Energy. on this world and elsewhere. Instructor: Gordon D. Cates Office: Physics 106a, Phone: (434)

Transcription

1 Energy on this world and elsewhere Instructor: Gordon D. Cates Office: Physics 106a, Phone: (434) Course web site available at click on classes and find Physics or at Lecture #17 October 19, 2017

2 Announcements All previous lectures are now posted (1-16). First draft of review sheets to be posted later today. Date for super-quiz/midterm: Thursday October 26 th. Review sheets and times for review sessions to be posted shortly.

3 History of ethanol The original Model T Ford was designed to run on gasoline, kerosene or ethanol, and various combinations thereof.

4 Henry Ford and ethanol Photo taken in 1933 in Lincoln Nebraska. Published: September 20, 1925 Copyright The New York Times

5 Is a particular technology realistic? Is it practical and economical? Is it scalable?

6 Corn-based ethanol In the U.S., ethanol is mostly made from fermenting cornbased feedstock. - - By volume, ethanol accounts for almost exactly 10% of the gasoline sold in the U.S., but only about 7% of the energy (it has lower energy density). Ethanol accounts for about 5% of the energy used for the entire transportation sector. Energy independence and security act of 2007 mandates that biofuels should include 36 billion gallons annually by 2022 (ethanol in 2011 was around 12.9 billion, and biodiesel production was 0.97 billion). Yield: around gallons/acre/year To replace all gasoline with ethanol would take roughly million acres. We have around 326 million acres in cultivation.

7 Crop land in the U.S. 326 million acres devoted to cropland. (for comparison). This represents about 600 million acres, roughly what you would need to replace all of gasoline with corn-based ethanol. Between million acres would be needed to replace all transportation needs with ethanol. Shown is roughly the acreage (around 600 million) needed to replace gasoline with corn-based ethanol. Around million acres would be needed to replace all transportation needs with ethanol.

8 Is there a net energy gain? Cornell Berkeley

9 Is there a net energy gain? While the net energy gain is not impressive, only around 10,000 BTU s of the input are in the form of petroleum, so according to these authors, ethanol can reduce our reliance on crude oil.

10 Corn ethanol - is there an energy gain? A report published in 2002.

11 Corn ethanol - is there an energy gain? The authors also said that the energy ratio was steadily improving. One hopes that today things are better still.

12 What about cellulosic ethanol? Produced using cellulose, which is not a sugar. - One technique is to break it down using enzymes, and then ferment it into ethanol. - Another technique is to gasify it and then make fuel chemically. Would make it possible to produce fuel using agricultural waste. Could also be produced using marginal cropland and feedstock such as switchgrass. At present, the production is very low, I cannot even find solid numbers. Nevertheless, interest in cellulosic ethanol remains quite high.

13 Cellulosic ethanol production

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15 Biodiesel - what is it? Biodiesel is renewable diesel fuel substitute that is made by chemically combining natural oils and fats with methanol or ethanol. A blend of 20% biodiesel and 80% petrodiesel, (often known as B20) can be used in almost any diesel vehicle. Engines using pure biodiesel (B100) may require minor modifications to avoid performance or maintenance issues. Some of the sources of feedstock from which biodiesel is made include: - rapeseed oil (most common source in Europe) - soybean oil (most common source in the U.S.) - canola oil - algae (presently very small percentage, but most efficient use of land)

16 Biodiesel in the U.S. in 2014 The US used around 69 billion gallons of diesel fuel for transportation needs in Production of biodiesel (in 2015) was roughly 2.1 billion gallons, or about 3%.

17 Biodiesel - how is it made? Inputs include oil from plants and methanol Outputs include glycerol and biodiesel

18 What do we do with all that glycerin? About one pound of glycerin is produced for every gallon of biodiesel Possibilities from the above article in a publication of the U.S. Department of Agriculture A feedstock for chemical production to replace petroleum-based chemicals. Converting it to hydrogen (and other stuff) to use as an energy source. An Austrian firm has devised a way of burning it in specially adapted engines to produce electricity (note that in general crude glycerin does not burn very cleanly). A Belgian firm is building... a methane digester system that uses crude glycerin and resulting biogas from a commercial-scale biodiesel facility to power the plant itself. But for now, make no mistake, there is a glut in crude glycerin supply.

19 Biodiesel from Algae, becoming a reality?

20 Biodiesel from Algae, becoming a reality?

21 Maybe not...

22 Research indicates biodiesel is quite promising: in particular, it is scalable!!

23 Land area needs for various biodiesel sources

24 Solix actually sold this system at some point Solix claims they have reached 3000 gallons per acre per year. Christi s lesser algae number, 58,700 liters per hectare, comes to 6,279, not that much bigger.

25 Solix s Dream? (Their illustration anyway) Artist s conception of large-scale Solix Biofuels plant in Colorado

26 Land area for creating sufficient biodiesel for all our transportation needs using algae 441 million acres devoted to cropland (for comparison) million acres The land required to produce sufficient biodiesel for all our transportation needs (upper estimate of Chisti, 2007) This is a very big deal - it is the first biofuel we have discussed that might actually solve our problems!

27 Comparison between algae and soybeans for creating sufficient biodiesel for all our transportation needs 441 million acres devoted to cropland (for comparison) million acres The land required to produce sufficient biodiesel for all our transportation needs using algae (upper estimate of Chisti, 2007) 2.67 billion acres The land area required to produce sufficient biodiesel for all our transportation needs using soybeans (Chisti, 2007).

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