Jay Apt

Carnegie Mellon University | CMU · The Carnegie Mellon Electricity Industry Center

Electrification with heat pumps is often cited as a preferred pathway to decarbonize US space heating in the transition to a net-zero energy system. However, fully electrifying building heat may significantly increase peak electric system loads during cold weather, thus challenging extensive adoption. A hybrid home heating system uses both heat pum...

The expert and policy communities have invested enormous effort in debating what greenhouse gas (GHG) emissions target to aim for, or which decarbonization policies and technologies should be mandated or banned. Because multiple trajectories can achieve similar targets and timelines, some scenario analysis is useful. However, with many players invo...

Areas with sparse transmission lines are common in regions with high solar energy potential and need voltage support. This may require installing expensive voltage compensators, such as static synchronous compensators (STATCOMs). This expense can increase the cost and decrease the acceptance of large-scale adoption of solar power. Unlike current ph...

We conduct a consequential lifecycle analysis (LCA) of greenhouse gas (GHG) emissions from North American liquefied natural gas (LNG) export projects, estimating the change in global natural gas and coal use resulting from the market effects of increased LNG trade. We estimate that building a 2.1 billion cubic feet per day (Bcfd) LNG export facilit...

A fundamental policy question for distributed energy resources (DER) is whether they create system benefits shared by all utility customers in addition to being profitable for the installing customer. This question has received considerable attention in “value of DER” and net metering reform proceedings for behind-the-meter solar photovoltaics in r...

In the Northeastern United States, natural gas supply constraints have led to periods when gas shortages have caused up to a quarter of all unscheduled power plant outages. Dual fuel oil/gas generators or local gas storage might mitigate gas supply shortages. We use historical power plant operational and availability data to develop a supply curve...

Using 2012–2018 power plant failure data from the North American Electric Reliability Corporation, we examine how many fuel shortage failures at gas power plants were caused by physical interruptions of gas flow as opposed to operational procedures on the pipeline network, such as gas curtailment priority. We find that physical disruptions of the p...

Competitive electricity markets can procure reserve generation through a market in which the demand for reserves is administratively established. A downward sloping or stepped administrative demand curve is commonly termed an operating reserve demand curve (ORDC). We propose a dynamic formulation of an ORDC with generator forced outage probabilitie...

We present a solar‐centric approach to estimating the probability of extreme coronal mass ejections (CME) using the Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph Experiment (LASCO) CME Catalog observations updated through May 2018 and an updated list of near‐Earth interplanetary coronal mass ejections (ICME). W...

Current grid resource adequacy modeling assumes generator failures are both independent and invariant to ambient conditions. We evaluate the resource adequacy policy implications of correlated generator failures in the PJM Interconnection by making use of observed temperature-dependent forced outage rates. Correlated failures pose substantial resou...

Most current approaches to resource adequacy modeling assume that each generator in a power system fails and recovers independently of other generators with invariant transition probabilities. This assumption has been shown to be wrong. Here we present a new statistical model that allows generator failure models to incorporate correlated failures a...

We assess the ability of distributed solar to defer distribution capacity projects in a typical low load growth utility in the Northeast USA, PECO. We find that targeted placement can increase the deferral value of solar up to fourfold, but that deferrable projects are rare. In our baseline scenario, we find a 5% solar energy penetration with Net E...

Flow batteries have different performance characteristics than established storage technologies such as lithium-ion and lead-acid. We model advanced lead-acid, lithium-ion, and flow batteries for commercial and industrial customers under various tariff scenarios providing retail and wholesale market services to determine if flow batteries can compe...

This is a Joint work between Center for Study of Science Technology and Policy (CSTEP), Carnegie Mellon University (CMU) under the Solar Energy Research Institute for India and United States (SERIIUS) Here, we examine the performance of four models of annual solar photovoltaic production that are appropriate for site selection against actual gener...

We examined the geographic smoothing of solar photovoltaic generation from 15 utility-scale plants in California, Nevada, and Arizona and from 19 commercial building installations in California. This is the first comparison of geographic smoothing from utility-scale and building-mounted PV and the first examination of solar PV smoothing in this reg...

Demand response (DR) for spinning reserve may be appropriate for customers whose operational constraints preclude participation in energy and capacity DR programs. We investigate the private business case of an aggregator providing spinning reserve in California across customer end uses and business segments. Revenues are calculated using end use l...

To keep the electric power system reliable, grid operators procure reserve generation capacity to protect against generator failures and significant deviation from the load forecast. Current methods for determining reserve requirements use historical generator availability data (recorded as failure events) to compute the fraction of the time each u...

A major use case for behind-the-meter (BTM) electricity storage is peak-shaving for commercial and industrial customers who must pay peak-demand charges. Quantifying the value proposition for individual customers currently requires an optimization model, the development of which can be costly in human and computing resources. We disclose here a sim...

Significance While many forecasters are moving toward generating probabilistic predictions, energy forecasts typically still consist of point projections and scenarios without associated probabilities. Empirical density forecasting methods provide a probabilistic amendment to existing point forecasts. Here we lay the groundwork for evaluating the p...

A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes...

The incidence of widespread low-wind conditions is important to the reliability and economics of electric grids with large amounts of wind power. In order to investigate a future in which wind plants are geographically widespread but interconnected, we examine how frequently low generation levels occur for wind power aggregated from distant, weakly...

Annual installations of behind-the-meter (BTM) electric storage capacity are forecast to eclipse grid-side electrochemical storage by the end of the decade. Here we characterize the economic payoff and regional emission consequences of BTM storage without co-located generation under different tariff conditions, battery characteristics, and ownershi...

Low natural gas prices, market reports and evidence from New York State suggest that the number of commercial combined heat and power (CHP) installations in the United States will increase by 2%–9% annually over the next decade. We investigate how increasing commercial CHP penetrations may affect net emissions, the distribution network, and total s...

Wind turbine power curves are calibrated by turbine manufacturers under requirements stipulated by the International Electrotechnical Commission to provide a functional mapping between the mean wind speed v and the mean turbine power output P. Wind plant operators employ these power curves to estimate or forecast wind power generation under given w...

Reanalysis data are attractive for wind-power studies because they can offer wind speed data for large areas and long time periods and in locations where historical data are not available. However, reanalysis-predicted wind speeds can have significant uncertainties and biases relative to measured wind speeds. In this work we develop a model of the...

Abundant natural gas at low prices has prompted industry and politicians to welcome gas as a ‘bridge fuel’ between today's coal-intensive electric power generation and a future low-carbon grid. We used existing national datasets and publicly available models to investigate the upper limit to the emission benefits of natural gas in the USA power sec...

Reanalysis data sets have become a popular data source for large-scale wind power analyses because they cover large areas and long time spans, but those data are uncertain representations of “true” wind speeds. In this work we develop a model that systematically quantifies the uncertainties across many sites and corrects for biases of the reanalysi...

http://iopscience.iop.org/article/10.1088/1748-9326/10/10/104001/meta We examine the potential for geographic smoothing of solar photovoltaic (PV) electricity generation using 13 months of observed power production from utility-scale plants in Gujarat, India. To our knowledge, this is the first published analysis of geographic smoothing of solar P...

Wind integration studies are an important tool for understanding the effects of increasing wind power deployment on grid reliability and system costs. This paper provides a detailed review of the statistical methods and results from 12 large-scale regional wind integration studies. In particular, we focus our review on the modeling methods and conc...

New research results in several areas that can help to facilitate the large-scale integration of variable renewable power sources into the electric power system are reviewed . Increasing the market share of variable renewable electric power generation in the United States from the present 4% is eminently feasible, and can be facilitated by recent...

We examine the implications of lowering electricity sector CO2 emissions in PJM through a Low Carbon Capacity Standard (LCCS) instead of a renewables portfolio standard (RPS). An LCCS would create a requirement for load-serving entities to procure new low carbon capacity (GW). The LCCS would provide a greater balance of energy and capacity supply t...

In power systems with many wind generators, market rules have been slowly changing in order to mitigate or internalize the system costs relating to wind variability. We examine several potential market policies for mitigating the effects of wind variability. For each market policy, we determine the effect that the policy would have on the operation...

Recent advancements in battery technologies may make bulk electricity storage economically feasible. We analyze the value of two electrochemical storage technologies and traditional pumped hydropower storage in the 2010 PJM day-ahead energy market, using a reduced-form unit commitment model. We find that large-scale storage would increase overall s...

We examine the cost of carbon dioxide mitigation to consumers in restructured USA markets under two policy instruments, a carbon price and a renewable portfolio standard (RPS). To estimate the effect of policies on market clearing prices, we constructed hourly economic dispatch models of the generators in PJM and in ERCOT. We find that the cost eff...

We analyze the cost of curtailing the active power output of a wind farm to provide secondary frequency regulation capacity. We calculate the regulation capacity available and its cost by simulating the active power output of a curtailed 100-MW wind farm with a hybrid of real wind speed data and simulated high-frequency turbulence. We find that a c...

The integration of renewable energy resources into the electricity grid presents an important challenge. This book provides a review and analysis of the technical and policy options available for managing variable energy resources such as wind and solar power. As well as being of value to government and industry policy-makers and planners, the volu...

Pumped hydropower storage can smooth output from intermittent renewable electricity generators and facilitate their large-scale use in energy systems. Germany has aggressive plans for wind power expansion, and pumped storage ramps quickly enough to smooth wind power and could profit from arbitrage on the short-term price fluctuations wind power str...

Wind forecasts are an important tool for electric system operators. Proper use of wind power forecasts to make operating decisions must account for the uncertainty associated with the forecast. Data from different regions in the USA with forecasts made by different vendors show the forecast error distribution is strongly dependent on the forecast l...

Day-ahead load and wind power forecasts provide useful information for operational decision making, but they are imperfect and forecast errors must be offset with operational reserves and balancing of (real time) energy. Procurement of these reserves is of great operational and financial importance in integrating large-scale wind power. We present...

Enhanced (or engineered) geothermal systems (EGS) for generating electricity may provide significant reductions in greenhouse gas emissions, if they can be successfully sited. One potential threat to that siting is induced seismicity, which has led to EGS projects being stopped in Switzerland and Germany. We create and implement a framework for ide...

When wind or solar energy displace conventional generation, the reduction in emissions varies dramatically across the United States. Although the Southwest has the greatest solar resource, a solar panel in New Jersey displaces significantly more sulfur dioxide, nitrogen oxides, and particulate matter than a panel in Arizona, resulting in 15 times m...

The U.S. Department of Energy has estimated that over 50 GW of offshore wind power will be required for the United States to generate 20% of its electricity from wind. Developers are actively planning offshore wind farms along the U.S. Atlantic and Gulf coasts and several leases have been signed for offshore sites. These planned projects are in are...

Fifteen of the United States and several nations require a portion of their electricity come from solar energy. We perform an engineering-economic analysis of hybridizing concentrating solar thermal power with fossil fuel in an Integrated Solar Combined Cycle (ISCC) generator. We construct a thermodynamic model of an ISCC plant in order to examine...

We develop a metric to quantify the sub-hourly variability cost of individual wind plants and show its use in valuing reductions in wind power variability. Our method partitions wind energy into hourly and sub-hourly components and uses corresponding market prices to determine variability costs. We use publically available 15-min ERCOT data, althou...

We use time- and frequency-domain techniques to quantify the extent to which long-distance interconnection of wind plants in the United States would reduce the variability of wind power output. Previous work has shown that interconnection of just a few wind plants across moderate distances could greatly reduce the ratio of fast- to slow-ramping gen...

We perform engineering cost analyses of systems capable of delivering 1–5 million metric tonnes (Mt) of albedo modification material to altitudes of 18–30 km. The goal is to compare a range of delivery systems evaluated on a consistent cost basis. Cost estimates are developed with statistical cost estimating relationships based on historical costs...

A reconfigurable network can change its topology by opening and closing switches on power lines. We use real wind, solar, load, and cost data and a model of a reconfigurable distribution grid to show that reconfiguration allows a grid operator to reduce operational losses as well as to accept more intermittent renewable generation than a static con...

We investigate the economic viability of coupling a wind farm with compressed air energy storage (CAES) to participate in the day-ahead electricity market at a time when renewable portfolio standards are not binding and wind competes freely in the marketplace. In our model, the CAES is used to reduce the risk of committing uncertain quantities of w...

We compare the power output from a year of electricity generation data from one solar thermal plant, two solar photovoltaic (PV) arrays, and twenty Electric Reliability Council of Texas (ERCOT) wind farms. The analysis shows that solar PV electricity generation is approximately one hundred times more variable at frequencies on the order of 10(-3) H...

As a result of Powell and Cocke’sletter(1)regardingourpaperon the hurricane risk to offshore wind turbines (2), we havereviewed and updated some of our analysis. However, ourconclusion remains that wind turbines in hurricane-proneareas face extreme wind conditions significantly differentfrom those for which offshore wind turbines are currently de-si...

Certain applications, such as analysing the effect of a wind farm on grid frequency regulation, require several years of wind power data measured at intervals of a few seconds. We have developed a method to generate days to years of non-stationary wind speed time series sampled at high rates by combining measured and simulated data. Measured wind s...

The United States produces over seventy percent of all its electricity from fossil fuels and nearly fifty percent from coal alone. Worldwide, forty-one percent of all electricity is generated from coal, making it the single most important fuel source for electricity generation, followed by natural gas. This means that an essential part of any portf...

While energy storage technologies have existed for decades, fast-ramping grid-level storage is still an immature industry and is experiencing relatively rapid improvements in performance and cost across a variety of technologies. In this innovation cycle, it is important to determine which properties of emerging energy storage technologies are most...

Danielle Changala graduated cum laude from the University of California, San Diego, with a double major in Political Science and Psychology, and completed her Masters in Environmental Law and Policy in 2010 while earning the Certificate in Energy Law. She has interned with New Generation Energy, a non-profit renewable investment firm focusing on ex...

The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United St...

Issues such as the cost of compensating for variability and intermittency must be considered (along with limits set by land use) in determining the likely contribution renewables may make to electric power. Here we present a framework that uses frequency domain analysis to elucidate integration characteristics that include the benefit of interconne...

R. F. Service's “Battery FAQs” (News Focus, 24 June, p. [1495][1]) attempts to answer the question “How will widespread adoption of electric vehicles affect CO2 emissions and possible climate change?” The answer Service provides—that CO2 emissions will not be affected unless renewable

Compressed air energy storage (CAES) could be paired with a wind farm to provide firm, dispatchable baseload power, or serve as a peaking plant and capture upswings in electricity prices. We present a firm-level engineering-economic analysis of a wind/CAES system with a wind farm in central Texas, load in either Dallas or Houston, and a CAES plant...

Plug-in hybrid electric vehicles (PHEVs) may become part of the transportation fleet on time scales of a decade or two. We calculate the electric grid load increase and emissions due to vehicle battery charging in PJM and NYISO with the current generation mix, the current mix with a $50/tonne CO(2) price, and this case but with existing coal genera...

Deaths and close calls have occurred in both the initial development and mature operation phases of human spaceflight. The spacecraft, ground operators, flight crew, and the structure of the spaceflight organization each present opportunities for risk analysis, management, and mitigation. An understanding of the nature of problem definition and ver...

Wind generation presents variability on every time scale, which must be accommodated by the electric grid. Limited quantities of wind power can be successfully integrated by the current generation and demand-side response mix but, as deployment of variable resources increases, the resulting variability becomes increasingly difficult and costly to m...

We present the first frequency-dependent analyses of the geographic smoothing of wind power's variability, analyzing the interconnected measured output of 20 wind plants in Texas. Reductions in variability occur at frequencies corresponding to times shorter than ~24Â h and are quantified by measuring the departure from a Kolmogorov spectrum. At a f...

With the implementation of state renewables portfolio standards (RPS) and serious consideration in Congress of a national RPS, a number of control areas are anticipating scenarios with greater than 20% of renewable electricity, principally wind, as part of the supply mix. At the federal level, H.R. 969 was introduced in the 110th Congress to requir...

We examine the potential economic implications of using vehicle batteries to store grid electricity generated at off-peak hours for off-vehicle use during peak hours. Ancillary services such as frequency regulation are not considered here because only a small number of vehicles will saturate that market. Hourly electricity prices in three U.S. citi...

The effects of combined driving and vehicle-to-grid (V2G) usage on the lifetime performance of relevant commercial Li-ion cells were studied. We derived a nominal realistic driving schedule based on aggregating driving survey data and the Urban Dynamometer Driving Schedule, and used a vehicle physics model to create a daily battery duty cycle. Diff...

In a restructured electricity market, utility-scale energy storage technologies such as advanced batteries can generate revenue by charging at low electricity prices and discharging at high prices. This strategy changes the magnitude and distribution of air quality emissions and the total carbon dioxide (CO2) emissions. We evaluate the social costs...

Geologic sequestration (GS) of carbon dioxide (CO2) is contingent upon securing the legal right to use deep subsurface pore space. Under the assumption that compensation might be required to use pore space for GS, we examine the cost of acquiring the rights to sequester 160-million metric tons of CO2 (the 30-year emissions output for an 800 megawat...

Using data from the North American Electric Reliability Council (NERC) for 1984-2006, we find several trends. We find that the frequency of large blackouts in the United States has not decreased over time, that there is a statistically significant increase in blackout frequency during peak hours of the day and during late summer and mid-winter mont...

Large numbers of proposed new coal power generators in the United States have been canceled, and some states have prohibited new coal power generators. We examine the effects on the U.S. electric power system of banning the construction of coal-fired electricity generators, which has been proposed as a means to reduce U.S. CO2 emissions. The model...

Each year, the effects of climate change are coming into sharper focus. Barely a month goes by without some fresh bad news: ice sheets and glaciers are melting faster than expected, sea levels are rising more rapidly than ever in recorded history, plants are blooming earlier in the spring, water supplies and habitats are in danger, birds are being...

Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid...

Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid...

America seems to have decided that a "smart grid" is what we need to solve the problems of our electric power system. But, what exactly is a "smart grid"? The answer is that it is many different things. Some of the things that get talked about are relatively inexpensive and can go a long way toward solving key problems. Others will likely be very e...

Geoengineering has been discussed for decades around the edges of the climate science community. However, today limited progress in abating emissions of GHGs makes the subject ever more salient. There is a growing need both for the foreign policy community to begin to consider how best to develop a framework for collective international governance...

We analyze the economic properties of the economic demand-response (DR) program in the PJM electricity market in the United States using DR market data. PJM's program provided subsidies to customers who reduced load in response to price signals. The program incorporated a “trigger point”, at a locational marginal price of $75/MWh, at or beyond whic...