Power - Notes from a talk by Ken Brennan
> In 2007, Pacific Gas and Electric Company (PG&E) announced
Public Utilities Commission approved two gas purchase
with biogas project developers Bioenergy Solutions and
These firms will each deliver a contract maximum of 8,000 Mcf
pipeline quality renewable natural gas every day. The methane gas,
from cow manure, will be generated onsite at large dairy farms
California, and delivered to PG&E through its extensive gas
pipeline network. In addition to producing renewable
each of these facilities can produce significant greenhouse gas
by capturing methane from cow manure. The city of Palo Alto is
biogas as a source of alternative energy.
Brennan, a Senior Project Manager in PG&E's Business Development
will describe the technology behind the initiative, and how
is a triple win for California, delivering clean, renewable
improving air quality and providing farmers with a new revenue
that would otherwise go unutilized.
Brennan began by stating PG&E's position on the need for climate
change. PG&E believes that the link between greenhouse gas
emissions and climate change is clear, and the reality is that the
electric and natural gas sectors are large contributors to U.S.
greenhouse gas (GHG) emissions. PG&E's position is that
industry participants should find responsible and effective solutions
to the threats posed by climate change. Not only will PG&E
minimize GHG emissions from its operations, the company will also
maximize the opportunity to lead efforts to address the problem.
turns out that in California there are 1.7 million dairy cows on 1900
farms, each producing about 100 pounds of wet manure every day. A
key gas given off by decomposing the stuff is methane, a GHG 21 times
more potent than CO2. The Europeans have done considerable work on ways
to capture this gas and turn it into a fuel source. The
technology is now mature enough that PG&E wants to see more of
California take advantage of it. The first project to go online
is the Vintage Dairy biomethane injection project put together by
Bioenergy Solutions in Riverdale. The project was officially
launched in March, and will shortly begin to flow renewable gas into
PG&E's gas transmission system.
project consists of a site where manure is collected into a lagoon with
a "hood" to capture the biogas as it bubbles up, or in a large tank
digester. Biogas is roughly 60% methane and 40% CO2. These
components are separated so that the gas injected into the pipeline is
no more than 1% CO2. PG&E would be happy to contract for the
renewable gas, and use it to generate electricity. Ken Brennan
emphasized that PG&E wants to be flexible based on what makes sense
for the individual dairies and the industrial gas customers he is
trying to connect together. He sees a potential for renewable
biomethane to provide 10% of PG&E's gas in a few years and wants to
is interested in getting as many dairies as possible online. Not
every dairy must have all the requisite equipment, such as gas clean-up
or "scrubbing" facilities, to inject biomethane into the PG&E
system. A host dairy may initiate the injection project, and the
surrounding local dairies can simply pipe biogas from their digesters
to the host scrubber. There are several permits that must be
issued to get a dairy biogas injection project going, including air and
water board permits. PG&E can certainly help to facilitate that
Brennan explained that Dairymen should consider this technology because
it provides them with a new and continuing revenue stream; it reduces
the GHG emissions of the dairy; and it gives them better tools for
manure management. PG&E wants to facilitate these projects
because biomethane is a renewable gas supply for California, at a time
when many producers are looking at declining yields on their wells;
PG&E can make the most efficient use of the gas for generating
electricity in their existing gas powered generators; and PG&E
already has an existing network of gas transmission pipelines, so
infrastructure build-out is not necessary.
During Q&A the following items came up:
PG&E's natural gas needs is a large percentage compared to what
most renewable sources can provide.
general, the break-even point for dairy biomethane injection projects
is 3,000 to 4,000 cows. This will allow for production of enough
manure to make installing a digester cost effective.
of the research into biogas capture and purification is going on in
Europe, although pilot projects in Tulare County go back to the 1970s.
hurdles are being mitigated by action through state agency
representatives in Sacramento. Dairy waste can now be considered
as a feedstock for the digester process, which will help to clean
groundwater and reduce GHG emissions.
effluent output of anaerobic digesters can still be utilized as good