Friday, January 8, 2010

Gas demand, miles travelled and salt for the roads

It has been a while since we looked at the TWIP and natural gas pages of the EIA, so (in order to maintain the historic record) a quick trip over there, and to the VMT page of the FHWA is in order. I will get to natural gas in another post, but the increase in natural gas prices in New York from $6 to $11 over the last week (it was as high as $14/kcf last Monday) is something eye catching. It is interesting to note that while domestic crude is about at the highest point it has been in quite a while (allowing for a little drop due to the weather and season), there is now also a slight uptick in imports as well, indicating that the domestic gains in production may no longer be enough to keep up.

Domestic crude production end of 2009 (EIA)

Crude oil imports end of 2009 (EIA)

Gasoline demand has been relatively stable , but if you go back to the seasonality of demand this is the time of year when gas prices have historically been lowest, as has demand. From now on the growth should be relatively slow but steady into June when it reaches the peak during the summer driving season. So how are we doing this year?

Gasoline demand at the end of 2009 (EIA)

The question becomes whether we will drop down in demand through February, as we did last year, or whether we will return to the more historic curve with the earlier minimum. We shall see. (Robert Rapier’s recent essay on the possible perils of making predictions is still in my mind).

So what is happening with the VMT? Well, bearing in mind that these reports run a little late (the latest is for last October, there was a y-o-y drop overall of 0.5% in miles driven, after having seen an uptick in driving for the past few months. Interstate driving has risen, but it is the traffic in the “other” urban that was hardest hit, with other rural also being down over 1% (arterial and interstates were less affected). And for the overall summary curve?

12 Month running total of travel on US Roads through October 2009 (FHWA)

Well it is flattening out a bit, and may well do so through the next couple of months, given the typical drop in driving in winter, which will be exacerbated this year by the colder weather and greater depths of snow that are curtailing driving at the moment.

One of the things that I pointed out in comments after yesterday’s post was a direction to the Youtube video of the Head of the British Met Office getting his head handed to him by the BBC, in an interview that connected three erroneous medium term forecasts (for last winter, last summer, and this winter) with a 25% performance based increase in his salary. There is a relevance to this that may not be quite immediately discernable – but basically when, in times that are financially tough, counties, cities etc look to their budgets for the year, they tend to take such predictions of future weather into account when then order grit and salt that can be used on the roads to improve driving in winters such as the current one.

Unfortunately for the second winter in a row the Met Office has that prediction wrong, and the problem that it has caused is that there is now not enough salt and grit to go around. Villages in Britain have been cut off for weeks without the county doing anything to help, and this is unlikely to change soon.
But County Councillor Keith Young, who has a responsibility for highways, gave residents little comfort, asking them to 'bear with us'.

He said: ‘At the moment we have a very extreme set of circumstances and the priority is to keep the main roads clear.

‘As soon as we can we will treat the other roads we will do but we will not jeopardise our grit stocks.

‘My message to the residents in Cow Ark is that we are not doing this deliberately and I am sure their community spirit will see them through.’
I am sure that is a great consolation.

The role that highways play in providing access and communication, whether of bread, fodder for sheep or tankers for milk is often underplayed in the needs of those that live in more rural parts, but it is equally critical to the overall national picture since the costs to those living in the city may become more evident as milk becomes less available in consequence.

Salt for highways is often produced from underground mines, it should be kept dry until used, and for best effect should be spread on snow at a density of around 20 – 40 gm/sq. m.. There were some lessons that could be learned from the harsh winter in the UK last year (pdf) unfortunately (as is now becoming evident) those lessons were not well learned and there is now a national shortage of salt to treat the highways, even as the cold is anticipated to continue for another couple of weeks or more. In the UK there is only one major supplier of salt, a mine at Winsford in Cheshire, and while they can increase production to a degree with demand, beyond a certain point that becomes impractical due to a lack of machines, operators and suitable transport to deliver it to the customer. Thus the criticality of counties knowing in advance how much they will need, and the results of the failure of the Met Office to perform as they should, given their claim to be the best in this business in the world. (Not perhaps something they should have been stressing against their current record).

In the USA salt comes from regional mines, but there is the same basic need for information, and the same reliance on forecasts to assess how much salt and grit to stock. It might not have been politically correct, just before the Copenhagen meeting, to admit that the Northern Hemisphere was going to have a severe winter against AGW predictions, but it should have been the correct step, had folk been concerned about doing what they are paid (and apparently very well) to do.


  1. Mr. Summers -- re Vehicle Miles Travelled, a figure which is in the range of 3 * 10^^12 miles per year.

    How is that estimated? Is it simply back-estimated from fuel sales, or is there something more tangible behind it? Any idea what the +/- uncertainty in the estimate is? Is the approx 3% drop around 2008 within that margin of uncertainty?

  2. The estimates come from the individual states and traffic meters. To quote the report that I cite above:

    "Traffic Volume Trends is a monthly report based on hourly traffic count data. These data, collected at approximately 4,000 continuous traffic counting locations nationwide, are used to determine the percent change in traffic for the current month compared to the same month in the previous year. This percent change is applied to the travel for the same month of the previous year to obtain an estimate of travel for the current month.Because of the limited sample sizes, caution should be used with these estimates. The
    Highway Performance Monitoring System provides more accurate information on an annual basis."