat and power (CHP) and recently introduced subsidies to support it, CHP adoption has not met its targets. One of the possible reasons for this is risk from uncertain electricity and gas prices. To gain insights into the risk management of a CHP unit, we develop a multi-stage stochastic mean-risk optimisation model for the medium-term management of a distributed generation system with a gas-fired microturbine with heat recovery and a boiler. The model adopts the perspective of a large consumer that procures gas (for on-site generation) and electricity (for consumption) on the spot and futures markets. The consumer's risk aversion is incorporated into the model through the conditional value-at-risk (CVaR) measure. We show that CHP not only decreases the consumer's expected cost and risk exposure by 10% each but also improves expected energy efficiency by 4 percentage points and decreases expected CO2 emissions by 16%. The risk exposure can be further mitigated through the use of financial contracts.
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| 19. |
- Maurovich-Horvat, Lajos, et al.
(författare)
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Optimal Selection of Distributed Energy Resources under Uncertainty and Risk Aversion
- 2016
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Ingår i: IEEE transactions on engineering management. - 0018-9391 .- 1558-0040. ; 63:4, s. 462-474
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Tidskriftsartikel (refereegranskat)abstract
- The adoption of small-scale electricity generation has been hindered by uncertain electricity and gas prices. In order to overcome this barrier to investment, we develop a mean-risk optimization model for the long-term risk management problem of an energy consumer using stochastic programming. The consumer can invest in a number of generation technologies, and also has access to electricity and gas futures to reduce its risk. We examine the role of on-site generation in the consumer's riskmanagement strategy, as well as interactions between on-site generation and financial hedges. Our study shows that by swapping electricity (with high price volatility) for gas (with low price volatility), even relatively inefficient technologies reduce risk exposure and CO2 emissions. The capability of on-site generation is enhanced through the use of combined heat and power (CHP) applications. In essence, by investing in a CHP unit, a consumer obtains the option to use on-site generation whenever the electricity price peaks, thereby reducing its financial risk. Finally, in contrast to the extant literature, we demonstrate that on-site generation affects the consumer's decision to purchase financial hedges. In particular, while on-site generation and electricity futures may act as substitutes, on-site generation and gas futures can function as complements.
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| 20. |
- Momber, Ilan, et al.
(författare)
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Risk averse scheduling by a PEV aggregator under uncertainty
- 2015
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Ingår i: IEEE Transactions on Power Systems. - 0885-8950 .- 1558-0679. ; 30:2, s. 882-891
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Tidskriftsartikel (refereegranskat)abstract
- Research on electric power systems has considered the impact of foreseeable plug-in electric vehicle (PEV) penetration on its regulation, planning, and operation. Indeed, detailed treatment of PEV charging is necessary for efficient allocation of resources. It is envisaged that a coordinator of charging schedules, i.e., a PEV aggregator, could exercise some form of load control according to electricity market prices and network charges. In this context, it is important to consider the effects of uncertainty of key input parameters to optimization algorithms for PEV charging schedules. However, the modeling of the PEV aggregator's exposure to profit volatility has received less attention in detail. Hence, this paper develops a methodology to maximize PEV aggregator profits taking decisions in day-ahead and balancing markets while considering risk aversion. Under uncertain market prices and fleet mobility, the proposed two-stage linear stochastic program finds optimal PEV charging schedules at the vehicle level. A case study highlights the effects of including the conditional value-at-risk (CVaR) term in the objective function and calculates two metrics referred to as the expected value of aggregation and flexibility.
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| 21. |
- Poemsl, Tobias F., et al.
(författare)
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Operational planning of distributed energy generation for a semiconductor fabrication plant : [Operative Planung dezentralisierter Energieerzeugung für eine Halbleiterproduktionsanlage]
- 2022
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Ingår i: e & i : Elektrotechnik und Informationstechnik. - : Springer Science and Business Media LLC. - 0932-383X .- 1613-7620. ; 139:8, s. 662-672
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Tidskriftsartikel (refereegranskat)abstract
- The semiconductor industry is well known for its high resource consumption due to its clean room usage and power-intensive manufacturing technology. This is a significant financial burden for semiconductor fabrication plant owners who wish to minimize the cost needed to cover the electricity and gas loads for their daily operations. From a historical perspective, those electricity and gas cost reductions have been enabled by more energy-efficient manufacturing technologies. Due to the complexity of factors influencing the energy system of a semiconductor plant, other aspects have often been neglected and also not been studied intensively in the academic literature so far. One possibility for reducing energy costs is the integration of a microgrid as on-site distributed energy resources (DER) may offer a less cost-intensive way to supply the energy needed. Therefore, this paper seeks to answer the following research question: How much expected cost can be saved and risk mitigated at a semiconductor fabrication plant via DER? More precisely, in this paper, a microgrid at a semiconductor fabrication plant that has installed DER with combined heat and power (CHP) applications and demand response (DR) is used to simulate the expected annual energy costs under given uncertain electricity and gas prices at different installed capacity levels. A simulation-based approach is used to evaluate several DER capacity sizes. The results of the simulation show that installations of DER at a semiconductor microgrid can dominate the base case of doing nothing, considering the expected minimized cost, the expected CO2 emissions, and conditional value-at-risk (CVaR). In fact, DER can reduce the expected annual energy bill by up to 6%, whereas annual expected CO2 emissions can even be reduced by up to 22%. Moreover, with DER, a microgrid’s risk is reduced as it can react to market conditions and local demand. Additionally, the true potential of microgrid cost savings can only be enabled when DR is allowed and proves particularly effective when energy prices are more volatile.
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| 22. |
- Reichenberg, Lina, 1976, et al.
(författare)
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Policy implications of downscaling the time dimension in power system planning models to represent variability in renewable output
- 2018
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 159, s. 870-877
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Tidskriftsartikel (refereegranskat)abstract
- Due to computational constraints, power system planning models are typically unable to incorporate full annual temporal resolution. In order to represent the increased variability induced by large amounts of variable renewable energy sources, two methods are investigated to reduce the time dimension: the integral approach (using typical hours based on demand and renewable output) and the representative days method (using typical days to capture annual variability). These two approaches are tested with a benchmark implementation that incorporates full time representation in order identify their suitability for assessing power systems with high renewable penetration. The integral method predicts renewable capacities within a 10% error margin, this paper's main performance metric, using just 32 time steps, while the representative days approach needs 160–200 time steps before providing similarly accurate renewable capacity estimates. Since the integral method generally cannot handle variation management, such as trade and storage, without enhancing the state-space representation, it may be more applicable to one-node models, while the representative days method is suitable for multi-regional models. In order to assess power systems with increasing renewable policy targets, models should be designed to handle at least the 160 time steps needed to provide results that do not systematically overestimate the renewable capacity share.
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| 23. |
- Rintamäki, Tuomas, et al.
(författare)
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Does renewable energy generation decrease the volatility of electricity prices? An analysis of Denmark and Germany
- 2017
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Ingår i: Energy Economics. - : Elsevier BV. - 0140-9883 .- 1873-6181. ; 62, s. 270-282
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Tidskriftsartikel (refereegranskat)abstract
- Although variable renewable energy (VRE) technologies with zero marginal costs decrease electricity prices, the literature is inconclusive about how the resulting shift in the supply curves impacts price volatility. Because the flexibility to respond to high peak and low off-peak prices is crucial for demand-response applications and may compensate for the losses of conventional generators caused by lower average prices, there is a need to understand how the penetration of VRE affects volatility. In this paper, we build distributed lag models with Danish and German data to estimate the impact of VRE generation on electricity price volatility. We find that in Denmark wind power decreases the daily volatility of prices by flattening the hourly price profile, but in Germany it increases the volatility because it has a stronger impact on off-peak prices. Our analysis suggests that access to flexible generation capacity and wind power generation patterns contribute to these differing impacts. Meanwhile, solar power decreases price volatility in Germany. By contrast, the weekly volatility of prices increases in both areas due to the intermittency of VRE. Thus, policy measures for facilitating the integration of VRE should be tailored to such region-specific patterns.
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| 24. |
- Rintamäki, Tuomas, et al.
(författare)
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How much is enough? Optimal support payments in a renewable-rich power system
- 2016
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 117:1, s. 300-313
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Tidskriftsartikel (refereegranskat)abstract
- The large-scale deployment of intermittent renewable energy sources may cause substantial power imbalance. Together with the transmission grid congestion caused by the remoteness of these sources from load centers, this creates a need for fast-adjusting conventional capacity such as gas-fired plants. However, these plants have become unprofitable because of lower power prices due to the zero marginal costs of renewables. Consequently, policymakers are proposing new measures for mitigating balancing costs and securing supply. In this paper, we take the perspective of the regulator to assess the effectiveness of support payments to flexible generators. Using data on the German power system, we implement a bi-level programming model, which shows that such payments for gas-fired plants in southern Germany reduce balancing costs and can be used as part of policy to integrate renewable energy.
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| 25. |
- Rintamäki, Tuomas, et al.
(författare)
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Strategic offering of a flexible producer in day-ahead and intraday power markets
- 2020
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 284:3, s. 1136-1153
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Tidskriftsartikel (refereegranskat)abstract
- The increase in intraday electricity market volumes due to intermittent renewable generation may give a strategic producer an opportunity to exert market power. We study offering strategies of a flexible producer in day-ahead and intraday markets using a bi-level model in which the upper level represents the profit-maximization problem of the producer and the lower-level problems clear the day-ahead and intraday markets sequentially. Using a three-node network, we first demonstrate that a flexible producer with perfect forecasts can increase its profit in both markets by coordinating its offer so as to cause transmission grid congestion or lack of competitive generation capacity. Moreover, we show that strategic behavior is possible even when the day-ahead and intraday markets are cleared simultaneously to lower balancing costs. We next assess these market designs in a Nordic test network and offer an explanation for high Nordic intraday prices. Finally, via an annual simulation using the Nordic market data, we verify that strategic offering in day-ahead and intraday markets under imperfect forecasts leads to increased profits vis-a-vis perfect competition but are mitigated through simultaneous market clearing.
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| 26. |
- Rocha, Paula, et al.
(författare)
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Energy-efficient building retrofits : An assessment of regulatory proposals under uncertainty
- 2016
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 101, s. 278-287
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Tidskriftsartikel (refereegranskat)abstract
- Improving energy efficiency in European Union buildings will require retrofitting much of the existing stock due to limited new construction opportunities. Given uncertainty in energy prices and technology costs stemming from deregulation, a stochastic optimisation framework is desirable for long-term decision support. We synthesise treatment of uncertainty and risk management to obtain insights about the impact of retrofits on energy consumption, costs, CO2 emissions, and risk at real buildings in Austria and Spain. The optimal strategy for the Spanish site is to invest in photovoltaic and solar thermal technologies. This lowers expected costs by 8.5% and reduces expected primary energy consumption and CO2 emissions by 20% relative to using existing equipment. By limiting exposure to volatile energy prices, the strategy also yields a nearly 10% reduction in risk. We obtain similar results also for the Austrian site. Via this framework, tradeoffs among competing objectives and the effectiveness of proposed regulation may be assessed. Specifically, we find that more stringent restrictions on energy efficiency are economically viable if regulation also facilitates enhanced operational decision support for buildings. Indeed, primary energy consumption can be lowered only through more on-site generation such as combined heat and power, which is more complex for building managers to deploy.
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| 27. |
- Siddiqui, Afzal S., et al.
(författare)
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Are Targets for Renewable Portfolio Standards Too Low? The Impact of Market Structure on Energy Policy
- 2016
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 250:1, s. 328-341
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Tidskriftsartikel (refereegranskat)abstract
- In order to limit climate change from greenhouse gas emissions, governments have introduced renewable portfolio standards (RPS) to incentivise renewable energy production. While the response of industry to exogenous RPS targets has been addressed in the literature, setting RPS targets from a policymaker's perspective has remained an open question. Using a bi-level model, we prove that the optimal RPS target for a perfectly competitive electricity industry is higher than that for a benchmark centrally planned one. Allowing for market power by the non-renewable energy sector within a deregulated industry lowers the RPS target vis-a-vis perfect competition. Moreover, to our surprise, social welfare under perfect competition with RPS is lower than that when the non-renewable energy sector exercises market power. In effect, by subsidising renewable energy and taxing the non-renewable sector, RPS represents an economic distortion that over-compensates damage from emissions. Thus, perfect competition with RPS results in "too much" renewable energy output, whereas the market power of the non-renewable energy sector mitigates this distortion, albeit at the cost of lower consumer surplus and higher emissions. Hence, ignoring the interaction between RPS requirements and the market structure could lead to sub-optimal RPS targets and substantial welfare losses.
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| 28. |
- Siddiqui, Afzal S., et al.
(författare)
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Bouncing Back : Assessing the Resilience of Infrastructure Projects and the Use of Average Outage Factors
- 2017
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Ingår i: Proceedings of the 21st Annual International Real Options Conference. - Boston, MA : Real Options Group.
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Konferensbidrag (refereegranskat)abstract
- Motivated by the need to bolster the resilience of infrastructure, such as bridges, nuclear power plants, and ports, in face of extreme weather events, we consider two types of projects: “riskier” and “safer.” Each type of project, once constructed, earns identical instantaneous cash flows and is subject to the same risk of outage, which causes its cash flows to diminish. The only difference between the two projects is that the repair rate of the “safer” project is greater than that of the “riskier” one. Naturally, the “safer” project is more valuable to an investor due to its greater resilience. However, how much extra would an investor be willing to pay for this resilience? Under which circumstances would it be reasonable to replace the outage and repair rates with average outage factors? Using a real options approach, we show that even though the proportions of up- and down-times remain fixed, changes in the transition rates affect the willingness to pay for resilience. This implies that use of average outage factors will incorrectly inflate the resilience premium. In fact, only in the limit when transitions occur at infinitely high rates does the use of average outage factors accurately reflect the investor’s willingness to pay for resilience. Somewhat paradoxically, very frequent transitions reflect a situation in which average outage factors may be used.
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| 29. |
- Siddiqui, Afzal S., 1975-, et al.
(författare)
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Market-Based Environmental Policies in the Power Sector : State of the Art and Future Research Needs
- 2023
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Ingår i: Current sustainable/renewable energy reports. - 2196-3010. ; 10, s. 59-74
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Tidskriftsartikel (refereegranskat)abstract
- Purpose of Review So-called Green New Deals aim to decarbonise the power sector via market-based instruments. Consequently, engineering-economic models for analysing the sustainable-energy transition have proliferated. This reviewcategorises existing approaches and identifies areas for extending the state of the art.Recent Findings We cluster the extant literature into two groups: engineering/operational research (M1) and environmentaleconomics (M2). While M1 focuses on the power sector’s technical and spatio-temporal aspects, M2’s emphasis is onincentives and externalities. Depending on the nature of the research question, either perspective (or both) may be suitable.Summary Since the envisaged electrification of the wider economy implies tighter coupling between formerly distinct sectors,e.g., power and heat, both M1 and M2 will have to adapt to the new paradigm in terms of methodology and application areas.Here, eliciting coordinating mechanisms, enhancing algorithms for solving hierarchical models, soft linking bottom-up andtop-down models, and crafting robust environmental policy in face of uncertainty over externalities are some of the vistas forfuture research.
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| 30. |
- Siddiqui, Afzal S., et al.
(författare)
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Sustainable transmission planning in imperfectly competitive electricity industries : Balancing economic and environmental outcomes
- 2019
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 275:1, s. 208-223
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Tidskriftsartikel (refereegranskat)abstract
- We explore the role of a transmission system operator (TSO) that builds a transmission line to accommodate renewable energy in order to lower emissions as required by government policy. In contrast to central planning, a TSO in a deregulated electricity industry can only indirectly influence outcomes through its choice of the transmission line capacity. Via a bi-level model, we show that this results in less transmission capacity and with limited emissions control in a perfectly competitive industry vis-a-vis a benchmark centrally planned system. A carbon charge on industry that fully accounts for the cost of pollution damage leads to a perfect alignment of incentives and maximised social welfare only under perfect competition. By contrast, a carbon charge may actually lower social welfare under a Cournot oligopoly as the resulting reduction in consumption facilitates the further exercise of market power.
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| 31. |
- Tanaka, Makoto, et al.
(författare)
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Economics of Power Systems
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This book describes the latest microeconomic concepts and operations research (OR) techniques needed to comprehend the design and operation of power markets, as well as the actions of their agents: producers, consumers, operators, and regulators. This is critical when it comes to addressing a constantly evolving power system environment that incorporates an increasing number of no-marginal-cost renewable sources, increasingly competitive storage facilities, increasingly responsive demands, and widespread communication channels that allow distributed decision-making. Such evolving environments call for a re-examination of the microeconomic concepts and OR techniques required by graduate students and practitioners in the electric energy field. This accessible, tutorial-style book features numerous illustrative examples to help readers grasp the economic concepts and OR procedures used by power market professionals. The authors explain these concepts and procedures and present a vision of a renewable-dominated marketplace. Each chapter also includes exercises.
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| 32. |
- Tanaka, Makoto, et al.
(författare)
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Regulatory jurisdiction and policy coordination : A bi-level modeling approach for performance-based environmental policy
- 2022
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Ingår i: Journal of the Operational Research Society. - : Informa UK Limited. - 0160-5682 .- 1476-9360. ; 73:3, s. 509-524
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Tidskriftsartikel (refereegranskat)abstract
- This study discusses important aspects of policy modeling based on a leader-follower game of policymakers. We specifically investigate non-cooperation between policymakers and the jurisdictional scope of regulation via bi-level programming. Performance-based environmental policy under the Clean Power Plan in the United States is chosen for our analysis. We argue that the cooperation of policymakers is welfare enhancing. Somewhat counterintuitively, full coordination among policymakers renders performance-based environmental policy redundant. We also find that distinct state-by-state regulation yields higher social welfare than broader regional regulation. This is because power producers can participate in a single power market even under state-by-state environmental regulation and arbitrage away the CO2 price differences by adjusting their generation across states. Numerical examples implemented for a stylized test network illustrate the theoretical findings.
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| 33. |
- Tejada-Arango, Diego A., et al.
(författare)
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A Review of Energy Storage System Legislation in the US and the European Union
- 2019
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Ingår i: Current Sustainable/Renewable Energy Reports. - : Springer Science and Business Media LLC. - 2196-3010. ; :6, s. 22-28
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Tidskriftsartikel (refereegranskat)abstract
- Purpose of ReviewThis paper focuses on the current possibilities for energy storage systems (ESS) to participate in different power system services. ESS can provide multiple services such as spinning reserve, deferral upgrades, and energy management. However, this versatility of ESS poses a challenge for regulators in designing markets where ESS have prominent roles. We assess recent regulatory proposals in the US and the EU in order to understand their implications for ESS.Recent FindingsThese proposals attempt to improve the current rules for efficient ESS deployment. Nevertheless, they have different approaches to the same problem. We discuss these differences in an attempt to shed light on the regulatory debate about ESS ownership and market design.SummaryThe successful integration of ESS will depend on proper incentives to provide multiple services without hampering the current market structure. New asset definitions could help to define the roles of ESS as either a generation or a transmission asset.
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| 34. |
- Tejada-Arango, Diego A., et al.
(författare)
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Opportunity cost including short-term energy storage in hydrothermal dispatch models using a linked representative periods approach
- 2019
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 188
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Tidskriftsartikel (refereegranskat)abstract
- Short-term energy storage systems, e.g., batteries, are becoming one promising option to deal with flexibility requirements in power systems due to the accommodation of renewable energy sources. Previous works using medium- and long-term planning tools have modeled the interaction between short-term energy storage systems and seasonal storage (e.g., hydro reservoirs) but despite these developments, opportunity costs considering the impact of short-term energy storage systems in stochastic hydrothermal dispatch models have not been analyzed. This paper proposes a novel formulation to include short-term energy storage systems operational decisions in a stochastic hydrothermal dispatch model, which is based on a Linked Representative Periods approach. The Linked Representative Periods approach disposes of both intra- and inter-period storage constraints, which in turn allow to adequately represent both short- and long-term storage at the same time. Apart from the novelty of the model formulation itself, one of the main contributions of this research stems from the underlying economic information that can be extracted from the dual variables of the intra- and inter-period constraints, which allows to derive an hourly opportunity cost of storage. Such a detailed hourly economic value of storage has not been proposed before in the literature and is not possible in a classic Load Duration Curve model that does not adequately capture short-term operation. This advantage is reflected in the case study results. For instance, the model proposed in this paper and based on Linked Representative Periods obtains operating decisions of short-term energy storage systems with errors between 5% and 10%, while the classic Load Duration Curve approach fails by an error greater than 100%. Moreover, the Load Duration Curve model cannot determine opportunity costs on an hourly basis and underestimates these opportunity costs of hydro (also known as water value) by 6%–24% for seasonal hydro reservoirs. The proposed Linked Representative Periods model produces an error on the opportunity cost of hydro units lower than 3%. Hourly opportunity costs for short-term battery energy storage systems using dual variables from both intra- and inter-period storage balance equations in the proposed model are also presented and analyzed. The case study shows that the proposed approach successfully internalizes both short- and long-term opportunity costs of energy storage systems. These results are useful for planning and policy analysis, as well as for bidding strategies of ESS owners in day-ahead markets and not taking them into account may lead to infeasible operation or to suboptimal planning.
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| 35. |
- Virasjoki, Vilma, et al.
(författare)
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Market Impacts of Energy Storage in a Transmission-Constrained Power System
- 2016
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Ingår i: IEEE Transactions on Power Systems. - 0885-8950 .- 1558-0679. ; 31:5, s. 4108-4117
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Tidskriftsartikel (refereegranskat)abstract
- Environmental concerns have motivated governments in the European Union and elsewhere to set ambitious targets for generation from renewable energy (RE) technologies and to offer subsidies for their adoption along with priority grid access. However, because RE technologies like solar and wind power are intermittent, their penetration places greater strain on existing conventional power plants that need to ramp up more often. In turn, energy storage technologies, e.g., pumped hydro storage or compressed air storage, are proposed to offset the intermittency of RE technologies and to facilitate their integration into the grid. We assess the economic and environmental consequences of storage via a complementarity model of a stylized Western European power system with market power, representation of the transmission grid, and uncertainty in RE output. Although storage helps to reduce congestion and ramping costs, it may actually increase greenhouse gas emissions from conventional power plants in a perfectly competitive setting. Conversely, strategic use of storage by producers renders it less effective at curbing both congestion and ramping costs, while having no net overall impact on emissions.
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| 36. |
- Virasjoki, Vilma, et al.
(författare)
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Market Power with Combined Heat and Power Production in the Nordic Energy System
- 2018
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Ingår i: IEEE Transactions on Power Systems. - 0885-8950 .- 1558-0679. ; 33:5, s. 5263-5275
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Tidskriftsartikel (refereegranskat)abstract
- The trend toward increasing energy efficiency and variable renewable energy (VRE) production has implications for combined heat and power (CHP) plants, which operate in both the price-driven power market and the district heating (DH) sector. Since CHP will be important in VRE integration, we develop a complementarity model to analyze CHP producers' roles in integrated markets. We use a Nordic case study to gain insights into (i) the effect of the link between CHP and DH on market power and (ii) market power's impact on operations in the DH sector. The results indicate that (i) the link of CHP to DH supply can increase market power and (ii) market power can induce shifts in DH production from heat-only to CHP.
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| 37. |
- Virasjoki, Vilma, et al.
(författare)
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Utility-scale energy storage in an imperfectly competitive power sector
- 2020
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Ingår i: Energy Economics. - : Elsevier BV. - 0140-9883 .- 1873-6181. ; 88
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Tidskriftsartikel (refereegranskat)abstract
- Interest in sustainabiity has increased the share of variable renewable energy sources (VRES) in power generation. Energy storage systems' potential to mitigate intermittencies from non-dispatchable VRES has enhanced their appeal. However, the impacts of storage vary based on the owner and market conditions. We examine the policy implications of investments in utility-scale battery storage via a bi-level optimization model. The lower level depicts power system operations, modeled as either perfect competition or Coumot oligopoly to allow for the assessment of producer market power. The upper-level investor is either a welfare-maximizer or a profit-maximizing standalone merchant to reflect either welfare enhancement or arbitrage, respectively. We implement a realistic case study for Western Europe based on all possible size-location storage investment combinations. We find that market competition affects investment sizes, locations, and their profitability more than the investor's objectives. A welfare-maximizer under perfect competition invests the most in storage capacity. Consumers typically gain most from storage investments in all cases, exceeding the gains for the investors. Specifically, our results show that storage investments may either not occur or be located differently than at social optimum, if market power is exerted. Thus, policy makers need to anticipate producer market power when setting regulation.
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| 38. |
- Višković, Verena, et al.
(författare)
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Implications of the EU Emissions Trading System for the South-East Europe Regional Electricity Market
- 2017
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Ingår i: Energy Economics. - : Elsevier BV. - 0140-9883 .- 1873-6181. ; 65, s. 251-261
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Tidskriftsartikel (refereegranskat)abstract
- As part of its climate policy, the European Union (EU) aims to reduce greenhouse gas (GHG) emissions levels by 20% by the year 2020 compared to 1990 levels. Although the EU is projected to reach this goal, its achievement of objectives under its Emissions Trading System (ETS) may be delayed by carbon leakage, which is defined as a situation in which the reduction in emissions in the ETS region is partially offset by an increase in carbon emissions in the non-ETS regions. We study the interaction between emissions and hydropower availability in order to estimate the magnitude of carbon leakage in the South-East Europe Regional Electricity Market (SEE-REM) via a bottom-up partial equilibrium framework. We find that 6.3% to 40.5% of the emissions reduction achieved in the ETS part of SEE-REM could be leaked to the non-ETS part depending on the price of allowances. Somewhat surprisingly, greater hydropower availability may increase emissions in the ETS part of SEE-REM. However, carbon leakage might be limited by demand response to higher electricity prices in the non-ETS area of SEE-REM. Such carbon leakage can affect both the competitiveness of producers in ETS member countries on the periphery of the ETS and the achievement of EU targets for CO2 emissions reduction. Meanwhile, higher non-ETS electricity prices imply that the current policy can have undesirable outcomes for consumers in non-ETS countries, while non-ETS producers would experience an increase in their profits due to higher power prices as well as exports. The presence of carbon leakage in SEE-REM suggests that current EU policy might become more effective when it is expanded to cover more countries in the future.
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| 39. |
- Višković, Verena, et al.
(författare)
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Regional carbon policies in an interconnected power system : How expanded coverage could exacerbate emission leakage
- 2019
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Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 134
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Tidskriftsartikel (refereegranskat)abstract
- Interconnected regional electricity markets are often subject to asymmetric carbon policies with partial coverage for CO2 emissions. While the resulting problem of carbon leakage has been well studied, its mitigation has received relatively less attention. We devise a proactive carbon policy via a bi-level modelling approach by considering the impact of an emission cap that limits the cost of damage from a regional power market. In particular, a welfare-maximising policymaker sets the cap when facing profit-maximising producers and the damage costs from their emissions at two nodes. A partial-coverage policy could degrade maximised social welfare and increase total regional CO2 emissions with potential for carbon leakage due to a higher nodal price difference. A modified carbon policy that considers CO2 emissions from both nodes tightens the cap, which increases maximised social welfare and decreases total CO2 emissions vis-a-vis the partial-coverage policy, albeit at the cost of greater scope for carbon leakage as it causes nodal prices to diverge. As a compromise, an import-coverage policy, implemented by California, that counts only domestic and imported CO2 emissions could alleviate carbon leakage at the cost of lower maximised social welfare with higher total emissions vis-a-vis the modified-coverage policy.
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