I've been meaning to provide updates on the output of our backyard solar system, but have fallen behind due to the press of other activities (relating to wind power and climate change).
In any event, while the winter months were, predictably, very slow, electricity production has picked up in the past six weeks, and our system currently stands at 2.42 MWh (megawatt-hours), or 2,420 kilowatt-hours).
So, let's run the numbers again.
In terms of energy, it's the equivalent of 72 gallons of gasoline, or enough to drive one of our hybrid autos about 3,200 miles.
In terms of generating electricity, the numbers are bigger, because the combustion process for fossil fuels wastes energy. 2,420 kWh is equivalent to burning about 2,400 pounds (more than a ton) of coal, or 142 gallons of diesel oil (New England, where we are located, still burns plenty of diesel oil to generate electricity).
In terms of carbon dioxide (CO2) emissions, the New England utility system gives off about 0.9 pounds of CO2 per kilowatt-hour of electricity, so our 2,420 kWh means about 2,200 pounds of carbon dioxide has been kept out of the atmosphere.
From February 15 to March 15, our system generated 208 kWh, just over two-thirds as much electricity as we used (308 kWh). Looking forward to seeing our utility bills dip below zero this month.
Showing posts with label climate change. Show all posts
Showing posts with label climate change. Show all posts
Saturday, April 6, 2013
Monday, September 3, 2012
Indispensable Arctic sea ice graph
A lot of ingenuity has gone into graphics displaying various ways of measuring the Arctic sea ice death spiral. There are graphs depicting sea ice extent (total area within the outer boundaries of the ice pack), area (extent minus the gaps of water), and volume. One can find web pages that specialize in mapping past and current measurements of one of these parameters against different trend lines, in an attempt to get a feel for when the ice will disappear entirely, or almost entirely, during the summer. There is even one that shows the death spiral as a ... spiral ... using a polar coordinate graphing scheme.
I personally find the most useful graph, though, to be this simple bar chart of sea ice volume. Bar charts are very familiar, so it's easy to understand at a glance, and when it comes to sea ice, volume seems to me like the most important measurement. Sea ice extent and area "recovered" rapidly last year to "near normal levels," but the all-time record low in both of those parameters this year makes it clear that much of the ice growth last winter was a very thin coating--which is where volume comes in.
Thanks to Lawrence Hamilton of the University of New Hampshire for permission to reproduce it.
What does this graph tell us?
Currently, volume stands at 3,600 cubic kilometers (cu-km), about half what it was as recently as 2008 (7,100 cu-km) and just over one-fifth what it was in 1979 (16.9 cu-km). Records begin in 1979 because this set of data is from satellite monitoring, which began in that year.
Also, the trend line is obviously sharply down. If you imagine a line connecting the 1979 number and this years, it looks as though it will reach zero sometime within the next decade, perhaps 2018.
A quick review of some basics concerning Arctic sea ice:
- Its melting will not affect sea level rise, because the ice is floating and displacing the same mass of water as is created when it melts.
- Its melting is, however, likely to continue because of the positive feedback loop created when ice, which reflects sunlight, melts to expose open water (less reflective), leading to warmer temperatures.
- Its melting may also be leading to changes in the jet stream and in the weather the jet stream affects further south.
You can learn much, much more on the topic from the Arctic Sea Ice blog, which I cannot recommend too highly as a resource.
I personally find the most useful graph, though, to be this simple bar chart of sea ice volume. Bar charts are very familiar, so it's easy to understand at a glance, and when it comes to sea ice, volume seems to me like the most important measurement. Sea ice extent and area "recovered" rapidly last year to "near normal levels," but the all-time record low in both of those parameters this year makes it clear that much of the ice growth last winter was a very thin coating--which is where volume comes in.
Thanks to Lawrence Hamilton of the University of New Hampshire for permission to reproduce it.
What does this graph tell us?
Currently, volume stands at 3,600 cubic kilometers (cu-km), about half what it was as recently as 2008 (7,100 cu-km) and just over one-fifth what it was in 1979 (16.9 cu-km). Records begin in 1979 because this set of data is from satellite monitoring, which began in that year.
Also, the trend line is obviously sharply down. If you imagine a line connecting the 1979 number and this years, it looks as though it will reach zero sometime within the next decade, perhaps 2018.
A quick review of some basics concerning Arctic sea ice:
- Its melting will not affect sea level rise, because the ice is floating and displacing the same mass of water as is created when it melts.
- Its melting is, however, likely to continue because of the positive feedback loop created when ice, which reflects sunlight, melts to expose open water (less reflective), leading to warmer temperatures.
- Its melting may also be leading to changes in the jet stream and in the weather the jet stream affects further south.
You can learn much, much more on the topic from the Arctic Sea Ice blog, which I cannot recommend too highly as a resource.
Wednesday, August 29, 2012
As the solar odometer turns
We have a new residential solar electric (PV, photovoltaic) system installed about a month ago, and its "odometer" will soon turn over the 5 in 500 kilowatt-hours (kWh) of electricity generated.
It's pretty impressive, just in a mechanical (or rather, non-mechanical) sense. It just sits there. Nothing seems to happen, but the kWh generated daily continues to rise. No muss, no fuss. Pretty neat.
But I digress. The reason for this post was to say something about what 500 kWh will represent, when we get there later today or tomorrow.
In terms of energy, it's the equivalent of 15 gallons of gasoline, or enough to drive one of our hybrid autos about 675 miles.
In terms of generating electricity, the numbers are bigger, because the combustion process for fossil fuels wastes energy. 500 kWh is equivalent to burning about 500 pounds of coal, or 35 gallons of diesel oil (New England, where we are located, still burns plenty of diesel oil to generate electricity).
In terms of carbon dioxide (CO2) emissions, the New England utility system gives off about one pound of CO2 per kilowatt-hour of electricity, so our 500 kWh means about 500 pounds of carbon dioxide has been kept out of the atmosphere.
So what? Well, that's where the numbers get truly impressive, because of the very long life and heat-trapping effect of carbon dioxide. In a post on his blog, Quark Soup, science journalist David Appell quotes David Archer's book, The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate, as follows:
"If we add up the total amount of energy trapped by CO2 from the gallon of gas over its atmospheric lifetime, we find that our gallon of gasoline ultimately traps one hundred billion (100,000,000,000) kilocalories of useless and unwanted greenhouse heat."
Burning one gallon of gasoline results in the emission of 19.6 pounds of CO2. That means that one pound of CO2, over its lifetime, traps 100 billion kilocalories divided by 19.6, or 5 billion kilocalories.
Now, I don't know about you, but I don't use kilocalories much on a day-to-day basis, so, how much energy is that? Using the handy Google converter for units of measure, I find that it is 2 x 10 to the 13th (10e13) joules--still not a very meaningful quantity. However, one Hiroshima-size atomic bomb releases 63 x 10e12 joules, and one pound of CO2 traps 2 x 10e13 (20 x 10e12) joules. In other words, just three pounds of CO2 added to the atmosphere, over its lifetime, traps as much heat as released by the Hiroshima bomb (a unit of measure Mr. Appell calls the "hiro").
This in turn means that, in a little over a month, our residential solar system has kept enough CO2 out of the atmosphere to trap the equivalent, over time, of the heat that would be released by 167 Hiroshima bombs.
(It also says a lot about how much heat you're adding, over time, to the climate system with every gallon of gas--about 7 Hiroshima bombs' worth--and why it's silly to claim that the billions of tons of carbon dioxide we're adding to the atmosphere each year have no impact on the climate. But that's another blog post.)
I expect to use these numbers more in the future, in other posts and in comments on the Internet, so if you find any errors, please let me know (Mr. Appell has made the same offer, and nothing has turned up yet).
UPDATE (Sept. 8, 2012): The odometer now stands at 626 kWh, which means we have passed another minor milestone--the first barrel of oil equivalent (BOE). Burning a barrel of oil generates about 600 kWh--and produces 940 pounds (almost half a ton) of carbon dioxide.
It's pretty impressive, just in a mechanical (or rather, non-mechanical) sense. It just sits there. Nothing seems to happen, but the kWh generated daily continues to rise. No muss, no fuss. Pretty neat.
But I digress. The reason for this post was to say something about what 500 kWh will represent, when we get there later today or tomorrow.
In terms of energy, it's the equivalent of 15 gallons of gasoline, or enough to drive one of our hybrid autos about 675 miles.
In terms of generating electricity, the numbers are bigger, because the combustion process for fossil fuels wastes energy. 500 kWh is equivalent to burning about 500 pounds of coal, or 35 gallons of diesel oil (New England, where we are located, still burns plenty of diesel oil to generate electricity).
In terms of carbon dioxide (CO2) emissions, the New England utility system gives off about one pound of CO2 per kilowatt-hour of electricity, so our 500 kWh means about 500 pounds of carbon dioxide has been kept out of the atmosphere.
So what? Well, that's where the numbers get truly impressive, because of the very long life and heat-trapping effect of carbon dioxide. In a post on his blog, Quark Soup, science journalist David Appell quotes David Archer's book, The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate, as follows:
"If we add up the total amount of energy trapped by CO2 from the gallon of gas over its atmospheric lifetime, we find that our gallon of gasoline ultimately traps one hundred billion (100,000,000,000) kilocalories of useless and unwanted greenhouse heat."
Burning one gallon of gasoline results in the emission of 19.6 pounds of CO2. That means that one pound of CO2, over its lifetime, traps 100 billion kilocalories divided by 19.6, or 5 billion kilocalories.
Now, I don't know about you, but I don't use kilocalories much on a day-to-day basis, so, how much energy is that? Using the handy Google converter for units of measure, I find that it is 2 x 10 to the 13th (10e13) joules--still not a very meaningful quantity. However, one Hiroshima-size atomic bomb releases 63 x 10e12 joules, and one pound of CO2 traps 2 x 10e13 (20 x 10e12) joules. In other words, just three pounds of CO2 added to the atmosphere, over its lifetime, traps as much heat as released by the Hiroshima bomb (a unit of measure Mr. Appell calls the "hiro").
This in turn means that, in a little over a month, our residential solar system has kept enough CO2 out of the atmosphere to trap the equivalent, over time, of the heat that would be released by 167 Hiroshima bombs.
(It also says a lot about how much heat you're adding, over time, to the climate system with every gallon of gas--about 7 Hiroshima bombs' worth--and why it's silly to claim that the billions of tons of carbon dioxide we're adding to the atmosphere each year have no impact on the climate. But that's another blog post.)
I expect to use these numbers more in the future, in other posts and in comments on the Internet, so if you find any errors, please let me know (Mr. Appell has made the same offer, and nothing has turned up yet).
UPDATE (Sept. 8, 2012): The odometer now stands at 626 kWh, which means we have passed another minor milestone--the first barrel of oil equivalent (BOE). Burning a barrel of oil generates about 600 kWh--and produces 940 pounds (almost half a ton) of carbon dioxide.
Sunday, August 26, 2012
Mything in action: Deniers and 'Antarctic warming'
I saw it on Twitter today, so it must be true: several posts in succession, all from self-avowed defenders of the Constitution, liberty, blah blah, etc., to the effect that the "Antarctic has been warming for 600 years."
Hmm, I thought as I added these individuals to my "disappear" list on TweetDeck (a time- and annoyance-saving strategy that makes their future tweets invisible to me), I wonder what that is all about?
As I continued to comb the Web for global warming items to tweet, I came across an article in an Australian publication, Crikey, titled "Antarctic melt alarm as scientists find 'very unusual' warming." Mystery solved.
The article's lead paragraph: "Scientists have drilled 364 metres into ice to complete the first ever comprehensive temperature record of the Antarctic Peninsula — and they’ve found evidence of 'very unusual' and dramatic warming over the last century." [emphasis added]
The article goes on to say, indeed, that the peninsula has been warming slowly for 600 years, but takes some pains to explain the reason for concern:
"The research showed that the Peninsula has seen a rapid warming over the past 100 years, but that this has also come on top 600 years of more gradual, natural warming in the region ...
"The leader of the research expedition, Dr Robert Mulvaney from the British Antarctic Survey, said: 'The exceptionally fast warming over the last 100 years came on top of a slower natural climate warming that began around 600 years ago — well before the industrial revolution — so it is possible that we are now seeing the combination of natural and man-made warming in this area.'
Hmm, I thought as I added these individuals to my "disappear" list on TweetDeck (a time- and annoyance-saving strategy that makes their future tweets invisible to me), I wonder what that is all about?
As I continued to comb the Web for global warming items to tweet, I came across an article in an Australian publication, Crikey, titled "Antarctic melt alarm as scientists find 'very unusual' warming." Mystery solved.
The article's lead paragraph: "Scientists have drilled 364 metres into ice to complete the first ever comprehensive temperature record of the Antarctic Peninsula — and they’ve found evidence of 'very unusual' and dramatic warming over the last century." [emphasis added]
The article goes on to say, indeed, that the peninsula has been warming slowly for 600 years, but takes some pains to explain the reason for concern:
"The research showed that the Peninsula has seen a rapid warming over the past 100 years, but that this has also come on top 600 years of more gradual, natural warming in the region ...
"The leader of the research expedition, Dr Robert Mulvaney from the British Antarctic Survey, said: 'The exceptionally fast warming over the last 100 years came on top of a slower natural climate warming that began around 600 years ago — well before the industrial revolution — so it is possible that we are now seeing the combination of natural and man-made warming in this area.'
"What this means is that climate change is adding significant extra pressure to the Antarctic Peninsula ice sheets that were already seeing some strain from the natural warming in the region." [emphasis added]
Just remove that context and presto, you have a tweet that implies global warming is nothing to worry about, when exactly the opposite is true.
Why now? Presumably in a transparent and rather desperate attempt to spread a counter to the news that Arctic sea ice melt has hit a new record.
(Disclaimer: I have nothing against the Constitution and liberty--they're great! But I do wonder sometimes why people act as though they are part of a valiant few who think so.)
Sunday, July 8, 2012
By the numbers: U.S. warming
OK, I admit it--I'm a numbers geek, er, guy.
Graphics are good, but numbers are better. It's fun to poke around them and try to understand the story they are telling.
A while ago, inspired by the Great March 2012 Heat Wave, I expressed concern about the ratio of new high daily temperatures across the U.S. to new low daily temperatures. I reposted a graphic from the blog Capital Climate that seemed to me to suggest that the high ratios of months like March 2012 (35:1, here after just "35") and January 2012 (22) indicated that wild swings in temperature are growing greater--that the weather system was looking more and more unstable due to global warming.
The Capital Climate graphic, however, didn't show everything I needed to confirm that hypothesis. In this particular iteration (the blog has published others previously, covering different time periods), only ratios from 2011 and 2012 were shown--not enough to get a feel for just how unusual the March and January ratios were. So I decided to go digging.
A week later (this is tedious and time-consuming work), I've created an Excel spreadsheet that shows new daily highs, new daily lows, and their ratio for months in the years 1993-2012. I also flipped ahead and took a peek at 1988 and 1936, two previous years with remarkable heat waves. All data is from the National Climate Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA), which maintains an online database of temperature extremes at http://www.ncdc.noaa.gov/extremes/records/.
There's still quite a bit of work to do (the database covers years back to 1850!), but even with the limited portion I've completed, there are some interesting results:
First, ratios of new highs to lows in recent years are not toooo extreme. While March 2012 (35) and January 2012 (22) are definitely unusual, there are other wilder outliers in the historical record. January 2006 (58:1) is the biggest I've found so far, and November 1999 (53) and February 2000 (50) also achieved ratios of 50 or better.
Second, there is a clear warming trend. That trend is, I think, best illustrated by looking at some yearly records:
Most recent year in which new daily lows exceeded new daily highs: 1997, with 16,469 new lows versus 15,964 new highs. That's a stopper right there, since if the climate were stable, it would be unusual for there to be 14 straight years (1998 through 2011) in which new highs exceeded new lows.
Most recent year with 20,000 or more new daily lows: 1996 (23,160).
Most recent year with 20,000 or more new daily highs: 2007 (26,067).
One might speculate that the number of new records is decreasing over time as the temperature data set gets longer/larger, but there's no reason for highs to exceed lows unless the average temperature is increasing.
Most recent year with 15,000 or more new daily lows: 2002 (18,166).
Most recent year with 15,000 or more new daily highs: 2012 (18,164 and counting, through July 7).
Pretty hard to refute this very impressive data. 2003, 2005, 2006, 2007, and 2011 also had more than 15,000 new daily highs.
Most recent year with 10,000 or more new daily lows: 2007 (10,355).
2010, 2011, 2012 all surpassed 10,000 new daily highs.
Number of months since January 1, 1993, with a ratio of new lows to new highs exceeding 10:1: 1 (March 1997, with a ratio of 12.7:1).
The following months since that date have had ratios of new highs to new lows exceeding 10:1: January 1995 (17), February 1997 (16), January 1998 (12), July 1998 (16), September 1998 (17), November 1998 (21), December 1998 (14), November 1999 (53), January 2000 (12), February 2000 (53), March 2000 (40), November 2001 (14), December 2001 (12), January 2002 (15), August 2003 (12), October 2003 (11), March 2004 (21), February 2005 (18), January 2006 (58), August 2007 (13), June 2011 (10), August 2011 (22), January 2012 (22) and March 2012 (35)--a total of 24 months in all.
Highest ratio of new highs to new lows for a year: 1998 (4.04).
At the moment, 2012 is on track to easily surpass 1998 (currently, its ratio is a remarkable 11.7), but the record makes it clear that significant changes can take place in a few months.
More generally, this work is inspired not only by the Great June-July 2012 Heat Wave, which we have just finished, but by a study of the ratio of new highs to new lows completed in 2009 by authors from the National Center for Atmospheric Research (NCAR), Climate Central, The Weather Channel, and NOAA. That study found the following ratios by decade:
1950s: 1.09 (to 1)
1960s: 0.77
1970s: 0.78
1980s: 1.14
1990s: 1.36
2000s: 2.04
The decadal record has the effect of smoothing variations and making it clear that since the 1990s, the ratio has taken a jump, with a larger increase from the 1990s to 2000s than any previous change. (I hope to extend this back to at least the 1930s and 1940s, since the Dust Bowl era of the 1930s had multiple very hot summers.)
I'll be continuing to build out my spreadsheet in the coming weeks, and will keep you posted on what I find.
Graphics are good, but numbers are better. It's fun to poke around them and try to understand the story they are telling.
A while ago, inspired by the Great March 2012 Heat Wave, I expressed concern about the ratio of new high daily temperatures across the U.S. to new low daily temperatures. I reposted a graphic from the blog Capital Climate that seemed to me to suggest that the high ratios of months like March 2012 (35:1, here after just "35") and January 2012 (22) indicated that wild swings in temperature are growing greater--that the weather system was looking more and more unstable due to global warming.
The Capital Climate graphic, however, didn't show everything I needed to confirm that hypothesis. In this particular iteration (the blog has published others previously, covering different time periods), only ratios from 2011 and 2012 were shown--not enough to get a feel for just how unusual the March and January ratios were. So I decided to go digging.
A week later (this is tedious and time-consuming work), I've created an Excel spreadsheet that shows new daily highs, new daily lows, and their ratio for months in the years 1993-2012. I also flipped ahead and took a peek at 1988 and 1936, two previous years with remarkable heat waves. All data is from the National Climate Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA), which maintains an online database of temperature extremes at http://www.ncdc.noaa.gov/extremes/records/.
There's still quite a bit of work to do (the database covers years back to 1850!), but even with the limited portion I've completed, there are some interesting results:
First, ratios of new highs to lows in recent years are not toooo extreme. While March 2012 (35) and January 2012 (22) are definitely unusual, there are other wilder outliers in the historical record. January 2006 (58:1) is the biggest I've found so far, and November 1999 (53) and February 2000 (50) also achieved ratios of 50 or better.
Second, there is a clear warming trend. That trend is, I think, best illustrated by looking at some yearly records:
Most recent year in which new daily lows exceeded new daily highs: 1997, with 16,469 new lows versus 15,964 new highs. That's a stopper right there, since if the climate were stable, it would be unusual for there to be 14 straight years (1998 through 2011) in which new highs exceeded new lows.
Most recent year with 20,000 or more new daily lows: 1996 (23,160).
Most recent year with 20,000 or more new daily highs: 2007 (26,067).
One might speculate that the number of new records is decreasing over time as the temperature data set gets longer/larger, but there's no reason for highs to exceed lows unless the average temperature is increasing.
Most recent year with 15,000 or more new daily lows: 2002 (18,166).
Most recent year with 15,000 or more new daily highs: 2012 (18,164 and counting, through July 7).
Pretty hard to refute this very impressive data. 2003, 2005, 2006, 2007, and 2011 also had more than 15,000 new daily highs.
Most recent year with 10,000 or more new daily lows: 2007 (10,355).
2010, 2011, 2012 all surpassed 10,000 new daily highs.
Number of months since January 1, 1993, with a ratio of new lows to new highs exceeding 10:1: 1 (March 1997, with a ratio of 12.7:1).
The following months since that date have had ratios of new highs to new lows exceeding 10:1: January 1995 (17), February 1997 (16), January 1998 (12), July 1998 (16), September 1998 (17), November 1998 (21), December 1998 (14), November 1999 (53), January 2000 (12), February 2000 (53), March 2000 (40), November 2001 (14), December 2001 (12), January 2002 (15), August 2003 (12), October 2003 (11), March 2004 (21), February 2005 (18), January 2006 (58), August 2007 (13), June 2011 (10), August 2011 (22), January 2012 (22) and March 2012 (35)--a total of 24 months in all.
Highest ratio of new highs to new lows for a year: 1998 (4.04).
At the moment, 2012 is on track to easily surpass 1998 (currently, its ratio is a remarkable 11.7), but the record makes it clear that significant changes can take place in a few months.
More generally, this work is inspired not only by the Great June-July 2012 Heat Wave, which we have just finished, but by a study of the ratio of new highs to new lows completed in 2009 by authors from the National Center for Atmospheric Research (NCAR), Climate Central, The Weather Channel, and NOAA. That study found the following ratios by decade:
1950s: 1.09 (to 1)
1960s: 0.77
1970s: 0.78
1980s: 1.14
1990s: 1.36
2000s: 2.04
The decadal record has the effect of smoothing variations and making it clear that since the 1990s, the ratio has taken a jump, with a larger increase from the 1990s to 2000s than any previous change. (I hope to extend this back to at least the 1930s and 1940s, since the Dust Bowl era of the 1930s had multiple very hot summers.)
I'll be continuing to build out my spreadsheet in the coming weeks, and will keep you posted on what I find.
Subscribe to:
Posts (Atom)