Thread by @mateosfo

So, there's a really stupid item coming up in Berkeley whereby a bunch of folks who consider themselves climate activists are defending solar panels against the scourge of shadows from tall homes/apartments.

As a solar homeowner, it always seemed bogus to me. So, I did math. 🧵

(First, context: Folks who suddenly care so much about climate change/solar panels are very same folks who actively oppose addressing the number one source of climate pollution in Berkeley -- cars, which cause 60% of our carbon emissions. Related: They're also die-hard NIMBYs)

Anyway, the math.

My house in Berkeley has solar panels that generate ~ 6.3 megawatt hours (MWh) of clean power per year. But that's a) more power than I use per year, and b) largely generated when I don't need it. So, I still buy ~ 2.8 MWh from PG&E; they buy ~ 3 MWh from me.

The carbon emissions of PG&E's electricity are about 206 pounds per MWh. So, my electricity use causes about 556 pounds of CO2 per year. I am deeply ashamed of this.

BUT batteries are still expensive, so, my declaration of a zero emissions house is still in future.

Anyway.

As I said, top source of carbon pollution in California is cars. One gallon of gas causes 20 pounds of carbon pollution. And the mean fuel economy in California is ~ 25 miles per gallon. So, 25 miles driving = 20 pounds carbon pollution. (chart source: transweb.sjsu.edu/sites/default/…)

Low-income Californians drive an average of about 25 miles per day, while high-income Californians drive about 50 miles per day (rounding up slightly from 2015 data).

A wealthy Californian burns as much carbon in their cars in 11 days as I produce from electricity (from PG&E) in a year -- about 14,600 pounds of carbon per year.

A low-income Californian burns as much carbon in their cars in 22 days as I produce from electricity in a year.

If a tall building cut my solar production by half, to ~ 3.2 MWh, the carbon from electricity on the grid would increase by 659 pounds.

If 10 low-income people lived in that building and each reduced their driving 50% (I'm four blocks from BART/bus/Berkeley Bowl)...

... they would cut carbon pollution by a collective amount of 36,500 pounds per year.

36,500 is more than 659.

If four wealthy people lived in luxury condos in that building and reduced their driving 50%, they would cut carbon by a collective amount of 29,000 pounds per year.

29,000 is *also* more than 659.

So, if you take my assumptions about density (more homes for lower-income apartments and fewer homes for luxury condos), the net benefit to the climate of building homes where people don’t have to drive ...

... but whose homes might block my solar panels and reduce their output by 50% -- is approximately 100x greater for low-income people, and 50x greater for high-income people.

And even if you completely blocked my solar panels, the cost/benefit ratios would be off the charts.

Do I want my solar panels to be blocked? Not particularly. But I bought them because I want to live a zero-carbon lifestyle in a zero-carbon city.

If building more homes that block my solar panels results in significantly less carbon emissions, then that is what I want.

If Berkeley is serious about climate action, then it will shitcan this stupid, NIMBY-driven shadow item and focus on the goal: cutting carbon emissions, by all means necessary, as fast as possible.

In Berkeley, that means more homes. berkeleyside.org/2018/05/01/opi…

cc: @KateHarrisonD4 and @SophieHahnBerk who seem to love all the glamour about climate action right up until someone asks them to show their climate math.

Here's my math, Kate and Sophie. It's been many, many years, and I'm still waiting to see yours.

Leadership: Matters a LOT

https://twitter.com/taplinterry/status/1458345024979025923