Study Limitations

Proxy Industrial Primary Products

Methanol from Natural Gas

LPG from Petroleum

· Emissions are associated with extracting the natural

· Petroleum extraction from Petroleum Extraction - 1987

gas from the well head and associated emissions

DoC Census Data adjusted by DeLuchi (1993) including

Exploration &

from processing of the gas (e.g. removal of inerts,

Alaska and Lower 48 Production

Production

recoverable products (NGLs, LPG), and removal of

· Includes natural gas flared during production

impurities)

· Segment efficiency 95.8%

· Emissions associated with national average

· Emissions are associated with shipping crude oil within

pipeline for natural gas. Based on Total Natural

Lower 48 and from Alaska to Lower 48 and shipping of oil

Gas Supply since this is the amount shipped

imported into United States.

Raw Fuel

through U.S. pipelines annually.

· Modes of transport included pipeline, barge, tanker, train,

Transport

and truck

· Includes evaporative losses; segment efficiency of 99.1%

· Methanol synthesis from synthesis gas made from

· Includes refining from petroleum for LPG production with

natural gas with segment efficiency of 66.5%

a segment efficiency of 95.3%

Primary

Product

Manufacture

Source: Arthur D. Little analysis based on work by DeLuchi, Emissions of Greenhouse Gases from the Use of Transportation Fuels and

Electricity, Volumes I and II, Center for Transportation Research, Argonne National Laboratory, November 1993.

Study Limitations

Notwithstanding the size of this report, the definition of the scope described above

carries with it a number of significant limitations. It is critical to understand these

limitations when reading the report, and even more so when using the information

contained within it. To that end, the most important limitations are described below. Of

course this does not absolve the reader from the responsibility to read the caveats made

throughout the report and to read the footnotes on the pages.

The most important limitation to understand results from the timeframe considered in

the scope. The study focused on near-term (up to 2010) and high-impact solutions. This

is a significant restriction. The 2010 target focuses attention on technologies that are

close to commercialization (have at least been proven at pilot scale). At the same time, it

focuses on technologies that could have broad impact. This excludes many technologies

from consideration. An artifact of the scope of analysis is that some longer-term

technologies (post 2010) that could have higher overall impact were excluded (e.g. some

of the advanced fermentation-based bioethanol technologies as well as biological

production of hydrogen were excluded for this reason). Conversely, other options that

may be attractive in the near-term but do not have the potential for broad impact in the

long-term were excluded. For example, negative feedstock values are unlikely to be

sustainable in a long-term, high-impact scenario, but could provide quite attractive

opportunities for early entrants in the near-term (e.g. Masada MSW to ethanol projects).

Similarly, the use of idled capacity plants (e.g. paper mills, biopower plants, etc.) could

provide significant capital cost advantages for some early applications (especially in

California). The entire list of options considered (for biopower, biofuels, and

CR.71038.BIOMASS.FINALREPORT.10-01