# Air Pollution - Types, Sources, and Fixes

I finished my PhD last week. Today I start posting again. This is a month-long series, one post each week, regarding air pollution and our health. First, we discuss types of pollution, then the health effects of different types based on where you live (US vs. China as case studies), then we move on to the health effects of each type, finally we end on how you filter it.

Hint: Two posts ago (and over a year ago) I said I wasÂ taking a break to build a better pollution filter. I did that, and the final post in the series will be telling you all about that part. In the meantime, please go to www.getblueskies.com, sign up for our upcoming release emails (which will let you know when we launch on indiegogo with a discount for the first buyers), and share our website with your friends that might be interested.

###### Air Pollution

I was speaking with a physician about air pollution, and about which types cause asthma, and she was stunned that there is background research indicating that different types of outdoor pollution have differing relationships with asthma.Â Part of the reason for this was that she didn't realize how easy it was to differentiate which types of pollution come from which sources.

Okay, then. There are several major types of pollution. And NO2 from traffic is far and away the outdoor pollutant that that is most highly associated with our increasing asthma rates in the US (more on this in a future post).

###### Major Pollution Types

Particulate Matter is big chunky pollution. It is called PM10, or PM2.5, for how wide it is. PM10 is 10 microns wide, PM2.5 is 2.5 microns wide. For comparison,Â the average human hair is on the order of 100 microns wide (thin hair is about 17 microns, thick hair is up to 180). PM can be dust, fine soot, pet dander, or pest droppings (think cockroach poop). These can be very easily filtered with HEPA-style filters (HEPA filters are physical filters that block large pollution particles using small holes).

A photo from my time in China. PM pollution is pollution you can see.

Chemical Pollution is very defined and very small. It's specific molecules. It's about 10,000 times smaller than PM2.5. It's also about the size of the the air we breathe, so you can't physically filter it. It is things that you've heard of, like CO (carbon monoxide), SO2, and NO2 (these both become strong acids in water, which causes acid rain. Note that our lungs are about 100% humid air, so they become strong acids, like battery acid, in your airways). These are extremely difficult to filter, and tend to require chemical reactions (more on that on a later post!). We are focusing on SO2, which just comes with fossil fuels, and NO2, which comes about every time you burn something in our atmosphere (our atmosphere is 78% nitrogen, and 21% oxygen, when you burn things, it uses the oxygen to convert stuff into CO2 and other emissions, but at high heats, it also produces NO2. Higher heats means more NO2). We ignore CO for now, and we ignore CO2 because it doesn't cause immediate health threats compared to these other pollutants.

Cars emit a lot of NO2. Catalytic converters help, but they still produce NO2 in amounts that are harmful

VOCs are complicated. They are typically things you smell, like the new car smell, new elevators, paint, permanent markers, etc. Some people are highly sensitive or allergic to these. They can typically be filtered by most activated charcoal filters, because the carbon radicals in VOCs tend to adsorb well onto charcoal (ie they bond to it). We are going to ignore this, because we're assuming you don't like to leave your child in a freshly painted room, in new cars, or on new elevators.

###### Pollution Sources and Types

Hokay, so, now we need to discuss which pollution sources produce each. So I've made this helpful chart. These are relative amounts of pollution within their category, with no clearÂ scaling criteria, but it gives you an idea of how different vehicles or power sources relate in terms of pollution. In other words, a two stroke engine clearly doesn't produce as much pollution as a coal fired power plantÂ More important, these areÂ rough relationships. You can have a wide range in each category, with a coal plant with no controls that burns high-quality coal producing significantly less pollution than the same design coal plant that burns low quality coal, for example.

Chart with differing sources of pollution, and relative amounts of pollution produced by each.

Let's go through this one-by-one.

Vehicles burn gasoline or diesel. Gasoline vehicles pretty much just produce NO2 (and CO! But we are ignoring that for now), and our catalytic converters help reduce that. Smog is a byproduct of NO2 interacting with other pollutants that are already in the air. The part of smog that we see is actually PM pollution, rather than chemical pollution. Diesel vehicles produce a lot PM, and some SO2, and relatively more NO2. Catalytic converters can reduce NO2. Using low-sulfur diesel can reduce SO2.Â A lot of developing countries do not use low-sulfur diesel or catalytic converters, so they produce a ton more of every type of pollution.Â Two Stroke Engines are common in India (and other places, but not so much in China, and almost never in developed countries, unless you count lawnmowers). These things burn oil alongside gas. They produce nasty fumes, like your weedwacker or small lawnmowers. This is part of the reason that India has a particularly nasty type of air pollution. These are being phased out over time, with bans on new models of two-stroke engines in many cities.

Power Plants are a lot more complicated. In the next post, I will be discussing pollution controls in power plants in more detail. Put simply,Â natural gas powerplants produce predominantly NO2. They burn CH4, and convert it to CO2 and H2O.Â NO2 emissions can easily be reduced by 90% with proper controls (discussed in the next post).Â Coal fired power plants can be nasty. With no controls and with using low-cost coal, they produce a lot of each type of pollution. PM is the result of impurities in the coal that can't be burnt, or unburnt specs of coal. Low-grade coal produces prodigious amounts of PM, and contains a lot of sulfur that burns to produce SO2. They produce a lot of NO2. All of this can be reduced greatly simply by building in controlling systems. These controlling systems are used in nearly every coal plant in developed countries and in many coal plants in advanced developing countries. They are completely ignored in nearly every coal plant in many developing countries.

## Traffic Pollution vs. Power Plant Pollution

Which of these should you care about? That depends on where you live. Most of the pollution in developing countries comes from power plants, but if you live next to a busy street or highway, traffic pollution could be the bigger concern. If you are in a developed country, particularly the US, traffic pollution is almost always the largest concern. Why? Because you are sitting directly next to the source. Whether you're biking or walking with your infant in a stroller, you are right next to the pollution. The problem exacerbates when you are nearby to a highway or major intersection, because there is a ton of traffic.

So, in short, if you are in the US and much of Europe, you should be worrying about the invisible (but smellable) traffic pollution that you are breathing in. If you are outside the US, it varies country by country. If you are in China or India, you need to be concerned about both traffic and powerplant pollution, and there is pretty much no escaping it.

- Jason Munster

# Adele and Hello - Math and a Carbon Footprint Analysis

I mentioned I wasn't going to post about the environment as much anymore, but I can't stop. I honestly started this just to show how fun math can be in looking at the number of views on Adele's Hello on youtube. It ended up with me being curious what the environmental impact was.

So today I looked at the youtube video of this song. For your convenience, here it is so you can listen to it while reading this post. Apparently it's blowing up, with an insane number of views per day.

It has 309,000,000 views and has been up for all of 20 days. Let's use some basic math to figure out how popular this song is!

Let's first see how many seconds there are in a day.

$24 \frac{hr}{day} \cdot 60 \frac{min}{hr} \cdot 60 \frac{sec}{min} = 86,400 \frac{sec}{day}$

And over 20 days:

$86,400 \frac{sec}{day} \cdot 20 days = 1,728,000 seconds$

With 309,000,000 views in that time, we end up with 178 views initiated per second, on average, for 20 days, nonstop.

But, hold up, it takes 6 minutes for this song to complete. So that means, on average, there are:

$6 min \cdot 60 \frac{sec}{min} \cdot 178 \frac{views}{sec} = 64,000$

Let's round that up to 65,000. On average, at any given time, there are 65,000 people watching the Adele Hello video on youtube. There are 15 million views per day. That's just one video on one source. In eight whole day, as many people listen to the song,Â on just youtube,Â as watch the superbowl.

If this clip keeps up (which is unlikely), she will surpass Gangam Style, with over 2 billion views, in less than 150 days. And medical stocks will go up, cause I worry that listening to this song tooÂ frequently may drive people into depression.

"But Jay," you say, "what about the energy and environment component?!?"

Let's figure out Adele's carbon footprint from youtube! Let's assume that Google's hosting emissions are negligible. Let's just focus on the energy used for a laptop. Let's say that it is 50W (this is conservative).

From a prior post, we know that a 100W lightbulb uses ~1kg of coal per day. So a laptop will use about 0.5kg per day. How much CO2 is this?

This is basic chem! Let's get really basic. Coal is mostly made up of carbon. So when it is burnt, every carbon molecule breaks off and bonds with O2. So we assume that all 0.5kg of carbon becomes CO2. You need to add that weight of the O2. C weighs 12 AMU (atomic mass units, pretty much the mass of a single molecule) and O2 weighs 32 AMU.

So we need to multiply the weight of coal, which is pure carbon, by the proportional increase of mass of CO2, cause each carbon atom gains O2 weight (12+32=44)

$0.5 kg-CO_2 \cdot \frac{44}{12} = 1.85 \frac{kg-CO_2}{day}$ for a 50 watt computer running all the time.

Also this song is 6 minutes, or 1/10th an hour, and an hour is 1/24th a day, so this song takes 1/240th of a day.

$1.85 \frac{kg-CO_2}{day} * \frac{1}{240} = .00771 \frac{kg-CO_2}{view}$

Don't forget, though, that we have 15,000,000 views per day!

$0.00771 \frac{kg-CO_2}{view} \cdot 15,000,000 \frac{views}{day} = 115625 \frac{kg-CO_2}{day}$

Or, you know, ~125 tons of CO2 per day. Just from Youtube and Adele. This is the generation rate of about 2000 Americans.

And why this analysis overestimates Youtube's and Adele's contribution to CO2 emissions

Most people are multi-tasking while listening to Adele (ie those 50 watts they are using are also going towards whatever else they do while listening to Adele, such as reaching for tissues to blot their tears), so you have to take a fraction of this number Â ðŸ™‚

Second, much of the power use in the US is now coming from natural gas, which is more efficient than coal, so you can cut down this number.

Third, tissues take a whole lot of energy to make. I'm betting that the raw number of tissues used while listening to Adele will increase the CO2 footprint.

How many times did you restart the song while reading this blog, BTW?

- Jason Munster

# Blue Skies

The name of my new company!

Check out my new digs at www.getblueskies.com. I'm building the first mobileÂ filtersÂ that can filter all the common air pollutants that kill you.

One year ago todayÂ I said I was going toÂ find ways to help people dying from air pollution. Sitting in academics and talking about the problem isn't enough for me. I have to help solve the problem.

Tomorrow my company is being featured on anÂ Autodesk blog. Autodesk is a $10B companyÂ that makes Computer Assisted Design software. I'm hoping for around 10,000 page hits to follow. So, pretty much, it's now a thing. Why did I name it Blue Skies? Cause it wasÂ named Clear Breath when we intended to launch in China first. The translateration roughly means "power and strength." Then IÂ decided to launch in the US first. To Americans, Clear Breath sounds like a breath mint. So. What do I have? Wait for the autodesk blog to come out to find out. Or check out my website. But for real though. Go to my website and sign up for my mailing list. You can be one of the first 100. I want to give a shout out to the Harvard Innovation Lab. For the most part, they've been supportive all along, and have given me a space to work and awesome training (although Neal and Yash really need to stop worrying about standard 150A air cylinders and let me bring those things into the prototyping space). From here on out, my posts on this website are going to be less about climate change and energy, and more about whatever I want to talk about. A lot of the energy stuff will be moving to www.getblueskies.com. Thanks for being with me this whole time! - Jason Munster # Let Them Eat Grass - Free Range Livestock are Better For Environment A friend and advisor, Chris Tuozzolo, more or less has a CSA for a free-range cow. He told me I should write a post, a rejoinder, actually, to my prior post on how beef causes nearly 10% of greenhouse gas emissions. A lot of people will think "free range cows must be better for the environment in every way, because they are natural!" Shortest version: free range cows are better than feedlot cows by a factor of 2-3, putting them closer to pig-meat, but they still aren't amazing. cows. Other short version: the amount of disinformation on this topic is astounding. You literally can't find a reliable link on the first search page of google. All the articles are either by free market groups (feedlots are market efficient!), corn lobbyists (feedlots use our corn!), or vegans (there is no such thing as good meat to eat!). Much of the information that is available is "science" is in fake journals. In other words, it really is fake information put into journals that are made up to let any information through, provided you pay them to publish it. A reader literally needs an understanding of journal impact factor (ie, ratings of whether journals are real or BS, as it turns out some peer-reviewed journals will literally publish anything for a fee) to figure what's real and fake, and most people without PhDs don't know what impact factor means. In other words, I don't know how the rest of you can pick apart the real from the BS on this topic. Full version I did research. Holy crap, the bullshit (heh, punny) information is fed to you with a firehose on this one. This is a prime example of very smart people being paid to lie to you very effectively. feedlot cows. Pic from EPA. I'll keep the important information short. Grazing cattle are far better for the environment than feedlot cattle. The best information I can find (published in Science with over 2000 other authors having cited the article in follow-on research) (note, this article is on sustainable food and covers a lot more than meat, but it has a good chart on water use and GHG in varying feeding areas) says the following: • Grazing cattle produce half as much methane (a powerful greenhouse gas) per year as feedlot cattle • Grazing cattle take 1/5th the water per day • Pigs produce about the same GHGs in either setting, but keeping them clean in a feedlot takes 3x as much water • Grazing cattle take up to 33% longer to reach edible maturity (but they are leaner, so you get more actual meat). This came from other, less reliable sources, but we'll take it at face value • Adjusted for time to market*, feedlot cattle make 50% more GHGs and use 450% more water (looking at you, California, with the 4th most cattle of any state) • I think that time-to-market number may be made up, which would make the numbers more like 100% more GHG and 500% more water from feedlots *That 33% more time to maturity also could be a manufactured number. I can't confirm it from reasonable sources. Even if it is true, then feedlot cows produce more pollution and take more to make. Other problems with feedlots: • It is quite possible that constant antibiotic use in feedlots, constantly fed to animals as a means mean to prevent them from getting sick (increasing profits), leads to antibiotic resistance. So next time you get a case of untreatable gonorrheaÂ from antibiotic resistance, raise a glass to industrial agro-farming (also known as American-style farming). • Grazing cows stand apart farther. Feedlot cows stand next to each other, helping spread of disease, so they need more antibiotics • Sustainable grazing (not often practiced in the US)Â promotes the change of deserts to land. • Once you start growing grass in desert areas, the grass holds the rainfall in place long enough so it absorbs into the ground rather than running off into rivers, making a positive feedback loop. Seriously, watch this TED talk. It's starts with a powerful message. "To stop the spread of deserts, we killed a metric fuck-ton of elephants. Desertification still happened. It turns out we killed a bunch of innocent elephants. The way to reverse desertification is to have managed grazing." Don't watch it when drunk though, cause you'll either get very angry or very sad. Hokay, so, we've now covered that managed grazing can actually reverse desertification, which means aquifers can start to take in more rainwater and some CO2 will be drawn down in the growth of new plants. Why Vegans hate this But yes, a subset of vegans (and likely a majority) love to argue that eating meat is an environmental disaster (it does push global warming happen faster), and so it upsets them that grazing cattle may actually be a positive net effect (counting the turning bare desert into growable land). Feedlot beef growth is definitely pretty bad, but it's highly likely that a well-managed grazing system for cattle will result in net positive benefits of environmental restoration. You can't blame vegans too much for pushing that grazing is bad, because, as the rest of this article points out, it's hard to figure out which is correct data. Journal Impact Factor and Judith Capper being a fake scientist Journal impact factor is a measure of how important and useful certain journals are. Science and Nature have high impact factors. Also Proceedings of the National Academy of the Sciences (PNAS - pronounced P-nass, best/worst acronym ever), much more rigorous, has a high impact factor. The article I cite above is from Science, which means it was cited 2000 times. As in 2000 other journal articles reference and talk about it. It's kind of a big deal. One counter article is by a "scientist"Â named Judith Capper. She publishes articles that say that feedlot farming is less GHG intensive than grazing. Except she published in a journal called Animals. It's literally a fake journal. It isn't listed as having impact factor. What's better, half of the 35 citing authors are her. She cites herself more than anyone else cites her. Pretty much, this is an udder bullshit article (haha) with awful science behind it. Typically when a majority of citations are yourself, it means everyone else thinks you're insane. So you, dear reader, having never had to write a PhD thesis where you had to defend the sources you chose, would just see that this woman is a professor and has a PhD and say, "This must be true!" Except it's not. Articles do things like say, "Cows emit methane, and cows that eat grass take longer to bring to market, so more methane comes out!" Except that cows that eat grass often emit less methane, cause there is less weird stuff in the grass (as the information earlier on in the article points out). So pretty much they take one true thing (cows produce methane) and then ignore the rest of the facts to lie about the ultimate maths. I call BS. In Closing This post has been all over the place, and it over 1000 words. Pretty much, grazing cows are far better than feedlot cows for the environment. Grazing pigs just use less water, which is useful in California. Good luck finding real information on any of this, though. # Calories Burnt by Running Harvard Stadium Harvard Stadium. For decades, masochistic people with a desire to be extremely fit have run up the "seats" of Harvard Stadium. The November ProjectÂ was pretty much born there.Â Some Harvard varsity athletes run it for extra endurance training. People bring their dogs, but it's so difficult the dogs say, "screw this noise" and go lie down. It's a beast of a run. You want ripped abs? Abs are made in the kitchen, eat less calories than you expend in a day. Want to earn a few extra calories? Run a stadium. Abs can also be made at the stadium. Harvard Students running the Stadium. Source. Current articles suggest a normal 180 lbs. person will expend 9 calories per minute while doing stairs. We are not normal people. We are beasts. We are animals. Metrics for mere humans aren't for us. Let's do a serious math review so we know exactly how wrong this number is. At the end I point out why stadiums are far better than running, even if they burn similar calories. As usual, skip to the end to read the important parts if you don't like details. Maths! 1. Each stadium "step" is 15 inches, or about 0.38 meters. 2. There are 31 steps per section. If you don't cheat, that is. Most people cheat and skip the bottom-most and top-most one because they aren't wide. If you skip both of these, you are eliminating 74 whole steps, or 2.3 whole sections. This is nearly 7% of the workout. You are depriving the world of 7% of the exercise that's supposed to make you beautifully buff. Run all the steps. 3. There are 37 sections. 4. Each step traverses 30 inches horizontally. 5. We are using my weight. Last weigh-in I was 215 lbs, or slightly less than 100kg (it's 98, but much like 5' 10" people like to say they are 6' tall, I like to say I am 100kg). There is a chart at the bottom to adjust for other weights. Part 1: Going Up! $0.38 \frac{m}{step} \cdot 31 \frac{steps}{section} \cdot 37 \, sections = 437m$ Hokay, so, 37 sections will net you 437m of vertical distance.Â Now it's time to figure out how much energy this is! We use the standard mass*gravity*height for this, using my mass. I'm aware that not everyone is a 100kg monster, so we'll have a scale farther on down. $100kg \cdot 9.8 \frac{m}{s^2} \cdot 437m = 430KJ$ Remember that 1 calorie equals 4.18 joules, but the calories we talk about with weight gain, etc., are actually kilocalories. So we have 430kj, and we need kilocalories. $430KJ / 4.18 = 102.9 \, kilocalories$ 103 (kilo)calories?!? "Oh no!" you say, "I do all that work and only burn 103Â calories? What a waste!" Now hold up there a second, we aren't done yet. We can assume a roughly 20% efficiency of turning our food into work output. So let's multiply this by 5. $103 \cdot 5 = 515 \, calories$ So for a 100kg fattyÂ like myself, the vertical distance alone from doing one stadium is about 515 calories. The flats! I measured the flat areas to be 30 inches, or about 0.762m. How far is an entire stadium? Well, first, we need to state that one of those 31 steps isn't traversed, cause it's the last step and we only do the vertical part before going back down. So we have 30 stairs per section that we move on the horizontal part of. $30 \frac{steps}{section} \cdot 0.762 \frac{m}{step} \cdot 37 \, sections = 843m$ Let's include the distance around the stadium, which we know to be about 250-300Â meters (100 yard field + out of bounds areas traversed twice plus the 75 or so yards for the width plus out-of-bounds). So let's guess here and just call it 1100m, or 1.1km. A 100kg man burns about 100 calories per km. See how well the metric system works? So I burn 110 calories doing the horizontal section of the steps (ie going forward as I go up) We are now at 625 calories for 100kg person running a stadium, 515 from going up, and 110 from going forward. Stepping Down Okay. This is complicated. We are going to take a mulligan here and reference a pubmed medical journal article. That's right, when I mulligan, it's by referencing peer-reviewed science. This particular article says going down steps takes roughly 1/3 the energy as going up them. Let's be a bit more conservative and assume we are in better shape than the average person, and say it takes 1/4 the energy.Â This might be false, but I'd rather come in slightly modest than slightly exaggerating when it comes to my calorie expenditure on a stadium. 515 calories for a 100kg man going up the stadium steps.Â One quarter of this is about 130 calories. Summing It All Up, and Burn Rate $515+110+130 = 755 \frac{calories}{stadium}$ Okay, that's a lot. Now on a good day, I run the stadium in 35 minutes (yes, I'm slow, but I'm also 100kg. Also I'm recovering from whooping cough and a sprained knee, so right now I'm at more like 45 minutes). My average burn rate is 21 calories per minute. Compared to an estimated 9-11 for a normal person taking the stairs. So pretty much you're doubling the work rate of a normal person doing normal steps. Comparison to Running: To burn 750 calories from running, I need to run 7.5km. This is 4.66 miles. To have an equal calorie burn-rate, I need to run 7.5 minute miles. Which is easy for me. In other words, I burn as many calories by running on the flat ground as I do on the stadium. In fact, running is much easier for me than the stadium. Are we missing something? Probably. While doing stadiums, you are using far more muscle groups that while running, and you are likely engaging a lot more core. In other words, the numbers I've calculated here are a pure energetic viewpoint. It doesn't account for wasted energy/motion that is much more likely in the uphill push that is a stadium. Finally, stadiums actually work your muscles. Running, less so. So What? The Difference Lay in the Details Hokay. So. Stadium vs. running. Both burn calories. But where do these calories come from? Turns out when you do resistance training, IE take stadium steps, you are working your muscles a lot more than endurance training. This is important. If you are trying to lean out, IE lose fat, running doesn't do a great job. When running, you are likely to lose muscle mass to produce some of those calories, or to burn them muscles afterwards when your body is starved for energy. When doing stadiums, you need those muscles, and your body preserves them. This isn't random bullshit. There are solid scientific studiesÂ that show that a diet + resistance training (stadiums, lifting) results in loss of fat, but a diet + endurance (running) results in loss of fat and muscle. In other words, run all you want, but you're just gonna make yourself skinny fat. If you want to look good naked, you have to push iron, do body weight exercises, sprint, and/or do stadiums and hills. Short story: you want abs for the summer? Run stadiums, lift weights, watch your calories. More Times and Maths! Here the math works out pretty well. If you run a 35 minute stadium, you have to run 5 miles in 35 minutes for equal calorie burn, or 7 minute miles. So a 30 minute stadium means 6 minute miles for 30 minutes, and a 25 minute stadium means 5 minute miles for 25 minutes for equal calories. Here is where the difference is. The fittest people I know can't run a 5 minute mile, much less five in a rown, but they can easily run 25 minute stadiums. Thanks for Adnan Khera for making me think about it that way! Charts! Okay, as promised, here is a chart for stadiums and calories burnt! Remember, these are probably an under-estimate! For Normal Sized People Now for some handy-dandy charts! Calories burnt from running a stadium (I made this!) Now, why did I leave off people under 100 lbs.? Cause no one under 100 lbs should be counting calories. They are either children or need to eat several more sandwiches. And why would I go up to 280? Cause Harvard football runs this thing, and many of those guys make me look tiny. That's all. Thanks for reading! - Jason Munster # Tesla's Powerwall - Not Economical Tesla Powerwall I'm gonna open by saying that I really like Tesla's powerpack. Technology isn't pushed past the bleeding edge without loss-leaders pioneering. That being said, the numbers, as usual, don't lie. On a per-unit-energy cost basis, these things aren't economic in most of the US. Once you consider the externalities, however, the overall benefit does make them "profitable." Likely you will see subsidies to internalize these externalities, thus making the powerpack work. Unless the inverter costs too much. More on that later. One major implication I haven't seen anyone talk about? Utility companies currently have to pay people with solar panels who produce excess electricity at market rates. They've been trying to get rid of this for years.Â This technology gives utilities every reason to demand they no longer pay people for their excess produced solar power. This has enormous implications. It's now indefensible to force utilities to buy at market rates the extra power produced by homes with solar. Read more near the bottom. Tesla's Powerwall next to a car. Small-ish and sleek. 7 inches deep, weighing 220 lbs # What is this Powerwall? Powerwall is a power pack that you hang on your wall. It costs$3,000 for a 7kwh pack designed for a daily cycle, meaning it's charged and used once per day. This is the cost without installation. Also, this is the cost if you already have solar cells and an inverter. If you want to work with the grid alone, you have to buy an inverter*. Even if you already have solar cells and don't need an inverter, this seems like it's a product designed for the wealthy. Let's look at the math (my favorite part!)

*Inverters. Batteries and solar panels produce DC current, or Direct Current. This means it doesn't change phase. What we use in our homes is Alternating Current or AC. The alternating current means that the positive and negative terminals switch sides of the power plug. In the US, they switch sides 60 times per second. DC means that the terminals do not switch sides. Hence batteries having a + and - terminal, and all your non-battery electronics not having these.

The Maths!

We are going to make some of the rosiest assumptions in the world. First, though, let's get some solid data lines up. Take a peak at NPR's cost of electricity infos.

1. On average, people pay 12 cents per kwh of electricity

2. In Hawaii, they pay 33 cents. We'll use this as a case study.

3. The Northeast and California, two other case studies, pay about 16 cents.

4. The average American uses 900kwh of electricity per month in their home (from eia.gov).

Really rosy assumptions

1.Â The sun shines for 300 days a year and provides enough electricity to power your house during shining and to fully charge the battery

2. The electricity grid doesn't buy back your excess solar*. If they do have to buy it back, then the economics discussed here don't play out

3. You've already paid for all of your solar installation and you aren't concerned about those costs of that electricity going into this powerpack

4. These things don't degrade over time (extremely rosy assumption)

Hokay!

300 days per year of 7kwh of electricity provided by this beast is:

$300 \frac{days}{yr} \cdot 7 \frac{kwh}{day} \cdot = 2100 \frac{kwh}{yr}$

So 2100 kwh/year. What's that get you in most of the US?

$\ 0.12 \cdot 2100 = \ 252$

So $252 per year. For a$3000 battery pack. In most of the US, if your solar panels worked perfectly for 300 days a year, it'd take you 12 years to pay back your investment. This is a 6% annualized ROI (Return On Investment). In other words, you'd make more money in the stock market, so it's a bad investment, not even accounting for installation costs and with impractically rosy assumptions, in most of the US.

What about in the Northeast and California, where electricity is $0.16? $\ 0.16 \cdot 2100 =\ 336$ Or payback in 9 years. This is an 8% ROI, making it a decent investment. Let's be realistic, though. In the Northeast, we have storms and winter. Solar panels don't work so great here. We aren't getting 300 cycles per year out of this. We'd be lucky to get 150, making it an 18 year payback, or about a 3% ROI. What about California? They actually might get 300 days of viable sun a year. So in California, you could be break-even. Now what's the problem here? Normal people don't look for 8% ROI on their home upgrades. They look for 15%. Pretty much they want 3-5 year payback periods. So pretty much, someone has to have a very green outlook on life to buy one of these. Or there have to be subsidies (more later) Hawaii Hawaii has sunshine and electricity costs 33 cents. Let's say you've paid off your solar panels in Hawaii. $\ 0.33.2 \cdot 2100 =\ 700$ In Hawaii, with our rosy assumptions and no installation cost, the powerpack will pay for itself in 4.25 years, for a whopping 18% return on investment, without any subsidies. There is a viable business model here. Seriously, someone go start a powerpack/solar panel installation company in Hawaii. Anywhere else, and these things will need hefty subsidies. Subsidies Why would you subsidize these things? Easy. There are only two reliable power sources that can compensate for variability in solar power: hydro and natural gas. Every other power plant takes far too long to spin up to be useful. In other words, nuclear power doesn't stop producing pretty much ever. Coal power takes about a day to get to capacity, so it can't cycle well. Hydro power is a limited resource. We are pretty much tapped out in the US, and what we have is already being used, so it can't ramp. We'd have to replace what's currently being used with coal, natural gas, or nuclear to use hydro for solar-grid reliability, so that entirely defeats the point. Natural gas ramps quickly, and we have excess capacity in the US. Natural gas still produces CO2 that spreads globally, and NO2 that spreads locally. NO2 becomes a strong acid when you breath it in, so we have healthcare reasons to reduce it. Thus it might make sense to subsidize these powerpacks to make people more likely to buy them. Second, this is good tech. It's pretty much where it needs to be in order to make sense to buy in many parts of the country, if you already have solar. Subsidizing it will cause further advancement in battery tech, making it that much more viable in a wider array of applications. Battery tech is one of the things holding us back from so many viable technology applications, so if there is something to subsidize that will more than pay for itself, it is battery tech that is nearly cost-even now. Some Extra Thoughts on my Rosy Assumptions *If Solar Companies don't need to buy back Electricity In most places, if you produce excess electricity that you don't use, the solar company has to buy it back at market rates. So buying this powerpack and storing energy for commercial purposes is useless. All of the economic discussion above is bunk if the grid needs to buy your excess power. In other words, only greenies would buy it. One important thing to consider.Â This product makes storing electricity from solar into a break-even cost in any sunny part of the country. Utilities have always hated paying for this. They lose money on it. They've fought legal battles to get it repealed. And now they have the ammunition they need to repeal it, because it's now no longer a burden to consumers to store their excess electricity for later use themselves. Maybe consider buying utility stocks if you find a company that is over-exposed to paying for home-solar-produced power? I'd tell you to look towards California here. Inverter Costs If you don't have solar already, you have to pay for the inverter to make this thing convert DC back to AC for your home. I can't see any reason to do this. The cost differential between peak power and non-peak is about 4-6 cents in most places. Far too little to justify the expense of both an inverter and a powerpack. A gas generator is a better bet if you need reliable power. Large Scale Efficacy I'm betting the large-scale systems are more cost-effective. They don't need to be as small and as sleek. And you can have one large inverter for all of the daisy-chained power packs. Who would buy these? Commercial electricity buyers, like stores. Who wouldn't buy these? Industrial complexes. They make deals directly with electricity companies and pay$0.07 to $0.10 per kwh. Thanks for reading! Â - Jason Munster # Electricity Basics (and some advanced) I received my second request for a post! This time the submitter asks for information about electricity, transmission, and how intermittent renewables like wind and solar fit in. So, the first question: 1. Electricity, for the most part needs needs to be consumed the instant it is produced? Yes. Storage of electricity can be done in batteries, or with pumped-water energy storage, but these are all just ways of being able to make electricity at some moment later in time. In short, electricity, once produced, is either used immediately or stored. Massive storage is not practical at the moment, so it's used. 2.Â Wind or Solar electricity is essentially in addition or parallel to the base load, and do little to lessen the use of coal, NG, or nuclear derived electricity! This bring up an interesting point about electricity production. In the US, we have 60hz electricity. It's made 60hz by the generator design (in the US, Europe and other places use 50Hz power). Thermal power plants,Â those that burn things to produce power, rely on spinning a turbine in a magnetic field to produce power. The magnetic field is part of the turbine design, and is too complicated for this post to discuss in further detail. The turbine is spun because water, turned into steam by the heat from burning things or other reactions (coal, natural gas, or even heat from fission), expands rapidly from water to steam. It creates pressure, and then pushes through the turbines to spin them. The turbines spin at the exact rate they need to in order to produce 60hz electricity. If we produce slightly too much electricity, the turbines start spinning slightly faster. To keep the grid at the right speed, electricity production is reduced at plants. If there is too little electricity, the turbines will slow down, and we'll fall below 60hz. There is a constant dance of the power plants and the electricity users to make everything balance. It's mostly automated, and happens very quickly. What does this have to do with solar and wind? A lot. Solar and wind power output can be predicted, but not perfectly. If we want to maintain a perfect 60hz grid, we need to be able to adjust for wind and solar output. Because, again, electricity is used when it is made, and not stored. Coal and nuclear power plants aren't great at changing how much electricity they produce in a short timescale, so if we are going to have power plants to make the balance necessary, we need hydro and natural gas to account for the variability of the solar and wind. There isn't enough hydro to do that all over the country. In Â other words, if we want to maintain a 60hz grid, we are always going to have some amount of natural gas power plants. But beyond that little wrinkle, solar and wind power absolutely offset coal-fired power plants. The more solar and wind we have, the less nuclear and fossil fuel power we need, in general. In practice, do renewables offset much? See the chart below. US primary energy consumption. Source: eia.gov info Short version: Wind was about 1.2% of primary energy (primary energy counts burning oil for cars as well), and solar is 0.16%. So wind and solarÂ can replace coal and nuclear, but it barely does currently. Longer version: We can let the 60hz grid go from exactly 60hz to let it slide between 58 and 62. And then we can fairly easily do away with a lot of other power plants, as long as we have enough wind and solar. Note, however, that there aren't enough good wind sites in the US for this, and solar is currently too expensive and resource-demanding to replace fossil fuels. 3. Electricity is bought and sold just like a commodity? In some ways, yes, but not exactly! There is a complicated daily bidding process, and several factors are brought into play. This one is a bit confusing. I'll do my best. Power plants bid on the day-ahead market. They submit their bids to what is typically called an ISO, for Independent System Operator (some places call it differently, like RTO for Regional Transmission Organization. The ISO/RTO looks at the bids, looks at their best guess for power the next day, and then figures out how many of the power plants they need to hire for the day. Those that don't get hired don't actually burn anything or produce power. Those that do get hired, get hiredÂ at the rate of the highest bidder. Let's do an example to explain better. Note that a MWh is one hour of one MW production. So a 600MW plant produces 600MWh in one our, and 1800MWh in 3 hours. A plant says, "I can produce this many megawatts at this many dollars per megawatt." Power Plant 1 might say, "I can produce 600MW of coal power at$80/MWh." Power Plant 2, "I can produce 1000MW of natural gas power at $100/MWh." Power plant 3, a nuclear power plant, doesn't shut down. They just keep running. They say, "I can produce 1200MW at$0/MWh." Why? Cause they have to run anyways. They are delivering that powerÂ at any price. Power plant 4 is an old coal-fired power plant that has already paid for itself, so it's really cheap, and says, "I can provide 300MW at $50/MWh" Let's assume it is determined that all of the less expensive power plants, along with Power Plant 2, need to run in order to satisfy electricity demand. They want$100/MWh. Power plant 1, despite bidding in at $80 per MWh, gets$100/MWh, nuclear plant 3 also gets $100/MWh, and coal plant 4 also gets$100/MWh.

On another day, it is determined that only enough electricity is needed for power plant 4 (and all the ones who bid below it). So Power plants 1 and 2 do not produce electricity, power plants 3 and 4 each get \$50/MWh.

Should inputs become more expensive, then the power plant has to raise its price. Natural gas, for example, became a lot less expensive in the past 5 years. So they now produce electricity for less than a new coal fired power plant would. So they bid in for less.

A bit confusing, right? It gets more complicated than that. This is a great example to show that electricity is not exactly treated like a commodity.

Now what about solar and wind? Pretty much, if solar and wind is produced in the US, it is purchased, pretty much outside the normal bidding system. What happens to the bidding system if all power becomes solar and wind? There probably will still be some version of it, changed to fit the new system!

That's all for now, thanks for reading!

- Jason Munster