Another Panel Solar Cooker

Poyourow demoing her solar cooker design

There’s no one size fits all solution when it comes to the world of solar panel cookers. All have their advantages and disadvantages. I got an email from author Joanne Poyourow, leader of the amazing Los Angeles Environmental Change Makers, with a simple and effective design she came up with.

Pouyourow’s cooker comes together much faster than the CooKit design that I blogged about earlier this week. There’s hardly any cuts to make and no glue needed. Her design makes use of a car sunshade which can be picked up cheap at your local 99¢ store. The sunshade is more durable than aluminum foil glued to cardboard. While you can also fashion a sunshade alone into a solar panel cooker, I’ve found that they don’t stand up well in even a moderate wind.

Plans for Poyourow’s cooker can be found here (pdf).

She also has a list of solar cooking resources here.

And yes, for most North Americans this is the wrong time of year to be blogging on this topic since, as the sun gets lower in the horizon, solar panel cooking season is almost over. But I’ve got a backlog of summer R&D to share. Stay tuned for the ups and downs of our summer gardening, a bike accident story and a taste test of beer made with our homegrown hops . . .

CooKit Solar Panel Cooker


I’ve been experimenting with a nice panel solar cooker for the past week and, so far, the results are impressive. Called the CooKit, it was developed in 1994 by a group of engineers and solar cooking enthusiasts associated with Solar Cookers International and based on a design by Roger Bernard.

It has a couple of nice features:

  • It produces ample heat to cook rice and simple casseroles.
  • When you fold it up it takes up no more space than an album (do I have to explain what an album is for the youngsters out there?).
  • A flat area on the base of the CooKit makes weighting it down with rocks easy. This is really important in windy places.
  • All you need to build it is a knife, cardboard, aluminum foil and glue.

As with all panel solar cookers you need an black enamelware pot wrapped in a turkey roasting bag to hold in the heat. You ain’t gonna deep fry things with a panel cooker, but they are great for slow-cooked crock pot type dishes. The only disadvantage to this design is having to cut curves, but with a sharp knife it wasn’t difficult. The other improvement would be a stand to lift the pot off the aluminum foil for more efficiency and to keep the cooker un-scuffed. When panel cooker season returns to LA in the springtime, you can bet I’ll be making a lot of rice with this thing.

Detailed instructions for how to build a CooKit can be found here.

Also, Mrs. Homegrown and I are writing a new book and we’d like to include some plans for solar cookers (any kind). If you’ve got a favorite DIY model, leave a comment with a link.

Another view with curious Doberman in the foreground:

Homegrown Evolution Podcast Episode #1

Subscribe to the Homegrown Evolution podcast in itunes here.

Download the mp3 on archive.org.

On this first episode of the Homegrown Evolution podcast we talk food preservation with author Ashley English who blogs at small-measure.blogspot.com. English will have two books out next year on food preservation and chickens, part of a series entitled “Homemade Living,” (Lark Books). She also has a weekly column every Friday on Design*Sponge at www.designspongeonline.com/category/small-measures.

In the second part of the show we talk to Wing Tam, assistant division manager for the Watershed Protection Program in the City of Los Angeles’ Bureau of Sanitation about a new rainwater harvesting pilot project. You can find out more about the program at www.larainwaterharvesting.org. We conclude with a reaction to this new program from river activist Joe Linton, author of Down by the Los Angeles River and one of the bloggers behind lacreekfreak.wordpress.com.

As we say on the podcast, we prefer gardening to staring at computer screens and putting a podcast together involves a hell of a lot of the latter. Don’t look for frequent updates, but we’ll probably put out another one in the fall. Please excuse the mike popping and other technical flaws, as we’re still working out the technical side. We hope you’ll enjoy the podcast while, say, gardening or prepping food for canning. We’re all about open source, so feel free to redistribute or rebroadcast.

Music on the program is from archive.org:

A bluegrass cover of DEVO’s Mongoloid by the Hotfoot Quartet. Bob Frank, guitar and lead vocal, Jim Blum, upright bass and vocals; Paul Kovac, banjo and vocals; Bob Smakula, mandolin and vocals. Available here.

Also from archive.org, a collection of surf music.

StoveTec’s Hot Rocket Stoves

StoveTec’s wood burning rocket stove on the left, charcoal and wood on the right.

A reader comment alerted me to a very cool product, the StoveTec Rocket Stove, offered by the “not-just-for-profit” wing of the Aprovecho Research Center. Profits from sales of the stoves benefit the Center’s research. StoveTec sells two rocket stoves, one for wood and the other for both wood and charcoal. While I haven’t tested one, the $37 to $40 price is a bargain.

Rocket stoves are a simple “appropriate” technology that burns small pieces of wood and charcoal efficiently. We’ve blogged about them before and even constructed our own out of a vent pipe and bricks. Instead of burning a log to cook you can use trimmings from trees, bushes and even agricultural waste. According to StoveTec,

“StoveTec Stoves, rocket stoves invented by Dr. Larry Winiarski, use 40-50% less fuel and reduce emissions by 40-75% while reducing green house gas (GHG) emissions an estimated 60% or 1-2 tons per year. These stoves are preferred over other improved cook stove and three stone fires by 95% of users in Uganda. High adoption and preference reported in India, South Africa, Ethiopia and Chile proves the stoves great versatility among many different users.”

Looks like they could find a nice home in North American as well. Do some pruning and then cook dinner. How about a rocket stove tailgate party?

Going Gray!



Got a nice note and some pics from Ben in Portland:

“I bought your book and it has become my mission manual. We own a house in Portland, OR, and I just today did my first project out of the book – routing the shower drain into the garden. It cost about $60 for all the pipe, glue, a 2″ hole saw to drill through the wall, and a new drain kit (my old drain was decroded as crap). Our house is only 750 sq. ft. (plenty for me, my gf, and our 3 dogs), and luckily our bathroom is right next to the garden plot I’ve had for about 3 years now. We’ve got a ton of squash going, which as you know takes a good bit of water, so I thought our not-so-gray shower water would be much appreciated by the little yellow bastards. Another benefit is that we won’t have to deal with the recurring shower clogs which have been forcing us to use drano.

The drain setup was super simple from a plumbing perspective, so all I did was cut off the old drainpipe, replace the drain assembly, and route a new pipe out to the garden. It took three 22 degree couplers, one 4 foot and one 10 foot section of pipe. the pictures sort of show what the finished piping looks like. I know it looks like I had to rip through the floor to get to the drain, but that’s just because whoever installed our shower years ago did a terrible job.

I drilled holes every 6 inches or so in the pipe that goes out into the garden. I may need to cover them with mesh (I’d appreciate your advice here) and dig some trenches to route the water into the rest of the garden, but for now it’s working great!

Thanks for your wonderful book and website. I will send you more pictures as i do more projects!

-Ben”

California’s New Greywater Code: Common Sense Legalized!

On the left is our yard which is irrigated by the washing machine. On the right, the neighbor’s yard which is never watered.

This Tuesday the California Building Standards Commission legalized our formally outlaw greywater system. For several years now, we’ve sent our washing machine waste water out to fruit trees in the front yard. The new regulations are a rare common sense moment for our otherwise troubled state government. Let’s hope our current hard times spur more innovation like this. Originally slated to go into effect in 2010, the plumbing code was updated as an emergency measure to deal with drought conditions that have plagued the southwestern US for years. Under the new California greywater code:

1. In most cases you won’t need a permit.

2. Allows discharge into a simple mulch basin rather than the expensive and complicated sub-surface emitters required under the old regulations.

3. No exspensive pumps or filters required!

Here’s the new code as amended (pdf).

Unfortunately the code can be superseded by local municipalities. Plumbers unions opposed loosening the code, no doubt fearing the loss of business. Combined with NIMBYs, they could put pressure on city governments to keep greywater illegal. It’s time for us Californians to be vigilant and start letter campaigns should cities try to restrict our new right to use our greywater.

As for the practical side of this new law, I’d suggest that anyone interested in installing a greywater system keep it simple and low cost. I can’t think of any better resource than Art Ludwig’s book The New Create an Oasis with Greywater: Choosing, Building and Using Greywater Systems and his website oasisdesign.net. Take note of Ludwig’s free open-source laundry to landscape plan.

And don’t forget, Homegrown Evolution is offering a DIY Greywater class on Sunday August 16th at 11 a.m. in Silver Lake (Los Angeles). Sign up here.

The Great Greywater Debate- PVC or Polyethylene?

PVC v. Polyethylene

Homegrown Neighbor here. I’ve been wanting a greywater system for a long time. My old house does not exactly make access to the pipes easy, so I’m starting with just the washing machine. The neighbor, Mr. Homegrown, is anxious to try out a new design from Oasis.

So we have been trying to get all the pieces and get it done- and here is where we get stuck. The system can either use polyethylene tubing or pvc. PVC is ubiquitous, cheap and toxic. Just how toxic, I don’t know exactly, but I’ve never chewed on any pieces just to be on the safe side. PVC is toxic to manufacture as well. This makes polyethylene the more ecological approach. But it is very hard to find in the size we need for the greywater system. And you have to buy a minimum amount- about 250 feet is the smallest we have found so far. For my yard, we probably only need about 40 feet. Plus, you have to mail order it. If we go the pvc route, it would cost far less and we could buy all the pieces at the local hardware store. We also want the system to be replicable so that we can share it with others and encourage them to use greywater. Searching for the parts for the polyethylene version is confusing – pvc is easy and accessible. This is the challenge. So what do people think- should we go with pvc or polyethylene?

Mr. Homegrown here. So I just found a local source for 1-inch polyethylene: Aqua-Flo. Cost is in the neighborhood of 33¢ a foot depending on how much you get. It comes in 20 foot and 100 foot lengths. So I think we’re gonna go with polyethylene. Incidentally, when I called Aqua-Flo they asked if I was going to make hula hoops.


A correction and update 7/25/09: The Aqua-Flo branch I went to does not have black 1-inch HDPE tubing in stock. Other branches have it, but only in 500 foot rolls that cost over $300. A roll that long would make sense for a contractor, but for DIY greywater installations it ain’t practical. Aqua-Flo does carry a new HDPE product called Blu-lock. You can get 1-inch Blu-lock in-100 foot rolls for a reasonable price (more info to follow in another post). Blu-lock uses special proprietary fittings that are easier to assemble than conventional mainline drip tubing and, intriguingly, allow for disassembly. I’m going to test Blu-lock and will report back on the results.

Washing Machine Greywater Resources

Pantyhose filter

For those of you attending our Wednesday night greywater workshop at Good and for those of you who can’t, here’s a list of resources for using your washing machine as a irrigation source:

The New Create an Oasis with Greywater: Choosing, Building and Using Greywater Systemsby Art Ludwig. This is the bible of greywater. Follow Ludwig’s instructions and you can’t go wrong. Buy a copy via the link, and you’ll help support Homegrown Evolution.

Ludwig’s open source Laundry to Landscape system.

1″ polyethylene tubing–an alternative to PVC pipe.

Oasis Biocompatible detergent, the only laundry detergent we can find that’s appropriate for greywater use. It works great and, again, click through the link and we get a little support.

A selection of three way diverter valves. Note the 1″ brass model for laundry systems. Use these diverters to shift between sending your greywater outside or back to the sewer. Great if you have to do a load of diapers. We don’t have one, but we’re both cheap and kinda extreme.

A local Los Angeles source for drums, the Apex Drum Company: www.apexdrum.com. Phone number: (323) 721-8994. Located at 6226 Ferguson Drive in the picturesque city of Commerce. You can also scavange drums, but make sure they didn’t have nasty chemicals in them. See our greywater surge tank post for what kind of barrel we like to use. Note that you can also turn a surge tank into a rain barrel.

A description of our greywater fruit mini-orchard.

Our greywater surge tank version 1.0. We’ve since added a pantyhose filter as seen above to catch lint that can clog the tank and garden hose. It’s just some threaded ABS waste pipe fittings screwed together with used pantyhose.

A liquid fertilizer of the type that you could add to your greywater surge tank during a wash cycle to fertilize your garden. You could also get a fish emulsion or sea kelp based liquid fertilizer from your local nursery.

Oaktown’s Greywater Guerrillas, another source for inspiration.

Greywater Workshop at Good Magazine

We’ll be doing a greywater workshop at Good Magazine this Wednesday May 27th from 7 to 9 p.m. Directions and RSVP info are here.

We’re going to focus on what I consider to be the easiest way to reuse your greywater: hacking your washing machine. We’ll take a look at a couple of approaches including our surge tank, pictured above, which we just got around to elevating with scrap lumber to get a gravity assist. We’ll also look at Art Ludwig’s direct “laundry to landscape” system.

Topics will also include:

  • Greywater compatible detergents
  • Choosing the best plants for greywater
  • Creating mulch basins
  • Greywater dos and don’ts
  • Plumbing parts
  • Water conservation and efficiency
  • Greywater cocktails (just kidding)

Hope to see you all tomorrow!