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Technology Diffusion Curves

Earlier this week, we wrote about embodied energy of buildings, and the concerns it poses when we think about legislating building efficiency measures.  Today we take a broader view, examining economic limitations of any technology replacement effort, from rebuilding houses to replacing lightbulbs.

Suppose that high-efficiency washing machines are a necessary part of a low-carbon economy (as we believe they must be).  Government tax write-offs are an effective way to encourage consumers to spend the extra money on these energy-saving machines.  If the U.S. started an incentive program so effective that every consumer chose a high-efficiency machine over a conventional one, however, it would still take quite some time to replace all the energy-hogging washers in the country.  Because they are such a large purchase, the vast majority of consumers replace their washing machine only when forced to do so by problems with the old machine’s operation.  If you assume the average [...]

Lovely solar mapping project at NREL.


They are seeking more data on PV solar installations for this map.  It’s fascinating to see the progression over time of installations, and I was startled at just how active California is compared to the rest of the nation.

578.5 MW to date !  only another 500GW to do !

Installed Capacity (MW)













Spaghetti diagrams, part 1


This “spaghetti diagram” (aka Sankey diagram, or Energy Flow Chart officially) is the 2008 version. Lawrence Livermore National Lab (LLNL) has been making these things since the 1970s. It’s more detailed than a simpler national energy flow diagram because it includes “rejected energy.” It’s also more complex — it actually includes within itself the electricity flow diagram. It’s a pretty cool visualization.

The main thing I dislike is that it doesn’t split up transportation or electricity generation “rejected energy” by sector. Since these are really the two biggest sources of “rejected energy,” you can’t see which group is the biggest “rejector.”

Below, in an undated but funkier design, they’ve not only split up transportation into light duty vehicles, freight/other, and aircraft, they’ve also added domestic and net imports to petroleum and natural gas. They still haven’t split up “Electricity Generation, Transmission & Distribution Losses,” so we don’t know who “loses” the most [...]

Solar roadways – a good or a bad idea?

Solar Roadway

At first blush, this looks like a fabulous idea:


Turn roadways into an enormous solar cell and get lots of other advantages like better new infrastructure.  A long while ago, I looked at making solar roadways (and parking lots and driveways and footpaths and….) under contract when I was at Squid-Labs : http://www.squid-labs.com/projects/cc.html

The very difficult thing about making a road is making it structurally sound enough to carry vehicles.  That means it has to take very high loads, and be very durable for up to 50 years.

So putting a solar cell there is completely possible, but then you’ll need to put some protective material on top that has some texture (so the roads are not slippery) and enough resilience to last a long time.  The problem is that that protective material uses A LOT of energy to produce.  Perhaps the company pitching this idea has some magic special sauce up their [...]

Land Use and Renewable Energy.


Before embarking on some enormous exercise like converting America’s energy use to 100% renewable energy, you might like to get a 20000 foot view of the impact on other things like land area use.  Here are some charts to put that in perspective:

1. Land Area of the US by state, (does not include water area in those states) – note the country has been reduced to a square where each stripe is the proportional area of that state, starting with the biggest (Alaska) to the smallest.

2. Land area by use category for the US:

3. Land area required for 1000GW (1TW) each of Solar, Wind, Biofuels, and Hydroelectric.  These are “all in” estimates that include capacity factor and the whole hog.  Think of it as a year-round average.

4. And now we overlay them all on each-other to get a sense of just how big this project is, and where the land [...]

Biofuels & perpetual motion.

This awesome little video made me laugh chronically as it reminds me of the numbers of perpetual motion machines people have asked me to do diligence on. Thank the lord there is Canadian public television. There is one thing we can be guaranteed of in time of uncertainty and it will be people selling solutions like this one:


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