Cow Power - Notes from a talk by Ken Brennan

> In 2007, Pacific Gas and Electric Company (PG&E) announced that the

> California Public Utilities Commission approved two gas purchase
> agreements with biogas project developers Bioenergy Solutions and
> Microgy.  These firms will each deliver a contract maximum of 8,000 Mcf
> of pipeline quality renewable natural gas every day.  The methane gas,
> captured from cow manure, will be generated onsite at large dairy farms
> in California, and delivered to PG&E through its extensive gas
> transmission pipeline network.  In addition to producing renewable
> energy, each of these facilities can produce significant greenhouse gas
> benefits by capturing methane from cow manure.  The city of Palo Alto is
> considering biogas as a source of alternative energy.
> Ken Brennan, a Senior Project Manager in PG&E's Business Development
> section, will describe the technology behind the initiative, and how
> biogas is a triple win for California, delivering clean, renewable
> energy, improving air quality and providing farmers with a new revenue
> stream that would otherwise go unutilized.

Ken 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.

It 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.

The 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 develop it.

PG&E 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 process.

Ken 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:

10% of PG&E's natural gas needs is a large percentage compared to what most renewable sources can provide.

In 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.

A lot of the research into biogas capture and purification is going on in Europe, although pilot projects in Tulare County go back to the 1970s.

Regulatory 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.

The effluent output of anaerobic digesters can still be utilized as good fertilizer.

Tian Harter