Efficiency of the Clarity Generator

[craze1cars]

Agreed. But when demand is, for example, only 5 watts? Even if RPMS come down on a running generator, we are a LONG ways from being economically efficient to produce a meager 5 watts on a gasoline generator. The waste would be stratospheric. A giant wasteful generator running at idle will cost exponentially more to operate than it would to simply plug the same 5 watt demand into the grid, give the power company a penny or two, and shut off the generator.

Grove's (jesting) question was specifically about running a whole house, on gasoline, in an effort to save money. The efficiency of small portable generators is frankly not relevant. To run a whole house's wildly changing and variable power demand with any amount of efficiency on gasoline, you would need a full blown integrated system, a computer control, and battery banks which would allow complete shut-off at times of low demand. All of which exist and are common in, for example, off-grid areas of Canada/Alaska. And all of which is a far more expensive option than for someone who has a grid available to tie into....which is why almost NOBODY near the grid outside of extreme preppers and conspiracy theorists will opt for running a house on generators 100% of the time.

My only point is there is much to consider to Groves Cook's comment about running a home, on gasoline, vs continuing to use the power grid in an effort to actually save money. Such an endeavor is not really possible in my estimation. However propelling a Clarity on gasoline vs grid electricity to save money is most certainly feasible in a large swath of the country with today's gas prices. It is 100% free to make the change, and is as simple as not bothering to plug in and buying gas periodically instead, and is an option for those who prioritize personal money savings above all else.

Like most Clarity owners, wife and I are still plugging ours in, despite the small extra cost. I agree it's nicer to drive that way, and saving a spoonful of pollutants of the mountain certainly occurs, and feels nice. But to drift a splash off topic...as I am one of the individuals who actually purchased this car to save a few bucks on gasoline? It cannot be denied that if gas prices in early fall of 2018 were $1.27/gallon as I paid today? Or had I predicted they'd reach this low level again? I personally would not have purchased the Clarity. Wife would probably be milling around in a comparably sized ICE sedan of some type. So with that in mind this current cheap gas situation has GOT to be hurting the general public's demand for EV's, PHEV's, and frankly even regular Hybrids and small/efficient ICE vehicles. To Joe Public, it's simply a heckuva great time to own a gas guzzler...and maybe even purchase another... Obviously nobody wants to hear such a thing here on this forum, but I believe it to be the truth.

 

[Cash Traylor]

Also, although in general all of the points about generators running "full tilt" are true in the sense that even the most basic speed governor (the centrifugal type in the crankcase) are tuned for a "running speed" that equates to some harmonic that results in 60Hz. This is usually around 3600 RPM, which is why we consider them running at "full tilt" speed. However, although their minimum load efficiency is somewhat poor, there moderate to higher load efficiency is actually not that bad. Now bear in mind we are talking about mostly "lawnmower" engines so efficiency is thermally relative. But they are not running with pedal down full fuel flow. The fuel demand increases with generator torque load (wattage demand) in an attempt to maintain that set RPM. This is why if you lightly load a generator it's fuel supply will last longer than under full load. It is also why sizing these "dumber" generators to the planned loading may make sense to avoid wasting gas. A 10,000 watt generator (not inverter based) will waste a lot of gas powering a 1500 watt load. Whereas a 2000 watt generator (constant rating) will be significantly more efficient powering that same load, all things being otherwise equal. Just my Sanders Penny add on to Ken's comment. However, when speaking of residential applications where daytime loading can swing my several orders of magnitude, it is almost impossible to achieve "whole house" efficiency without a series/parallel hybrid generator that has an inverter/battery/generator system than can run "intelligently" and that looks and sounds a lot like a giant Clarity without it's tires. As a side note, there is another Clarity on ebay being broken down for parts. Saw the traction/gen being sold as a "automatic transmission" unit for $2500 or so. The ICE was $3K, and the inverter unit was... something under 3K. Didn't find the HV pack listed. Guess I will stick to my Harbor Fright gen for now.

@insightman , I am still working on your "nerd" display...

Cheers,

Cash

 

[ashmtl]

I am not an expert on EVs or any type of vehicle, just an experienced car enthusiast with over 40 years of experience in driving and maintaining different types of vehicles. With my Electro-Mechanical Engineering background, I can compare, understand, and explain few things connected to Hybrid vehicles, that I have no experience at all. I am buying a Honda Clarity Hybrid now and that is the reason I was browsing the EV forums. Enough of introduction, let us get to the point.

A little of theory: The main international measure of energy is (in my knowledge) Joule (J) and it compares to one kWh as this 1kWh=36000000 J or 3.6MJ or with BTUs 1kWh=3412 BTU. As you can see the easiest way to measure today’s energy is kWh, because we become more and more energy hungry.

1L of regular gasoline produces, give or take, about 8.9 kWh of energy. Honda accord with 2.0 L ICE and sport trim (that is comparable to Clarity) consumes average 7.6 L / 100 km, i.e. 67.64 kWh of energy. Tesla 3 standard range plus has 54 kWh battery that moves it for 395 km (without heating or A/C used), or it uses 13.67 kWh energy for 100 km. We can say that energy wise the full electric vehicle is about 5 times more efficient than the gasoline powered vehicle. From the same logic the Honda Clarity averages 2.1 L / 100 km in combined mode, i.e. 18.69 kWh to go the 100 km. The plugin hybrid is more economic than the pure gasoline consuming brother because of the electric portion. So, if we use more of electric power instead of gasoline, we save the power usage about 5 times, which means that the gasoline must be 5 times cheaper than electricity to run on it. In Quebec (Canada) the electricity for residential use averages to about $0.075 CAD per kWh, i.e. we spend about a dollar to drive a Tesla for 100 km. The gasoline is $0.82/L, i.e. to drive the Honda Accord with ICE we need to spend $6. The only electric range of Clarity is 76 km with a 17-kWh battery, so we need to spend $1.67 CAD to go the 100 km in electric mode only. This confirms that unless the gasoline goes down to $0.26 CAD (the level of 1980s), the hybrid or electric car wins. We all know that today’s low gas prices will not stay for long.

There are many factors why the electric car is that efficient, I can name a few reasons:
1. In fully electric cars there is no CVT or other type of transmission that changes the gears. We can say that the power goes directly to the wheels. You can even put the motor inside the wheel.
2. The electric AC motor average efficiency is 90%.
3. The electric AC generator efficiency is about 85%.
4. The average ICE efficiency is 33%.
5. The average efficiency of a CVT is 90%.
If we subtract just those losses, we will have that ICE has about 77% of loss (but part of that loss is used for heating) when the pure electric has only 15% loss, because the generator and the motor are the same unit, so the loss doesn’t add.

All those comparisons are done for just driving mode without A/C or heating, same for heating of the batteries in electric cars. I was using the official numbers from the manufacturers that of course do not reflect the real consumption, but because they lie in the same way, the comparison is more or less accurate.

Coming back to the main question of this thread if one should plug in the Clarity or just use the ICE, the answer is obvious: do not be lazy and plug it in. Specially if you do not do more than 50 km per day, you should use the grid electricity instead of gasoline. You do not even need to buy a 240V charger.

For the question of generating electricity using an ICE: the generation of electricity becomes efficient only when you have a large number of users (i.e. the grid) or you can accumulate it. Also, the ICE that is used just for electricity is tuned to run efficiently at the constant RPM and load. Anything different from it makes it not efficient at all.

I still have to say that I do not agree that electric cars are that much green. Yes, they are less pollutant, but they still pollute. Most of the electricity is generated in oil or NG burning stations. Even the hydro stations are not as green as one can think. Most of them flood huge territories changing the natural balance of flora and fauna. And of course, you need to produce new batteries all the time and store the used batteries somewhere in the end of their life cycle.

I apologize for a long post.

 

[Landshark]

Coming back to the main question of this thread if one should plug in the Clarity or just use the ICE, the answer is obvious: do not be lazy and plug it in.

Fuel and electricity rates are a bit different in the US. For many here it makes financial sense to use gasoline.

 

[craze1cars]

x2

@ashmtl: For comparison sake I did a couple conversions to help illustrate what we are describing. Today where I live in the US, gas can be purchased for $1.25/gallon. For you that would be 33 cents per liter. And my electricity is about 11 cents per KWH, where you say yours is 7.5 cents.

So it's undeniably more beneficial to my personal pocketbook to burn gasoline in my Clarity than it is to plug it in. And a few are doing this. Thus this discussion.

Sounds like your gas prices are almost triple mine, and your electric prices are 40% lower than mine. So it doesn't make sense to do the same where you are. As you stated, you will still save money by plugging in.