In principle, re-fueling the transportation sectior of the US economy with some non-GHG producing feel has the most immediate and effective impact. This is easily seen by looking at the long term greenhouse gas inventory, in simplified sectors:

Below we show the 2015 version of the previous to see that little actual evolution has occurred. Yes fuel economy in vehicles is improving, but total US miles driven continues to increase and so these two offset each other so that the transportation contibution to total US GreenHouseGas emission stays about the same.

For vehicle miles traveled (VMT) in the US, there was a relatively flat period from about 2008-2014 but this has recently risen with a new peak record set in August of 2017.

As discussed in the last class, gasoline is the only known "natural" substance that has sufficient energy density that can power a 4000 lb piece of metal, for 300 miles, at 70 mph:

The following alternative all have various limitations that we will discuss:

Batteries for Electric Vehicles growth will occur but will be limited by the materials need that can be haversted on an annual basis for the battery packs. You will do a homework exercise on this to quantiatively illuminate you on the nature of the limitations.

While the graph below looks favorable, numbers always need context.

As of end of 2016 there were 3100 (thousand) = 3.1 million vehicles but the current global vehicle fleet is about 1.5 billion so that is a penetration of 0.2% !

Next might come Hydrogen Fuel Cells but until we have discovered how make Hydrogen from renewable electricity souces (see material later on about The Hydrogen Economy) and how to use material that is more abundant than platinum as a catalyst, fuel cell vehicles will be even less than EVs. Again, note the numerical value of the Y-axis.

Next might come from Natural Gas (NG) since it so clean:

NG is primarily used in buses and trucks and mostly in parts of the world other than North America:

While this growth has continued so there are about 15 million vehicles world wide -- there are only 150,000 in the US. In the US we have a NG fetish love affair with NG fired electricty cause is "cleaner than coal"

For the US, this then leaves us with only one viable alternative, substituting some kind of biofuel for gasoline.

Ethanol has long been a viable substitute for gasoline fuel. However, the energy content of Ethanol is 10-20% lower than gasoline and consequently fuel economy will be lowered by 10-20% when using a strictly ethanol bases fuel. Indeed, in many states (including Oregon) most of the "gasoline" you buy at the pump has some amount of ethanol already mixed in.

A definitive guide to all things BioFuel

Ethanol comes from two kinds of feedstocks a) Grain and b) the whole plant (cellulosic)

Grain-Based Ethanol:

Ethanol is an alcohol-based alternative fuel produced by fermenting and distilling starch crops that have been converted into simple sugars. Feedstocks for this fuel include corn, barley, and wheat. Today's commercially available vehicles that can use E85 (85% Ethanol and 15% gasoline) are called flexible fuel vehicles (or FFVs), meaning that they can run on E85, gasoline, or any mixture of the two.

The market for FFVs is continuing to grow and we will see that Brazil is an interesting special case - note that the UK has a huge growth rate but the actual volume of fuel is quite low. Once again, numbers in context. Its really only Brazil and China that are producing large amounts of ethanol for internal use and having the residual to export to other countries.

Currently there are about 20 million FFVs in America (20 million out of about 400 million light duty vehicles = 5%) which are supported by a growing number of fuel stations.

Sequential BioFuels is located in Eugene and is a local distributor of biodiesel and grain ethanol fuels. Their production process is shown here:

Note that Suquential BioFuels started in 2001. It is now 17 years later but they only have dedicated 3 stations (one is diesel only facility in Salem). This slow growth is a consequence of the relatively low available yield of raw material to convert into biofuels.

However, Sequential does now sell small amounts of BioDiesel (B20) - primarly for use in 18 wheel trucks, to a vareity of gas stations in the NorthWest. However, they are unable to scale of their ethanoal distirbution to support FFVs.

A promising source of ethanol based transportation does come from sugar cane. Brazil is a major producer of sugar gain and now has an aggressive initiative to change out most of their transportation fleet from gasoline/diesel based to sugar cane based. The market response in terms of sales of FFVs in Brazil has been phenomenal, as shown below, and Brazil is well on their way to achieving this goal.

Cellulostic BioFuels: this may have large potential:

Conventional ethanol is derived from grains such as corn and wheat or soybeans. This has somewhat limited yield per unit acre of crops grown. As a result, grain based ethanol, as derived from US Corn growth, is simply not scalable (as will be shown shortly) and will be relegated to local markets mostly located in the Midwest.

Cellulosic ethanol can be produced from a wider variety of cellulosic biomass feedstocks including agricultural plant wastes (corn stover, cereal straws, sugarcane bagasse), plant wastes from industrial processes (sawdust, paper pulp) and energy crops grown specifically for fuel production, such as SWITCHGRASS

Overall Ethanol Production Scheme
Sugar Cane has direct advantage as it offers a more direct route to the final product

Notes:

large scale biomass production for alternative fuels potentially creates a lot of jobs

The major technical/scientific problem is sugar extraction with reasonable efficiency. This is why Sugar Cane is the best feedstock (e.g. Brazil). The current efficiency from converting pretreated cellulosic material into sugar is very low. With R&D investment, this can increase and it has to in order to cellulosic ethanol to become a serious fuel source.

Details on the Potential Yield of Cellulosic Ethanol:

The overall net energy gain of ethanol has been a source of intense research for some time. Ethanol opponents are quick to say that it takes more energy to make ethanol than you get out of it. That statement, was once true, about 30 years ago. Most people never evolve their opinion once it has formed and never pay much attention to advances in the field, since they have already formulated the truth.

The figure below shows that most all studies indicate that Ethanol production is a net energy gain. It is only one group that consistenly finds the oppposite.

A definitive 2008 report concluded that the net energy gain was 2.3. Some studies have even found energy gains as large as a factor of 5.

Among things that you should know when this course is complete is that the production of ethanol is a POSITIVE net energy gain

So now let's consider some yield scenarios for both grain baised and cellulosic based ethanol - keeping in mind that annual fuel use is 150 billion gallons of gasoline. Note that a gallon of ethanol has about 75% the energy content of gasoline at standard room temperature. Therefore 150 billion gallons of gasoline is equivalent to 200 billion gallons of ethanol.

Grain Based Scenario:

10 Kg of corn produce 1 gallon of grain based ethanol
1 Ideal acre of corn produces 850 gallons
We assume that 1 real world acre of corn is 2/3 of the ideal acre or 570 gallons per acre
Required acreage to meet this 200 billion gallons goal would then be 350 million acres on which to grow corn is this is a little or a lot?
A recent acreage report is HERE . According to that report, there are 90- 100 million acres on which corn was planted, well short of the required 350 million acres. So, grain based ethanol does not scale.

And of course, you can not devote all of the 95 million acres to growing corn for fuel. The maximum mix is likely 75% for food and 25% for fuel bringing you down to about 25/350 = 7% market penetration with corn feed grain based ethanol.

The Promise of Cellulosic Ethanol: 100 Billion gallons

Switchgrass is a common prarie grass that grows in dense and high bundles and is an ideal feedstock for cellulosic ethanol. Potentially vast areas of Canada could be seeded with switchgrass for fuel which is a hell of a lot better than currently using Canadian tar sands for gasoline.

Current average yields for switch grass are 5--10 dry tons per acre.

With improved breeding and cultivating techniques yields approachin 15 dry tons per acre may be possible. Indeed, a recent experiment done at UC Davis has produced 17.6 tons per acre

To produce the target goal of 100 billion gallons (meaning market penetration of 50%) would require 88 Million acres dedicated to growing switch grass.

For context, currently 83 million acres are dedicated to growing soybeans for animal feed and switchgrass has more animal protein per unit mass than soybeans. Thus there are two markets for switchgrass: pet food and fuel.

The production costs of switchgrass based biofule have been estimated to range from 60-90 cents per gallon and a more recent and very comprehensive study supports these production costs

These production costs are less than crude oil costs and this will continue into the future. For reference, if crude oil is at $100 per barrel then the production cost of gasoline is 100/42 = $2.38 per gallon.

The current price of oil is about 60$ per barrel =60/42 or $1.42 per gallon.

So a realistic scenario based on the above information is:

By the year 2030 fuel economy will improve to an average of 50 mpg.
Switchgrass yields will be 15 tons per acre
10% of available cropland will be dedicated to growing switch grass.
1/2 of all vehicles can now be powered by switchgrass. Wow - this could actually be done, if we just decided to do it. This effort, at the national scale, would also create a lot of jobs.

note: increased fuel economy is essential no matter what fuel is under consideration.

Finally, there are attempts to develop various kinds of environmental indices to determine which kind of fuel mixes have the most impact. An example is shown below. The higher the index number the better. There are three impact variables to consider:

a) which fuel mix results in the lowest total greenhouse gas emissions (G);
b) which fuel mix represents real reductions in actual petroleum use (P);
c) which fuel mixes produce the largest changes in total fossil usage (including the fossil inputs to make the fuel) (F).

While interrelated, each of these are different goals to achieve.

The table below summarizes

Alternative Fuels Index (AFI) = weights P and G
Renewable Fuels Index (RFI) = weights F and G

for various fuel considerations. In most cases the AFI and the RFI are not well correlated.

Let's go through these results:

NANG = North American Natural Gas (e.g. fracking) and the production of NG powered vehicles (which now are mostly busses). This technology scores well in terms of reducing greenhouse gas emissions ( but does not properly account for methane leakage from pipelines and production sites ) relative to gasoline as well as directly reducing crude oil usage. However, the RFI is low because a) this is still a fossil fuel and b) a lot of fossil based energy input is required to compress NG so it can be used as a fuel.

Methanol is now deemed too toxic and its use has been discontinued.

E85, from cellusoic sources, has both very high AFI and RFI and therefore accomplishes all three goals of reducing ghg emissions, reducing crude oil use, and lowering fossil use.

Hydrogen: this will be discussed in more detail later. The above table assumes Hydrogen would be made via its current process, steam reformation of CH₄ (natural gas) - but this is only necessarily true no and not in the future. In any event, the biggest winner in the table above is achieved when the Carbon is sequestered in the steam reformation process.

In general, this process of producing index scores so that technologies can be compared in a relative sense, can be a very important input into policy. For instance, from the above table it would seem foolish to invest in NG powered vehicles and foolsing to invest in Ethanol at any level less than E85.

Moreover, two viable solutions arise: E85 and Hydrogen as long as the Carbon is sequestered. We will see later that producing Hydrogen from OFF shore wind facilities maybe a very good thing to pursue.