GENSCAPE
- ESSENTIAL ENERGY INFORMATION
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Section: data resources
Daily Gas Burn Report FAQ (US)
Questions
1. How is the gas burn data calculated? Our approach is based on power flow measurements at all our plants. We take into account the nuclear, coal and gas fired generation in an area – at the moment, we are only doing gas areas – and combine that with load in the same area. Where we don’t have an hourly load measurement, we use a population-weighted temperature index as a proxy. The gas figure is derived as a result of a multiple regression approach
using those data inputs.
2. The EPA data is hard to interpret. How do you know what portion of the reported power output is gas-generated? In the EPA CEM reports, some plants provide heat input measured at the point of fuel delivery (“direct approach”), while others estimate the heat input by measuring the quantity of gases or carbon at the emissions stack (“CEMS-based approach”). Plants using the direct-approach submit hourly natural gas and oil input measured in MMBtu (record type 302 and record type 303, respectively). For those plants, it is clear what portion of the heat input is attributable to which fuel for every hour of operation. Plants using the CEMS-based approach submit formulae that can be interpreted to derive the fuel contribution to the heat input. A majority of the CEMS-based approach submittals use an F-factor which is the ratio of either carbon mass or gas volumes to the heat content of the fuel. The portion of each fuel can be derived from the standard formulas used, which are described in record type 520. The formulae have essentially this format: F = Xi * Fi + Xii * Fii…+ Xn*Fn where F is the f factor that is published for every hour in record type 300, Xi the portion of fuel i and Fi a constant specific to fuel i. The constants that are needed for these formulas are published by the EPA in table 11 in the documentation for record type 520. Some plants use their own constants, which they then provide in record type 520 in the formula description. The formulas can be used to derive a gas burn estimate only if the
plant is burning no
These assumptions will lead to an overestimation of gas burn at those
plants that use distillate in addition to gas as a startup fuel.
3. How do you validate that your calculated EPA gas number is accurate? We compare the monthly sum of the gas burn derived from the EPA data with the numbers published by plant by the EIA in form 906. Our approach yields congruent results.
4. How do you account for dual-fired plants?
5. What inputs do you use in your calculation? Beside the power flows measured and reported by Genscape, we use temperature and load data.
6. How do you calculate the temperature-adjusted change? In order to provide a clearer picture of the gas trend in the power sector, Genscape strips out the effect of temperature from the calculation of the year-on-year change in gas burn. This is done by using a simple regression to fit the gas burn to the temperature, and then using the fitted numbers to calculate the change. In essence, what this approach does is calculate what the gas burn should have been at the week’s average temperature. The difference between what the value should be and what it actually is represents the portion of the change in consumption that is not due to temperature changes.
7. Do you ever deviate from your calculation methods? Yes, we do. When unusual events impact the industry in ways that cannot be reflected in our input parameters, we will adjust the calculation to reflect those events. For example, if there is a sharp decline in demand because of weather-related or other events in areas where no publicly available load data is available, we will adjust our calculation to reflect that decline.
8. How frequently is the report produced? The report is published daily on weekdays and contains the data for the previous calendar day, except on Mondays, when the report will reflect the data for Friday, Saturday and Sunday.
9. In what formats is the data delivered? The Gas Report is available as an Adobe Acrobat (*.pdf) file or a comma separated values (*.csv) file. Customers may choose to get the data in both formats simultaneously.
10. How much does it cost to subscribe to the report? A site license to the report is $60,000/year. Existing clients of Genscape’s real-time power products may qualify for a discount.
11. Will the data matter when the weather cools? The Gas Burn data has the most pronounced impact when consumption by power plant operators is high. In our analysis we have seen an improvement in predicting the gas storage number in both the peak winter and summer months. During some weeks of the spring and fall, the gas burn data also has a marked effect as coal and nuclear plants are taken off line for maintenance.
12. What portion of each NERC region’s installed capacity is primarily fired by natural gas? The portion of the nameplate capacity that has natural gas listed as its primary fuel by NERC region is as follows: ASCC 45% 13. How much of the gas-fired capacity does Genscape monitor? Genscape monitors about 13% of all the gas-fired capacity in the contiguous United States. The monitored sample is biased toward newer, bigger and more efficient gas plants. The breakdown of the coverage is as follows: Nerc Region Coverage 14. Do you take pricing into account when you do your calculation? Genscape only uses fundamental data in the calculation of its gas numbers. Price data is not used. 15. Do you publish a gas storage prediction? At the moment, Genscape does not publish its own gas storage prediction. The aim of the Genscape Gas Burn Report is to provide data input for gas storage models. 16. How can I be sure that your data will help me? Genscape will provide a year’s worth of historical gas burn data to qualified clients to be input into gas storage models to gauge the effectiveness of the data in predicting the EIA storage number or for other calculations. 17. How does your data compare to scraped pipeline data? Genscape does not now provide data on storage and therefore there can be no comparison between our data and the scraped storage data. In our own analysis, we have found that incorporating the Genscape Gas Burn data into a model using temperature and scraped storage data improves the accuracy of the model by 1 to 2 BCF. We have also compared scraped pipeline data that shows deliveries to gas plants to the data reported by the EPA on those plants. Out of 10 plants, only one showed a statistically significant correlation between the amount of gas delivered and power output. And even at that one plant, the correlation, while statistically significant (0.6) was weak.
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