Sunday, February 26, 2006

Fueling Transportation - Renewable fuels

Is President George Bush grasping at the straws of hydrogen cars and cellulosic ethanol fueled cars - to replace our oil addiction? Let’s take a look at energy options for transportation.

Today most ethanol is produced using by letting yeast have at corn sugars. That is a bit of a shame because those sugars also feed us humans.

To offset the USA's oil imports the quantity of corn need, to convert into the ethanol using current ethanol production technology, is simply staggering. American would need about 400 million acres of land in corn with all the corn going to ethanol production to replace all of our current oil imports. Currently there are about 325 million acres of cultivated land and about 80 million acres are in corn.

Also remember corn is fertilizer hungry- and fertilizer is mainly natural gas. The Haber-Bosch process is used world-wide to manufacture ammonia. The process reacts nitrogen (N), from the atmosphere, with hydrogen (H), typically from natural gas, to produce ammonia (NH3) over an iron catalyst under conditions of 200 atmospheres, 450°C. The chemical formula is:
N2(gas) + 3H2(gas) = 2NH3(gas)

Manufacturing 1 ton of anhydrous ammonia (which is 82% nitrogen) fertilizer requires 33,500 cubic feet of natural gas. Applying 80 lbs of nitrogen per acre get you about 135 bushes of corn in Kansas. In other words it takes 12 cubic feet of natural gas to grow one bushel of corn and it takes 1630 cubic feet of natural gas to produce the nitrogen fertilizer per acre of corn.

For that 400 million acres of land in corn - needed to displace our oil imports, it would take 6.5 trillion cubic feet of natural gas to make the fertilizer.

So corn based ethanol has two huge limitations
  1. There isn't enough land to grow the corn with out starving the nation (and other nations that depend on our corn and wheat exports), and
  2. it requires massive amounts of natural gas.

If ethanol is to supply a significant share of US's fuel needs the hope is that it can be based on cellulosic feedstocks. "Cellulosic" includes stuff like wood chips, grasses, leaves, that is found in agricultural and forest residues (e.g., the corn stock), and trees.

But it all hinges upon new bio-technologies, a.k.a. enzymes, being developed to break down cellulose and release the plants’ sugars for yeast fermentation into ethanol. Those enzymes do not exist yet - and they need to be able to break down many types of cellulosic feedstocks into sugars.

Other options

Biodiesel from soy. Basically this process squeezes the oil out of soy (hemp could also be used, or other oil seed crops). The soy oil is processed into diesel and the solid soy materials are used in food or feed. It is simple but requires lots of agricultural land, although soy needs much less fertilizer and corn.

Aqueous phase reforming (APR) hydrogen production. This is a hydrogen production method being developed by a start up here in Madison WI called Virent Energy Systems. The APR system generates hydrogen from aqueous sugar solutions such as ethylene glycol, biomass-derived glycerol, sugars and sugar-alcohols. It uses a catalyst (platinum coated beads) that under moderate temperature and pressure breaks the hydrogen off the aqueous sugars. That hydrogen is collected and is a fuel - like gasoline or ethanol.

To date the APR process only works on a few types of sugars, so they need purity in the aqueous solution... unlike the ethanol process that can use hundreds of sugars and be pretty messy. However Virent is just starting up and are working to expand the sugars, reduce the purity needs of the sugars, etc.

It does seem like the APR process is more energy efficient than the ethanol process.

Check out their presentation at:
http://www.virent.com/pdf/Website%20Presentation.pdf

Algal Hydrogen - has been in the news recently. Here is some information from Wired News of 25-February-2006 - (I edited it down)

Researchers at the University of California at Berkeley have engineered a strain of algae (known as C. reinhardtii), that with further refinements, produce vast amounts of hydrogen through photosynthesis. The work, led by plant physiologist Tasios Melis, if it proves correct, would mean a major breakthrough in using algae to produce a wide range of products, from biodiesel to cosmetics.

Melis figured out how to get hydrogen out of green algae by restricting sulfur from their diet. The plant cells flicked a long-dormant genetic switch to produce hydrogen instead of carbon dioxide. But the quantities of hydrogen they produced were nowhere near enough to scale up the process commercially and profitably.


The new strain of algae allows more sunlight deeper into an algal culture and therefore allows more cells to photosynthesize. Researchers hope to further boost hydrogen production, and reduce carbon dioxide production by using genetic engineering to close up pores that oxygen seeps through. "When we discovered the sulfur switch, we increased hydrogen production by a factor of 100,000" says Seibert. "But to make it a commercial technology, we still had to increase the efficiency of the process by another factor of 100."

Researchers are now trying to adjust the hydrogen-producing pathway so that it can produce hydrogen 100 percent of the time. A bigger challenge, and one that’s further down the road to solving, is improving the efficiency of getting hydrogen out of the "algal culture". Whether or not scientists can find solutions for those two problems will have a lot to do with realizing the vision of a hydrogen-powered economy based on algae farms in desert areas.

Some algae are also viewed as an ideal source for biodiesel because they can produce oils at a much higher rate than other plants. For all these applications, Melis’ antenna-truncated algae should be a major breakthrough.

Batteries - Plug in Hybrids Whatever the fuel, hybrids make sense. Basically hybrids are an energy efficiency improvement where:

  1. energy is taken when the car's breaks are applied,
  2. to spin a generator,
  3. producing electricity,
  4. storing the electricity in a battery
  5. using the electricity to drive a motor to power the wheels when power is needed.

For years this was known as regenerative braking. If I recall correctly they use it on locomotives and large cranes, and the electric generator and the electric motor can be the same component. With regenerative breaking cars get more miles per unit of fuel (gallon of gasoline to algal hydrogen).

Hybrids also get additional fuel savings, by turning the internal combustion IC) engine off when it is not needed (e.g., at a stop sign or when the electric engine is power the car) and by being able to use a small more efficient IC engine. Or course they tend to be small light and aerodyanmic as well.

Now add onto hybrids, plugging the car in and adding larger batteries. What this allows you to do is start the car off with a full tank of batteries even if you parked with an empty tank. The smart system would wait until electric power is "cheap" to fill batteries. Cheap power today is between midnight a six in the morning. But in the future it could be when the wind is blowing or the sun shining.

You could also have solar electric panels on your home's roof that help charge up the car's batteries. Simply adding panels on the car - charging the batteries whenever it is sunny could improve its efficiency a bit. This is a link to someone that has done it - created a solar prius. Now with charged and larger batteries the car would get even more miles per gallon of gasoline, biodiesel, hydrogen or ethonal.

If you plug your car in at your job downtown - and there is a power shortage spiking up the value of electricity (to where it is worth more than what is in your battery) the smart utility grid would drain your battery - and pay your for it.

Both of these technologies, hybrids and smart charging systems, are ready - all we have to do is implement them.

Also expect cars to get lighter and smaller. And people to drive less.


Comments:
why not use geo thermal as a source for heat to generate steam to drive turbines for power to split water? Simple and no carbon, Iceland is a good place i am sure there are others,
 
There are two types of geothermal - basically low and high temperature. High temperature you find in active volcanic areas (New Zealand, Iceland, Hawaii, California...). With it you can get high temperature steam and drive turbines. In fact that is what they are already doing in most of those places.

However the other type of geothermal is low temperature - about 55 degrees in fact. That is the Wisconsin type of geothermal... and it can only really be used with heat pumps (i.e., ground-sourced heat pumps) or for refrigeration caves.

Vermont has a program moving cheese production out of air conditioned/refrigerated buildings and into naturally cool caves.
 
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