Sunday, August 10, 2008

Fuel economy

Again I have been ignoring my blog in favor of kibitzing on others people’s blogs. Also, I have not had an idea that seemed real … well, “post-worthy” (with apologies to Seinfeld). But there have been a few things rattling around the back of my brain.

First, the question of how fast people should be allowed to drive keeps nagging at me. I have settled for myself that about 45 miles per hour is an optimum speed for my car. I had purchased a little plug in on-board computer that calculates fuel economy. I believe if does that by measuring the speed of the car against the rpms, although I have read it is something to do with the speed of aid moving through the engine. So all that is a little suspect, but I will say my MPG as measured by how many miles I go versus how much gas I put in my car when I fill up has shown improvement (up to an average 36 MPG overall in my last thankful). But if I try to use my car as an example, people may say that their eight cylinder is different than my four. Plus the EPA seems to support the idea that 55 MPH is the optimum of efficiency with graphs like this.

But I have been thinking about why that graph might differ so much from my own experience. Then it occurred to me that the Feds do their mileage testing in a lab. They put the car on a dynamometer, a device that has rollers and measures how fast the wheels are turning. I believe it might also provide resistance, but clearly it wouldn’t take into account wind resistance. The Feds may try to take this into account, but given the chart above, it doesn’t look like they succeed totally.

I saw this next chart elsewhere on the web. It looks like a Volkswagen made an effort to measure the fuel efficiency of the cars (Volkswagen TDI’s) of several of their members. It must have been a long process, measure fuel efficiency at several MPH points, say 25, 35, 45, 55, 65 and 75 (or something like that). I myself am struck by how, even though the cars (all the same model) get different levels of mileage, how the curves are shaped exactly alike. The mileage is clearly highest at a point between 35 and 40 MPH, and drops from there.

I think that this graph would justify calling for a return to the national 55 MPH speed limit, although it would make an even stronger case for a 50 MPH speed limit. After all, my car seems to max its fuel economy around 40 MPH, except up hills, where anything below abouit 48 MPH makes the car lug or at least strain some in fifth gear. So 50 would be a good catch all for all makes of vehicles.

By the way, the top image above came from, and the bottom from, although they clearly got it from someone else.

On another related front, conservative commenters over at the Burgh Report, as well as everywhere else, have called for drilling in the OCS and the ANWR. One rather obnoxiously phrases it as drill through a polar bears head to get to oil (and then they wonder why liberal bloggers call them names). National polls show the same sentiment among regular voters, 67% want drilling now in at least the OCS. Conservatives claim their motives are patriotic, while I think voters just want to go back to the way it was three months ago, when all you has to worry about was foreclosure, getting laid off or healthcare. Even Obama has picked up on this, now supporting limited drilling.

So we want to drill now, to get this oil out so that we can reduce our dependence on foreign oil. For how long, a couple of years? Maybe ten years, if we are lucky. If it takes ten years to get to the oil, the longest we could be looking at the oil lasting is maybe twenty years from now. Does anyone thing we will be off oil by then? Plug in hybrids are coming, but Toyota can’t keep up with demand for it’s hybrids now. Unless no new cars are sold that aren’t plug in hybrids, then we will have heavier users of oil with us for some time to come.
What I am leading up to is that there may come a time when we really need that OCS oil, not like now where we want the oil to return to an easier life style. Possibly even in a couple of years, four dollar a gallon gas may seem like the good times.

Now, going partially electric in cars is going to put a strain on the electric grid, with all those cars recharging over night. Any additional contribution made from wind farms will need to go to augmenting the electric grid before it goes to replacing coal burning power plants. And plug in hybrids will still need some gas sometimes, for trips between cities. By which I mean that we are not going to get off oil dependence in four years, or even eight. We may be looking at slowly reducing our use of oil over the next fifty years. So we may need that OCS oil in forty years, when everyone else runs out, and we can turn a good buck selling (and using) it. So we should resist using it now. Our children will thank us.

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