Synfuel

Synthetic fuels (synfuel): usually coal to liquid (CTL) or (natural) gas to liquid (GTL) but also sometimes based on biomass (biofuel). A way to achieve energy security– e.g. the U.S. has massive natural gas reserves and even more massive coal reserves. If we want to cut our oil dependency, synfuel is one answer Muller, 107
Synfuel from coal and natural gas doesn't make economic sense– CTL is about $60/barrel, and though oil can get that high, it's not dependable (oil price fluctuation can be enormous and is not dependent on true supply/demand but more on supply chain and OPEC) so building infrastructure for synfuel is too risky when Saudi Arabian oil can be drilled for around $3/barrel Muller, 107

Biofuel

Brazil weaned themselves off of global oil dependency via the National Alcohol Program (1975). Required oil company to blend at least 22% ethanol (made from local sugarcane) into its fuel, while offering low-interest loans. Lovins, 160
Ethanol is not an efficient energy source. The energy content of ethanol is 65% that of gasoline Smil, 98
Corn-based ethanol requires more land than we can use. If all of America’s gasoline were from corn derived ethanol, the growing of corn to cover American fuel use would require 220mil hectares, 20% more than American arable land Smil, 101
Ethanol-providing crops can contribute to environmental degradation. In corn crops, nitrogen fertilizer runoff is a key negative effect (p103). In other crops, such as sugar cane, expanding need for arable land can contribute to deforestation Smil, 101
Sugar cane is better than corn for ethanol production because it requires minimal fertilizer and has a higher power yield per hectare of planting Smil, 104
The United States has high tariffs on Brazilian sugar cane ethanol, so it is not commonly imported into the United States Smil, 105

There is government support for cellulosic ethanol plant development in the United States
Cellulosic ethanol is a promising technology to turn waste into biofuel, but it is yet unproven as commercially viable. Though it will take decades to scale up this industry, it is worthwhile to research potential processes for creating cellulosic ethanol Smil, 108.
Biodiesel: can be made out of many things - not just waste oil and food but also "trash" such as dirty diapers and styrofoam cups. Typically, these types of solutions create cellulosic ethanol Lovins, 162-163

Since energy density is lower in biofuel than in gas (and we have inefficient vehicles) miles per gallon would be low and fuel weight could be significant in a biofueled car Smil, 114
Issues with upstream emissions (e.g. deforestation for plantation of fuel-source plants) crimp spread of biofuel as savior Lovins, 161

Learn more about: landfill gas (LFG). This is an RPS qualifying renewable in some states

[aggarwal]: https://www.sciencedirect.com/science/article/pii/S1040619013001917 "Aggarwal, Sonia and Harvey, Hal. 'Rethinking Energy Policy to Deliver a Clean Energy Future.' Energy Innovation, 2013."