Building High Performance Solar Collectors

Oil embargoes and hour-long lines to purchase gas in the 1970s started me developing high performance solar collectors that harness todays energy, reducing need for ancient fuels. The primary design challenge was making solar equipment affordable, with efficiency a secondary goal. The reason: fossil fuels were becoming ever more difficult to procure. These relics inherited two hundred million years of chemically processing ancient plants to become highly concentrated stored energy, readily available for power. Digging and selling coal, oil and gas have been very profitable. Those profits helped grow government, build highways and airports, manage world trade markets, and provide food, jobs, education, and healthcare. And we’ve burned a lot more of these resources since the 1970s.

Each US person currently consumes about 50 pounds of fossil fuels every day. Remaining fossil fuel supplies cannot sustain this demand and highly profitable fossil fuel reserves are almost gone. The oil price needed to extract a barrel of oil is double today’s $60 price. Yet low cost renewable solutions are not available for heating homes, driving industrial thermal processes, or simply harvesting solar energy to minimize burning fossil fuels.

    

Forty years ago, we had to build every solar collector module from scratch. There still are no “off-the-shelf”, affordable solar concentrating modules to work with. After building a few prototypes that used flat mirrors to direct sunlight to a receiving area, intensifying it up to 500 times, I learned that it was better to slightly warp flat mirrors so that each image intensified sunlight around 10 times. An array of hundreds of mirrors then readily magnified the sun’s radiant energy 1,000 times or more, without adding cost. The concentrator with its array of mirrors follows the sun so its reflections enter the opening in a receiver that converts sunlight into other energy forms such as heat and/or electricity. A low cost, high performance concentrator, like a “Swiss Army Knife”, should become a primary tool for using solar energy cost effectively today.

Why not just use solar panels mounted on roofs?

Rooftop solar collectors are expensive and typically deliver less than 20% of what’s available. Those that convert sunlight into electricity cover the area with semiconductor material. Heat collectors use insulated metal and fluid lines for transferring heat that have to be protected from weather. Both types deliver rated outputs only when the sun shines directly on them. Solar collectors that are fixed to a roof miss sunlight that does not directly shine on the front. When covered with snow, they collect nothing at all.

Won’t high performance solar collectors that track the sun be too expensive?

High performance solar concentrators do not have to cost much. Mirrors for a solar collector that can supply half the energy for a typical home can cost $300 to $500. The structure, controls, tracking, foundation and heat transfer equipment collectively cost about the same amount. A module that converts intensified sunlight into six kilowatts of power along with 12 kilowatts of heat in the area the size of a typical frying pan should become available for less than $3,000. But it will take a few teams tending engineering prototypes to prove simple equipment that runs itself and can be maintained by anyone handy.

Can high performance solar collectors diminish our consumption of fossil fuels?

High performance solar collectors can certainly reduce our fossil fuel use and one with three hundred square feet of mirrors can deliver the energy required for a typical home. However, the timing of sunshine does not exactly match a home’s heating need. Night, bad weather, and winter diminish how much sun we get. Much comes during long summer days, not long and cold winter nights. A logical goal when adopting solar energy might be to displace half the electric power and conventional heat (gas, propane, fuel oil) of a home, cutting in half the carbon footprint.  High performance solar collectors should be able to do almost anything fossil fuels do now but it will take time to commercialize technologies and prove energy storage strategies. Oil, gas and coal burning power plants have more than a century of development and we all expect that level of performance and cost. Many do not realize the potential nor support research into alternatives that enable living without altering climate. It’s easier to kick the oilcan down the road until it’s empty rather than develop equipment that allows living well without transferring underground energy resources into the atmosphere.

Processes that utilize intense solar power are shown below along with an option of substituting conventional photovoltaic panels for mirrors until modules that deliver both heat and power become available. Tracking these aims them directly at the sun enabling them to collect over 40% more energy and turning them away from the sky when the sun is not out keeps them clean and frost/snow free.

Point-focus Solar Concentrators Can Power a Variety of Processes

What is the current program for making the next solar collector?

Now that the maple-sugaring season is over, seven cords of firewood for heating my home are drying, and an acre of garden mulched and growing; I’ll be building our next solar collector. Over the next weeks I’ll present short histories of each module: mirror assembly, tracking structure, drives, foundation, receiver/pump module and controls before detailing the latest design. Over the years I’ve made lots of missteps while trying to develop cost effective solar collectors and these histories may enable others to pursue more promising possibilities. My next effort will be to build a solar collector that provides our hot water year-round and to significantly diminish how much wood we burn to keep our home comfortable. I’ll also use it to preserve food, dehydrate fruit and vegetables, sterilize soil, dehumidify our basement, transform sap into maple syrup and other heat intensive tasks.

This next solar collector should:
1.    Intensify sunlight 1,000 times so it can power tiny receivers that deliver both heat and power;
2.    Harvest more than 80% of available sunlight;
3.    Require home shop tools (no welding or costly equipment) to build it;
4.    Utilize only materials that can be readily reused or recycled;
5.    Go up using only hand tools and follow the sun by itself;
6.    Provide year-round hot water, air conditioning and space heating when integrated with backup systems;
7.    Power itself and connected systems that work in any weather;
8.    Return the energy invested in materials used in fewer than six months;
9.    Operate for 30 years: with any part easily repaired or replaced; and
10. Pay back money invested in fewer than ten years, without subsidies.

My wife and I are bootstrapping this effort. To minimize cost, I’ll primarily use materiel left over from past projects. The mirrors and aluminum extrusions will prove function but an optimized design will require new extrusions that incorporate features that reduce labor and minimize material. 

Freeze Protecting Tomatoes, Beans & Peppers

Our typical last day of frost is May 15th and in a good year, the last freeze occurs in April. This year we have had a very cold spring but once it warmed up, it stayed warm - until last night, May 22, there were frost warnings. In addition to hundreds of flowers, we have about 300 peppers, 150 tomatoes, 100 beans and few hundred sweet corn plants in outdoor gardens. A severe frost would kill or severely damage any not covered by containers or blankets. We simply don't have enough of these to cover thousands of square feet.

For the last week I've been mowing fields and using the dried grass clippings for mulch - a few acres of the stuff. It's been very dry so the grass has remained very fluffy. I do this every year to eliminate weeds, conserve moisture, and add nutrients. By the end of the summer, worms have consumed more than half of this organic matter. I realized that loose mulch on either side of sensitive plants can be pushed together to support a cap of more mulch placed on top without hurting 2 to 5 inch tall pepper, tomato and corn plants. Using the mulch in the beds, it took only an hour to build grass huts over more than 600 plants!

Rows of Dried Grass Covering Sweet Corn

Close-up of Dried Grass Mounded Over Pepper Plants

Row of Covered Tomato Plants

Hot Pepper Plant Garden With 180 (Five Varieties) Covered in Mulch

Ground Up Dry Leaf Mulch Covering Tomato Plants Worked Too!

Our supply of blankets, towels, tarps and boxes readily covered the sensitive flower beds.

Raised Flower Beds Covered by Blankets Over Inverted Boxes

This morning, May 23, I got up at 5 AM. The thermometer I had placed on a flower bed overnight registered 28 F, a killing frost. I waited a few hours for the sun to warm the air before removing the grass tents. Wind gust had uncovered a few taller tomato plants and beans which were severely damaged, with limp and blackening leaves on top. They may come back. Peppers and corn all looked okay. It took two hours to uncover all the plants and redistribute the mulch, including pulling a few weeds.

Pepper Plants Uncovered

Pole Beans Uncovered Before Adding Climbing Trellises

A Row of Tomatoes Uncovered

Smoking Fish

When a friend announced that he was going fishing for pike but he didn't like to eat them, I asked him to bring them to me. A few days later, seven fish arrived, packed in ice. I built a cold smoker last year to cure some large bass from our pond and it took 24 to 48 hours of cool smoke to cure them. Guidance from the department of Alaskan fisheries suggested that cold smoked fish subsequently be brought to a high internal temperature to kill any parasites. An alternative: freezing for more than a month also works. But we didn't want to wait to make our own version of "White Fish Salad".

Smoke Chamber Reusing a Dishwasher Shell in Action

This year, instead of having a remote generator that fed smoke through four feet of stove pipe, I made a compact smudge pot out of a one gallon stainless steel vessel and mounted it inside the smoke chamber, an old porcelain enameled dishwasher body. That way its heat also warmed the fish enough to kill any internal parasites. It also was more efficient in making smoke so it took only 24 hours to cure fish.

Adequate Smoke Volume Exiting Chamber

Earlier in the spring I had trimmed some apple trees and had many branches that were easy to cut with a hand clipper into little pieces (0.5 to 1.25 inches long). It took me an hour to fill a five gallon bucket. I made a hole in the bottom of the smudge pot for lighting it and admitting air. I covered the top with pieces of aluminum that could be adjusted to let out a modest amount of smoke. The smudge pot covered the hole in the bottom of the dishwasher that allowed the apple wood to be ignited with a torch. It took about an hour to establish the tiny slit in the cover required to choke the flow from the smoldering wood boosted by the chimney effect of hot gases rising and pulling in air for combustion. 

A Bit Too Much Smoke!

After eight hours of smoking, the filets of the fish with skins easily peeled away from the ribs and backbone with halves ready for the final smoking. Using hooks made from stiff stainless steel wire, I hung them all around the smoke spot at the center and suspended a stainless steel colander near the top for the pieces that were too small to hang individually. I refilled the smudge pot with apple twigs three more times: late afternoon, at 11 PM and again at 6 AM. When the smoker cooled mid afternoon the next day, I removed the fish, peeled off the skins, picked out bones and packaged all but one portion for freezing in zip-lock bags. There is lots of room in the freezer this time of year so it is a good place to store them, though the low temperature is probably not needed. They have quite a powerful smoky smell and my wife would complain if I kept them in a cupboard, or worse yet, on a counter!

Whole Pike Smoked for Eight Hours

Herbicide Horror Story

This month new owners are taking over the 57 acre farm across the road from us. I've been caring for the place for quite a few years through the elderly couple's heath issues and his passing. We've known them since we moved here almost four decades ago. I've help unload hay, repaired equipment, watched over their place every winter while they stayed in Florida, gathered cords of dead wood from fencerows, and cross country skied around their fields almost every day they were covered with snow.

Last fall a large truck sprayed while driving up and down all the fields. When I asked Alice about this she informed me that she gave permission for the future owners to apply Roundup so they can start with a clean slate of crops the following spring. The fields had all been used for hay for many, many years and had a wide variety of grass, weeds and some small woody plants. These fields slowly turned brown over many weeks but were not very noticeable because unsprayed fields and roadside plants also faded as fall turned into winter. 

Spring has come late here but it has arrived and lawns and most fields are becoming very green, except for the roughly 50 acres that were sprayed with Roundup. It's unbelievably good at killing hundreds of varieties of plants! They following photos show what these fields look like today, with some contrasting strips and neighboring fields that did not get sprayed.

View Out Our Front Door with the Near Field Herbicide Free. The Field Beyond Is Covered in Dead Grass and If Not for the Herbicide, Would Also Be Green.

View of the Northwest Corner of the Property Showing the Green Buffer Field and the Green Hedgerow

View of the Southwest Corner and Herbicide Free Hedgerow

View to the Southeast Showing the Neighboring Farm All Green

Backyard View of Barn, Sheds, House, Garage and Lawn

View of Pond Where the Ground Was Too Soft to Let the Herbicide Truck Get Too Close 

View of Hedgerow Showing How Precise the Herbicide Works

View to the North Showing a Gully That Prevented Herbicide Truck From Entering: Note the Daffodils Just Under the Barn on the Left

The Daffodils, with Belle, a Bit Closer

Lucky Daffodils!

One Tiny Spot Missed on 50 Acres!

Having primarily used organic methods of pest and weed control my whole life, I'm upset that these new neighbors rely on herbicides to eliminate any competition for seeds they plant.

Planting Mushrooms

Inoculating logs with mushroom spawn is similar to starting seeds indoors for planting outdoors when danger of frost is over. Both require procuring growing media, tending nursery beds of growing organisms until they are ready to take off on their own, and lots of watering. This year we are trying a more challenging variety than oyster mushrooms that we've grown successfully for a few years. Oyster mushrooms grow in a much wider variety of soft hardwoods, including trees that commonly grow around here: popular, ash, willow and many "weed" varieties. This fungus aggressively colonizes these woods and out competes fungi that are commonly found in these logs. This year we will use a large ash-leaved maple for producing golden oysters. For growing the more difficult to grow shiitake mushrooms, a friend brought us a pickup truck full of red oak logs, the best medium for growing this hardwood loving variety.

Although we placed our popular logs on corrugated cardboard to prevent soil organisms from competing with the oyster mushroom spawn we used, two years later there are shelf fungi emerging from many of the logs. To prevent this from happening this year, we are placing our logs on old two inch thick solar panels that have an aluminum skin to keep them elevated above the ground. We have kept the bark very clean, minimizing any contact with soil. Within a few days of harvest, the cut ends of the logs and limb nubs have been coated with latex paint both to conserve moisture and to prevent airborne fungi spores from colonizing these wounds.

Red Oak and Ash-leaved Maple Logs Ready for Inoculation

Shelf Fungi Competing with Oyster Mushrooms in Two Year Old Popular Logs

We cut our mushroom logs to lengths that are readily handled. Since we did not have the luxury of ordering uniform logs that optimize the amount of sapwood available, three to eight inches, for mushroom mycelium to colonize, our diameters from only three trees vary from four inches to well over a foot. We ordered 5.5 pounds of each variety of mushroom spawn growing in sawdust that will colonize about 30 logs each. The process starts with drilling 7/16" diameter holes evenly spaced about 6" apart along and around each log. The tool I use pulls itself into the log and automatically stops at an inch deep. A fixture with four wheels makes it easy to rotate a log so that it takes only a minute or two to make the 25 to 40 holes required. These holes are then filled with the sawdust impregnated with mycelium using an injection tool that compresses the mixture so the top is just below the surface of the log bark. This depression is then sealed with hot cheese wax that we've saved from two years of fancy cheeses. The completed logs then look like they have a bad case of chicken pox!

Drilling Holes in a Log on a Fixture That Facilitates Rotating the Log 

Sealing Injected Mushroom Spawn with Molten Cheese Wax

Wax Both Seals in Moisture and Prevents Competing Organisms From Entering the Wound

Completed Red Oak Logs with Shiitake Spawn Sealed In

Closeup of Logs with a Bad Case of Cheese Pox

Once the logs have been inoculated and sealed, they are stacked close together on the north side of a building so they are  always in shade to prevent them from drying out. They are also under the eaves so that they are directly watered every time it rains. When it doesn't rain for a few days, I'll spray them with water. I'll place boards on the east and west sides of the piles to keep early morning sun from shining on them and minimize wind from drying them.

If we're lucky, we'll be getting the first blush of mushrooms from these logs this fall, but real production won't occur until next year. Then, with any luck, we'll get up to seven more years of mushrooms in diminishing harvests.

Gathering Wood and Putting Away Firewood

Now that maple sugaring season is over, my primary outdoor activity is replacing the wood we've burned heating our home, cooking and making maple syrup. This winter was very cold and seems to be going on forever. Today, April 23rd, it's in the 30's with snow flurries. The stove is keeping us warm and is cooking our meal for tonight. We've burned over six cords of wood this heating season making room for another six cords for the 2016 heating season. We still have five cords of well seasoned wood for next season.

The Lighter Colored Wood on the Left Is for Next Heating Season, the Darker Colored Wood on the Right Replaces Half of What We Burned This Heating Season

Today I cut down a few dead cherry trees and placed lengths of trunk on the trailer. I cut up wood to the largest pieces I can readily handle, usually two or three times as long as readily fit into the stove firebox. This minimizes handling and trips to load the trailer. I can get a half cord load of wood on the trailer if I place larger pieces two deep on the bottom and cover these with ever smaller diameter limbs. 

A Half Cord Load of Wood

Same Load as Above with One Side of Cart Removed Showing Large Pieces on Bottom and Tree Limbs on Top, Chain Saw in Its Holster

I try to minimize burning diesel fuel in the tractor and gasoline/oil in the chainsaw by using them very sparingly. Gathering wood for one heating season takes less than one gallon of each. I'll eventually use solar panels to charge batteries that will enable accomplishing both tasks without burning fossil fuels by using an electric tractor and electric chainsaws. I've been removing all the limbs smaller than a thumb with hand clippers and slightly larger ones with lopping shears. Limbs up to two inches diameter I cut with an efficient hand saw. I've cut a few of the foot diameter logs into stove lengths with a crosscut saw but it would take me too long to do all of them this way. There are gardens to plant! To cut logs to length I now use a corded electric chainsaw or chop saw that can be readily solarized with photovoltaic panels and a battery bank. Maybe next year. 

Newly Stacked Wood Showing Halves, Quarters and Sixths of Logs and a Variety of Smaller Limbs: Sizes Reduced to Dimensions That Fit Through the Firebox Door

When I cut down a tree, I try and use as much of the wood as possible. Since you need kindling to start fires and burning any wood produces heat, any wood that fits through the stove firebox door is good. I leave only rotten wood and twigs too small to readily handle on the forest floor or hedgerow.

Superlative Maple Sugaring Season

Sap started flowing here in upstate New York on March 12th and ended a few days ago. We pulled out our spiles on April 18th. These 14 maples delivered over 460 gallons of sap that my neighbor and I reduced to 12 gallons of maple syrup. I had to carry our portion in five gallon buckets of sap about a quarter mile, usually two at a time, together almost 80 pounds, almost a ton and a half altogether. The best part? The daily activity and multiple trips helped me lose 7 pounds of winter weight.

Early season maple syrup is quite light in color and as the season progresses, it get ever darker from nutrients trees add to the plasma. Some trees add more and their sap seems to diminish before the others. A few of the clear sap trees were still producing a quart or two of sap when all the others had stopped.

Eighteen of our 34 quarts of 2015 Maple Syrup

Quarts of Syrup Showing Changing Color, Sunshine from Behind, One Shaded

Every day we collect sap (some cold days none flowed) we boil off the excess water on our wood stove that's burning anyway for heating our home and cooking.  Periodically we carefully bring the ever thicker syrup to 104 degrees Celsius that indicates the proper amount of water and sugar. We let the refined maple syrup settle for a day or two at room temperature and then decant the clear portion so that we don't have to filter it. The solids that settle to the bottom, usually a quarter inch in a quart jar, we collect in a separate jar for use in cooking. We keep collecting full jars of clear syrup in the refrigerator until the season ends and then can them by steaming them for 10 minutes above a hot water bath. The canned syrup keeps for years.

Last Maple Syrup Finishing with First Batch of Canning

All the equipment used in the sugaring operation have to be cleaned and disinfected before being used again and I prefer to do this before storing it away. Altogether, this year we used nine pails for carrying and storing sap, two pails for collecting sap from the most prolific trees, and eleven milk jugs. Next year, if we tackle maple trees at all: not so many.

Pails and Jugs Ready for Cleaning