Category: Non-disposable

Posts that may have some sort of permanent value, or that I consider to be the best of what I have posted here.

Post #1775: Gas versus electric mowing, Part 5: Finally, a sensible estimate

To cut to the chase:  I use a 21″ push mower with a modern Honda overhead-valve engine.  Starting from EPA data on emissions for engines of that type, I calculated two simple rules of thumb, for the pollution generated by my lawn mowing.

If the standard of comparison is the typical car on the road — call it a mid-2010s full-sized sedan — then gas lawn mowers are 100 times dirtier than gas cars, per horsepower.  And an hour of mowing generates about as much pollution as an hour of driving.

That’s just the mower.  That doesn’t include emissions from your gas can, as outlined in the just-prior post. Continue reading Post #1775: Gas versus electric mowing, Part 5: Finally, a sensible estimate

Post #1774: Gas vs. electric mowing, part 4: A correction on vapor recovery, and why you’re not supposed to top off your car’s gas tank.

 

In my just-prior post, I was about a decade out-of-date in my understanding of the gas vapor recovery systems installed on U.S. gas pumps.  I’m going to correct that here.

  1. Gasoline vapors are a major contributor to photochemical smog, and, in particular, to the creation of ground-level ozone.
  2. Once upon a time, the U.S. EPA required that gas pumps in some urban areas have vapor-recovery nozzles.  These were designed to collect the gasoline vapors that would otherwise just pour out of your car’s gas tank as you refilled it.
  3. By and large, these were only mandated in areas that could not meet federal air pollution standards for ground-level ozone.
  4. But by 2006, virtually all new cars and trucks were equipped with on-board vapor recovery systems.  They collected their own gasoline vapors during refueling, stored them, and burned them
  5. In 2012, the EPA dropped its requirement for vapor-recovery nozzles (reference).  At that point, so many cars had the new on-board systems that the vapor-recovery nozzles no longer offered sufficient benefit to justify their cost.
  6. Whether or not gas stations were required to keep up those vapor recovery systems was left up to the states.  For example, Virginia chose to decommission all those vapor recovery systems in 2017 (reference).

The upshot is that gas pumps in my area haven’t had those vapor-recovery nozzles for more than half a decade.  They still have some sort of rubber cup on the fuel nozzle, but I guess that’s just to prevent splashback or possibly to aid the car’s own on-board recovery system.

Some implications

With this, a lot of things now click into place.

Vehicle fuel tank filler necks now have an elastic seal in them.  I’m sure that older cars did not have those.  That seal is required on a modern car because the on-board vapor recovery system needs a tight seal against the gas nozzle.  That’s the only way to make sure that the gas vapors in the tank end up in the on-board charcoal canister.

The standard advice of “Don’t top off your tank” now has a new rationale.  In the ancient past, that was the advice because gas expands as it warms, and if you topped off your tank in summer, you’d end up spilling gas out the fuel filler as you drove down the road.  Now, that advice is there to protect your on-board vapor recovery system.  If you top off you tank, you can end up shoving liquid gasoline into your vapor recovery system, something it was not designed for.

My old two-gallon gas can produced four gallons of gasoline vapors before I even considered spills, venting, and the gasoline-permeability of the plastic.  Every time I filled that at the gas pump (since 2017), that displaced the two gallons of vapors, in the gas can, into the atmosphere.  And then, as I repeatedly filled the tank on the mower, that sums up to another two gallons of gasoline vapor displaced into the atmosphere.

How does that compare to gasoline vapor emissions from cars?

The EPA estimates that these on-board vapor recovery systems capture about 98% of gasoline vapors, at least according to this presentation.  The same source shows that the EPA estimates an average of 0.32 grams of gasoline spilled per gallon dispensed at a typical gas station.

The U.S. averages about 650 gallons of gasoline consumed per licensed driver.  Based on that, a year’s worth of fill-ups, for the typical licensed driver in the U.S., would generate:

  • 13 gallons of gas vapor spilled directly into the atmosphere (2% of that 650 gallons).
  • Another 12 gallons of gas vapor due to the average 208 grams of fuel spilled (0.32 g/ gallon).

In other words, the average driver with properly-functioning vapor recovery equipment and average diligence about spilling gasoline will generate about 25 gallons of gasoline vapors annually.

In that context, the 4+ gallons of gas vapor directly emitted by my old gas can seems quite material.  Particularly because my wife and I now exclusively drive her Prius Prime.  We seem to use on-order-of 40 gallons of gas a year, with the rest of our travel being electric.  From that 40 gallons, based on those EPA averages, we’d only be emitting about 1.5 gallons of gasoline vapor per year.  So that, in our household, the lawn mower and old gas can were responsible for far more gas vapor emissions than our car was.

That said, it’s worth noting that the lawn mower — even with the old gas can — is nowhere as bad as the average American passenger vehicle, in terms of venting gas vapor to the atmosphere as a result of refueling.  That’s not because the lawn equipment is clean — it’s not.  That because the average driver uses such a vast quantity of gasoline.  Even those small fractional losses during refueling add up to far more gasoline vapor than the lawn mower / old gas can emit in a season.

But that’s only for refueling-related gasoline vapor losses.  That does not include any gasoline vapor losses by the mower during operation.  For example, losses through the charcoal-filled gas cap, losses from the vented carb bowl after engine shutoff, and so on.  I still need to track those down.

The new gas can ought to eliminate half of those “displacement” gas vapor emissions.  The new can vents through the end of the pouring spout, so it’s “inhaling” the gas fumes out of the tank as it puts new gas into the tank.

The only gas vapor that will be directly emitted as a result of displacing vapor during refueling will be from refilling the gas can, at the local gas pump.  That, because our gas pumps no longer have vapor-recovery nozzles.  And apparently haven’t had them since 2017.

Post #1773: Gas vs. electric mowing, part 3: Why do all gas cans suck?

Source:  ACE Hardware.

I’m not the sort of person to buy something new, when the old one still works.  But my deep dive into lawn mowers and air pollution has convinced me to buy a new gas can, shown above.

There was nothing wrong with my current gas can.  In the sense that it worked exactly as it did when I bought it about three decades ago.

But technology that was fine three decades ago doesn’t really cut it in the modern world.

In this post, I’m going to explain why I took this momentous step. Continue reading Post #1773: Gas vs. electric mowing, part 3: Why do all gas cans suck?

G23-012: Luke 13:6-9, and the chainsaw of time.

Then he told this parable: “A man had a fig tree planted in his vineyard; and he came looking for fruit on it and found none. So he said to the gardener, ‘See here! For three years I have come looking for fruit on this fig tree, and still I find none. Cut it down! Why should it be wasting the soil?’ He replied, ‘Sir, let it alone for one more year, until I dig around it and put manure on it. If it bears fruit next year, well and good; but if not, you can cut it down.’ ”

— Luke 13:6–9, New Revised Standard Version, via Wikipedia.

Dödsträdgårdsskötsel

I’m not normally one for literal interpretation of the Bible.  But in this case, I’m going for it.

I have a fig tree that will not bear fruit.  I have now made up my mind to give it the final New Testament treatment, as above. After which, I shall cast it into the fire.  Once the wood has seasoned enough to burn well.

I’m not quite sure what prompted me to take action.  I’ve been putting in new raised beds.  After my Nth shovelful of dirt, I kind of woke up and realized that I had been looking at the same big, ugly fig bush for going on 15 years now.  Patiently waiting that one more year, for fruit that never appeared.  Year after year after year.

But once my eyes were opened, I could not help but notice the fig was just one of many lingering gardening failures that fill my yard.   The in-ground deer-feeding stations that were mistakenly labeled “blueberry bushes” when we bought them.  The 30′ tall fruit trees bought as dwarf varieties.  The landscaping that has to be hacked back twice a year so that the mail carrier can get to the front door.  The azaleas that overtop the windows.  And so on.

Nothing that, by itself, jumped out at me.  Nothing that couldn’t be ignored for yet another year.  Just the result of slow accretion over time.  A bush here, a tree there.  And as long as I could still walk around in the back yard, I let them be.

It finally dawned on me that the outside of my house was just like the inside.  It was full of stuff that I had accumulated over the years.  Stuff that no reasonable person would want, de novo.  Stuff that I kept only because, at some point, I bought it.

The fig tree that would not bear fruit made me see that it was time for some dödsträdgårdsskötsel.  A bit of Swedish death landscaping, to match the döstädning (Swedish death cleaning) I’ve been doing inside (Post #1667).

 

Never a dull moment

That’s when I decided to pull out my chain saw.  Because, hey, what could possibly go wrong when an old, out-of-shape Joe Homeowner with mobility issues decides to chain-saw down a bunch of trees.  In close proximity to buildings and fences.  Trailing a great big power cord.

In all seriousness, my wife forbade me to use my chain saw when she’s not around.  And rightly so.  She’s the designated dialer.  This, under the theory that it might be a challenge to type 9-1-1 with the stump of an arm, before I bleed out.

 

Much like the trees I’m going to cut down, this chainsaw is a leftover from an earlier time.  I bought it when I was much younger.  It’s not clear at this point that I should have kept it.  Arguably, it may now be an age-inappropriate power tool.   But unlike a geezer in a sports car, there’s no equivalent of the DMV to make me prove periodically that I’m still capable of using it.  Thus, the decision to put down that chain saw, once and for all, is supported by the slenderest of reeds, the common sense of the aging user.

But, my life is pretty dull.  My health insurance is paid up.  So what the heck.

To be clear, this is about as wimpy as chain saws got, back in the day.  It’s a Sears Craftsman 18″ plug-in electric chain saw.  That size being about as big as electric chainsaws can get, and still operate on a standard 120V household circuit.

That said, a wimpy chain saw is a like a low-powered shotgun shell.  Use it wrong, and there’s no question it’s going to hurt.  It’s only a question of how badly.

I recalled that the last time I used it, the blade seemed a bit dull. 

Which, by itself, sent me down a little philosophical trail, trying to recall how often I had used that chainsaw.  I definitely recalled cutting up some firewood at my current house.  Which led me to my wife’s grandmother, because I distinctly recall cutting up a bunch of firewood for her, a few years back.  And I was pretty sure I hadn’t sharpened or changed that chain in the intervening years.

Seemed like that might have been a few years ago, that I did that little favor for my wife’s grandmother.  So I checked with my wife. Her grandmother passed away 25 years ago, in 1997.

The upshot is that the chain is the original.  It was on the saw when I bought it about 30 years ago.  It was on it when I cut up that firewood for my wife’s grandmother.  When I cleared trees and brush from my last house.  When I cut up my own firewood.  And it just got duller and duller, so gradually that each time I used it, well, it worked about as well as the last time I used it.  And as long as it still worked, I wasn’t going to mess with it.

Anyway, I splurged for a new chain.  They still make them to fit, and a new one is about $12.

The upshot is that my 30-year-old electric chain saw cuts like it’s brand-new.  Took maybe two minutes to cut down that non-productive fig bush.

I retain all of my appendages.  So far. And I’m looking forward to taking down the rest of my landscaping mistakes when the rain lets up.

So, happy ending all around.

Any larger lesson?

I was going to try for some sort of larger life lesson here, but it’s not worth the effort.  The larger lessons are pretty obvious.  Age creeps up on you.  Getting rid of stuff is just part of life.

I guess the only one that surprised me is that a chainsaw with a new blade is a joy to use.  I spent years struggling with a dull blade on that saw.  And so I missed out on a lot of joy.  All for my unwillingness to spend $12 for a new blade. I now wonder how much of the rest of my life has been like that.  And whether its too late to change those long-ingrained habits of cheapness.

 

Post G23-010: No-dig potatoes, using leaf mulch

Today is St. Patrick’s day.

That’s the traditional day for planting potatoes, in this climate.

But my new raised beds aren’t ready yet.  And the old ones are a weedy mess.  Which I didn’t much feel like hoeing out of the way, this rainy St. Patrick’s day morning.

So I planted this year’s potatoes as no-dig (no-till) potatoes.  I placed them on top of an existing weedy garden bed, and buried them under half-a-foot of free leaf mulch.

Edit 7/23/2023:  Near-total failure.  See Post G23-041. Continue reading Post G23-010: No-dig potatoes, using leaf mulch

Post G23-009: New garden beds. Working harder, not smarter.

 

At the start of the pandemic, I recycled some political yard signs and bamboo into a set of raised garden beds (Post G05).   After three years of intensive use, a) those are now in disrepair, and b) I know a whole lot more about gardening.

My plan is to replace those beds with something better.  With St. Patrick’s day just one week away — the traditional day for planting potatoes — I can’t procrastinate much longer.   Time to finish pondering and start shoveling.

This post documents the final design.  The next post will show the construction.

Continue reading Post G23-009: New garden beds. Working harder, not smarter.

Post G23-008: Simple geometry of sun and shade, or, keep your gnomon pointing north.

 

This post is about making sure my new garden beds don’t end up in the shadow of my back porch, during the summer.  Based on the length of the shadows today, in late winter.  And, ultimately, based simply on the height of the porch roof.

To cut to the chase:  If you use Excel, and the NOAA sun-angle calculator, you can accurately predict the length of a shadow, for any date and time, anywhere on earth, via this formula:

Shadow length = obstruction height * cotangent (solar elevation angle in degrees * π / 180)

The π / 180 is there because Excel wants to see angles expressed in radians.  If you’re using a calculator that accepts angles in degrees, omit that.

 

Continue reading Post G23-008: Simple geometry of sun and shade, or, keep your gnomon pointing north.

Post #1716: COP out. Does it ever get cold enough, in Virginia, to make gas heat cheaper to run than a modern heat pump?

In Post #1706, I determined that, for heating my home here in Virginia, it was far cheaper to run my heat pumps than to run my natural gas furnace.  That’s based on costs of $1.70 per therm of natural gas, and $0.12 per kilowatt-hour (KWH) of electricity.  Like so: Continue reading Post #1716: COP out. Does it ever get cold enough, in Virginia, to make gas heat cheaper to run than a modern heat pump?

G23-006: The sunniest spot in a shady yard? Part 1, geometry.

 

This is the first of two posts on finding the sunniest spot in a yard that has shade trees on either side.  This one uses geometry.  The next one will use time-lapse photography on a sunny day.

With any luck, both approaches will tell me the same thing.

If your yard is bordered by shade trees, locate the beds so that due south (180 degrees) splits the compass bearing from your bed to each line of trees.  This gives a surprising-looking result for my back yard.  It’s not at all what you’d naively think, just looking at the trees and the yard.

Garden bed location 1:  Wrong.

I started gardening seriously during the pandemic.  Temporary raised beds were made from recycled campaign yard signs and bamboo.  I placed those in seemingly-reasonable locations in my back yard. In part, they were filling in low spots on the lawn.  But it seemed like they were located so as to get the best sun.

I’m now getting around to putting in something more permanent.  This time, I’m not going to wing it, but instead want to know what spot in my back yard gets the most sunlight.

It’s not obvious.  I have tall trees on either edge of my yard.  And, interestingly enough, what appears to be the obvious solution — locate the garden beds in the middle of the yard, away from both tree lines — isn’t even close to being right.

So, eyeball a couple of birds’-eye views of my back yard, and see if you think I put the beds in roughly the right place:

Looks pretty good, doesn’t it?  You might even say that the location doesn’t much matter, because you’re going to get the same number of hours of sunlight almost anywhere in that back yard, regardless.  What’s shaded in the morning will be sunny in the afternoon, and vice-versa.

Problem is, an hour of sun is not an hour of sun.  Sunlight is much stronger around solar noon, and is weaker the farther you are from noon.  And, because the sun is due south at noon (in the Northern hemisphere), you have to know which direction is south, in order to judge what part of the yard gets the most solar energy.

Source:  Curtonics.com

You need to figure out the locations in your yard that place due south directly between those lines of trees.  Those locations get the greatest amount of high-intensity, near-noon sunlight.

To cut to the chase, you need to calculate where your potential garden site is, relative to the obstructing trees, and to due south.  The sunniest locations in the yard will have these two properties.

  • Due south (180 degrees) bisects the angle from your location to each side of obstructing trees.  E.g., find a spot where the bearing to one set of trees is 150 degrees (180 – 30), and the bearing to the other set of trees is 210 degrees (180 + 30).  That is, you get equal hours of morning and afternoon sun.
  • The angle from your location, to the obstructing trees, is as wide as possible.  For example, the location with a 60 degree spread above will get more total sunlight than a location with a 40 degree spread.   That is, you get as many total hours of sun as possible.

So now, take a look at my back yard, oriented so that south is directly down.  Do you want to change your prior answer?  By the look of the shadows, this is about 11 AM solar time.  Note that the left edge of the yard is already in sunlight.

 

Skirting a couple of pitfalls.

Let me take a brief break to mention a couple of pitfalls that can mess up your attempts to locate your garden in the sunniest spot on the yard.

Daylight savings time.  Man I hate having to get up at 2 AM to turn all the clocks forward, as required by law.  But the upshot is that solar noon occurs around 1 PM during daylight savings time.  For example, on the hourly insolation graph above, peak insolation occurs around 13:00, or 1 PM.  That’s not a mistake, that’s just daylight savings time.  So if it’s summer, and you look to see where the shadows fall at noon, you’re screwing up.  Because noon, daylight savings time, is actually 11 AM solar time.

Above:  Compass set up for 10 degrees west magnetic declination

Magnetic declination.  Declination is the extent to which magnetic north — where the compass needle points — deviates from true north.  Because of magnetic declination, you can’t simply use the raw readings from a standard magnetic compass in order to locate your garden in the right spot.

If you have a compass made for use on land, and it’s anything but the most basic compass, chances are you can adjust the compass to account for declination.

You can find the magnetic declination for your locality at the US Geological Survey, among other places. Currently, magnetic declination at Vienna VA is about 10 degrees west.  That means that the compass needle actually points to a heading of about 350 degrees, not 360 degrees (true north).  That’s about 2.5 degrees further west than when I was a kid in the 1970s.

Magnetic declination is one of those incredibly simple topics that always manages to get an incredibly opaque explanation.  But as long as you have a compass that can be set to account for your local declination, it’s really simple.  The picture above shows a compass set up for 10 degrees west declination.  Despite the fuzziness of the photo, I think it’s obvious that the compass body has been offset 10 degrees relative to the degree ring.  When the needle points to 350 degrees (10 degrees west of true north), 360 or 0 on the degree ring shows you true north.

The sunniest spots in my back yard are directly next to the trees.

I can now take Google Earth, and start drawing in the angles between various backyard locations, and the ends of the lines of shading trees at the sides of the yard.  It’s a little crude, but the conclusion is inescapable.  I put the temporary beds too close to the middle of the yard.  For the most solar energy possible, they ought to be almost under the trees at the side of the yard.  Like so:

Which, to be honest, I would not have guessed, just eyeballing it.

Over the coming weekend, I’ll set up a stop-motion camera to film my back yard for one sunny day.  With that, I should be able to validate that the area that gets the most solar energy is the one outlined.  And I should be able to determine just how much energy I lose if I move away from that optimum spot.