The best replacment for gasoline is ?

I suggest it is either batteries charged with solar energy OR alcohol derived from sugar cane (or possibly sugar beets at latitudes too high for sugar cane's economical growth). More on both in later posts, but first, for reasons long known,* we rule out corn as the source of alcohol:

In summary: Corn raised for ethanol means more fertilizers, pesticides, and herbicides in waterways; more low-oxygen “dead zones” from fertilizer runoff; and more local shortages in water for drinking and irrigation.

* The US's corn to alcohol program was created for political reasons. To a large extent the above known damaging effects and great cost have nearly ended it now.

 

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Please note at ALL alternatives suggested at start of the OP, are recently received solar energy. I. e. wind power and sugar cane are low tech versions and solar cells are a high tech version. We need a sustainable energy source, not a finite one, even if fossil fuels were not causing potentially very serious threats to many life forms.

 

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Liquid fuel? Biodiesel. Higher EROEI (5.5) than any ethanol based fuel, due mainly to the lack of requirement of fermentation and distillation.
Gaseous fuel? Methane. Available from a wide variety of chemical and digester processes. (Fuel from waste)
Overall? Battery storage of solar (as you mentioned.)

 

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Fermentation does not need energy input. (Is actually slightly exothermic, I think.) The crushed cane remaining after the sugar juice has been sent to fermentation burns with high quality (high temperature) heat. This heat generaof ttes about 4% of Brazil's total electrical energy on an annual basis.* The temperature of the electric generator's turbine exhaust is well above distillation requirement so the heat exchanger used is small. The energy content hat exhaust is much more than distillation requires, so some low quality heat is just dumped to the air.

Net result is only significant** energy input, is truck fuel that brings the cut cane to the distillation center and for some fertilizer (not essential, sugar cane is a grass - grows without fertilizer) which is used as the increase it gives in yield per acre more than pays for buying it. Thus the EROEI is greater than 10 for sugar cane alcohol. This contrast sharply with alcohol from corn. It EROEI is never even 1.2 as natural gas supplies the distillation heat. Most disinterested studies, such as large one done by Cornell University show corn based alcohol's EROEI is significantly less than unity. AFAIK only the university of Iowa has it EROEI as high as 1.1, but I have not checked this EROEI question for a few years.

* I don't think the EROEI analysis gives any credit for this energy production as it is not energy in the alcohol produced.

** we don't count the food eaten by workers cutting the can or re-planting it about every 5 or 6 years (the cane grows back from the roots, like all grasses do.)

 

Sure it does. It needs temperature control and pumping, as well as pH control of the mash.

Considerably exothermic. And while all those yeast are making alcohol they are also making heat and CO2.

You're making the argument that you can use tricks to get that energy for the process, and that's fine - but that is energy that is not available for other energy production (like the electric energy production you mention.) It needs to boil water for distillation, which means it is not low quality heat.

That is absolutely not true, and if you are using a source that claims that, it is severely flawed and not trustworthy.

The more competent studies I have seen put EROEI for cane sugar ethanol at about 5 to 1 (which is still quite good.) If you have any competent studies that put it significantly higher than that I'd be interested in seeing them.

 

Food is the best replacement for gas.

 

I would like to see your reference which makes it that low! Here is one I posted long ago. Its data is about a decade old now, and the genetics have been improved for higher sugar content, etc. now:

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Here is some EROEI data only four or five years old:

Its way past my bed time now. I'll trying to find some showing the improvements that have recently been achieved.
I think almost 15 has been achieved, with no fertilizer used.

 

I agree with battery power, but not with solar power to charge the batteries. The best time to charge batteries is at night and the grid peaks on bright, sunny, hot days. Charging at night and using solar to reduce grid peaks results in cheaper power, cheaper solar installations and/or more solar power generated, less fossil fuel usage and fewer fossil fuel plants being built.

 

All will agree that "load leveling" should be done as much as is economically viable. It makes for higher average utilization of the capital invested in the energy system, but it also often requires capital, so there is an economic optimum.

The question is mainly how much should be local (at the consumer) and how much should be central? With "smart grids" more can and should be done locally as the capital per peak KWH shaved off (reduced) can be dozens of times (if not a 100 times) less than with central energy storage. Better than even fixed time of day rates achieve and even those are at least a few dozen times less costly per KWH of peak reduction.

It is not inconceivable, but I think highly probable, that NONE of the energy storage should be at the central generation facility. I.e. It should all be local or "quasi-local" (at the neighborhood's sub station where higher voltages are stepped down to 110V or 220V). This reduces not only needed peak generation capacity, but also the capital invested in the distribution system. Very economical per KWH stored, but heavy batteries already exist and better ones are nearing or in final life-cycle testing / evaluation. One of the older ones, based on iron, still has 90% of its initial capacity after two decades of daily deep discharge, is very safe, and is quite cheap, as iron is!

Furthermore, solar cells are always made in panels the size a couple of men can easily install (or smaller) and generally speaking, are more economical if they do NOT track the sun per annual KWHs generated. (I.e. a few more provide the same output at less capital cost than those that do have sun tracking motors, controls, etc.) Very modular for "roof top" installations. Note the panels have no latitude tilt. - Possibly to avoid wind torques in the "once in 30 year storm" ? Also note the rows are about a panel length apart but contact each other side to side. That, and their lack of tilt, will double the rain fall on ground between the rows and the panels are higher than need be, unless cows will graze the rows of growing grass. The Chinese lead the world in solar cell production and use and know what is best.
See these facts in photo below.

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China will add 3 times more PV cell power this year than US did last year!

 

Extending my post 8 a little:
The "no fertilizer" approach is not as profitable as with fertilizer so only used now in smaller scale. There also the cutting is manual still. A decade or so ago, most cane was manually cut and finding work for the former cutters, with low skill (many functionally illiterate) in Brazil has been a problem. Typically these smaller, but still commercial sugar cane fields were planted with soy beans for at least one year every five, so the available soil nitrogen would be restored.

If the world were to switch to alcohol fuel for all its cars needing liquid fuel, the conversion would take about 10 year (much faster than if done by switch to EV powered cars, in part because even Musk's "gigafactory" battery production could not achieve that and secondly because people will not scrap the new car they bought last year. Not to forget at least 40 times less costly a change - Li/ion batteries of adequate range, ain't cheap.

Modern car will be on the road for at least 15 years, on average before being "junked." They can, however, be converted to alcohol only (or flex fuel) in less than a day, as are IC engines, with less than 1% of the cost of Musk's projected price ($35,000) for his new "popular" model 3 now planned. I. e. Every gasoline powered car, more than a year from its final trip to the junk yard, could be converted to use alcohol in much less than a decade (and when done in large volume at conversion centers, at a cost of less than $150.)

About a decade would also be required to plant new cane fields, mainly in African grass lands and abandoned pasture land AND build the many new fermentation / distillation centers needed. They should be relatively small so can be supplied with cane grown on less than 25 miles away, on averge. I can imagine a great economic and social change in Africa with new, planned towns. Each centered on it "energy and civil" center. I.e. where the cane is converted into alcohol, where the schools, hospital, courts, police, government, restaurants, food stores, entertainment and sports facilities etc. are. No cars would be allowed there - only shared publicly owned bikes,* (Some three wheelers for the old and some with cargo bin between the two rear wheels.)

The towns base load electric power would be generated in this center too. In part from the crushed cane and in part from solar cells (and wind power made in the cane fields) with some waste heat thermal recovery for heating hot water used the in the restaurants (washing dishes, etc.) and other demand** for low temperature water (even public baths, like in old Rome, or swimming pools in winter.)

Surrounding this central zone probably is a hexagon shaped band of residential units, mainly apartments, each with communal gardens, for those who wish to grow some of their own food. Beyond this is a second, much larger in area hexagonal band where the sugar cane is grown. A hexagon is suggested for each town, as that "close packs" with six others, all about 70 miles separation, town center to town center. A large fraction of the African population, lives out-side the "cash economy" This could be changed, making them with salaries and into buyers of 1st world production. - A win/win for all but "big oil."

* In many of the world's cities, recently public shared use bikes now exist. In Sao Paulo the first hour of use is free and you can leave the bike in a "capture stand" different from where you got it. On side panels next to rear wheel are ads, mainly for banks. I think the ad fees paid for the buying of the bikes. Your small charge, made via you cell phone, for more than hour of use pays for the city's trucks that come to swap out bikes needing repair.

** Quite possible the hot water needs of the near by residential zone too, a charged by volume used service.

P.S. I have not investigated, but bet many of these "hexagon" (or square?) adjoining towns could be along side of rivers, which would assure water table for town's well is not deep AND possibly cheaper than pipeline transport of the alcohol for sale to an ocean port. If the boat "African Queen" of a famous old movie could survive going over a water fall, then about 100 gallon, reusable, plastic drums full of alcohol could too. That would be even cheaper transport to the port than a pipeline, I think. Alcohol is lighter than water, but I have not estimated the least volume required for drum full to float. 100 gallons is just a quick guess. Each town's drums could be a different color.

 

Billy,

What about also switch grass? I seem to recall reading something about switchgrass and sugarcane being the 2 that has the highest EROEI.Also switch can be grown in many arid places.

Heck if in America all the grass yards,golf courses etc were replaced with plants for fuel we would have plenty! I assume?

Tim

 

There are two problems with switch grass:
(1) Its EROEI is much lower (factor of more than 4) than sugar cane - It is essentially the same as the "wheat straw" shown in right chart of post 7. Economically wheat straw (or saw dust) are much better than switch grass as they are free by-products of an already economically viable agricultural activity.
(2) It requires "2nd generation" technology, which thus far (more than a decade of intense billion dollar effort) is a total failure economically. I.e. "cellulosic alcohol" may be a pipe dream, even with by-product, nearly free, cellulose as the feed stock.

 

Liquefied and compressed natural gas

Natural gas vehicles, operating on either liquefied or compressed gas, produce mileage similar to gasoline but burn more cleanly. The Energy Department estimates that some 112,000 vehicles powered by natural gas are currently in operation. Most are medium and heavy-duty trucks, but Honda HMC 0.87% has offered a natural gas Civic (above) since 1998. It is slower than a gasoline one, has a limited range and refueling network, and costs thousands of dollars more. In its favor are cheaper prices for a fuel that is produced domestically and lower emissions.

hydrogen-powered fuel cells

Like a fictional El Dorado glimmering in the distance, affordable hydrogen-powered fuel cells have been an elusive goal for a generation of researchers. Hydrogen is appealing because it can be produced domestically and burns cleanly, and fuel cell vehicles are two or three times more efficient than gasoline-powered ones. What's held them back has been the cost of building the cells themselves and a network of fueling stations to distribute the hydrogen. As a result, small fleets of FCVs are being tested by manufacturers, but no fuel cell vehicles have reached the consumer market. Two notable models in limited tests: the Honda FCX Clarity, and the 2012 Mercedes-Benz F-cell (above), which gets 52 miles per kg of hydrogen (roughly equivalent to a gallon of gasoline).

 

I agree. Both should be (and will be) given a shot at being the replacement for gasoline. The natural gas powered car makes significant reduction in the volume of CO2 released annually but is still a "fossil fuel" {With economically competitive production of it}. If made, as H2 is, then it is not directly a CO2 source. Then it really is, like H2, only an energy transport and storage system, not a fuel.

In the US there is a big "how to switch" problem, almost insolvable for H2. Not so in Brazil. At least a fourth of all filling stations already offer natural gas as nearly 100% of taxi use it. They mainly make shorter trips, and have just removed the gas tank the car maker put in and have replaced it, with a yellow (fiber glass reinforced, I think) plastic cylinder with hemisphere ends. They may have lost a small amount of road clearance - easy to see these yellow tanks from behind the taxi, but as they need to keep the trunk space for passenger going to air port, etc. the full trunk space is preserved.

I don't think the DoE's count is including global natural gas vehicles as I bet there are 50,000 taxis in the state of Sao Paulo alone and well more than their 112,000 in Brazil.

 

Why not mount them on the tops of the cars? They can redesign them to lie flat on the roof and make them shaped like a wing. That way there's no problems with ground clearance and it would be easy to service or change if needed.

 

That will work for a while. Eventually you have the "duck curve" problem, and those batteries will be needed to absorb the excess energy generated during the day (and, on occasion, releasing it in the evening just after sunset.)

 

Not a significant return on investment. You can get about 500 watts if you covered every single surface of a car with PV. That would take 48 hours of direct sunlight - or 12 days - to recharge a Nissan Leaf, assuming every day was sunny. (And of course would add significantly to the cost of the car, as well as reducing its range.) Much better to mount 5 kilowatts on your roof then feed the power into the grid. Then the grid is there when you need it to recharge.

 

Sorry , I was referring to a natural gas type of taxi that had the refill tank under the car.

 

Oh, sorry. In that case I agree. Works for buses. Only issue is they get hot, so you have to reduce the amount they carry to prevent explosions due to overpressure.