"When it comes to solar energy per acre, a photovoltaic solar plant which on average produces 1 GWh per year, will require around 2.8 acres of land. Therefore, we can say that for every acre, the plant produces an average of 0.357 GWh or 357 MWh of energy per year." [1]
They claim 4000 tons per year, I did the math on 4000 tons per day.
So ~3-4 acres of PV to power, not 1000 acres.
To completely counteract the 37 billion tons per year produced worldwide, and do it with PV only, assuming desert southwest conditions, would require ~30 million acres of PV. That sounds impossibly high, but is only about the size of the US state of Mississippi. 20% of the land area of Texas, on the El Paso side, would be sufficient to keep pace with the entire world's carbon dioxide emissions.
I remain skeptical that this is the most cost-effective approach, as well as skeptical of its ability to scale, but I apologize for crapping on it at first gloss.
So definitely he is purposely understating the potential of solar. Because it does not include future growth of tandem solar cells (Si + perovskite) taking it to more than 25-30% efficiency, or the fall in costs if they continue (albeit at a slower pace). Co-located Wind & solar power plants at suitable sites can be even more efficient with their reliability and capacity factors increasing if batteries added to the mix.
> Global PV cell production is about 1 million square meters per annum.
I think you are of by a few magnitudes as this is only 1 square kilometer? The largest solar park in India is 56 square kilometers in area (or 10 million solar panels which are at least(?) 2 square meters in size).
I’ve yet to see any renewable plan that could cover big northern cities.
Where are we going to build a solar farm to cover NYC, DC, and Philadelphia? There is 9 hours of daylight in the dead of winter, and it’s not exactly known for being sunny in January.
NYC alone needs 11,000 megawatt hours per day. My back of the envelope fermi estimate is a solar farm covering approximately 16,000 acres. Forget the metro area, that’s just for NYC. Probably double if you include the entire metro area.
You aren’t going to find that kind of land within 300 miles of NYC.
New York State is 35 million acres. You don't think 0.2% of that, including rooftops of existing buildings, might be useable for solar/wind/battery storage? And again, NY already uses tons of out-of-state energy.
Have you looked at a map? I live in NY, and there is absolutely no place for such a massive solar farm.
The numbers I quoted were just for NYC, and they weren’t adjusted for the winter sunlight problem. To power the entire metro area would likely require 40,000 acres. To cover the entire region likely 60,000 acres. This land does not exist.
Right! This demonstrates how little land mass needs to be used to power the world entirely from solar. Total solar potential is clear, total land use necessary is clear, ergo solar can power the world. Anything else is hand waving and excuses.
The article you cited said we need 43,000 square miles of solar to power the earth costing 5 trillion dollars, I consider that to be a huge amount of land and money. That would be half the area of Minnesota the state I live in devoted entirely to solar panels. Sure it wouldn't all be in one place but that is still a significant amount of land world wide that have to change land uses.
Also isn't that article also assuming that all of the solar panels would be in the Sahara desert? Where solar power is extremely efficient. If we spread these solar panels across the world we would need significantly more because they would located in places much less suitable for solar power.
Which indicates (correctly or not) a current capacity of 314MW for Solar Star 1 (still less than the 1GW needed for Zuckerberg's projected SOTA data center).
On paper, 22M acres is enough room for 1.78 TW annualised over a year[0], which is about 61% of current global electricity demand.
I doubt they'll get close to filling this land up with PV, but perhaps at least making this much available will reduce the rate at which people ask how much land PV needs to take up.
a useful piece of context here is what it would mean to cover 20% of the sahara with solar farms and why the authors think it's unlikely
i haven't read the paper, so i don't know what fill factor they're considering. say it's 50%, so the spaces between the panels occupy as much area as the panels
9.2 million sq km · 20% occupancy · 50% fill factor · 21% efficiency · 29% capacity factor (which is probably a bit low) · 1000 watts/m² works out to average production of 56 terawatts, roughly three times current global marketed energy consumption, which is 18 terawatts
that is, building such a thing involves quadrupling the energy budget per person. right now the humans use about 18 terawatts, about 2.25 kilowatts per person, roughly equivalent to the labor of 22 workers. we're talking about boosting that to 10 kilowatts, so the average person has the equivalent of 100 laborers at their disposal, so it will be a vast reduction in the cost of energy
and the sahara isn't the only place you can put solar panels, even on earth, even on land
what would a human society that's four times as energy-intensive look like
they also say that if you only cover 5% of the sahara in solar panels, so that this one power plant produces more energy than the entire human race does today, 'the global effects become mostly negligible'
— ? —
in the other direction, consider their opening declaration, 'the sun's energy is effectively limitless.' the sun only outputs 380 yottawatts, which is only greater than the 18-terawatt number above by a factor of 21 trillion. so human energy consumption can only grow by 21 trillion times before finding other, larger energy sources
okay but is that a lot or what
if we take the historical post-industrial-revolution growth rate of 5 percent per year and apply it to energy consumption (perhaps on the assumption that there's a lower limit to how much energy we can dissipate per unit of value produced, even if we haven't reached that limit yet) that's only 629 years of growth. that's longer than a human lifetime but still an eyeblink in the two-million-year story of humanity or the ten-thousand-year span of recorded history
if, by contrast, we start building von neumann replicators that mine mars and venus in order to double their population and energy consumption on average every year, it's only 44 years, and many people still alive will see it happen
so i think 'effectively limitless' is shortsighted
My local solar power plant is nowhere near that kind of output.
http://newsroom.fpl.com/2019-03-28-FPL-announces-plan-to-bui...
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