John Arnold
@johnarnoldfndtn.bsky.social
Co-Chair, Arnold Ventures
For all the headlines, nothing changed with overall spending trends.
July 15, 2025 at 12:15 AM
For all the headlines, nothing changed with overall spending trends.
Good illustration of how much the Texas grid has changed in just 6 years.
yellow = solar; purple = batteries; dark green = wind; blue = gas; brown = coal; light green = nuke
via @gridstatus.io
yellow = solar; purple = batteries; dark green = wind; blue = gas; brown = coal; light green = nuke
via @gridstatus.io
July 12, 2025 at 8:55 PM
Good illustration of how much the Texas grid has changed in just 6 years.
yellow = solar; purple = batteries; dark green = wind; blue = gas; brown = coal; light green = nuke
via @gridstatus.io
yellow = solar; purple = batteries; dark green = wind; blue = gas; brown = coal; light green = nuke
via @gridstatus.io
India’s fertility rate has fallen from 6 to 4 to 2 in successive generations. The world isn’t just undergoing its greatest tech transformation, it’s also living through its most dramatic demographic shift, two trends that are of course deeply related.
June 2, 2025 at 2:05 PM
India’s fertility rate has fallen from 6 to 4 to 2 in successive generations. The world isn’t just undergoing its greatest tech transformation, it’s also living through its most dramatic demographic shift, two trends that are of course deeply related.
Cities like Tampa used to be affordable.
May 28, 2025 at 2:13 PM
Cities like Tampa used to be affordable.
This is a positive step, but the nuclear industry’s biggest hurdles are technical and economic, not regulatory. Government policy must address those if we're to have a nuclear rebirth.
May 24, 2025 at 3:25 PM
This is a positive step, but the nuclear industry’s biggest hurdles are technical and economic, not regulatory. Government policy must address those if we're to have a nuclear rebirth.
How many times have I heard a GOP member of Congress say something along the lines of "the US doesn't have a revenue problem; it has a spending problem" or "the current level of spending is unsustainable" or "out-of-control deficit spending is the greatest threat to the country."
May 3, 2025 at 9:48 PM
How many times have I heard a GOP member of Congress say something along the lines of "the US doesn't have a revenue problem; it has a spending problem" or "the current level of spending is unsustainable" or "out-of-control deficit spending is the greatest threat to the country."
This is the fuel mix in ERCOT (Texas) for the past week (top) vs same week 4 years ago (bottom). Solar generation is in yellow. Solar barely registered in 2021; today it accounts for roughly 50% of generation during the day in the shoulder months.
data via @gridstatus.io
data via @gridstatus.io
April 13, 2025 at 1:29 PM
This is the fuel mix in ERCOT (Texas) for the past week (top) vs same week 4 years ago (bottom). Solar generation is in yellow. Solar barely registered in 2021; today it accounts for roughly 50% of generation during the day in the shoulder months.
data via @gridstatus.io
data via @gridstatus.io
This is A+ philanthropy:
Find a field neglected by other funders (nursing ed) that has broad benefits (economic mobility & health outcomes), identify the constraint (shortage of faculty and space), do strong due diligence, fund it at scale, and give while living.
www.philanthropy.com/article/bill...
Find a field neglected by other funders (nursing ed) that has broad benefits (economic mobility & health outcomes), identify the constraint (shortage of faculty and space), do strong due diligence, fund it at scale, and give while living.
www.philanthropy.com/article/bill...
February 27, 2025 at 4:55 PM
This is A+ philanthropy:
Find a field neglected by other funders (nursing ed) that has broad benefits (economic mobility & health outcomes), identify the constraint (shortage of faculty and space), do strong due diligence, fund it at scale, and give while living.
www.philanthropy.com/article/bill...
Find a field neglected by other funders (nursing ed) that has broad benefits (economic mobility & health outcomes), identify the constraint (shortage of faculty and space), do strong due diligence, fund it at scale, and give while living.
www.philanthropy.com/article/bill...
Kudos to the DOJ. Defending Medicare and Medicare Advantage necessitates vigilance against those who seek to defraud these programs.
February 21, 2025 at 11:39 PM
Kudos to the DOJ. Defending Medicare and Medicare Advantage necessitates vigilance against those who seek to defraud these programs.
The # of K-12 students in US is set to fall 12% by 2041, but that masks large state variation with several to fall by 30%+. That, itself, masks wide variation at local level, as some districts to lose 50%+. Navigating this will be an unprecedented political & financial challenge.
February 19, 2025 at 2:18 PM
The # of K-12 students in US is set to fall 12% by 2041, but that masks large state variation with several to fall by 30%+. That, itself, masks wide variation at local level, as some districts to lose 50%+. Navigating this will be an unprecedented political & financial challenge.
This article illustrates the most common flaw in evidence-based policy movement. If the program is selective about admission, the comparison set can't be the broad population. Smarter, more motivated, better behaved inmates might have lower recividism even without this program.
February 7, 2025 at 7:23 PM
This article illustrates the most common flaw in evidence-based policy movement. If the program is selective about admission, the comparison set can't be the broad population. Smarter, more motivated, better behaved inmates might have lower recividism even without this program.
A single aircraft fueling hose delivers more joules of energy per minute than a nuclear power plant. The energy density of liquid fuels is incredible.
fueling hose: 1900 L/min * 35 MJ/ L = 66.5 GJ/min
nuke: 1000 MW = 1000 MJ/s * 60 s/min = 60 GJ/min
fueling hose: 1900 L/min * 35 MJ/ L = 66.5 GJ/min
nuke: 1000 MW = 1000 MJ/s * 60 s/min = 60 GJ/min
February 6, 2025 at 6:31 PM
A single aircraft fueling hose delivers more joules of energy per minute than a nuclear power plant. The energy density of liquid fuels is incredible.
fueling hose: 1900 L/min * 35 MJ/ L = 66.5 GJ/min
nuke: 1000 MW = 1000 MJ/s * 60 s/min = 60 GJ/min
fueling hose: 1900 L/min * 35 MJ/ L = 66.5 GJ/min
nuke: 1000 MW = 1000 MJ/s * 60 s/min = 60 GJ/min
To get elected mayor of Chicago you have to promise to do things you have no ability or resources to do and then voters understandably get mad when you don't do them.
February 5, 2025 at 8:12 PM
To get elected mayor of Chicago you have to promise to do things you have no ability or resources to do and then voters understandably get mad when you don't do them.
Contrary to the prevailing narrative, energy has become more affordable over time, especially of late.
February 3, 2025 at 6:39 PM
Contrary to the prevailing narrative, energy has become more affordable over time, especially of late.
The Gartner Hype Cycle represents the stages of maturity often seen in new ideas. The criminal justice reform movement fits this pattern perfectly.
January 13, 2025 at 3:23 PM
The Gartner Hype Cycle represents the stages of maturity often seen in new ideas. The criminal justice reform movement fits this pattern perfectly.
This is just the staffing crisis that Georgia is facing. Prisons are often in rural parts of a state that are losing working age population, the work is tough, pay has significantly lagged private sector jobs, and the work conditions are lousy and unsafe.
January 10, 2025 at 3:22 PM
This is just the staffing crisis that Georgia is facing. Prisons are often in rural parts of a state that are losing working age population, the work is tough, pay has significantly lagged private sector jobs, and the work conditions are lousy and unsafe.
States hate allocating $ for prisons. It doesn't win votes. Thus, many prisons are at breaking points w/r/t staffing, safety, infrastructure and programming that lead to inhumane conditions for staff and inmates and is counter to rehabilitative. Took a crisis but kudos to GA for finally addressing.
January 10, 2025 at 3:20 PM
States hate allocating $ for prisons. It doesn't win votes. Thus, many prisons are at breaking points w/r/t staffing, safety, infrastructure and programming that lead to inhumane conditions for staff and inmates and is counter to rehabilitative. Took a crisis but kudos to GA for finally addressing.
The growth of Texas suburbs over the past decade shows the massive demand people have for housing that is both affordable and near urban job centers.
January 8, 2025 at 10:24 PM
The growth of Texas suburbs over the past decade shows the massive demand people have for housing that is both affordable and near urban job centers.
The difference between tax cut proposals and pay-fors is that, during the process, the former always increases in scope while the latter always gets narrowed.
January 6, 2025 at 1:29 PM
The difference between tax cut proposals and pay-fors is that, during the process, the former always increases in scope while the latter always gets narrowed.
Kudos to WSJ for a series of great investigative pieces on UnitedHealth. wsj.com/health/healt...
January 5, 2025 at 2:18 PM
Kudos to WSJ for a series of great investigative pieces on UnitedHealth. wsj.com/health/healt...
To be successful, DOGE must prioritize programs that have both very large expenditure and are rife with waste and abuse. Medicare Advantage sits squarely in that intersection.
January 5, 2025 at 2:17 PM
To be successful, DOGE must prioritize programs that have both very large expenditure and are rife with waste and abuse. Medicare Advantage sits squarely in that intersection.
After very strong solar growth in '23, it's plateauing this year and the forecast is muted. At least 3 large issues, interconnection, permitting and lack of transmission, must be addressed if solar is to meet its potential. Without policy reforms, solar growth is not assured. 2/2
December 10, 2024 at 7:21 PM
After very strong solar growth in '23, it's plateauing this year and the forecast is muted. At least 3 large issues, interconnection, permitting and lack of transmission, must be addressed if solar is to meet its potential. Without policy reforms, solar growth is not assured. 2/2
I've had a several year debate with solar bulls who argue the cost trend of panels towards zero & increasing efficiency makes massive solar proliferation inevitable. My counter is panels are a small % of total cost, evidenced by doubling of solar power prices in past 5 years. 1/2
December 10, 2024 at 7:21 PM
I've had a several year debate with solar bulls who argue the cost trend of panels towards zero & increasing efficiency makes massive solar proliferation inevitable. My counter is panels are a small % of total cost, evidenced by doubling of solar power prices in past 5 years. 1/2
A good way to estimate construction costs in NYC is to imagine what you think a project should cost and then add a zero to it.
December 7, 2024 at 2:33 PM
A good way to estimate construction costs in NYC is to imagine what you think a project should cost and then add a zero to it.