How To Turn Compost Into Electricity or Farmers Market Vouchers (+ the #SeedMoneyChallenge!)

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Yesterday I volunteered at a community garden in East Palo Alto called Collective Roots. I spent an hour and a half there, and my task was sifting compost.

This garden actually has a program where people can trade kitchen scraps, which the garden group turns into compost, for vouchers to the farmers market. Participants have to take a short training course (to learn what food waste can go in the compost bin and what food waste should not). The garden then provides them with compost buckets which they fill for food waste and return to the garden. I’m intrigued, and I’ll have to look into it further to see if I’d be eligible to participate. It might only be open to East Palo Alto residents.

In the house where I’m living, the kitchen waste is picked up by the city every Monday. My landlord used to have a compost pile behind the garage, but abandoned it when the city began its compost collection service. The city turns the compost into electricity.

A company called GreenWaste collects and processes compost from Palo Alto residents. Sherry Listgarten, who writes blog posts for A New Shade of Green, part of the online Palo Alto newspaper, wrote a very informative post on how our compost is handled back in 2019. I recommend you read her original post, but here’s my tl;dr version: The compost is put into large ventillated chambers and allowed to partially break down, at which point microbes are added that digest the compost and produce methane. The methane is collected and burned to form energy. The digested compost is then able to be used for agriculture or other landscape needs.

How much electricity does this process generate? According Listgarten’s article, “The plant generates 1.6 megawatts of electricity, as well as heat for the percolate [the fluid that contains the added microbes]. The digesting facility uses only 330 kilowatts, so 1.3 megawatts is sold back to the grid through a contract with PG&E. That is enough to power over 1600 California homes.” This sounds great, but I don’t think she specifies in the article how much compost input was needed to generate this much electricity, so I can’t translate our 96-gallon yard waste bin into kilowatts. Also, there are 26,000 “households” in Palo Alto alone (according to the US Census data), so “1,600 California homes” only amounts 6% of Palo Alto. I don’t mean for that to sound discouraging. Composting is great for our soil! And powering 6% of Palo Alto homes with clean energy from food waste is better than powering that same number of homes with coal or oil. I’m simply putting it all in perspective.

Another point I found interesting from her article was this graph showing the breakdown of waste in each of our curbside waste bins (one for trash, one for recyclables, and one for compost).
Image source: Sherry Listgarten

People are actually doing a pretty good job of sorting their compost and recyclables! It’s also encouraging to see that “problem materials” (i.e. garbage?) only account for a small fraction of overall waste.

The soil here is quite hard and dry, and I wish we were making compost, but I think my landlord is perfectly happy giving his compost to the city, and doesn’t want to deal with the extra work of maintaining a compost bin. C’est la vie.

On a completely different note:

My former community garden group in Seattle is participating in the #SeedMoneyChallenge, which is a 30-day fundraising challenge for community gardens. The community gardens raise money from individual donors and compete for a chance to win additional grant money (up to $600) from SeedMoney.

There are 470 community gardens doing the #SeedMoneyChallenge. Our garden is the Meadowbrook Community Garden and Orchard (MCGO). They’ve already surpassed their initial fundraising goal of $800, and are thrilled with that! They’ve created a new stretch goal of $1500. With the money, they’re hoping to build a garden shed and install irrigation to both the fig orchard and the apple and pear plantings. The 200 gardens that raise the most funds will get an additional $100-$600. The competition is running from Nov 15 – Dec 15. IF you are so inclined to donate, the link to donate can be found here or by clicking on the image above.