Bug Power
The Institute of Science in Society
Science Society Sustainability
http://www.i-sis.org.uk
Waste-gobbling bacteria may be our dream ticket to clean renewable energy. Dr. Mae-Wan Ho
Bacteria
that gobble wastes are a godsend. They prevent the build up of wastes
in our environment and play an indispensable role in making wastewater
safe for domestic animals, wild life, and human beings. In many Third
World countries, these same bacteria are working miracles turning
manure and other wastes into valuable resources to support highly
productive farms that require no input and generate little or no waste
(Dream farm, this series). When these bacteria are confined in
anaerobic digesters with limited or no access to oxygen, they ferment
the wastes, release and conserve nutrients for livestock and crops, and
produce ‘biogas’ as by-product, which typically consists of about 60%
methane (CH4) and a small amount of hydrogen (H2), both of which can be
burnt as smokeless fuel.
Within
the past two years, these same bacteria are showing even more
remarkable potential for producing clean and renewable energy while
reducing greenhouse gas emissions.
Hydrogen economy on potato waste:
The
hydrogen economy is on everyone’s lips as the answer to the
ultimate clean energy. Burning hydrogen produces pure water instead of
green house gases, and it is by far the most energetic fuel on earth,
weight for weight. But in order to really reduce green house gas
emissions, hydrogen must be produced sustainably with renewable sources
such as sun, wind and biomass. About half of all hydrogen produced
currently is from natural gas, the rest is produced primarily using
other fossil fuels. Only 4% is generated by splitting water using
electricity derived from a variety of sources.
At
BIOCAP Canada’s First National Conference in February 2005, a research
team at the Wastewater Technology Centre and the University of Waterloo
in Ontario, Canada, presented a poster describing a prototype process
for producing substantial amounts of hydrogen as well as methane from
potato waste.
The team
used a two-stage anaerobic digestion to get first hydrogen and then
methane. In this way, it was possible to optimize the first stage for
producing hydrogen. The key appears to be an acidic pH of 5.5 in the
hydrogen reactor, instead of pH 7 in the methane reactor. Both reactors
were run at 35C.
They
pulped the potatoes bought from a store and treated the slurry with
peptone (an enzyme that breaks down protein), then seeded the two
reactors – one for hydrogen the other for methane – with digested
sludge from the local wastewater treatment plant to get the bacteria in
place. For the hydrogen reactor, the seed sludge was pre- cultivated in
a sucrose medium for a few days before switching to potato waste when
high hydrogen production was confirmed. For the methane reaction, no
precultivation of the sludge was required.
From the
4th day, the potato pulp replaced sucrose and hydrogen biogas was
produced continuously for a further 90 days. The maximum production
rate from the one litre reactor was 270ml/h on the 17th day, and the
average rate over the entire 90-day period was 112.2ml/h. The hydrogen
fraction fluctuated between 39 and 51 percent of the biogas (v/v). The
average chemical oxygen demand (COD) concentration (a measure of the
amount of waste present) of the fluid coming out of the hydrogen
reactor was 7 220mg/L, at an input concentration of 12 800mg/L. So more
than 40 percent of the waste was removed.
Once
hydrogen production became stable after the 20th day, the outflow from
the hydrogen reactor was transferred to the second, bigger (methane)
reactor, 5 litres in volume. During the 70 days of operation, methane
biogas was produced continuously; the maximum rate was 410ml/h, and the
average rate, 213 ml/h. The concentration of methane in the biogas was
between 69 and 79 percent. The average COD concentration in the methane
bioreactor outflow was 4 130 mg/L. Again, the process removed more than
40% of the wastes. Together, the two reactors removed 68% of the waste.
Based on
the hydrogen and methane production rates, the average energy yield
from each kilogram dry weight of potato waste was 4.96 MJ (1.4kWh) and
the maximum energy yield, 9.58 MJ (2.7kWh). For comparison, burning 1
kg wood yields about 20MJ. But because the energy is generated from
waste, it is essentially free, and does not require chopping down
trees.
Potato
is the third largest food crop in the world, and Canada is one of the
leading producers (4.7million tonnes annually). Large amounts of potato
waste come from food and potato processing plants. This is potentially a huge source of renewable, clean energy.
(To read the entire article, click here)
Blog For Iowa 
As much as I love renewable energy, an inescapable fact is that the amount of energy retrieved from it on the average will never be as concentrated and large per mass, compared to fossil fuel, which is milliions of years worth of the sun's energy trapped into carbon lifeforms, pressed and compacted over those years. Bio-energy is energy extracted at the initial stage of plant concentrated solar energy. It takes energy to release the energy into usable forms too, by growing the plants, or pre-process with herbivores or eating plants ourselfs, and making the extracting/digesting machinery and processes.
The same urges to myopically raize the Amazon forests for cattle and crops, would probably create the same push for the destruction of the Earth's environment to grow vast swaths of bio energy crops. The uneven and extremes of weather represents the energy pouring onto the earth, without the regulation of plants, forests, and ocean plantlife. So I laugh when we expound about the wonders of wind energy, when some of the increased airflow is a direct result of global warming created from overuse of fossil fuel energy and the destruction of forests.
Basically, in the end planetwide, the human race is going to have to reduce it's wasteful consumer comsumption culture, recycle, conserve and live within smaller means to survive and maintain. The perpetual explosion of growth for growth's sake matched with expanded populations, fed by 300 years of careless use of fossil fuel as energy. Sustainability will be key and control of ourselfs in the way we constantly seek to control feral cats and dogs, or urban deer. Otherwise, it'll be humans mimicking lemmings.
An article in the March Scientific American magazine has an article summarizing the research by William Ruddiman, that the very discovery by humans of large scale agriculture started changing the Earth's environmental balance between 9,000-5000 yrs ago, such that the next ice age was thwarted. Our fantastic brains and imaginations have contributed to our possible demise.
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I absolutely agree with every point you made. I found the science fascinating and potentially one avenue to weaning ourselves off of fossil fuels. But I do see the potential for over harvesting our forests in order to make room for more bio-crops, which would definitely defeat the purpose of not having to chop down the trees in the first place. But if regulated, perhaps we could utilize this technology based on the level of waste product which we are currently generating. As far as humankind goes, NEED really should trump GREED but unfortunately many people perceive them as two in the same. I do believe we will all be forced to acknowledge a necessary reigning-of the lifestyles we have all grown accustomed.
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I'm really into farmers being self sufficient using bio gas from farm wastes and wind energy. I helped write and develop the renewable energy plank for the state Democratic party, egged the Senators on going for the expansion of tax credits for all forms of renewable energy. I inadvertently emailed a policy staement and idea directly to the governor's Blackberry when I was interning at the state house, so the governor knows about other efforts being done in other states on a larger scale, like executive orders making transportation departments use soy diesel for all large equipment, all government cars running on 85% ethanol, regional
bio gas plants that use collected farm waste from livestock.
Additional ideas could be the planting of switch grass on CRP government set asides, and watersheds/buffers. There could be duplication and expansion of the Ames waste treatment process, by building another county/regional high temperature waste plantthat burns nearly all types of non-metal trash for energy to fuel steam turbine to produce electricity. Many of those processes could produce hydrogen for use in high-ultra efficient vehicles.
The main thing is learning TRUE NEED and not the fake induced NEED touted by merchants. They create markets of imagined needs and wants.
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