California Energy Flow (Energy Balances)
Page last updated: 7/1/2008
The California Energy Balances (CALEB) project was an effort by Lawrence Berkeley National Laboratory (Berkeley Lab) to provide a comprehensive set of data for energy production, transformation, and consumption for the State of California for the period 1990 to 2000. The California Energy Commission funded the project through its Public Interest Energy Research (PIER) Program and requested that these data distinguish among fuels and incorporate the maximum degree of sectoral and sub-sectoral disaggregation possible. The Energy Commission also requested that Berkeley Lab compile energy data from different sources, determine the quality of the data, and explain and resolve any data discrepancies. These data have been used to produce the CALEB database, a versatile database that allows users to explore California energy data in a variety of formats. This report documents the data collection effort as well as the resolution of data discrepancies for the energy production, transformation, and consumption data for the CALEB project. Most of the data used for CALEB were taken either from the Energy Commission or the U.S. Energy Information Administration (EIA).
The final report from the project, Development of Energy Balances for the State of California, publication number CEC-500-2005-068, published June 2005, is available to download below.
Download Report in Acrobat PDF ( 72 pages, 458 kb )
Energy balance databases arrange data into three principal dimensions: (1) products, (2) flows, and (3) time. Products are simply the various energy sources. They consist of natural gas, crude oil and petroleum products, coal, electricity, and other minor energy sources. This report distinguishes between primary electricity from sources such as hydro, wind, and solar photovoltaic and secondary electricity produced from converted thermal energy. Flows refer to processes of supplying, transforming, and consuming energy. The transformation phase refers to the energy used to extract and process energy resources as well as the energy inputs themselves that are transformed into secondary sources (for example the crude oil that is refined into petroleum products). The consumption phase signifies all of the end uses of energy throughout the economy. Time denotes the calendar year or years of the energy data available. An energy balance per se consists of a balancing of supply, transformation, and consumption data in a given year.
Figure ES-1 below depicts the energy balance data for 2000 as an energy flow chart. Reading from left to right, the figure shows all the inputs of primary (and imported secondary) energy into California's economy in 2000. These are summed by major fuel types in the middle of the figure: petroleum and associated products, natural gas, coal, and inputs to electricity generation. The right side shows how all of the fuels are allocated to the various end uses.
The energy supply phase of an energy balance documents those flows of energy available to the economy prior to transformation and consumption. The energy supply flow includes indigenous energy production, imports, exports, international marine bunkers, and net stock withdrawals.
Indigenous energy production accounts for the primary energy extracted from within the country (or state). This consists only of primary forms of energy such as natural gas, crude oil, coal, and production of primary electricity. The treatment of international bunker fuels (fuels used by airplanes and ocean-going vessels for transit to foreign destinations) presents a number of methodological and statistical challenges. For the purposes of constructing national greenhouse gas (GHG) inventories, the Intergovernmental Panel on Climate Change (IPCC) recommends that emissions from all international bunker fuels be excluded from national totals. In practice, deliveries of these fuels are not reported separately for domestic and international trips. The figures in the CALEB database have been adjusted to reflect the consumption of intrastate, interstate, and international travels. Deliveries of international marine bunker fuel are shown in energy balance tables as part of "Energy Supply"; whereas, total consumption of aviation fuels is shown in the "Transport" category and is not deducted from the energy supply. However, the share of aviation fuel used for international travel is reported as a separate item and should be deducted from consumption totals for purposes of calculating a GHG emission inventory. Net stock withdrawal indicates the net quantities of fuels taken from or added to stock over the course of the year.
Supply data for most energy sources are complete for the years 1990 to 2001. However, complete data for imports and exports of petroleum products are only available from 1996 to 2001.
Unless imported or exported, electricity per se does not appear in the "Energy Supply" portion of the energy balance. Rather, it is the inputs to electricity generation that are shown. An energy balance distinguishes primary energy from secondary energy. There are two different methods used to "back-calculate" the primary energy necessary to produce non-fossil fuel electricity: (1) the partial substitution method, and (2) the physical energy content method.
The partial substitution method calculates how much primary energy this production of electricity would require if it were generated by fossil fuels. The EIA uses this method in its Annual Energy Review. The second method-the physical energy content method-is used by the International Energy Agency (IEA) and was adopted for the CALEB database. Following this convention, the electricity produced is considered the primary form of energy for non-thermal energy sources (e.g., hydro, wind, solar, and wave power). Following the IEA convention, the electricity produced is considered the primary form of energy for non-thermal energy sources (e.g., hydro or wind), while heat is commonly accepted as the primary form of energy in the production of electricity from non-fossil thermal energy sources (e.g., nuclear fission or geothermal).
The transformation phase of an energy balance accounts for two distinct aspects of energy provision: (1) energy inputs that are ultimately converted to secondary sources, and (2) the energy used for the extraction and processing of energy resources (e.g., coal mining, oil and gas extraction, process energy use at refineries). The electricity sector is disaggregated into five types of energy providers, following the EIA classifications currently used in the Electric Power Annual publications and data sets. These consist of: (1) utilities; (2) independent power producers (IPPs); (3) combined heat and power (CHP), electric power sector; (4) CHP, industrial sector; and (5) CHP, commercial sector. Combined heat and power facilities are required to report only the fuel used to generate electricity that is either consumed onsite or sold. The quantity of fuel used to generate heat or steam for industrial/commercial purposes is not included, and is therefore shown as part of end use consumption (included either in manufacturing or services).
The consumption of energy needed to operate refineries or power plants is provided under the "Energy Sector: Own Use" category, as is the energy required to extract energy resources. This may consist of purchased electricity or natural gas or energy recovered on site. For example, a significant portion of the crude oil that enters a refinery is ultimately used for process energy. This category also includes the energy used for oil and natural gas extraction and energy used for coal mining. In California, major transformation sector consumers of energy include natural gas power plants, oil refineries, and the energy used for oil and gas extraction.
Electricity distribution losses occur in the transmission and distribution of electricity to consumers. Because actual data on losses are difficult to obtain, losses are currently estimated by induction, using an assumption of 8% losses of electricity delivered to the grid.
For the purpose of the CALEB database, energy consumption data have been categorized into four principal end-use sectors: (1) industry, (2) transportation, (3) services, and (4) residences. Consumption of petroleum products by the end-use sectors remained relatively stable overall during the period 1990 to 2000, but among the individual sectors, industry's use of petroleum products decreased significantly, while use in the transportation sector grew. Use of motor gasoline increased substantially over this period, with consumption in 2000 more than 10% higher than in 1990. Industry's consumption of other petroleum products dropped sharply after 1990, largely due to a corresponding drop in "other petroleum products" as reported by the EIA, as well as drops in the reported use of liquid petroleum gas (LPG) and residual fuel oil. Coal is used for some electricity generation at CHP facilities, but otherwise its use is limited mostly to the cement industry.
This report presents the findings from the first stage of the CALEB data project. Overall, the total statistical difference between supply and consumption for 2000 was a little less than 1%. Unfortunately, this encouragingly low difference in the totals does not apply to all of the individual fuels or all of the years covered by the database. The statistical differences for coal, natural gas, and certain petroleum products remain quite large.
With respect to transformation of petroleum products, Berkeley Lab and Energy Commission staff need to collect and analyze petroleum product data for years other than 1995 to 2001 in order to complete the CALEB flows back to 1990. Additional effort is needed to improve the petroleum product balance even for 1995 to 2001, due to the complexity of refinery operations and petroleum product flows.
Three aspects of petroleum product consumption also need to be further developed to improve the balance. First, detailed subsector-level data are not maintained due to the decentralized nature of petroleum product distribution. Data are only reported at highly aggregated, sectoral levels by sources such as the EIA's State Energy Data System. However, any attempt to allocate consumption to more detailed subsectors would require significant analysis and would ultimately rest on a number of assumptions. Second, improved estimates of bunker fuels for interstate and international shipping and aviation are needed. Currently, data on sales of jet fuel and marine bunker fuels are not disaggregated by vehicle destination. Berkeley Lab has conducted an initial analysis of maritime shipping and flight records for a few recent years to allocate international bunker fuel consumption for all years in CALEB. Finally, more data are also needed to better estimate the use of petroleum products, natural gas, and NGLs for feedstocks.
The electricity sector has also presented several analytic hurdles. Data on actual power flows into and out of the state are not publicly available; hence, Energy Commission figures on estimated net imports were used. A future research task entails the examination of Federal Energy Regulatory Commission (FERC) 714 forms to quantify bulk exchanges between power control areas, in order to more precisely estimate imports and exports. Two other forms, the FERC 1 and EIA 714, provide considerable detail on power purchases by supplier. Despite the level of detail provided by these two data sources, there are two main obstacles to using them to accurately account for all electricity imports and exports for the State of California. The first is that from 1998 to 2000 the investor-owned utilities (IOUs) began to purchase large shares of their power from the California Power Exchange. The sources of power that supplied the Power Exchange are not publicly disclosed. Second, California utilities purchase some power from energy marketers and California Department of Water Resources (DWR), and these organizations do not disclose the sources of the power they sell on either the FERC 1 or EIA 412.
An additional task for completing the consumption data for natural gas entails estimating the fuel consumed to produce useful heat from CHP units. This has been done for the years 1998 through 2000 for the current version of CALEB, but missing data complicate estimations for other years.
In the future, inclusion of economic activity data (such as population, value added, passenger-miles traveled, and service sector floor space) would enable CALEB to produce indicators of energy intensity (energy consumed per unit of activity) for various end-use sectors. With sufficient data, a decomposition of structural and intensity trends driving energy use in California may be possible.