Monthly Archives: February 2016

Cars and Cold Weather

Anyone who pays even passing attention to their fuel economy know that regardless of the vehicle driven, colder weather means poorer performance for a myriad of reasons. Important to all vehicles is inefficiency due to rolling resistance and wind resistance. Electric cars have additional inefficiencies due to battery issues.

In cold weather lubricants, which keep parts which move with respect to each other moving, are more viscous and therefore more resistant to movement causing drag. Another source of resistance to motion comes from the lower tire pressure in cold weather. Students in introductory chemistry classes learn Guy-Lussac’s Law: Pressure is directly proportional to temperature. Lower temperatures mean lower tire pressures.

Both friction due to viscous lubricants and lower tire pressure are overcome because both cause friction and friction generates heat. Depending on how cold it is, and how long the vehicle is driven, parts warm up lowering lubricant viscosity and tires gain pressure as they heat up.

Even the air itself conspires in cold weather. Vehicle designers pay careful attention to “slipperiness,” as wind resistance is a big factor especially for a fast moving car or truck. Wind resistance is a function of the density of air and air density is inversely proportional to temperature. Colder air is denser air and provides more resistance.

Internal combustion engines (ICEs) have to be tuned to run rich to get started in cold weather. This means that more fuel is used to get the engine started and up to operating temperature. Additionally, in the winter people tend to start up their engines to warm up the interior of the car before it even hits the road.

Hybrids, plug-in hybrids, and pure electric vehicles suffer an additional problem, because they all are powered to some degree by a battery and batteries in cold weather are a problem. A hybrid electric vehicle like a Toyota Prius has a traditional ICE connected to the drive wheels, with an electric motor which supplements the ICE. Plug-in hybrids are a little different. They have an electric drive train with an ICE used exclusively as a generator to charge the battery when it is discharged. Of course all electric vehicles have only the electric motor and a comparatively large battery to extend the range on a charge.

Two factors contribute to cold weather reduced range in battery powered cars. The colder a battery is the less charge in will accept, thus lowering the vehicles range until the next charge. A factor called internal resistance increases as the temperature decreases. This means you don’t have as much energy stored from the outset. Further reducing range is the process which converts chemical to electrical energy. The distance you can travel on a unit of energy is lowered in colder weather.

Electric cars have reduced range on a given charge in cold weather, but overall are still cheaper to operate than an ICE vehicle. Basically the cost of electricity for a given amount of travel is much less than the cost of gasoline for an ICE vehicle, even at today’s greatly reduced cost for gas.

State Support for Sustainable Energy

The data are in and the numbers are crunched. 2015 is officially the hottest year for the planet in recorded history. Last year raced past the previous hottest year, 2014. In fact the 10 hottest years on record have occurred since 1998.

The science is clear, the heating is due in the main to burning fossil fuels. Governments around the world are developing strategies to decarbonize their economies. Here in the United States we have federal various tax credits which lower the cost for both individuals and businesses to be less reliant on fossil fuel combustion. Purchase tax credits are available for energy efficiency and sustainable energy production. Also, production tax credits for wind produced energy are available.

Variable levels of subsidization from the states for both purchase and production of sustainable energy is also available. These can come as purchase savings: income tax credits, income tax deductions, sales tax rebates, and cash rebates. Production of sustainable energy, for example solar photovoltaic systems or wind turbines are subsidized by feed-in tariffs or net metering. Levels of support also vary by sector such as homeowners, coops, or for profit businesses.

California is generally recognized as the nation’s leader in clean renewable energy because they have committed to a renewable portfolio of 50% by 2030. This means they expect 50% of energy production in the state to come from renewable energy. Their success thus far is driven by a combination of all the above, credits for efficiency, the purchase of equipment, and for energy produced.

An example of a production subsidy is a feed-in tariff. This is a rate structure for electricity where the producer of clean energy, say a homeowner with solar panels, signs a long term contract to produce energy to the grid at a premium price. In Michigan the average cost of electricity is about 11 cents a kilowatt hour (kWh). Producers with a feed-in tariff are paid 24 cents a kWh. Payback times at this rate could be less than five years!

Here in Arkansas we are about in the middle of the pack, renewable energy support-wise. There is essentially no state purchase support, but net metering provides some assistance for the production of clean, carbon free energy. Net metered systems in Arkansas use bidirectional meters. When the sun shines and production is in excess of consumption the meter runs backwards, at the same rate as it runs forwards when consuming energy. There no additional access charge or fee for net metered systems. What this means is that the home producer is paid retail cost for the power sent to the grid.

Less valuable but still of some help are net metered systems where the producer is only paid the power company’s avoided cost, the wholesale rate. This doesn’t reward the expense of providing clean power to the grid as the avoided cost is the cost of the oldest, cheapest, and usually coal fired power production. Nevada recently downgraded their net metered systems to pay only the wholesale price for production, rather than the retail price.

Only two states, Tennessee and South Dakota, have no production support for distributed clean energy.

Guns, Guns, and More Guns

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

So reads the second amendment to the constitution. The ambiguity of the construction of the sentence has been a cause of disagreement for centuries. Some view the amendment to give carte blanche to gun ownership, that is, anybody can own any kind of firearm. The other end of the extreme think that it only allows for the formation of organized state militias.

The reality of the courts’ decisions lie somewhere in between these extremes. Most can possess a gun but not all. Guns can be restricted from some locations but not all. Some kinds of guns can be owned but not all.

There is probably no better example of why there must be a final arbiter of what is the meaning of the words strung together in the constitution, it’s amendments, and laws. It doesn’t matter what you or I may think those words mean. It only matters what at least five members of the supreme court think. Their decisions become the law of the land, but even those decisions aren’t static. As the membership of the court changes so may the legal interpretations change.

Equally interesting are the changes to gun ownership. An obvious trend is that every time we have a mass murderer in the news, and every time there are discussions of gun safety, gun sales spike upwards as some fear that they won’t have access to a gun in the future. The Bureau of Alcohol, Tobacco, Firearms, and Explosives recognizes that we now have more guns than people in the United States.

Does that mean every man, woman, and child has a gun? Of course not. NORC at the University Chicago recently did a study which produced some interesting results. Paradoxically, at the same time the total number of guns in the country is increasing, the number of households with one or more guns is decreasing! More and more guns are held by fewer and fewer people.

This has be attributed in the main to fewer hunters. In 1977 someone in 32 % of households hunted. By 2014 that number had been cut in half to 15 %. This follows the demographic change of increasing urbanization. Fewer and fewer people live a rural life which favors hunting for sport or filling the larder.

Gun ownership by region of the country is unsurprising. Most guns are in the old south because, well, the old south. Sparsely populated Rocky Mountain region was next with the heavily populated mid Atlantic region at the bottom with the fewest households with guns.

Apparently the more money you have the more likely you are to own a gun as there is a straight line correlation between household income and gun ownership. Finally the gender gap for gun ownership is narrowing. Even as total gun ownership by household goes down, the share of guns owned by women is going up.