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My Thesis! Or Everything You Wanted to Know about Anaerobic Digestion

I haven’t posted here regularly for a year now, but school is officially over, so I can jump back in again. If you’re interested in (part of) what I’ve been doing all this time, check out my thesis: Municipal Development of Anaerobic Digestion/Combined Heat and Power in Massachusetts.

If you just want the CliffsNotes version, anaerobic digestion is basically breaking down organic materials (like food) with bacteria in an environment without oxygen. Composting is aerobic digestion, meaning it does roughly the same thing with oxygen. But with anaerobic digestion, we can collect the gas that’s produced (roughly half methane) and use it to generate energy. This happens in landfills, anyway, and there are some landfills that have gas capture systems, but if we control the process ourselves we can tweak it to be faster and generate more methane, and we can make sure the methane doesn’t escape into the atmosphere (very important, since methane is a greenhouse gas).

Anaerobic Digestion


There are a few places already doing this in Massachusetts. There are six wastewater treatment plants with anaerobic digestion and three farms. Manure and wastewater are both reliable feedstocks, but if you mix food waste with them it’s even better, generating more biogas, reducing the volume of the sludge, and making the process more stable. The three farms are adding food waste to the mix, but the wastewater treatment plants aren’t yet. However, Deer Island—the wastewater treatment plant that serves most of us in the Boston area—is planning a pilot food waste project for the fall.

Anaerobic Digestion in Massachusetts


Here in Massachusetts this is especially relevant, because we have a commercial organic waste ban coming up in October. This only applies to entities that generate a ton or more of food waste per week, not residents. But some towns are  considering doing residential food waste pickup, too. Hamilton has been doing so for about a year now, and Cambridge is doing a pilot project in one neighborhood. Anaerobic digesters are a great place for all that food waste to go.

Carbon Footprint by Zip Code

Have you seen this great visualization from the Cool Climate Network? It’s household carbon footprint by zip code, based on home energy use, transportation, and consumption of goods and services. It’s really striking how green Boston and its immediate suburbs are, and how red the circle around them is. The companion carbon calculator lets you estimate your own carbon footprint more accurately.

Carbon Footprint by Zip Code

That’s dramatic.

Since taking a GIS class this fall I’m really interested in data visualization. Did you know the New York Times dialect map had the most views of any article in 2013? And it was posted on December 20! It really pushes home that we need to be thinking about more interactive ways to communicate information.

Local Energy Planning in Medford

I know it’s been forever since I’ve posted anything (see the usual excuses: school, work, buying a house), but I just had to share some videos that I helped create at MAPC. I’ve been interning in the Energy Division of the Metropolitan Area Planning Council for the last nine months, assisting local governments with energy efficiency and renewable energy work. I think this video about our Local Energy Action Program with the City of Medford sums it up really well. And I especially love it because I helped them with the two residential outreach programs they mention: the National Grid Community Efficiency Initiative and Solarize Medford. More than 550 Medford residents completed home energy audits and 48 residents and businesses installed solar panels in 2013 as a result of these programs.

Nontoxic Pest Control

As you know, we have a tiny garden in self-watering planters on our porch. This makes caring for our herbs and veggies easy. We only need to refill the water reservoirs about once a week, and we get much better results than we did with the old pots. However, we hit a bump in the road in our mini garden paradise  last weekend: tons of tiny, long-legged, red bugs all over the tomato plants. After a little research, I found out they were red aphids, and although they don’t usually kill full-grown plants, they can destroy new growth. Not on my tomato plants.



I’d rather avoid pesticides, if possible, so I started looking online for organic ways to get rid of aphids. A gang of ladybugs would be great, but failing that, the most common suggestion was spraying the leaves with a mixture of dish detergent and water (a couple tablespoons per gallon, spray both sides of the leaves, and rinse off after a couple hours). Even better, some people suggested just blasting the plants with a garden hose, or in my case, a particularly powerful spray bottle. And it worked! I sprayed away all the aphids that I could see, then did the same every other day for the few stragglers left. A week later, I don’t see any aphids at all. Who knew it would be that easy?

I suspect the aphids may have been drawn to the high nitrogen content in the vermicompost that we used this year. Our greens to browns ratio is always a bit top heavy. Now we have more of an incentive to keep it balanced: not wanting to deal with disgusting bugs!

Easy Limeade

It’s almost embarrassing to call this a recipe because it’s so simple, but it’s a great thing to have in the fridge on hot days like this weekend.



Easy Limeade

(Adapted from Martha Stewart – sorry, Cheryl!)

3/4 cup lime juice
1/2 cup sugar
5 cups water

1.     Make simple syrup by boiling 1 cup water in a small saucepan, adding sugar, and stirring until dissolved.
2.     Add lime juice and the rest of the water. Stir.

Yeah, it’s that easy. We usually buy bottles of lime juice at the store, but if you want to get fancy, you can juice 6 limes instead. It *does* taste better that way.