SoCal LEAF & EV Gathering, Y7 - Finished - 19 Aug 2017

[tbleakne]

As part of my internet upgrade project, which includes a new pfSense firewall/router and my own DOCSIS 3.0 cable modem, replacing the one rented from TimeWarner/Spectrum, I am replacing and re-arranging my existing ethernet cables in my home with Cat 6.

On the 24th I will be bringing an assortment of my ethernet cables being swapped out that need a new home.

Speeds quoted below are burst speeds for packet transmission port-to-port. Average speeds are quite a bit slower.
Modern 1000BaseT ports will default back to the slower speeds if they sense too much crosstalk on the cables.
Most new computers, routers, access points, etc have 1000BaseT ports.

1. An assortment of Cat 5.
Cat 5 is supposedly rated up to 100BaseT speed, 100Mbits/sec, but I don't trust it, especially for long lengths. Free, if you don't want them, they are going to e-waste.

2. An assortment of Cat 5e.
Cat 5e is supposedly rated up to 1000BaseT speed, 1000Mbits/sec., but it should be fine for 100BaseT systems. Very nominal price.

3. A 250' spool of new Cat 6, solid conductor, Riser-Rated, from Monoprice. I will be using this for long runs in my attic, but I don't need all 250'. I am happy to share some with others at my cost.
I also have Cat 6 plugs and boots for above.

[tbleakne]

Today, Tuesday, Gary and I joined Boomer at "Driving Mobility 4" the 4th annual advanced transportation symposium held at UCI. Biggest disappointment: Almost no questions taken from audience. What I found interesting/important:

Fast Charging: EVgo spokeswoman reported their net cost of electricity for some 400 evGo fast chargers stations has been $2/kWh, due to demand charges and low usage at many of these stations. However, recent inceases in usage (more kWh) has reduced this to $1/kWh. Bills have been introduced in CA state legislature to create special demand-free tariffs for public fast chargers.

There was no acknowledgement of the leadership Tesla has shown in this area. Of course their demand chargers are high, but their utilization is much higher, so the demand charge per kWh is much less. They have the efficiency of sharing 2 hoses per charger, with a slow charging car near full balanced with a fast charging car near empty, and large groups of chargers, now as high as 18 stalls in one location. In rural areas with low utilization, they have installed batteries to smooth out the demand.

RNG: Renewable natural gas, basically bio-gas. By capturing methane from manure, etc, that would otherwise be vented to the atmosphere, and cleaning it up to pipeline standards, this fuel can claim a negative carbon footprint. A company in Hemet, that has large contracts for collecting household garbage is building a big digester facility to produce RNG. A company backed by T Boone Pickens has built many truck fueling stations across the country to facilitate the conversion of the truck fleet from diesel to methane, which can be either natural gas or RNG.

Fuel Cells/Hydrogen: Honda reported on their Clarity, which now has 3 versions: all-electric, natural gas, or hydrogen fuel cells. The electric version, just introduced this Spring, has a range of only 80 miles.
First Element Fuel, a company building hydrogen fueling stations, reported that they are abandoning high pressure gaseous H2 in favor of liquid H2. The development of affordable, light-weight 5000 psi tanks made GH2 practical, but it has problems: the dispensing station must have refrigeration to mitigate the heat buildup as the high-pressure tank in your car fills, and there is lots of residual gas left in the dispensing tank. They didn't mention the safety issue of the very high pressure. The cost is high, $30/kg.

Boomer asked me: doesn't the physics say that more energy is required to liquify H2 than just compress it? Yes, of course, but there are inefficiencies. The boiling point of liquid hydrogen at one atmosphere is -297 C, 24 K. From DOE, sparing lots of interesting details:

DOE Technology Validation Project data for compression from on-site H2 production is 1.7 to 6.4 kWh/kgH2. The minimum theoretical energy to liquefy hydrogen from ambient (300 K, 1.01 bar) conditions is 3.3 kWh/kg LH2 or 3.9 kWh/kg LH2 with conversion to para-LH2 (which is standard practice).
Actual liquefaction energy requirements are substantially higher, typically 10-13 kWh/kg LH2, depending on the size of the liquefaction operation [5,6]. Novel liquefaction methods such as an active magnetic regenerative liquefier may require as little as 7 kWh/kg LH2

LH2 production benefits from the existing large volumes necessary to support the space program, with costs of $3/kg. Similar dramatic improvements in very well insulated LH2 tank technology now make LH2 practical for cars, It is easy to pump the liquid without high pressure. Counter-intuitive, but no refrigeration needed at the dispensary station. One downside they did not mention: eventually the pricey LH2 you filled your tank with is going to boil off if you let it sit in your garage. A refrigerator that operates at these temperatures would be very expensive. Most low-temperature physics labs that work with liquid helium just buy it as it boils off because it is too difficult to refrigerate.

The session on Autonomous Vehicles was disappointing, because the speakers were only doing Connected Vehicles. They talked about smart signals that would talk to cars and buses, and perhaps getting cities to invest in this gradually, a few corridors at a time, but I heard no cost estimates. SPAT is buzzword, transportation's.org, Transformational Mobility System is UCI buzzword. Obviously big infrastructure opportunity here, if anyone in Washington cares, but the speakers were expecting local and state support.

Fianally, two very young looking dudes (UCI students) talked about their entry in the HyperLoop competition. They got points for doing air levitation like Musk proposed, vs others using magnetic levitation which has eddy field losses. UCI is building their own test track so their entry in the competition coming up will have been tested.

[garygid]

Boiling off hydrogen, ... seems like a huge fire and explosion danger, in almost any space.

So, the on-board tank must not be vented, thus its pressure would generally become huge,
making it impossible to refill the tank by simply pumping very cold LH2.

Please, what am I missing?

[GlennD]

At Long Beach we had a venting problem with a bunch of LNG trash trucks. Due to the venting they had to be worked on outdoors. Our installers stored one over night indoors and its alarm on its dash was going off in the morning loudly. We had some vents but not nearly enough. Our parts guy was the first to arrive and I think he thought the building was going to blow!

[GRA]

Did First Element say they were looking at switching to LH2 delivery and storage rather than gaseous, or were they talking about LH2 on the cars as well? Boil off wouldn't be an issue for that, assuming reasonable use rates, and the tanks all have vents direct to atmosphere with nothing above them for emergencies - any boiled off gas is going to rise and quickly dissipate. Presumably the major benefit of LH2 would be in reduced delivery costs, as you can pack a lot more H2 into a single trailer. Less than liquid ammonia, though, which seems to be the coming thing as far as H2 delivery and short-term storage (with on-site extraction of the H2), and it also has energy efficiency benefits.

I recently talked to the Air Products driver delivering H2 to my local station, and he mentioned that his truck had multiple tanks which were essentially cascaded, switching between them as the pressure in each dropped below the on-site storage tank. He had a chart where he recorded each tank's pressure as it started and shut off. Said the max. pressure in his tanks was about 7k PSI, and a booster pump was used to get the on-site service tank up to service pressure (700+ bar/10k+ PSI) - the on site mass storage tank is apparently at more like 350 bar/5k PSI). He also mentioned that this was the second time that day they had to fill this station, making the run from Santa Clara to Hayward, so apparently usage is increasing. Air Products supplies all six of First Element's stations in the Bay Area from Santa Clara. currently with two trucks that alternate dispensing and fueling up.

Note, this is all my understanding of what he was saying while we were standing outdoors in the station with the machinery going and a busy street (and freeway) nearby, and my lousy hearing means that I might well have misunderstood some/all of it. The surprising thing to me was that I was expecting a tube trailer, but it was actually a flat bed with a couple of maybe 10-foot long containers on it with the doors facing each other, each of which contained banks of tanks plus monitoring and pumping equipment.

[tbleakne]

GRA, thanks for your direct report from the Air Products H2 driver. His cascading tanks make sense, but they also illustrate the problem of dispensing gaseous H2. Your question:
Did First Element say they were looking at switching to LH2 delivery and storage rather than gaseous, or were they talking about LH2 on the cars as well?
He talked about how easy it was to pump LH2 into the car, so I believe he was talking about the car storing it as liquid. Some years ago at a Caltech event BMW displayed a prototype with LH2 storage. The presenter invited me to hold my hand on the tank storing the LH2. I could not feel any sense of cold, but he said it was full. He said the tank insulation was equivalent in R-value to 10s of feet of styrofoam. Apparently since then the cost of this quality of LH2 storage has declined.

Gary, yes the tank has to be ventilated to maintain atmospheric pressure and avoid buildup of pressure, but the boil-off rate is inversely proportional to the insulation R value of the tank. A boil-off rate of perhaps 1 % per day might be doable and tolerable, and at that rate the gaseous H2 boiling off would be very low and dissipate immediately as GRA suggests, with no risk if vented to the atmosphere. It would also disperse rapidly from the leaks around any normal garage door. Storing the car in a sealed garage, however, could be a problem.

[GRA]

GRA, thanks for your direct report from the Air Products H2 driver. His cascading tanks make sense, but they also illustrate the problem of dispensing gaseous H2. Your question:
Did First Element say they were looking at switching to LH2 delivery and storage rather than gaseous, or were they talking about LH2 on the cars as well?
He talked about how easy it was to pump LH2 into the car, so I believe he was talking about the car storing it as liquid. Some years ago at a Caltech event BMW displayed a prototype with LH2 storage. The presenter invited me to hold my hand on the tank storing the LH2. I could not feel any sense of cold, but he said it was full. He said the tank insulation was equivalent in R-value to 10s of feet of styrofoam. Apparently since then the cost of this quality of LH2 storage has declined.

The biggest problem I see with LH2 is if consumers are supposed to be dispensing it. I'd think they'd need really serious interlocks on the connector to eliminate any possibility of a customer coming in contact with LH2, and the connector itself would be very cold, requiring lots of insulation and making the whole thing very clumsy to use. I can foresee all sorts of safety issues, so while I think LH2 makes sense for some commercial uses, I'd have my doubts about letting the typical untrained car owner anywhere near it. I'd think the stuff's normally dispensed while wearing full protective gear. Anyway, here's some slides showing Linde's take on gaseous versus liquid H2: https://energy.gov/sites/prod/files/201 ... hankar.pdf

[garygid]

For NG or H2, no matter liquid or gas, the production and distribution chain still appears to be energy use intensive, and likely releases a lot of greenhouse gas to the atmosphere. Solar panels to generate electricity ... seems like a better process to me, and distribution is often already in place. In my Garage, I think H2 and the gas water heater would be a ... bad mix. Even at only 1% per day boil off, it seems like too big of a risk in many garages, underground parking, and in typical service facilities.

[GRA]

For NG or H2, no matter liquid or gas, the production and distribution chain still appears to be energy use intensive, and likely releases a lot of greenhouse gas to the atmosphere. Solar panels to generate electricity ... seems like a better process to me, and distribution is often already in place. In my Garage, I think H2 and the gas water heater would be a ... bad mix. Even at only 1% per day boil off, it seems like too big of a risk in many garages, underground parking, and in typical service facilities.

Somewhere over in the H2 thread, I provided a link to a study of whether or not H2 could build up to a flammable concentration (4%) in a typical garage given a leak. Even sealing it to a much greater extent than would be the case with a real-world garage (or house FTM), achieving such a concentration was a practical impossibility. Service facilities are even more open. Underground garages may be another matter, but I imagine it all depends on how they're ventilated. Remember, gaseous H2, being such a tiny molecule and lighter than air, will rise and diffuse through just about everything (which is why pure H2 pipelines are so expensive, and they prefer to mix it in low concentrations in NG pipelines). It's not going to pool on the floor.

[GRA]

Somewhere over in the H2 thread

Gary, found it (or a couple of similar ones), so you can judge for yourself:

HYDROGEN RELATED RISKS WITHIN A PRIVATE GARAGE:
CONCENTRATION MEASUREMENTS IN A REALISTIC FULL
SCALE EXPERIMENTAL FACILITY

https://www.hydrogen.energy.gov/pdfs/safety_biblio/ichs2007/1.1.51.pdf

HYDROGEN RELEASE AND
COMBUSTION MEASUREMENTS IN A
FULL SCALE GARAGE

http://ws680.nist.gov/publication/get_pdf.cfm?pub_id=905528