I wrote these notes while reading Bill Gates’ book How to Avoid a Climate Disaster. It’s really a wonderful book, and I encourage you to read it, especially if you’re motivated by the problem and want a sense of perspective of both the challenges and possible .
I loved the book on first read, but after a few months realized I forgot a lot. So I reread it and wrote these down. They’re a little informal, but it’s how I like to remember things.
Chapter 1
- 51 Billion. That's how many tons of CO2e we emit per year (~2021).
- Through doing the Gates foundation, he met a lot of poor people. And in developing parts of the world, he encountered a lot of people who had much less access to energy
- Plot: income/person and energy usage/person are highly correlated (source: world bank)
- Conclusion: world needs cheaper energy so the poorest can survive. But also need to do it with less emissions
- He got educated by: read the IPCC reports. Watched Earth's Changing Climate. Read Weather for dummies.
- Conclusion 1: renewable energy (wind, solar) can help with energy, but we aren't deploying them enough.
- Hydro is also a great source of renewables, but there's not that much extra capacity
- Also by themselves is not enough. Wind doesn’t always blow, sun doesn’t always shine. Don’t have enough big batteries for this.
- Also, electricity is only 27% of GHGs
- Anyway, need to → to net 0.
- In 2019, divested from all oil and gas.
- By 2015 (COP21), private funding for climate was drying up. VC firms going into greentech were pulling out.
- Talked about breakthrough energy coalition. Mission Innovation - accelerates clean energy
- Economic activity slowed during covid. Probably decreased 5%. Meaningful, but it's not... sustainable sustainability
- Addresses a few things, but finally, that his carbon footprint is high. So, started buying sustainable jet fuel, and will offset his family's aviation emissions. For non-aviation emissions, is buying offsets through a company that does DAC.
- Invests in zero-carbon tech. Has put >1 billion into net zero approaches.
- Goal of the book: show pathways to net 0.
Chapter 1: Why 0
- Easy answer: GHGs trap heat. Cause avg surface temperature to go up. 20% of the CO2 emitted today will be there in 10k years
- No realistic paths that go to 0 and abandon those fuels completely. So, best we can do is to get close to 0 and remove the carbon these processes emit.
- 50% drop doesn’t stop the rise in temp. Only slows.
- To avoid worst climate scenarios, need to also start doing air capture.
- 2 degrees C is a big deal. During last ice age, avg temp was just 6C lower than it is today. Also, avg numbers belie a big daily variance.
- Even though global mean has just gone up 1C since preindustrial, some places have experienced increases of >2C. Those places house like, 20-40% of the population
- Couple of different GHGs. Everything gets squished down to CO2e.
- In the end, he comes up with 51 gigatons of CO2e. You might see 37 Gt elsewhere, but that's just CO2 (not equivalents), and 10 Gt, which is just the carbon itself.
- Visible light goes through the atmosphere, hits the earth, which reemits in its own spectra. Some of this gets absorbed by GHGs.
- Also, molecules with 2 of the same atom (Nitrogen, Oxygen) let radiation pass straight through them. Only molecules made of diff atoms (like CO2, CH4) have the right structure to absorb radiation and heat up (why?)
- Problems. Computer models imperfect. Climate is complex. But, what we know:
- Earth is warming. We can say statistical things: will be hotter days, sea level will go up. But can't do exact explanation: whether heat wave was due to climate change.
- There will be more hot days. In the 1970s, temp in Albuquerque was over 90F just 36 times a year on average. By ~2100, Albuquerque will be >90 about 114 days
- Storms probably worse, getting wetter.
- Some places getting more rain, other places getting more drought (increased variance)
- Food will get affected. Wheat, other plants, will grow faster and need less water when lot of carbon in air. But, corn very sensitive to heat.
- Talks about heatstroke, and the wet bulb temperature. As atmosphere gets hotter and more humid, it gets to be a bigger problem.
- One message. The countries that build great zero-carbon companies and industries will be the ones that lead the global economy in the next decades
Chapter 2 - This will be hard.
In moving away from fossil fuels, realizing that it’s frickin everywhere.
- Toothbrush prob has plastic, made from petroleum
- Grains in your bread grown with fertilizer, which releases GHGs.
- Basically: Fossil fuels pop up everywhere
- Looking at oil, world uses >4B gallons a day. Fuel is cheap. Oil is cheaper than a soft drink.
- Have big companies that drill, process, and move them. And their prices dont reflect the environmental damage.
- By 2060 the world's building stock is likely to 2x.
- No Moore's law for energy
- Ford Model T got 21 mpg. Top hybrid at time of writing gets 58 mpg.
- Energy industry is about 5 trillion a year industry. Has a lot of inertia.
- Looking at other industries. Huge upfront capital costs. Also, conservative because society doesn't tolerate risk in energy. People want reliability. And then, safety. Chernobyl and Three Mile Island really killed nuclear chances in USA
- Laws are outdated. For example, clean air act (best-know US law w.r.t. air) barely mentions GHGs. That's because was written in the 70s.
- Election cycle also creates big problems for long-term planning.
Chapter 3 - Five questions to ask in every climate conversation
- How much of the 51 Gt are we talking?
- For example, program that decrease 17 Mt a year. Divide it by 51B, it turns to .03% of annual emissions.
- Breakthrough Energy — only fund tech that could remove at least 500Mt/yr if successful. That's about 1% of global emissions
- What's your plan for cement?
- Steel and cement are about 10% of all emissions. If want to solve climate, need to do more than just electricity and cars.
- Approx breakdown:
- Making things (cement, steel, plastic): 31
- Plugging In (electricity): 27
- Growing things (plants, animals) 19
- Transportation (planes, trucks, cargo): 16
- Keeping things warm/cool (heating, cooling, refrigeration): 7
- How much power are we talking about?
- Some sense of scale.
- World uses ~5k Gw
- USA ~1k Gw
- NYC: ~23 Gw on average, but can go to 50 Gw in summer.
- avg american house: ~1 kw
- How much space do you need? (in power generation, space is pretty important).
- Power density. Watts per sqm:
- Fossil Fuels: 500-10k
- Nuclear: 500-1k
- Solar: 5-20
- Hydro: 5-50
- Wind: 1-2
- Basically, solar has much more density than wind. You'll need less land
- What's the cost?
- Most carbon-zero solutions are expensive. This is green premium. Different green premiums for different products
- Deploy solutions with low green premium. Do basic research where there’s high green premium
Chapter 4 - How we plug in
- 27% of the 51 Gt
- Hydropower is good, but some downsides.
- Cover land with water, if carbon in soil, that carbon → methane. So depending on where it's built, a dam can be worse than coal before it makes up for the methane it causes
- seasonal effects
- Breakdown of world's energy:
- Electricity is 200x cheaper in 2000 vs 1900
- Lot of subsidies for coal. In addition to the US, people think gov subsidies for consumption of fossil fuels is ~400B.
- Together, fossil fuels are ~2/3 of world electricity. Solar and wind: ~7%
- On the bright side, green premiums for electricity arent that high.
- Changing USA electric grid to carbon-neutral sources is about 1.3-1.7 cents/kwh, which is about 15%. So, green premium of ~$18/mo for average home.
- Less affordable for low-income americans, who spend about 10% of income on energy
- US and Europe are pretty well off. Other countries are not as lucky. USA has lot of renewables: hydro in PNW, winds in midwest, and solar in SW and cali.
- Africa, Asia are in tough position. Next wave of countries: India, Indonesia, Vietnam, Pakistan, Africa.
- Big problem with this: people want electricity all the time. But sun and wind are intermittent. Seasonal variation also a problem.
- If we want batteries, we need to finance the batteries. And then have to think about interest on financing.
- Also have to plan for backup storage in case of big externalities (eg. if Tokyo went all wind and had a typhoon pass through).
- Some possibilities.
- Fission. the only carbon-free energy source that can reliably deliver power day and night. Nothing else comes close.
- USA gets ~20% of its power from nuclear
- France gets ~70%
- Nuclear also super-efficient when using materials like cement, steel, glass. If look at thousands of tons per TWh, nuclear is less than even coal. Solar and Hydro are pretty high.
- Nuclear is expensive to build. Human Error can happen. 3 mile island, Chernobyl, Fukushima.
- Offshore Wind. Can put turbines in ocean. Many major cities near the coast. So can create energy close to the consumption. But, offshore wind only .4% of world energy in 2019. Most of that is in EU.
- Geothermal. Pump water underground, get heat, come up, turn a turbine.
- But, energy density low. David Mackay estimates geothermal can meet <2% of UK energy needs.
- Also have to dig wells. About 40% of wells for geothermal are duds.
- Batteries. Has learned a lot about batteries. Also lost a lot of $ investing on batteries (still rich tho)
- Hard to improve on lithium-ion. He believes can improve by 3x, but not 50
- He's met innovators working on grid-scale batteries (enough for a city).
- Example: pumped hydro. When electricity cheap, pump water up a hill. When demand goes up, you let the water flow down, spin a turbine.
- Right now, biggest form of grid-scale electricity. But isnt saying much. 10 largest instances in the US can store less than an hour of the country's needs.
- Natural enemies: need a lot of water, and a hill.
- Thermal storage. Heat up a material, and then generate power with heat engine. Can work at ~50-60% efficiency.
- Cheap hydrogen. Right now, hard to create hydrogen without emitting carbon.
- Other tech.
- Capturing carbon. Special devices at fuel plants (point capture) to absorb emissions. Have existed for decades, but are expensive to buy. Only capture 90% of GHGs. Power companies dont gain anything from installing them. Very few are in use.
- DAC. More flexible, can do it anywhere. But, technical problems. CO2 is much less concentrated in air than in a smokestack.
Coal- 36%.
Nat Gas: 23%
Hydro: 16%
Nuclear: 10%
Renewables: 11%
Oil: 3%
Other: 1%
Chapter 5 - how we make things
- 31% of 51Gt
- Every year, US makes >96 Mt cement. China makes even more. In 1901-2000, US made 4.3 Gt cement. China in 2001-2016, 25.8Gt
- US: about 600 lbs cement/person
- In addition, there's steel. Americans use 600 lbs steel .
- Plastics. Glass. Aluminum. Materials exist.
- Making this material emits GHGs. How do we decrease emissions while making these materials?
- Explains the steelmaking process. Need to get iron and carbon. Add the right amount of carbon in iron. Heat it up (~1700 C) in presence of oxygen and coke (typeo f coal). Then, iron ore releases oxygen, coke releases carbon. Some of the carbon bonds with iron, making steel, rest makes CO2.
- 1t steel makes about 1.8t CO2.
- We do it this way because it's cheap.
- Concrete making. Mix together gravel, sand, water, cement. To make cement, need calcium. To get calcium, get limestone, (calcium, carbon, oxygen), and burn it with some other stuff.
- After burning, get calcium for cement, plus CO2. Nobody knows how to make cement without this process. 1 ton of cement gives 1 ton of CO2.
- Just like steel, no reason to think we'll stop making cement.
- Plastics. All contain carbon. Get it by refining oil, coal, natgas, and refining.
- Though, when make cement and steel, we release CO2. When we make plastic, about half stays in plastic. The "nice" thing about plastics is, even though microplastics are f-ing up the environment, they don't contribute to climate change.
- Survey of green premiums.
- Plastics: 9-15%
- Steel: 16-29%
- Cement: 75-140%
- Green premiums... still an issue.
- It's hard to get around: limestone + heat = CaO + CO2. But some companies have ideas.
- 1 - take CO2 captured during cement making, and reinjecting it in the cement. Can reduce emissions ~10%.
- Another approach: get cement from seawater, and CO2 from power plants.
- For other situations, will just need cheaper clean electricity, and then use electricity instead of fossil fuels for industrial processes.
- So, a proposed high-level path:
- Electrify everything possible
- Get that electricity from a clean grid
- Use carbon capture to absorb remaining emissions
- use materials more efficiently
Chapter 6 - how we grow things
- 19% of 51 Gt.
- Animals for food is the highest contributor for agriculture, forestry, other land use. Within ag, the biggest culprit is methane. Methane is 28x more GWP than CO2, and N2O, which is 265x Gwp
- In addition, have to do stuff w/ deforestation, which add 1.6B CO2e.
- Food is not more scarce. That's because... people developed wheat w/ higher yields. Similarly, people worked on corn and rice.
- Global pop going to 10B by 2100, and need to feed everyone. People get richer, eat more calories, and pref more meat and dairy.
- Chicken: 2 calories worth of grain to eat 1 calorie of poultry
- Pig: 3x
- Cows: 6x
- Other problem: if want to generate energy from land-expensive sources, will need to fight with like, agriculture
- Looking at cows, enteric fermentation from bacteria, break down cellulose and creates methane. Cows burp the methane. From cows alone, about 2 Gt CO2e
- Poop also a problem. Emits stuff like N2O. About half of poop emissions come from pig manure. Second-largest cause of emissions
- Cows in South America are up to 5x more than North America. African cattle do even more. So I guess breeds matter.
- Downplays the vegan argument. People want meat too much, not realistic.
- Option: plant-based meat, like beyond meat and impossible foods. Convincing substitute for ground beef. But, green premiums. Ground beef substitute has 86% premium.
- Also mentions lab-grown meat. This is meat that's grown in lab, not fake meat. Has the same fat, muscles, tendons. Done with less GHG emission, other than the electricity.
- Can also cut down on emissions by wasting less. In Europe, >20% of food is just thrown away. In USA, it's 40%. In addition to excess production, when it rots, it also produces enough methane to cause as much as 3.3 Gt CO2e.
- Fertilizer. Alot of its nitrogen never gets absorbed by plants. It runs off, and can go into air in form of N2O, which has huge GWP.
- Fertilizers responsible for ~1.3 Gt in 2010.
- Not a good solution to phasing out fertilizer. And there's no equivalent of carbon capture for N2O.
- Technically, possible to get crops to absorb nitrogen more efficiently than they do.
- Onto the last bit of GHG source. 70% is food stuff. Other 30% is from deforestation. World Bank: world has lost more than half a million square miles of forest since 1990 (about size of Peru). Combination of problems: CO2 from emissions to air. Also disturb oil, and lot of carbon in soil (more carbon in soil than in atmosphere and all plant life combined).
- In Brazil: forests removed for cow pastureland. American-style diet is kind of responsible.
- In Africa, some of it is for fuel reasons. Nigeria - lost more than 60% of forest cover since 1990, exports a ton of charcoal
- Indonesia - being cut down for palm trees, for palm oil. Indonesia is the world's fourth-largest emitter of GHGs.
- Some factors:
- Tree can absorb ~4 tons CO2 over 40 years
- If burns down, all the CO2 it was storing will be released
- If a tree would've grown there naturally, you didnt add any extra carbon absorption
- Trees in snowy areas cause more warming than cooling (because of lack of albedo). But trees in tropics cause more cooling, bc they release moisture, which → clouds, which reflect sunlight
- Was anything else in that spot? If you eliminate a soybean farm, what are the knock-on effects?
- Take all this in effect. Probably want to take a bunch of trees to the tropics.
Chapter 7 - how we get around.
- 16% of the 51 Gt
- Although transport isn’t the biggest emitter worldwide, it is #1 in the US
- Maritime shipping handles a ton of trade, and makes ~3% of emissions.
- Breaking emissions down by category:
- Cars, SUVs, Motorcycles: 47%
- Garbage trucks, busses, 18-wheelers: 30%
- Cargo and cruise ships: 10%
- Airplanes: 10%
- Other: 3%
- Cars. About a billion cars in road. Electric cars have gone down in price. Mostly due to cost of batteries decreasing.
- Garbage trucks, etc. Harder to electrify. Because batteries are heavy. Medium duty things like garbage trucks and busses are light enough that can use electricity
- Shenzhen has electrified whole fleet of 16k busses and almost 2/3 of taxis
- For long-haul trucks, harder situation. Lithium-ion battery is about 35x less energy dense as gas
- Ships and planes. Battery density... it just wouldnt be able to get off the gorund. Maybe best bet is replacing gas with electrofuels or advanced biofuels
Chapter 8 - How we keep cool and stay warm
- 7% of the 51 Gt
- In average American home, AC is the biggest electricity consumer. More than lights, fridge, computer
- In addition to energy, AC units contain refrigerants, F-gases, which have high GWPs.
- Furnaces and water heaters account for 1/3 of emissions that come from buildings. They usually run on fossil fuels
- Nice property: these things could have a negative green premium
- Costs go down if you replace electric AC and gas furnace and replace them with a heat pump
- Looking at major cities, the green premium for a heat pump is about a 20% discount
- Unfortunately, switching heating fuels with 0-carbon alternatives have a high (>100%) green premium
Chapter 9 - Adapting to a changing world
- In Kenya, about 1/3 of pop works in agriculture. Worldwide, about 500m smallholder farms
- About 2/3 of people in poverty work in agriculture
- However, are responsible for few ghg emissions, because cant afford to use products.
- Though poor are doing little to cause climate change, will suffer the most. Climate will create droughts, floods.
- In Sub-Saharan Africa, farmland will become drier.