|Solar Collector Integrated with Outdoor Burner Readily Provide Comfort Year-round|
Wednesday, January 28, 2015
Divesting in firms that extract fossil fuels makes powerful statements but does not reduce responsibility for keeping fossil carbon deep underground. Corporation profit when we buy fuels and power to drive, fly, heat our homes, and warm our showers.
Solar power charges electric cars, cools homes and runs lights and appliances. But available solar thermal systems are small and expensive. We need larger inexpensive high performance solar collectors for heating homes, making alternative fuels and powering industry. I’ve been working to perfect solar dishes for over 40 years enabling them to perform well in winter. We need simple,high performance solar collectors that:
1. Intensify sunlight 1,000 times to power tiny receivers that deliver heat and power;
2. Harvest more than 80% of available sunlight;
3. Are made with home shop tools without welding or expensive equipment;
4. Can be installed using hand tools and then operate without expert attention;
5. Replace in less than six months the energy invested in making it;
6. Operate for 30 years: all parts easily repaired or replaced;
7. Utilize only materials that can be readily reused or recycled;
8. Power both themselves and connected systems so they work after storms;
9. Provide year-round hot water, air conditioning and space heating; and
10. Pay for themselves in fewer than ten years, without subsidies.
Working alone, progress is slow. Anyone interested in helping make solar tools that enable life without burning fossil carbon?
Wednesday, January 21, 2015
Yesterday a bright yellow plastic bag with a fuel delivery ticket inside hanging on her mailbox flag announced that my neighbor just received 389 gallons of #2 fuel oil. Her farmhouse is empty because she now lives in an assisted living facility but to prevent mold issues and keep toilets, traps and pipes from freezing she has the thermostat set at 50 degrees. I’ve been looking after her place for years as her husband’s health failed, then passed away and her own health deteriorated. Later this spring her home that sits on 57 acres and where her family lived for 40 years is under contract for sale.
|Fuel Oil Delivery Ticket: 388.8 gallons 10-24-14 to 1-19-15|
The coming deadline gives me almost three months to cut dead or dying trees along fencerows and gather fallen branches that make good firewood. I’ll miss checking the indoor temperature every day by glancing, from outside, at the large thermometer hanging inside her kitchen window. I’m usually on skis chasing my daughter who is much faster than I and we always include this point in our varied routes that cover two or three miles. The snow melted this past weekend so we’re covering rougher terrain on foot, looking for signs of owls, fox and coyotes because they are unusual compared to mice, rabbits and the four dozen deer we saw yesterday.
So far this heating season it’s taken over a ton and a half of fuel oil to keep her farmhouse from freezing. It would have taken more to maintain 65 degrees. Since we’re midway through the heating season, it’ll take more than 3 tons of fossil oil costing more than $2,500. Carbon dioxide contribution to the atmosphere? 17,400 pounds, almost nine tons! Could solar do better? Not without a lot of progress that no one seems to be addressing.
The sun often shines 15 hours during a day in June when it’s warm but energy is needed for only for heating water for washing and showers. Because upstate New York is downwind from the great lakes, we get very little sun during November and December when home heating issues become serious. Burning wood for heat is popular and most neighbors have a parlor stove or fireplace insert to reduce the cost of heating with electricity, propane or oil. In rural New York there are no natural gas lines so we don’t have that option.
One carbon neutral approach for using high performance solar collectors would be to combine them with furnaces that burn either wood pellets or cordwood. Pellets can be delivered in bulk and ignited/fed automatically so tasks become adjusting the thermostat and emptying ash. Wood chunks have to be created by cutting trees, hauling logs and branches, and reducing them to sizes that are easy to handle. And they have to be strategically loaded into the firebox filled with coals. A cold firebox requires the extra work of lighting kindling. A solar collector could supplement these burners so keeping warm would require only half the wood. In our case we would have to process only 12,000 pounds of wood instead of 12 tons. For six months solar would provide both hot water and heat: no need to start fires. But we’d have to handle wood in bad weather during the coldest months, a process that I’ve enjoyed for decades. It keeps me active and often exposed to awesome starry skies, meteors and northern lights that I would not see if I stayed indoors.
|Combining a Solar Collector with an Outdoor Wood Furnace|
We’re developing solar technology so folks in rural communities can fabricate components, assemble solar collectors and use them for 30 years heating water and homes. These solar collectors still need appliances like air conditioners, clothes driers, cooking appliances or thermochemical reformers so that they utilize the abundant energy available at temperatures up to 1,000 degrees during the summer. Intensifying sunlight 1,000 times even here in the cloudy northeast, these high performance solar collectors readily collect 80% of the energy available and return money invested in an installation without subsidies in five years and energy invested in the equipment in five months. Not using sunlight available during the summer extends these paybacks. These costs do not include backup heating equipment needed to keep warm when the sun doesn’t shine, stored heat has cooled down and it’s getting cold. Homes already have hot water and central heating so these can fill in when there is not enough sunlight.
Monday, January 19, 2015
Although we’re only a month into “winter”, theoretically we should have burned half our fuel for the heating season. We burn our wood in a kitchen cook stove that also heats our meals, helps seeds sprout, dries outdoor clothing when we come in from skiing and skating and makes maple syrup. The photo below shows that we’ve uncovered one window in the garage that was hidden by stacked firewood. This year we’ve been burning well-seasoned maple and oak so we’ve used less than a quarter of the woodpile so the wood we put away this year we may not start burning until 2017. Less dense wood like poplar and pine burns more quickly and a given amount of heating value takes up more volume, though pound for pound, they are similar.
|View of Half Our Wood Pile with a Window Uncovered|
Yesterday I removed the mower deck from underneath the tractor and put on chains that reduce the chances of getting stuck in snowy or muddy fields as it pulls a trailer loaded with tree trunks and branches.
|Diesel Tractor Without Mower Deck but With Tire Chains|
This year I’m going to try cutting down trees with an ancient cross-cut saw that a friend refurbished and loaned. Chain saws are noisy and burn gasoline/oil and also use quite a bit of heavy oil to lubricate the chain. In a year we typically go through over a gallon of bar oil that ends up in the sawdust. Our garden worms have not complained about having to deal with the oil but they would probably prefer not having to process oil in the wheelbarrows of the tiny pieces of wood that a chainsaw makes that we spread on garden paths. Old-time manual saws don’t need lubrication because no chain runs against a steel bar. The set of the teeth creates a gap in the groove made by the saw as its cutting so lubrication is not needed between the blade and log. Information on how to maintain, repair and sharpen these saws: http://www.fs.fed.us/t-d/pubs/pdfpubs/pdf77712508/pdf77712508dpi300.pdf
|One-Person Cross-cut Saw With Cutting Teeth and Twin Raker Pattern|
I also installed new golf cart batteries in one of our electric tractors so that we can use it for plowing snow. I prefer to shovel snow but my wife likes to use one tractor or the other. Although we have an amazing snow blower attachment for our diesel tractor, I don’t like using it because it requires completely removing all the connecting pieces for the mower to install different assemblies for the blower. Having the snow blower attached also negates using the tractor for carting firewood. Finding opportunities for collecting firewood when the soil is frozen and without deep snow is difficult enough without having to wait until there is little chance for more snow.
|Electric Tractor With Plow|
Wednesday, January 14, 2015
Actually, they need oxygen. Fish die in ice-covered ponds that do not have water flowing into them when they deplete the available oxygen. Plants under water can make oxygen when sunlight shines through clear ice but deep snow makes it dark. A few years ago we lost our large fish when we neglected to aerate our pond soon enough. After the ice thawed, we gathered them up and planted them in the garden but would have preferred to have them alive.
Many ponds in our neighborhood have this problem and support only small fish, reptiles and amphibians. A few fish in a deep pond or any number of fish in apond with a babbling stream running into it can live under ice until it melts. We feed the fish in our acre and a half pond so there are quite a few larger ones that seem to need more oxygen than minnows and young ones. We use a small air compressor that creates a stream of tiny bubbles (through air stones) that pump warmer water from ten feet down up to melt a large hole in the ice, see photo below.
Some winters here in upstate New York have had well spaced thaws that periodically aerated the water so that we didn’t have to bubble the pond but the last few winters have been quite cold for long periods that required attention to keep our animals under the ice healthy.
Saturday, January 3, 2015
How do smart phones and tablets orient screens? Inexpensive sensors inside readily define “up” and can also measure tilt, register motion and detect taps. I’ve been combining an Arduino with digital accelerometers (http://www.adafruit.com/products/2019) to see if together they can point a solar collector when the sun doesn’t shine. This should enable them to point at the horizon just before sunrise, track the sun behind clouds, and know when they’re facing down so they can sleep overnight or during storms, protecting solar panels and mirrors from hail, dirt, frost, freezing rain and snow.
My approach, outlined in the figure below, tries to create a gravity direction scale that matches a time scale so that the controller can reset its internal clock when the direction of the collector and earth coincide. The earth establishes time for solar collectors that rotate on axes parallel to the earth’s polar axis. A tracking controller simply has to synchronize its internal time base with the earth that consistently rotates one revolution per day. Only longitude matters and conventional “clock” time with time zones does not. Concentrating solar collectors that use mirrors to direct sunlight into a receiver work best when the energy, often intensified 1,000 times, is centered inside the receiver. When sensor pairs, with an equal number of thermocouples on opposite sides of the receiver aperture, are balanced (when the temperature on both sides are equal), the tracking structure and concentrator optics are exactly aligned with rays from the sun.
The elliptical orbit of the earth around the sun makes solar noon, when the sun is highest in the sky, vary slowly throughout the year but only by up to a few seconds per day. Complex celestial mechanics equations can correct for this perturbation but require significant computing power and expensive sensors with minutes of arc resolution. “Open loop” approaches that use encoders and time to point at the sun also require expert installation service with exacting setup routines. Even a power failure or perturbation of a sensor can require a service call.
One goal for this work is to enable a simple controller to program itself, using sunlight sensors to direct the collector at the sun so that intensified sunlight hits sensors mounted on the edges of the receiver. One set on a left-right axis controls east-west motion and another set controls up down motion. “Closed-loop” tracking that use sun sensors have had maintenance issues when one side gets dirtier than the other (e.g. from bird poop). This approach uses thermocouples that face the mirrors (downward) when operating and routinely get cooked above 1,000 degrees as the intensified sunlight enters and leaves the receiver aperture (that should keep them clean – it works for self-cleaning ovens!). In any event, since they work on temperature differences, differential soiling should not affect them very much.
In coming weeks I’ll be playing with both digital and analog accelerometers to see which are easier to use and what programming techniques are appropriate. I’d appreciate feedback if anyone has suggestions on how to proceed. I have spreadsheets of data from sensors as they rotate and am trying to develop code that accommodates latitude so that anyone can simply erect a solar collector, tilting it at the latitude angle, along a line of longitude and have the controller take it from there. Bump the collector with a tractor? It'll reprogram itself!
|Programming Flow Diagram for Tracking the Sun Using an Accelerometer|