Article

Residential Solar PV Systems in the Carolinas: Opportunities and Outcomes

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Abstract

This paper presents a first-order analysis of the feasibility and technical, environmental, and economic effects of large levels of solar Photovoltaic (PV) penetration within the services areas of the Duke Energy Carolinas (DEC) and Duke Energy Progress (DEP). A PV production model based on household density and a gridded hourly global horizontal irradiance dataset simulates hourly PV power output from roof-top installations; while a unit commitment and real time economic dispatch (UC/ED) model simulates hourly system operations. We find that the large generating capacity of base-load nuclear power plants (NPPs) without ramping capability in the region limits PV integration levels to 5.3% (6,510 MW) of 2015 generation. Enabling ramping capability for NPPs, would raise the limit of PV penetration to near 9% of electricity generated. If planned retirement of coal fired power plants together with new installations and upgrades of natural gas and nuclear plants materialize in 2025, and if NPPs operate flexibly, the share of coal-fired electricity will be reduced from 37% to 22%. A 9% penetration of electricity from PV would further reduce the share of coal-fired electricity by 4-6% resulting in a system-wide CO2 emissions rate of 0.33 tons/MWh to 0.40 tons/MWh and associated abatement costs of 225-415 (2015$/ton).

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... Third, the low operational flexibility of the several nuclear reactors operating in the service region hinders the integration of variable renewable energy [30,31]. These nuclear reactors account for 20% of the installed capacity in the DEP [32] and 25% in the DEC [33], and due to their low air emissions and marginal cost, constitute the core of the base-load supply and generate almost 50% of total electricity in the service region with capacity factors surpassing 99% [34]. ...
... In this case, the maximum hourly generation is set according to historical production information obtained from the United States Energy Information Administration (EIA) Application Program Interface [35] and the operational restrictions imposed during the systeḿs refill season as described in [36] (more information on this procedure is included in Section 5.3. of the SI). The required minimum hourly generation for units online is set as a fraction of the maximum nameplate capacity depending on the type of fuel and prime mover description as follows: 40% for coal steam turbine units [37], 30% for fuel oil combustion turbine units [38], 20% for hydroelectric units (hydraulic turbine and reversible hydraulic turbine) [38], 30% for natural gas steam turbines (both combined cycle and noncombined cycle) [39], 50% for natural gas combustion turbines (both combined cycle and non-combined cycle) [39], and 90% for nuclear reactors [6,30,31]. The generators' capability to ramp up and down their electricity production is expressed as their capacity to reach a power output equal to a fraction of their nameplate capacity in one hour. ...
... The generators' capability to ramp up and down their electricity production is expressed as their capacity to reach a power output equal to a fraction of their nameplate capacity in one hour. These capabilities are set as 100% for coal, fuel oil, hydroelectric, and natural gas [38], and 10% for nuclear reactors consistent with [6,30,31]. The minimum downtime and uptime are set based on the fuel, prime mover, and capacity as shown in Table 1 in accordance to values from previous studies [40][41][42][43][44]. ...
Article
This study explores the performance of the Duke Energy Carolinas/Progress (DEC/DEP) electric power system under one hundred forty-one configurations combining different capacities of utility-scale photovoltaics (PV) and battery energy storage (lithium-ion batteries or BES). The different configurations include PV installations capable of providing 5–25% of the systems energy and batteries with varying duration (energy-to-power ratio) of 2, 4, and 6 h. A production cost model comprised of a day-ahead unit commitment and a real-time economic dispatch simulates the optimal operation of all the generation resources necessary to supply hourly demand and reserve requirements during the year 2016. The model represents in detail the generation fleet of the system, including 221 nuclear, natural gas, coal and hydro power generators with a combined installed capacity of 37.8 GW. Results indicate that: 1) adding BES to a power system that includes PV further reduces carbon dioxide emissions while also lowering the cost of carbon abatement. 2) The optimal power rating of a BES system that supports PV seems to be lower than 25% of the capacity of the PV. 3) BES of short duration (2-h) are more cost- effective (i.e., result in a lower cost of abatement) when the level of PV penetration is low (lower than ~12.5%), while BES of longer duration (6-h) are more cost-effective when there are larger shares of PV. 4) The installation of optimal configurations of PV +BES to reduce carbon emissions in the DEC/DEP system by ~14–57% would increase the levelized cost of electricity (LCOE) ~8–65%. 5) If projections of declining costs for the next decade materialize, the installation of up to 15 GW of PV +1.88 GW / 3.76 GWh of BES would reduce the LCOE while achieving up to 33% reduction in carbon emissions.
... China is implementing reforms [3,4] that will remove challenges for renewable energy integration that have been well known since the last decade [5], but key obstacles persist [6,7]. One of such barriers is the decentralization of scheduling and dispatch at the provincial level [8,9] and the allocation of minimum generation quotas [10,11], which result in limited ramping capability to start up and shut down conventional generators [12] as needed to balance intermittent renewable production and minimize cost and emissions. ...
... Table 3 summarizes the demand data publicly available on the websites of the 7 ISOs in the U.S. that account for more than 50% of the U.S. electricity demand. Similar data is available for regions without wholesale electricity markets (for example, the Duke Energy Carolinas/Duke Energy Progress region [12,70] or the Bonneville Power Administration region [71]. ...
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The ongoing transformation of the world's energy system requires detailed power-system models that help plan a cost-effective and reliable integration of variable renewables and demand-side resources. The quality and depth of the results of these models depend on the existence of trustworthy, complete, and high-resolution data on extant electric power assets and the demand they serve, wind and solar resources, and projections on costs and performance of technologies that could be developed during the next three decades. This paper assesses the quality of China's power system's publicly available data compared to the U.S. It concludes that despite growing use of power system models to inform and analyze Chinese energy policy, the availability of necessary data is still a significant barrier that severely limits the transparency, replicability, relevance, and usefulness of their results.
... Using these results, the avoided generation cost for a year is calculated. Since the generation fixed cost data [36] considered a range for the cost: (i) high case e 0.116 $/MW-year, and (ii) low case e 0.069 $/MW-year, the avoided generation capacity cost for those two cases are calculated. Table 5 shows the results. ...
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The recent increase in Renewable Generation (RG) has prompted many states, utilities, and other stakeholders to improve the methods used to determine the value of RG in efforts of replacing the Net Metering approach. However, these studies result in a wide range of values. This paper proposes a methodology based on the RG valuation studies conducted in recent years. The method includes the most common cost and benefit components considered in these studies and adopts a comprehensive method to calculate each component. The main categories include avoided energy, avoided generation capacity, avoided transmission capacity, avoided system losses, price hedging benefits, environmental benefits, and grid integration costs. A realistic case study emulating a large utility is also conducted to illustrate the application of the proposed method. The results show that all the main components can be estimated based on detailed system models or simulations. The results also illustrate some of the data challenges associated with such a study.
... economic, environmental, and social. The readers are referred to Alqahtani et al. (2016), Denholm et al. (2014), Gowrisankaran et al. (2016), Mills et al. (2013) for explorations on the other types of impacts. ...
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As the number of photovoltaic (PV) installations across the world keeps on increasing, their impacts on power systems are becoming more visible and more severe. In this two-part review, the implications of high PV penetration on the stability and reliability of power systems are comprehensively assessed. This paper, the first of the two, reviews the impacts of PV on the power systems’ voltage, frequency, protection, harmonics, rotor angle stability, and flexibility requirement in detail. Factors contributing to those impacts, as well as the level and timeframe at which they occur, are carefully analysed. Subsequently, the limits of PV penetration observed in the literature are reviewed. To allow the readers to verify these impacts and limits, the tools and models typically employed in power system analysis are also elaborated. The second part of the review then completes the investigation by assessing the existing solutions to the PV integration challenges and suggesting the way forward.
... These capabilities are set as: 100% for coal, fuel oil, hydroelectric and natural gas and 10% for nuclear reactors. The minimum down time and up time are set based on the fuel, prime mover and capacity as shown in Table 2 in accordance to values from previous studies [26][27][28]. ...
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