See, I want ethanol (or ANY renewable, clean fuel) to work. I really do. BUT...the numbers don't add up in most all scenarios. I see time and time again where the pesticides, fuel for harvesting/processing, and many other environmental issues are just ignored in claiming ethanol is good. Why would we expend oil to make a fuel that isn't as good as oil? Where's the logic in this? Oh, wait, govt. subsidies, got it...hey, that means I'm paying for this already...how is it cheaper then?

Why even mess with the the liquid fuel? Doesn't it seem we are increasing steps to power our cars when we should be turning windmills, capturing solar energy, charging a battery to turn the wheels. Done. No oil wars, no oil spills. KISS. (keep it simple stupid)

 

Solar, yeah. I guess the parking garages will be free and we'll pay to park out in the sun.

I'm at work and don't have much time. Here is some calculations I did in the past. Note that the total amount of solar energy in a square meter isn't that great even before you start adding up inefficiencies. You mentioned batteries, but I was using the hydrogen model. With batteries, you might only need 27 square meters of high tech solar panels for a car my size (20 mpg) in the summer. Winter, different story. That's gonna be a tough one, and that is only for 10,000 miles per year.

Here we go:

In the continental US, an average of about 4KWhr of solar energy per day per square meter reaches the surface (I deduce this from using the southern area of Iowa as a reference). This is much lower in the winter than the summer. I'm assuming we can store enough hydrogen so that peak demand and low winter production isn't an issue.

For my calculations, I will assume that we're using 25% efficient solar cells. I don't think these are readily available in the market, but they exist and are used in megabucks solar car competitions.


Last year my household energy consumption was 21,680KWhr of electricity, and 300 therms of natural gas. Assuming my furnace and water heater is 80% efficient, I used 240 therms of actual heat, which is 24,000,000 btu, which is 7034 KWhr. My total energy consumption in KWhr is 28,714.

4000 watt hours daily per square meter x .25 (solar cell) = 1000Whr daily per square meter
1000Whr daily x .65 electrolysis efficiency = 650Whr of hydrogen daily per square meter
650Whr daily x .5 fuel cell electrical efficiency = 325Whr daily per sqare meter
325Whr daily x 365 days = 118.6KWhr per year per square meter

My usage of 28,714KWhr divided by 118.6KWhr = 242 square meters for my household energy consumption.

FYI, my car at 10,000 miles per year at 20MPG would require an additional 77 square meters using fuel cells. That's below average milage, and average fuel economy. In a household with two 14MPG vehicles and a total of 30,000 miles per year, you'd need 330 square meters (3,550 square feet) of solar panels just for the vehicles!

 

I agree. And corn is one of the most pesticide/chemical intensive crops there is.

 

Nice post.

The only reason Ethonal has a chance is because the lobbiest are pushing this issue which is totally the wrong approach. Yes ethanol has its place in the economy but its a limited use case. Biodiesel is the right approach... and only a certain type of bio diesel, that produced from algae. The rest of the biodieel also have a very limited application.

 

Well that's what the middle of the US is for. There nothing there.


The algae study to produce biodiesel has a much lower number and would go into places like deserts where it thrives. Ideally you would have these plants scattered throughout the US so that distribution is made easier and more importantly, security. This way you can't just blow up one plant to damage the economy.

 

OK. I looked into biodiesel from algae. The article I read said we can get 7.5 billion gallons from 780 square miles. I did some math, and something isn't adding up:

780sq miles = 7,500,000,000 gallons biodiesel
1 gallon biodiesel = 130,000 btu = 38,100 Watt Hours
780sq miles = 285,750 gigawatt hours
1 sq mile = 2,588,881 square meters
1 sq meter algae = 110,375,882 watt hours annually
1 sq meter algae = 302,399 watt hours daily

This is 50x more than the actual solar energy that reaches the earth daily in a square meter in Iowa as an example. Sure, some places receive more... maybe twice as much? It still doesn't add up.

Is my math wrong here?

 

Sorry, my math was wrong.

1 sq meter algae = 141,507 watt hours annually
1 sq meter algae = 388 watt hours daily

I guess that's doable. I guess we can conclude that algae is less than 10% efficient, since over 4000 watt hours a day reaches the surface, especially in candidate areas.

 

The beauty of the algae is that it returns over 50% of it's weight in energy. The other thing that is really nice is that it thrives in areas that we really can consider "waste" land... yes the desert is beutiful and all that and we should not destroy every desert with an algae plant but we are talking a small amount of land compared to other forms of bio-fuels.

 

I've seen estimations that we use about 140 billion gallons of gas/diesel a year. We'd need about 18x the 780sq miles I mentioned earlier, or 14,040 square miles of algae.

I wonder what sort of energy inputs and infrastructure would be required to support that. For example, don't you need to replensish a lot of water all the time?

Just trying to better understand the algae option.

 

depends on what you mean by "we", C.O... [ethniccian joke}....

how about 7,300,000,000 [that's 7.3 billion (corrected: barrels)] per year for the USA, per the DOE at http://www.eia.doe.gov/pub/oil_gas/p...20see%20detail

(ok, that is 306.6 billion gallons per year... i sit corrected. )

(i took what i estimated as 20 million barrels per day for the USA and multiplied by 365. per that graph, the whole world's using about 28,470,000,000, or under 30 billion barrels a year. check my decimal points, please?)

or don't believe the DOE. so that would be about 3.6 times the original estimate, not 18 times......

did i miss something, here? (yes, a factor of 42... )

hmmm... now how many states or parts of states would it take to generate 14,000 square miles? http://nationalatlas.gov/articles/ma...neral.html#one

if we all chip in, .004 of the country....

by the way, if you want a clear picture of why gas prices shot up after the hurricanes hit texas and louisiana? click here:
http://www.eia.doe.gov/pub/oil_gas/p...USregl_cap.htm