Friday, January 13, 2017

Electric First

The new bus looks pretty much like its diesel counterparts

The cool new electric bus has been inspected and registered so it can go into service next week carting Amherst elementary school children back and forth with less noise, pollution and annual maintenance costs.

The bus is owned by Amherst since the state grant was given to the Elementary  schools -- not the Region -- although it is stored at the Amherst Regional Middle School.

But Amherst does make up roughly 80% of the Region.  Since the bus is limited to about 70 miles per charge it would not be overly practical for the Region which is spread out over four towns (some of them pretty hilly).

The state awarded us a $400,000 grant to acquire the bus which of course is four times more than the internal combustion counterparts, so not a great bet the town or Region will be buying a fleet of them in the near future.

Town Meeting approved spending $93,000 for a traditional diesel bus last Spring which is now unnecessary, so maybe when the "independent analysis" of AFD staffing comes back later this month suggesting a much needed increase, that $93K could help make it happen sooner rather than later.


Dr. Ed said...

People may wish to read the State Fire Marshal's memo on fighting fires in MVAs involving electric vehicles: "Let them burn" -- do NOT use water unless/until the battery is disabled.

Batteries are in the range of 200 volts or more, and that's DC, no sine curve, and hence an effectively higher voltage than AC.

I'm all for saving the planet, but where does the electricity to recharge the battery come from, and remember that there is great inefficiency in recharging batteries. Hence this is a Coal-fueled bus.

But if I had a child riding it, my concern would be a potential MVA with fire...

Anonymous said...

I wish the PVTA would have more buses running too in the Summer where it's very hard to get around without a car. Then again I hardly rarely ride the bus, I uber myself around now, now that there is such a thing as Uber.

Anonymous said...

Now to inspire solar panels strong enough to re-charge the bus in situ. !!!

Anonymous said...

"Hence this is a Coal-fueled bus."

Wrong again, as usual, Ed, as our electricity is not from coal-fired plants. The Mt. Tom generating station was closed. It is being converted to a solar farm.

Anonymous said...

People are not so ignorant that they think local power comes from solar are they? Maybe some but....

If the bus is not practical, why have it even with a grant from the nice giving folks outside of town. Waste is waste and if it is not practical, it is also immoral to do something known to be impractical with someone elses earned money. It also prevents us or them from doing practical things with the same funds.

Most houses locally would need about 30 to 40 panels to make power. A kW is about 3500 btus, one gallon of deisel is 140,000 btus. 40 kW to a gallon of no.2. A gallon takes a local bus perhaps 10 miles so about 4 kW per mile. At around .2 kW per panel and 3 hours of full sun ave per day in mass, you get .6 kW per panel per day. So about 7 days for one panel to move a bus one mile, but vehicles are about 50% efficient with fuel 14 days one panel for 1 mile....and the town and government knows this or is responsible to know it.

Perhaps regardless of how we get them buses use huge amounts of energy. Want to make it so so so much worse....many parents bring their kids one by we have wasted more energy in one drop off morning than my house uses in a decade.....just the waste. Any parent that does such should shut up about energy policy.

I live off grid. We have 9 panels that make 100% of our home power. Just FYI. We focus on saving energy, not just talk here.

But solar math is 3rd grade math, perhaps some 4th grade. How can someone possibly think a few local solar farms privide everyone's power. That is like feeding a nation with a backyard garden...just one.

Again, this is yet another primary educational issue in a town that claims to have an edge on education...

Why did the folks that care about energy let this happen? get 30% of the energy produced at 50% efficiency at the power plant out of your the best of cases. That is 15% efficiency on tansported electricity from the source fuel. Vehicles run at around 50% efficiency. Battery storage looses about 10%.

Amherst is an energy pig and like the budgets, the schools drive quite a bit of this. The $21,000 per year is just part of the huge cost of such a design for teaching kids to read and write ok.

Anonymous said...

Anon 8:21 you are incorrect, base load electricity in Western Massachusetts is mainly generated with coal, oil, and natural gas. There are several coal fired stations in southern New England and eastern New York that provide power to our area. It is from this electricity that this bus and countless "zero emissions" vehicles get their energy from. The Zero Emissions marketing ploy is a total fallacy and people who buy into it are simply moving the emissions to someone else's back yard. Solar panels could never provide the energy density required to charge the batteries that bus contains in-situ. The solar farm that may replace the Mt. Tom power plant will produce a fraction of the power it did and only when the Sun shines.

The bigger concern here? Massachusetts taxpayers just shelled out $400k for a SCHOOL incredibly disgusting and inefficient use of public funds given the safety and infrastructure issues the state and its cities and towns currently have.

Dr. Ed said...

"Now to inspire solar panels strong enough to re-charge the bus in situ. !!!"


A DT-466 engine produces 300 horsepower at 2,200 RPM. There are larger engines in 400 horsepower range, but the DT-466 engine is (or was) often used in school buses.

That's 220.6 Kilowatts, or (roughly) the usage of 220 homes -- remeber the GVW of a bus is 14 tons (my guess is the electric one is more due to the weight of the lead in the batteries).

Remember too that this is 220.6 KW to the drivetrain, which means an electrical motor would consume more to produce that, but forget that. Forget too that solar panels are no where near 100% efficient, I'd be surprised if 10& of the solar radiation was converted to electricity.

So you have any idea how much solar radiation would have to fall on the roof of a bus (say 8' x 30') to equal 220.6 KW? We're talking enough to light both the bus and everything else on fire -- radiant energy in the level of a thermonucular weapon.

Folks, the best we could ever do with solar is 100% of what the sun provides per square inch -- and remember the reason why we have winter is the angle of the sun in the winter.

Dr. Ed said...

12:25 -- the bigger problem is that gas supply (i.e. pipelines) hasn't kept up with gas consumption of the new gas-fired plants. ISO New England is worried about this...

Compressed Natural Gas (CNG) is viable technology, the MBTA has been using it for years, particularly in tunnels(NB: this is compressed, not liquid!) and (liquid) Propane (LP) has been used for engines since the 1970's -- most of your forklifts run on LP.
The problem with CNG is infrastructure, a supply of it to refill vehicles from, which a $400,000 grant would go a long way toward establishing.

And the real technology that might be viable for school buses is regenerative braking, but even if this bus has it, there is the sheer weight of the batteries to make it moot.

But if you really want to "save the planet", don't build a MegaSkool that requires more buses!!!!!

Anonymous said...

Larry, last summer, WWLP said the electric bus only cost $150,000 -- how do we get to the $400,000?

Larry Kelley said...

Probably because TV journos are always in a hurry.

Anonymous said...

27 school buses at $400K = $10 million+

Dr. Ed said...

"27 school buses at $400K = $10 million+"

27 school buses recharging would probably require their own substation.

300 Horsepower = 220.6 Kilowatts of energy. What's the average total KW (not KWH) consumption for Amherst, less UMass?

Anonymous said...

12:13 et al:

There seems to be some confusion between the physical concepts of power and energy:

• kW is unit of power=(energy/time)

• BTU is unit of energy

How can you equate these? Did you mean kWh (kilowatt-hour)?

Please go back and do your homework; then feel free to return with something that makes more sense, please.

- Your Physicist Friend

Anonymous said...

FWIW, solar radiation power flux (that's power/area) on Earth's is roughly 1kW/square-meter. So the area (2 meters by 10 meters) of the roof of a school bus might at most generate 2 or 3 kW at the present 10-15% efficiency. And carrying the panels around not only adds weight to the bus, but the vibration isn't good for the panels, etc.

Instead, considering when buses are used, it makes more sense to have a set up like UMass is doing at its parking lots: cover them with solar panels! These shade the vehicles parked below; the morning-midday sun will help charge the bus-batteries for its early-afternoon run, and the afternoon sun (and the lower-priced, overnight grid-sourced electricity) will take care of the morning bus run.

But the price of these buses (likely with Li-ion batteries, not Pb-acid) is still ridiculous.


Anonymous said...

Yeah, Ed. Firefighters just stand there and watch a Prius burn.

Dr. Ed said...

• kW is unit of power=(energy/time)

Ummm, no. At least not involving electricity.

KW is a measure of an electrical current -- the *right now* flow of electricity going through a circuit.

Specifically, a Kilowatt is AMPS times VOLTS times 1000 (or WATTS times 1000.)

A 100 watt incandescent light bulb uses 0.1 KW, 10 of them will use 1KW.

It's Kilowatt-HOUR (KWH) which is the measure of energy/time -- it's a 1 KW load for one hour, 1000 watts used for an hour.

If you use 1000 watts for six minutes (1/10th of an hour) you will have a load of 1 KW and a usage of 0.1 KWH.

Now AC gets slightly more complicated because its an average voltage -- it's a sine curve that goes through zero 120 times a second, and then when you get into three phases, each 120 degrees from the other, you have a greater voltage between the phases than to ground -- e.g. 13,600 volts versus 8,700 -- but I digress.

And both batteries and solar cells are DC anyway.

Dr. Ed said...

Yeah, Ed. Firefighters just stand there and watch a Prius burn.

Well, that's essentially what the State Fire Marshal told them to do...

And a Prius is only 170-200 volts. Buses range from 350 volts to 700 volts -- a subway's deadly "third rail" is in the 500-600 volt range...

As the USCG says, you gotta go out, you don't have to come back.

And a battery fire involving a 4.5 volt cellphone or 19 volt laptop is one thing, a 700 volt bus is something else...

Dr. Ed said...

And remember one other thing: It only takes 1/10th of an amp to kill you.

1/10th of an amp is enough to fry the neural network that keeps you alive -- voltage is only the pressure, amperage is volume (sort of).

So a bunch of batteries wired in series can kill you....

Anonymous said...

Ed ...hold a battery and stick your head under a faucet...then open your mouth and drown.

Anonymous said...

Sorry, Ed - you're confused - you get an F in Fiziks.

Anonymous said...

An ampere=coulomb/second is the measure of electric current (electric charge/time)

A volt=joule/coulomb is the measure of electric potential (energy/electric charge)

Thus an ampere•volt=joule/second=watt is another way to measure power (energy/time), and kilowatt(kW) is 1000 watts,
which is still a measure of power, not a measure of energy.

Now, please redo your homework....

Anonymous said...

I don't care about any of this. I just wanna put gas in it and go!

Anonymous said...

Keep drilling.

Dr. Ed said...

Thus an ampere•volt=joule/second=watt is another way to measure power (energy/time), and kilowatt(kW) is 1000 watts,
which is still a measure of power, not a measure of energy.

Yes, but most electricians (let alone everyone else) start getting lost when you mention joules & coulombs -- it's bad enough if you use the word "potential."

I argue that if a joule is defined as "the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second" then it inherently is a measure of energy, even if nonstandard.

In other words, it can be converted to calories, Calories or BTUs -- and this serves in the same capacity.

Notwithstanding this, horsepower is also a measure of power, memory is some guy did something with actual horses to define it.

Hence, if a school bus needs a 220 KW Diesel engine turning a shaft -- won't you need 220 KW of power to turn that shaft, and hence (at least) 220 KW of electricity, however defined?

And isn't 220 KW a s-load of electricity? Regardless of what we define a KW as being?

Dr. Ed said...

"kilowatt(kW) is 1000 watts,
which is still a measure of power, not a measure of energy."

Wrong, and I should have realized this:

If a Kilowatt is 1000 watts for one second, then it is 1/3600 of a Killowatt-Hour, which
is legally defined as a unit of electrical energy. QED, it also is a measure of energy.

Anonymous said...

Yes, a Kilowatt-second is 1/3600 of a Kilowatt-hour. Nevertheless, a Kilowatt-second (energy) is NOT a Kilowatt (power), but
it's trying to get Ed to understand the distinction between energy and power=(energy/time), and the other readers don't seem to care either.....

Anyway, if you put together the various posts, and correctly do the math and physics (which you can do if you want - let's spare the details - a back-of-the-envelope or maybe back-of-the-blog computation):

Running one of these electric buses for a couple hours in the morning and a couple hours in the afternoon, would require
on the order of 1000kWh=1MWh per day which a solar panel array of about 1000 square meters at 15% efficiency could supply, at least on sunny days in late-May, June and July. The middle schools parking lots are big enough to accommodate an array of at least 20,000 square meters, so enough for a fleet of 20 buses, etc. (Of course, the array would have to be grid-tied, with excess generation going to the grid when the buses are on the road, and bus charging current coming from the grid when the sun's not shining.)

But the cost of installing these arrays, and the cost of the buses themselves, would be pretty steep. Maybe some electric buses should be parked over at Marks Meadow instead, where UMass just installed a solar panel array close to this size?