Wednesday, October 14, 2015

Why the future of diesel engines matters

No other automotive vehicle fuel surpasses the energy density of diesel by weight or by volume.

Chart from US Energy Information Agency
More fuel comparisons from energy.gov 
Gasoline Gallon Equivalent from Wikipedia (they agree w/ energy.gov figures)
GGE via Wikipedia
Until the advent of gas-electric hybrids (like my Prius), nothing matched the driving range of diesel engines. That made them ideal for long-haul trucking and passenger vehicles in remote areas.

Diesel engines also produce more torque than gasoline engines.  (Explained by my friend's husband, who sounds mighty defensive about his grad school.)  This made them a good choice for buses, trucks and locomotives that pull heavy weights over steep grades.  It also makes them fun to drive--that famous Fahrvergnuegen.

We knew that diesel engines are polluting.  We also know that they emit more CO2 than conventional gasoline to produce the same amount of energy if you take the alkane lengths and balance the redox equations.  (You can do that in your sleep, right?)

We knew all that.  But the diesel car manufacturers were telling us they could dramatically reduce the downsides of diesel without sacrificing performance.  They said that they could reduce smog-forming NOx and SOx (nitrogen and sulfur with various numbers of oxygen atoms) that hurt plants and animals.

We now know that is a lie.  Real-world driving tests now show that diesel automobiles of many companies exceed the legal limits.  VW is just the most egregious of the violators (by nearly an order of magnitude!).

And then there is Black Carbon (BC).  It's not only unsightly and unhealthy in the cities, but it's also melting snowpacks and glaciers and accelerating global warming.  Notice the high BC emissions in Europe, India and China due to their heavy reliance on diesel for transportation?  It's no coincidence that the snowpacks in the Alps and the Himalayas are declining so rapidly.

Black Carbon emissions inventory courtesy of epa.gov.

The problem is that these projections are based upon vehicle emissions tests that we now know are frauds.
Projections courtesy of epa.gov.
It's time to do some deep thinking about how we get around.

Now I'm going to stop hyperventilating and knit with some pretty yarn while streaming something escapist on Netflix.

Another angle:

Bad apples or bad culture? Explaining Volkswagen’s malfeasance

No comments:

Post a Comment