Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Semi-transparent solar panels allow concurrent production of crops and power

onlinelibrary.wiley.com

Post reply on HN
Print view View original

211–220 of 226 posts

Re: Semi-transparent solar panels allow concurrent production of crops and power

#211

Post by christkv »

samatman wrote: post #128
manfredo wrote: post #49

Earlier quoted context omitted.

Apparently each of these structures stores 20 MWh of energy. By comparison, the US consumes 11.5 TWh of electricity daily. To reach the 12 hours of storage estimated to be necessary to reach 80% renewable generation we'd need 287,500 of these towers. To reach the 3 weeks of storage necessary for 100% renewable generation we'd need 12,075,000 of these towers.

The former is easily achievable, if the towers are profitable to install. We only have to build them one at a time, and if a collection of 10-50 is cheaper than a peaker gas plant, then the utility decommissions the latter and builds the former. The latter is simply not necessary. There are a number of ways to solve the last few percent, including leaving a few peaker plants running; presumably, we'll do all of them.…

Thorium reactors or pebble bed reactors might be options. The only reason we have the current designs is due to the us navies need to build a reactor that would fit on submarines and ships. That technology became the basis for our deployed reactors. Since then nothing else has been tried outside of small experimental plants from what I understand.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#212

Post by BurningFrog »

hutzlibu wrote: post #210
tsimionescu wrote: post #158

Earlier quoted context omitted.

Algae in the ocean, mostly. But also, any growing plants - you could compute for every kg of dry plant matter, how much oxygen is released, as the dry plant matter is almost entirely carbon produced from breaking up CO2. So unless you're collecting tens or hundreds of kilograms of dead plants from your roof every year, it isn't producing much oxygen.

And algae are plants last time I checked. Because op said "Plants don't produce any useful amount of oxygen" And I am aware, that room plants do not really add meaningful O2 to the room, their value is in humidifying.

Googling "are algae plants?", gives this as the first answer:

> Algae are in the plant kingdom, but technically they are not plants. ... Algae range in size from microscopic to meters long and from single-celled to complex organisms that rival large plants. These organisms may look like true plants, but unlike plants, algae do not have roots or true stems and leaves.

Either way, I wasn't thinking of algae or aware that they might be net oxygen producers for the atmosphere.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#213

Post by m463 »

khawkins wrote: post #21

Only people who spend most of their life in densely crowded cities could think that the planet has so little space that you'd need to grow crops underneath solar panels for efficiency's sake.

Exactly. Elon musk said something about the amount of solar required to power the entire country, and it was a very very small fraction of the land area. There is plenty of room for both plants and solar - separately.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#214

Post by m463 »

xxs wrote: post #114
newyankee wrote: post #6

I cannot imagine the revolution that solar power will produce if it can fall another 3-5x in the next 10 years. It is already at grid parity. Although my personal hope is for storage, inverters, controllers and other technologies to get cheaper. Especially longer term storage beyond 4 hours.

Instead of inverters, there should be a push for DC network. Virtually all SMPS would be able to to work with DC (right now) and they won't even need active power factor correction either. Washing mashines with brushless DC motors, most ovens would be fine too. When I think almost everything that I have home, save for geothermal pump and three-phase appliances would be ok powered by DC(0). DC has its own issues: galv…

I see DC used in electric cars, general automotive and RVs.

I will say 12v is not very useful, except maybe for LED lighting. It has high losses to travel any distance. To power anything of significance requires higher voltage (or enormous cables).

I do agree that it would be really good to use DC, but I kind of wonder what the reality of efficient and useful DC would be like.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#215

Post by Izkata »

dehrmann wrote: post #97
nxc18 wrote: post #80

Earlier quoted context omitted.

Empowerment isn’t really a fantasy if there are rolling blackouts but your own power is still on. Sadly, not a hypothetical in California. Im thinking just from a national security/redundancy/risk reduction standpoint it makes sense to move more generation closer to demand. There are lots of single points of failure in our power grid currently. Edit: this is assuming the solar setup is designed to enable use when pow…

> Empowerment isn’t really a fantasy if there are rolling blackouts but your own power is still on. Sadly, not a hypothetical in California. Seems easier to get a generator or a Power Wall, but either ends up being pretty expensive for handling the 2 hours of rolling blackouts for the first time in 20 years. There are also longer-term outages, maybe several hours every few years? And this is for people in population…

> Seems easier to get a generator or a Power Wall, but either ends up being pretty expensive for handling the 2 hours of rolling blackouts for the first time in 20 years.

The price of electricity changes over the day along with demand. I don't know by how much, but maybe if the Power Wall could be used in the high-cost hours and charged in the low-cost hours, it would make a difference?

Re: Semi-transparent solar panels allow concurrent production of crops and power

#216

Post by brianhorakh »

khawkins wrote: post #21

Only people who spend most of their life in densely crowded cities could think that the planet has so little space that you'd need to grow crops underneath solar panels for efficiency's sake.

Transportation of food is an issue, it also damages or controls food quality. Certain types of food (usually the tastiest varietals) don't transport well. Climate change may disrupt large portions of growing zones / home gardens in the next 5-50 years. Food in stores is grown & treated for how it will look on a shelf in a grocery store.. Not for nutritional value or taste.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#217

Post by carvink »

UnpossibleJim wrote: post #186
carvink wrote: post #121

Earlier quoted context omitted.

That slight colour blockage, or the tint those solar panels have is helpful. There are two reasons. One, plants grow better under red light. Red light has the highest efficiency for photosynthesis in plants, that why LED grow lights are tuned for certain wavelengths. Plants use blue light to know what direction to grow. And for a certain category of tints or dyes that are fluorescent, additional red light. Luminescen…

Is that why indoor LED growing lights have that purple-ish tint to them? I never knew that. I knew about the red, but never the blue. You're awesome. Thanks so much.

Here's my source material: https://youtu.be/Y1nlQ6bGX4c?t=4018

Re: Semi-transparent solar panels allow concurrent production of crops and power

#218

Post by ballenf »

jws wrote: post #99
dghughes wrote: post #85

My mother ayed tomatoes in the spring when it was still cool. She covered them with clear plastic bags as she always has. But she needed one more bag so she used a blue recycling bag on one of the plants. Blue tinged really it's almost clear. I pointed out to her one of the plants had yellow leaves. It was the plant with the blue bag. Later in the summer the blue bag plant produced fruit just like the other plants. B…

The ratio of red and blue light controls various functions of a plant. In the context of aquarium plants, more red light makes them get tall and leggy, more blue light makes them be compact and bushy. https://gpnmag.com/article/effects-of-blue-light-on-plants/ talks a bit about it in the context of greenhouses and tomatoes, the picture in the middle shows 6 plants grown with wildly different red/blue ratios. If the b…

Is that how they know how close to the surface of the water they are?

Re: Semi-transparent solar panels allow concurrent production of crops and power

#219

Post by philipkglass »

Manfredo_1 wrote: post #167
philipkglass wrote: post #164

Earlier quoted context omitted.

Nuclear plants can throttle down. But the economics of nuclear power make it prohibitive to satisfy peak demand from nuclear reactors. Even France relies on gas plants and power imports to satisfy its electricity demand peaks, despite being a net electricity exporter over the course of a full year. The CAISO grid had an average power demand of 25 GW in 2019 but a peak demand of 46 GW (Table 1.1): http://www.caiso.com…

This is true not because of any shortcomings of nuclear, but by virtue of the fact that demand is not uniform. The same need to have excess capacity during non peak hours in order to have sufficient capacity during peak hours exists with fossil fuels. If peak demand is 130 GW and trough demand is 100GW you need 130 GW of capacity.

Nuclear has never been inexpensive enough to be the first choice for meeting peak demand in the absence of storage. Some pumped hydro plants were built in the 20th century to be charged by nuclear generation so nuclear could effectively supply peaks too. Peaking batteries could also be charged by nuclear power.

Gas turbines have a construction cost under $1/watt in the US while Vogtle's AP1000s were estimated at $6/watt even before all the cost overruns started. If you're going to leave an asset idle most of the time, much better to idle a sub-$1/watt asset than a $6/watt asset.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#220

Post by Manfredo_1 »

philipkglass wrote: post #219
Manfredo_1 wrote: post #167

Earlier quoted context omitted.

This is true not because of any shortcomings of nuclear, but by virtue of the fact that demand is not uniform. The same need to have excess capacity during non peak hours in order to have sufficient capacity during peak hours exists with fossil fuels. If peak demand is 130 GW and trough demand is 100GW you need 130 GW of capacity.

Nuclear has never been inexpensive enough to be the first choice for meeting peak demand in the absence of storage. Some pumped hydro plants were built in the 20th century to be charged by nuclear generation so nuclear could effectively supply peaks too. Peaking batteries could also be charged by nuclear power. Gas turbines have a construction cost under $1/watt in the US while Vogtle's AP1000s were estimated at $6/w…

This is just factually wrong. France had generated the majority of it's electricity from nuclear since the 80s, and Belgium now generates the majority of it's power from nuclear. Nuclear had repeatedly been used to satisfy peak demand.

Nobody doubts that fossil fuels are cheaper. Yes, that's why fossil fuels are still in widespread use outside of France, and several countries with lots of hydroelectric power. But if we want to halt climate change we need to eliminate - not just reduce - usage of fossil fuels. Any plan to use renewables as a significant source of energy either involves the continued use of fossil fuels, or the involvement of staggering amounts of energy storage.

Post reply on HN