Re: Some questions I got from a listener by email

Hi Ben,

thank you for checking my comment. After reading your reply I first was a little bit surprised of the difference in the calculation. But then I found out what the reason for that is. And guess what?
It's this tricky changing-the-point-of-view-thing.

In your 30-mpg-gasoline-car-example, the "kWh" with which the 268 g CO2 correlate, are not the same as the "kWh" with which my 702 or 438 g CO2 correlate. Yours is the energy content of the gasoline and mine is the energy contained in the kinetic work of the car. So, they are very different types of energy and between them there is this conversion, which my engine does with an energy efficiency of approximately 0.39. And now we can close
this circuit by saying, that CO2 produced from diesel fuel is about 270 g CO2/kWh and that diesel fuel contains about 37 kWh/gal or ~42500 kJ/kg.

So, we are both right, only the point of view is a different. I took the kinetic work of the car as a common reference point, because if both cars have almost the same size, weight and shape, their kinetic work will be the same, as long as the resistance and time are the same.
Now, if I take my car's consumption and the energy content of the diesel fuel multiplied with the energy efficiency of my car, I get 0.23 kWh/km, which sounds quit realistic to me.

If you are interested in, here are some facts about the car:

Its a 1995 Peugeot 306 1.9 Diesel
dead weight: 1130 kg
rated power: 50 kW or 68 bhp
at rpm of 4600
max. speed: 160 km/h (100 mph)
measured average consumption: 6.1 ltr/100km or 38.5 mpg (on diesel fuel) and 6.5 ltr/100km with mixture of canola oil & diesel fuel (ratio: 3/4 canola oil to 1/4 diesel fuel) due to higher density and lower calorific value of energy of the mixture
energy efficiency: ~0.39, when run with ~30 kW load at ~3500 rpm
(This load is approximately the same as traveling on an even highway at a speed of 130 km/h or 80 mph. The input of fuel energy is then ~77 kW continously.)
CO2 output per km: 162 g (110 g with canola oil)

Actually the energy efficiency is bad for a diesel engine. It could easily be better if it had a turbocharger and thus the option to recover some waste heat from the exhaust gases. Then the engine could be of a smaller size, let's say 1.5 ltr and would easily have the same rated power, but less consumption. (perhaps it would then reach ~0.49)

But unfortunately this was not the case, because the understanding of a turbocharger in the automobile industry was a different one. They used this device to boost up engines to be more powerful, instead of downsizing them. Probably this attitude is changing now, but it's a very slow process.

Now to come to another subject. I saw that you and Robb were discussing this vehicle-to-grid thing and I believe this is a very interesting point and I totally agree with what both of you said.

I encountered this problem of the grid and its intermittent load or input on a smaller scale. I'm studying "ship's operation" which is a kind of technical engineering, dealing with ships and their technical operation and maintenance. And I've allready worked onboard ships for about 5 years.
So, in this business we face the same problems. For example onboard of a standard containership we also have an electrical grid, even though its a very small one. Probably comparable with a small town. We have something like a power plant for the base load, which is the main engine. We have several smaller power plants, called the auxillary engines. They can be used in case of a peak load or if the main engine is not in operation. And of course
we have lots of different consumers. We have a bow thruster, which is a very big consumer. We have all the electric motors of pumps, winchen and so on. And we have the lighting system and lots of reefer containers, which also need to be supplied by the grid. Now our advantage, compared with the engineers managing the grid ashore is, that our consumers are very patient machines. They are not getting angry, if we switch them off for half an hour
just because we don't want to start an auxillary engine, while our main engine cannot provide the full power to the grid, due to navigational manoeuvring.

So, in our small grid we are in full comand of the supply and demand of electrical energy and we can plan ahead the production and use of electricity. Ashore things look a bit different. I suppose, today the large grids are managed almost only from the production side, apart from the few large consumers. And once in a while this allready ends up in a blackout, because the electrical processes on the consumer side are much faster than the
mechanical processes, which provide the electricity. So, there's no doubt, that we need better management on the consumer side, if we want to add our vehicles to the grid as consumers. And of course we need this management more than ever, if we decide to use the vehicles as a storage place in the grid. But I'm not sure, if the majority of us is then ready to accept this management regarding our mobility, because it might interfere with our understanding of using mobility when ever we want it. I believe people will change their attitude towards this point more quickly, if there are enough incitements.

And that brings me back again to the efficient use of energy. As Robb said we all need to reduce our consumption of energy. In the matter of transportation I observe that this is allready happening. Within the last 10 years the growing use of the internet and the increasing fuel costs made instant ridesharing very popular among a certain part of our society, which has a special profile or habit of traveling. For example students like me. Here in germany
the students have to buy a special ticket for the local traffic for each semester they are studying. Because of the obligation the price is very low. Ok, probably there is also a little subsidy. But the point is, that this ticket makes us need no cars for traveling through our city and its close by surrounding. Of course the supposition is, that we live in range of the local traffic. So the only reason for people like me to use a car is to travel long distances.

Now the problem occurs, that the less often I use the car, the more expensive its use get's, due to the fixed costs. So one solution is to reduce the variable costs, by increasing the utilization. So, I do this instant ridesharing and on average the car is transporting 3 people. Sometimes 4 and sometimes only 2, but rarely only one person. In the end this leads to 54 g CO2 per km and capita (or 37 g when running on canola oil). Of course it could be less if I had an more efficient car, but at the moment this is a financial problem. So that's one fast solution to reduce the consumption, but to induce people to do this it need's the right conditions and incitements, because not everyone has a good imagination of this problem. So it's the job of our politicians to set up these conditions and incitements and of course the people have to get a better imagination of the problems related to the use of energy. But I guess this is one purpose of this website. ;-)

Ernesto