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Self-Sustaining Solar Greenhouses Generates Electricity

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Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby vox_mundi » Sat 04 Nov 2017, 11:19:22

Solar Greenhouses Generate Electricity and Grow Crops at the Same Time

Video - "We have demonstrated that 'smart greenhouses' can capture solar energy for electricity without reducing plant growth, which is pretty exciting," said Michael Loik, professor of environmental studies at the University of California, Santa Cruz, and lead author on a paper that appears in the current issue of the American Geophysical Union's journal Earth's Future.

Electricity-generating solar greenhouses utilize Wavelength-Selective Photovoltaic Systems (WSPVs), a novel technology that generates electricity more efficiently and at less cost than traditional photovoltaic systems. These greenhouses are outfitted with transparent roof panels embedded with a bright magenta luminescent dye that absorbs light and transfers energy to narrow photovoltaic strips, where electricity is produced. WSPVs absorb some of the blue and green wavelengths of light but let the rest through, allowing the plants to grow. WSPV technology was developed by coauthors Sue Carter and Glenn Alers, both professors of physics at UC Santa Cruz, who founded Soliculture in 2012 to bring the technology to market.
... "Plants are sensitive not just to the intensity of light but also to color, but it turns out the plants grow just as well."

Loik's team monitored photosynthesis and fruit production across 20 varieties of tomatoes, cucumbers, lemons, limes, peppers, strawberries, and basil grown in magenta glasshouses at two locations on campus and one in Watsonville, California.

"Eighty percent of the plants weren't affected, while 20 percent actually grew better under the magenta windows," said Loik. Tomatoes and cucumbers are among the top greenhouse-produced crops worldwide, he said.

Greenhouses use electricity to control temperature and power fans, lights, and other monitoring systems. "This technology has the potential to take greenhouses offline," said Loik, who specializes in climate change, plant physiology, water resources, and sustainable technologies. Cost per panel of WSPV technology is 65 cents per watt—about 40 percent less than the per-watt cost of traditional silicon-based photovoltaic cells.

"If greenhouses generate electricity on site, that reduces the need for an outside source, which helps lower greenhouse gas emissions even more," said Loik. "We're moving toward self-sustaining greenhouses."

Image


Supporting data for Loik et al. 2017 Wavelength-Selective Solar Photovoltaic Systems: Powering greenhouses for plant growth at the food-energy-water nexus. Earth's Future

Solar Greenhouses: China's Solution to Global Energy Crisis

LEDs Reduce Costs for Greenhouse Tomato Growers
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby ROCKMAN » Sat 04 Nov 2017, 12:17:20

vox - Very interesting...thanks. Assuming a modest local electricity rate (say $0.15/kWh) can you estimate the payout of such a system? And to be fair the solar cost should be reduced by the cost of the normal glass since it would have to be purchased anyway if you're building a new greenhouse.
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby vox_mundi » Sat 04 Nov 2017, 13:36:00

ROCKMAN wrote:vox - Very interesting...thanks. Assuming a modest local electricity rate (say $0.15/kWh) can you estimate the payout of such a system? And to be fair the solar cost should be reduced by the cost of the normal glass since it would have to be purchased anyway if you're building a new greenhouse.

I don't know. Not sure what you mean by payout.

What would the payout be for a diesel powered greenhouse in Barrows, AK.

A gallon of unleaded gas will set you back $7.50 in Fort Yukon, a community of less than 600 on the Yukon River roughly 145 miles northeast of Fairbanks. Prices at the pump in other places are even higher, like for the 160 people in Kobuk east of Kotzebue above the Arctic Circle, where the price of gas was $10 per gallon in July, according to the state Division of Community and Regional Affairs, which just started its biannual survey of current fuel prices in 100 Alaska communities.

Fresh produce in Barrows

9 oz lettuce - $5.69
1 lb tomato - $4.79
1 small watermelon - $19.99
1 lb onions - $4.79
10 lb potatoes - $24.00
1 pineapple - $35.00

Subscription Prices start at $43 for a week's worth of produce for a small family in Anchorage and vary in rural areas, topping out at about $74 including shipping. A typical box includes 10 to 12 items such as lettuce, beets, chard, peaches and cantaloupe.

http://jskouri.com/2014/barrow-alaska-food-prices/

Worst food spending of all time: $41.14 at a little restaurant in a small bush village. There were literally no other options and we were all starving. We got two corn dogs for the kids and two plates of whatever inedible nonsense this claims to be:

Image
Yummy! [smilie=icon_puke_r.gif]
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby Shaved Monkey » Sun 05 Nov 2017, 19:52:44

Solar updraft tower would be another way to do it
Surround the skirt with green houses.
Downside is initial build cost, upside is virtually free power and lots of glasshouse surface area to drive it and grow stuff.
They pilot plants built in Spain proved they work night and day too
https://en.wikipedia.org/wiki/Solar_updraft_tower
This is the one proposed for Australia but still not happening yet
https://www.youtube.com/watch?v=0tWlP0knKQU
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby Zarquon » Wed 08 Aug 2018, 08:50:53

Interesting development. Here's a newer, in-depth paper on WSPV greenhouses:

https://agupubs.onlinelibrary.wiley.com ... 16EF000531

And the IMO most interesting part is about the cost, compared to traditional Si-cells:

"Performance and production costs of WSPVs can be lower than standard Si‐PV cells. The WSPV technology reduces PV module cost per Watt by up to 50% by replacing relatively expensive Si‐PV (∼$300 per m2 at 20% efficiency) with a very low cost (∼$10 per m2) luminescent sheet. Material costs of the WSPV for a greenhouse are approximately $30/m2 for the narrow PV cells + $10/m2 for luminescent film + $5/m2 for hardware = $45/m2. At 7% power efficiency, the power price is about $0.65/W, an approximately 40% decrease compared to the Si‐PV cell."

Assuming that the above numbers work out, that leaves one big question: how long does this stuff last?
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby Pops » Wed 08 Aug 2018, 09:07:59

Very cool. They've been selling red Hot Caps and red plastic mulch for quite a while now because certain plants, like tomatoes, like the red light for some reason.
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby GHung » Wed 08 Aug 2018, 09:36:44

Looks like they need to fix their gutters...

... or maybe not. I'm in the planning phase for a new smaller kitchen greenhouse which will be largely powered with some extra PV I have in storage. I need to rebuild my large high tunnel after it collapsed under a very heavy snowfall this winter (waiting for cooler Fall temps), then I'm building a 12' x 16' four season greenhouse near the house for a kitchen garden. Hoping to use some geothermal + thermal mass to offset heating in winter. The sides will be insulated patio doors I salvaged from remodeling jobs, but a red PV roof would be great if the costs are acceptable. I'm wondering how these panels affect heat gain.
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby Outcast_Searcher » Wed 08 Aug 2018, 10:43:26

vox_mundi wrote:A gallon of unleaded gas will set you back $7.50 in Fort Yukon, a community of less than 600 on the Yukon River roughly 145 miles northeast of Fairbanks. Prices at the pump in other places are even higher, like for the 160 people in Kobuk east of Kotzebue above the Arctic Circle, where the price of gas was $10 per gallon in July, according to the state Division of Community and Regional Affairs, which just started its biannual survey of current fuel prices in 100 Alaska communities.

Fresh produce in Barrows

9 oz lettuce - $5.69
1 lb tomato - $4.79
1 small watermelon - $19.99
1 lb onions - $4.79
10 lb potatoes - $24.00
1 pineapple - $35.00

Yes, and apparently the bulk of those prices is for shipping, at least according to the folks on the reality series (which at least isn't a complete farce, BTW) "Life Below Zero" about living in remote parts of AK, on Netflix.

Seems harsh, but that's the way viable economics needs to work. For folks who can't afford that, they either need to live somewhere else, or be able to use a skill or trade to make a lot of money so they CAN afford it.

Seems like a lot of barter goes on with people who trap/shoot/fish the majority of their food.

Given that the summertime middday temps are frequently in the 50's (53 degrees as I write this) in Anchorage (southern AK), IMO people must REALLY like the outdoors and isolation to be willing to live in such environments, unless they are making a ton of money in the oil business, etc.

...

I live a quiet, relatively isolated existence (by choice) in a top 100 US city in central KY, and have moderate weather, access to services as I age, and I SURE as hell don't have to pay anything remotely like $35 for a pineapple.

There's nothing better than the freedom to have choices, IMO.
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby vox_mundi » Wed 08 Aug 2018, 11:19:32

GHung wrote:Looks like they need to fix their gutters...

... or maybe not. I'm in the planning phase for a new smaller kitchen greenhouse which will be largely powered with some extra PV I have in storage. I need to rebuild my large high tunnel after it collapsed under a very heavy snowfall this winter (waiting for cooler Fall temps), then I'm building a 12' x 16' four season greenhouse near the house for a kitchen garden. Hoping to use some geothermal + thermal mass to offset heating in winter. The sides will be insulated patio doors I salvaged from remodeling jobs, but a red PV roof would be great if the costs are acceptable. I'm wondering how these panels affect heat gain.

Not sure about the heat gain. I wouldn't expect too much loss because the panels are reflecting only a small portion of the visible spectrum. But, for thermal mass (and bench supports) you might try recycled 55 gal. Polyethylene barrels filled with water.

Image
https://www.bluebarrelsystems.com/blog/ ... ic-barrel/
Black might absorb more heat.

I got a half dozen of them free from a local soda company that had syrup shipped in them.
They're cheap otherwise http://www.sccfl.com/container-prices.html

p.s. yeah, the gutters need fixin'

The color also has another advantage ...

Photoselective Films For Greenhouses

... Studies of ornamental crops, traditionally grown in shade-net houses, revealed distinct responses to the Red, Yellow, Blue Grey and Pearl nets, compared with common black nets of the same shading factor. These include stimulated vegetative vigor, dwarfing, branching, leaf variegation, and timing of flowering. The photoselective netting concept was further tested in vegetable cultivation in either net-houses, or in combination with insect-proof nets or greenhouse plastic film covers. The Red repeatedly increased the productivity of leafy crops, bell peppers and ornamentals, compared with each crop’s standard cover.
Red and Yellow nets were found to specifically stimulate vegetative growth rate and vigour, the Blue net caused dwarfing, and the Grey net specifically enhanced branching and bushiness, and also reduced leaf size and variegation in Pittosporum

Although the shade-net holes allow free passage of small pests, the rates of pest infestations and vector-borne viral diseases were affected by the color and reflectivity of the nets. ...


Far-red light filtering by plastic film, greenhouse-cladding materials: effects on growth and flowering
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Re: Self-Sustaining Solar Greenhouses Generates Electricity

Unread postby Tanada » Wed 08 Aug 2018, 11:54:50

Outcast_Searcher wrote:Seems like a lot of barter goes on with people who trap/shoot/fish the majority of their food.

Given that the summertime middday temps are frequently in the 50's (53 degrees as I write this) in Anchorage (southern AK), IMO people must REALLY like the outdoors and isolation to be willing to live in such environments, unless they are making a ton of money in the oil business, etc.
...
I live a quiet, relatively isolated existence (by choice) in a top 100 US city in central KY, and have moderate weather, access to services as I age, and I SURE as hell don't have to pay anything remotely like $35 for a pineapple.

There's nothing better than the freedom to have choices, IMO.


'Moderate' weather is more or less defined by 'what weather I like' rather than by an external definition. Yes Anchorage has 50 degree days in summer at times, but it also has 80 degree days from time to time. What really matters for growing crops are 'degree days' meaning the number of hours of sunlight in a location where the temperature is above the minimum needed by the plant in question to grow. Kentucky Bluegrass for example thrives when temperatures are between 55 and 85 degrees F and grows more slowly between 35-55 and 85-95. Many other types of grasses, including the main northern Cereal crops like Rye and Oats grow like mad in Alaska because during the months of June and July daylight is nearly constant and temperatures are in their golden zone of 55-75 degrees F. Wheat does less well in Alaska because it likes it hotter, after all the Fertile Crescent where it was evolved and developed for agriculture is hot to desert type weather. Maize which initially grew in semi-desert Mexico is the same way, it doesn't do very well in Alaska. However Potato, Rhubarb, Cabbage, Lettuce and many types of Squash thrive in Alaska. Prices on the North Slope are nuts partly from climate but mostly because nobody grows stuff on the north slope, they haul every plant food item up the road from Fairbanks or the rest of the world.

I wouldn't necessarily want to live on the North Slope either, but the reason there is so little agriculture in Alaska has far more to do with industrial farm competition from the lower 48 states than it does with the climate. The parts of Alaska where Farming was started before the industrialization of Farming still grow respectable quantities of food. Taking a raw piece of forested land and converting it into a modern farm is a very large financial investment. So long as there are tens of thousands of acres of arable former farmland in the lower 48 sitting fallow and reverting to woodlot that are much more easily returned to farmland at need there is no economic incentive to expand farming in Alaska. Just since the year 2000 the amount of crop land in the USA has fallen 35 million acres as small farms have ceased operation and fallen fallow across the continent. As world population grows we will hit a tipping point where that former farm land becomes desirable as crop land again, at which point the big corporate farm system will start buying up all those old farms and combining them into new mega farms operated by corporate employees. Only once those old farms are put back in production will it make good economic sense to put more of Alaska into crop production. At the rate world population is continuing to grow this switchover could happen soon.
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