[Date Prev][Date Next][Date Index]

E-M:/ RE: / green plants, fossil fuels, biofuels



-------------------------------------------------------------------------
Enviro-Mich message from "John Riley" <rileyj2@michigan.gov>
-------------------------------------------------------------------------

We continue to hear various analyses of the amount of energy input
required to produce ethanol versus the amount of energy return from the
final product. Does anyone know how traditional formulations of gasoline
and diesel compare, using similar methodology?

>>> "Link, Terry" <link@mail.lib.msu.edu> 11/22/06 1:00 PM >>>
Ted,
 
Thanks for sharing this. I think the science is still not convincing in
this area one way or another(although I'm no scientist!!). I base this
on both an article in the latest Union of Concerned Scientists
newsletter and on review of a study that reviewed numerous studies on
ethanol 
<http://apps.isiknowledge.com/WoS/CIW.cgi?SID=K1pLg7ahGDPpE8FMn14&Func=Abstract&doc=2/1>
Ethanol's energy return on investment: A survey of the literature 1990 -
Present 
ENVIRONMENTAL SCIENCE & TECHNOLOGY 40 (6): 1744-1750 MAR 15 2006,
including Pimentel's. Seems like there are differences in assumptions
that drive results of the research. MSU's Bruce Dale's research seems to
suggest that there are particularly good possibilities for cellulosic
ethanol if some of the technical efficiencies can be improved (worth
working on). UCS position seems to suggest that we need some of this as
a bridge to cellulosic future and other renewables. 
 
 
 
Terry Link, Director
Office of Campus Sustainability
Michigan State University
106 Olds Hall
East Lansing, MI 48824
1-517-355-1751 (Phone/fax)
link@msu.edu 
www.ecofoot.msu.edu 
 
One planet, one family, one future
 
-----Original Message-----
From: owner-enviro-mich@great-lakes.net
[mailto:owner-enviro-mich@great-lakes.net]On Behalf Of ted schettler
Sent: Monday, November 20, 2006 9:00 AM
To: hcwhplan; SustainBio; enviro-mich@great-lakes.net 
Subject: E-M:/ green plants, fossil fuels, biofuels
 
Editorial: Green Plants, Fossil Fuels, and Now Biofuels 
BioScience  Volume 56: 875.  November 2006 
For 700 million years, green plants contributed to the formation of
soil, oil, natural gas, and coal. As the human population increases, so
too does the consumption of soil and fossil energy. If this trend
continues unabated, humans will consume most of these precious resources
within the next few hundred years. 
By 1850, when wood accounted for 91 percent of US energy consumption
and the US population was less than 10 percent of the current 300
million, serious wood shortages already existed. Now, with only about
4.5 percent of the world population, the United States accounts for a
quarter of total fossil fuel use, the largest per capita consumption of
any country. Between 1850 and 2000, 90 percent of the US oil endowment
was mined. 
Converting grain or other biomass into ethanol is currently a popular
idea, but it is not a new one. It requires fertile soil, large
quantities of water, and sunlight for green plant production. Green
plants in the United States collect about 53 exajoules of energy per
year from sunlight. Americans consume slightly more than twice that
amount, however. Enthusiasts suggest that ethanol produced from corn and
cellulosic biomass could replace much of the oil used in the United
States. Yet the 18 percent of the US corn crop that is now converted
into 4.5 billion gallons of ethanol replaces only 1 percent of US
petroleum consumption. If the entire corn crop were used, it would
replace only 6 percent. And because the country has lost over a third of
its agricultural topsoil, no large increase in the corn crop is
possible. 
Our up-to-date analysis of the 14 energy inputs that typically go into
corn production and the 9 invested in fermentation and distillation
operations confirms that 29 percent more energy (derived from fossil
fuels) is required to produce a gallon of corn ethanol than is contained
in the ethanol. Ethanol from cellulosic biomass is worse: With current
technology, 50 percent more energy is required to produce a gallon than
the product can deliver. Investigators differ over the energy value of
the by-products of making corn ethanol, but the credits range only from
10 percent to 60 percent. In any event, biomass ethanol is a bad choice
from an energy standpoint. 
Moreover, the environmental impacts of corn ethanol are enormous. They
include severe soil erosion, heavy use of nitrogen fertilizer and
pesticides, and a significant contribution to global warming. In
addition, each gallon of ethanol requires 1700 gallons of water (mostly
to grow the corn) and produces 6 to 12 gallons of noxious organic
effluent. 
Using food crops, such as corn grain, to produce ethanol also raises
major ethical concerns. More than 3.7 billion humans in the world are
currently malnourished, so the need for grains and other foods is
critical. Growing crops to provide fuel squanders resources; better
options to reduce our dependence on oil are available. Energy
conservation and development of renewable energy sources, such as solar
cells and solar-based methanol synthesis, should be given priority. 
David Pimentel
College of Agriculture and Life Sciences, Cornell University 
      Tad Patzek
     Department of Civil and Environmental Engineering, 
     University of California-Berkeley 

==============================================================
ENVIRO-MICH:  Internet List and Forum for Michigan Environmental
and Conservation Issues and Michigan-based Citizen Action.   Archives at
http://www.great-lakes.net/lists/enviro-mich/

Postings to:  enviro-mich@great-lakes.net      For info, send email to
majordomo@great-lakes.net  with a one-line message body of  "info enviro-mich"
==============================================================