i-WESTAT is a multi source database containing more than 115 000 records from 20 primary international and national sources and defined by around 400 reference categories, with queries designed to filter information utilized as a user interface. Each record contains the information registered by product, country, primary and secondary information source and year.
The database contains information for 213 countries from year 1961 to 2003, with projections to 2030 for model data. The variables include woodfuel, fuelwood, charcoal and black liquor production, import, export and consumption. Data on consumption by sector and by urban/rural areas were also included where available.
The main features and functionalities of i-WESTAT are described in the User's guide (Version 2.0 October, 2004).
The structure of the main table of the i-WESTAT database is described in Table 1.
TABLE 1
Structure of “wf”, the main table of i-WESTAT database
Fields |
Description |
contcode |
Fields linked to Table “COUNTRYWEIS” |
srcode | |
CTYCODE | |
Countryname | |
Source1_ID |
Primary sources, linked to table “Source_name” |
Source2_ID |
Secondary sources linked to table “Sec_sources” which include the variables “Ref_type” that qualify the references (see Table 10 ) and “Derived_item” that provide the formulae used for derived items. |
Year |
Year of observation |
Item |
Woodfuel type and flow. See below. |
Unit |
Measurement unit. ‘000 m3 for fuelwood; ‘000 tons for charcoal; PJ for woodfuels and black liquor |
Sector |
See below |
Area_U_R |
See below |
Value |
Numeric entry |
PJ_Equiv |
Correspondence of “Value” in energy units (PJ) |
Kg_percapita |
“Value” / total population. If fuelwood, the volume is converted in weight. |
TJ_percapita |
“PJ_Equiv” / population. Not available for black liquor and for import and export. |
The categories under “Item” adopted in i-WESTAT, which identify the woodfuel type and flow, are listed in Table 2. These items reflect the conceptual scheme defined in UBET [5], shown in the figure in Appendix 2 and follow the definitions reported in the same Appendix.
TABLE 2
i-WESTAT variables
Item code |
Item name |
Item code |
Item name |
||
FwCons |
Fuelwood consumption |
WfCons |
Woodfuel consumption |
||
FwProd |
Fuelwood production |
WfProd |
Woodfuel production |
||
FwImp |
Fuelwood import |
WfImp |
Woodfuel import |
||
FwExp |
Fuelwood export |
WfExp |
Woodfuel export |
||
ChCons |
Charcoal consumption |
BlkLiq |
Black liquor |
||
ChProd |
Charcoal production |
TraLoss |
Transformation losses (charcoal) |
||
ChImp |
Charcoal import |
||||
ChExp |
Charcoal export |
PsbCons |
Primary solid biomass consumption (IEA) |
||
Sector |
Description |
||||
All |
Including all sectors |
||||
Household |
Limited to household sector |
||||
Non-household |
All non-household sectors combined. Calculated by deduction in cases where the source provides only figures at total and household level, without further subdivisions |
||||
Commercial |
Limited to the commercial sector |
Details rarely available |
|||
Industries |
Limited to the industrial sector |
||||
Services |
Limited to the services sector |
||||
Transformation |
Limited to the transformation sector |
||||
Area_U_R |
Description |
||||
All |
Including rural and urban areas |
||||
R |
Limited to rural areas |
Details rarely available |
|||
U |
Limited to urban areas |
National population statistics are released annually by the UN Population Division and used by all UN agencies. The annual revisions of population statistics do not simply add one year to the previous time series but are complete re-estimations of the entire time series, adjusted on the basis of new census data and other inputs. The most recent data series includes 2002 statistics.
In i-WESTAT, population data are used to produce per capita values of fuelwood and charcoal production and consumption. These per capita values are useful when comparing several countries’ production and consumption.
The aim of converting original values in common units is to allow the comparison of different data sources and the aggregation of specific fuel data in terms of estimated energy contribution. The standard conversion factors applied in converting volume and weight units into energy units and vice versa are reported in Appendix 3.
True conversion factors may vary widely from the standard ones applied in i-WESTAT, as a result of local factors, such as specific wood characteristics and conversion technologies, which are generally unknown. Consequently, the values resulting from the application of standard factors should be considered as tentative, providing orders of magnitude rather than actual values.
Accurate measurements are further complicated by the fact that the original measurement units are not consistent. Each institution collecting country data faces the need to harmonize the original values to common units therefore, in some cases, measurements might be converted back from a derived unit to the original unit using different factors and finally creating a new value significantly different from the originally measured one.
Another aspect related to unit conversions which strongly affects data consistency is the application, or otherwise, of efficiency losses related to conversion technologies. Energy units are considered sometimes as total fuel energy content and sometimes as actual energy production, the latter depending largely on the conversion technologies used.
The highest risk of inconsistency resulting from conversion processes is when a value determined with efficiency loss consideration is re-converted without efficiency consideration, artificially inflating the resulting value1.
This problem can only be resolved with a coordinated effort by all concerned agencies in truly developing metadata on original sources and estimation procedures.
1 An example of this risk is given by the Slovenia case. The household fuelwood consumption was determined in energy units at 8.7 PJ (derived from census data on dwelling size of fuelwood users and energy requirements for house heating and cooking) and converted into cubic meters of fuelwood, i.e. 1.3 million m3, using average energy content of common fuelwood species and efficiency loss related to common conversion technologies, which was defined as 35 percent of wood energy content. Obviously, if the fuelwood volume is converted into energy units using the standard factor the result in energy units will be 35 percent larger than the original estimate.