Sean K.'s Comments

With 219,000 TWh of energy available from the sun every year... How so? ... you might ask.

Insolation at the Earth's surface is approximately ~1000 watts per square meter for a surface perpendicular to the Sun's rays at sea level on a clear day. So, the Sun sends on average ~1000 Watts for every square meter (~1 kW/m^2) of infrared, visible and ultraviolet electromagnetic radiation only where it shines down directly at 90 degrees, like at noon on the Equator. Accounting for lower sun angle evening and morning of each day and sun angle changes over seasons the average insolation for the Earth is approximately 250 watts per square meter (6 (kW*h/m^2)/day). or (~1 kW/m^2)(6 hrs/day).

The Earth's land surface area is ~148,940,000 km^2 (29.2 % of the total surface area) or ~149E12 m^2.

365 days/year * 6 (kW/m^2)(hrs/day) * ~149E12 m^2 = ~326,000 TWh/year

Taking into account clouds and/or haze @ ~1/3 of the time ...

~219,000 TWh/year = 0.67 * (~326,000 TWh/year)

other wise known as ~219 PWh (peta-watt hours).

When the AURORA Wind Inverter is operating, is the DC source power "electrically isolated" from the AC output at all times? I.e. does the Inverter use a transforemr or does it only use high speed IGBT H-bridge switching?

Hydrogen molecules H2 have the greatest energy density (by weight) of any combustible fuel in the universe.
As a highly volatile gas it is still safer than gasoline because all free hydrogen molecules released into a normal pressure and temperature environment (1ATM, 25 degrees C) rise at 17,000 miles per hour, while gasoline is liquid in that same environment and the vapors are heavier than air, so its flammability stays on the ground.

If hydrogen gas (H2) is produced by electrolysis of water using strictly renewable energy sources and not by reforming fossil fuels, then it is carbon neutral energy. It can be liquified, put into tankers, or into pipelines and carry more energy per kilogram than any other fuel. One kilogram of liquid hydrogen has the approximate same energy as one gallon (about 3kg) of gasoline.

Further, since liquid hydrogen (cryogenic @ -253 degrees C) is a superconductor, then pipelines containing it can serve as superconducting transmission highways to deliver electrical power without the now existent power losses endured by transmission through high-tension (and resistive) wires.

Hydrogen can run an internal combustion engine more efficiently than gasoline. Fuel cells are not needed to utilize hydrogen and serve as the power source in hydrogen vehicles. Liquid hydrogen can be stored in zero pressure tanks (actually unsealed) that are surrounded by liquid air cooling jackets and high density insulation. The enrgy to volume density of these types of tanks can rival normal automobile gasoline tanks. As I mentioned earlier the energy to weight density of liquid hydrogen far outstrips any current liquid fuel.

Hydrogen gas or liquid can be but need not be (an maybe should not be) produced using fossil fuels, either as the raw material (reforming methan (CH4) to H2 and CO2, for instance) or as the source for electrical power.
Hydrogen produced from renewables is CARBON NEUTRAL energy. Hydrogen from renewables serves as the best way to "CARRY" the energy from those sources. This is the most IMPORTANT part of using Hydrogen, as an "energy carrier".

One sun insolation means no concentration. So, with concentration, the "footprint" area for the solar collection panel does not change, but rather the number and area of the solar cells within the device. Concentration allows the devices to be potentially less expensive for the same output wattage. Increaseing the effciency of conversion from photon energy (solar) to electric energy will allow solar electric panels to deliver more watts per square foot. Efficiency of 40.7% through the use of multijunction cells is a great achievement! Now, the test will be the reality of the claim at $3.00/watt installed and $0.08-0.10/kwh in operation.

Hi Jeff Birkby,

I accept your analysis that rotting vegetation under the water in large resevoirs produces substantial greenhouse gas emissions (CH4 and CO2, etc.)

There is a solution to this problem. If the vegetation on "to-be-flooded" land is denuded by burning and burying the charcoal, then it will stay. The half-life of charcoal in the soil is measured in thousands of years! (See Terra Preta De Indio soils). If the biomass were gasified rather than burned (a co-product of gasification is charcoal), then the off-gas (synthesis gas) could be used as a fuel and the charcoal (~30% of the carbon in the original biomass) could still be buried. The best solution of all would be to harvest all of the biomass from the "to-be-flooded" land, convert it to gaseous fuel (or liquid fuels, like methanol) and charcoal, then use the charcoal as a soil amendment in the land surrounding the resevoir. Charcoal is a tremendous soil amendment (again, see Terra Preta De Indio soils).

Hi E.F.Lucas

Oil, coal, and nuclear power currently receive much larger subsidies than any of the alternative energy sources. On a level playing field (i.e. no subsidies for anyone, taxes on the public, incentives for corporation, tax relief for corporations, etc.) and a true costing of things like pollution, national security, carbon emissions, land remdiation, etc, then 21st century Alternative Energy sources could easily compete against oil, coal, and nuclear energy.

The big footprints of the 20th century energy industry will cost us dearly in the 21st century.
Alternative Energy in the 21st century is THE ONLY WAY to reduce those costs. The 20th century energy industry has to be made to play fair and be accountable for the mess they put us into, also.

I agree with Charles Butterfield and Paul Johnson. The very best incentive for renewable energy is the huge price increases in the fossil fuel industry. Renewables will soon or can maybe even now provide more BTU's at more favorable prices than fossil fuels. Consumer's can appreciate simple supply and demand economics and the resulting price increases. They can be educated by renewable industry marketers on how to make changes that will benifit their expenditures. Sell them! If the renewable industry has any market forces whatsoever, then they will find a way to compete favorably against fossil fuels and win more market share. In Europe, where petroleum prices have been $3-5 a gallon for a long time, solar and wind energy installations more than double what we have in the US.

I read an article in the journal "Science" once, about a method for extracting H2 from 100 proof ethanol. It involved passing vaporized ethanol/water over a heated Rhodium catalyst. It said that more H2 could be extracted from 100 proof ethanol (that's 50% ethanol, 50% water) than from pure ethanol. Some of the H2 was cracked off the water molecules in the process. I think that the "drying" of ethanol is the largest energy input into the production of ethanol. It seems to me, then, that a more efficient way to extract the energy from corn would be to harvest H2 from "wet" ethanol.

Dave Pimentel's "study" is outdated, having been done in 1991. Modern fertilizer production and ethanol production have greatly improved the net energy value of producing ethanol to 1.34.

It should also be noted that a gallon of gasoline doesn't just blow up out of the ground in Saudi Arabia and into your gas tank for free. There is an approximate 20% net energy loss to produce a gallon of gasoline from raw petroleum and transport it into a vehicle in the USA.

On balance, local ethanol production using local energy resourses to produce a cleaner liqued fuel for use locally seems like a better way to go, for our local economy and for our global environment.

Producers of biofuels need to buy crops at prices those market prices, and pay to transport the raw materials to their plants. Those costs need to allow them to make profits. If the energy required to farm the crops exceeded the energy output from the produced biofuel, then these businesses could not afford the crops, nor would they pay to transport the raw materials, because you cannot buy what you cannot afford.

Then the energy inputs and associated costs of production for biofuels would also play into the economics and should also bear out that these costs (for energy inputs), plus the crop and transport costs are lower than the price of the produced fuel. With a subsidy of only 20 cents per gallon and a price of $1.89/gallon for Ethanol, I do not believe it would be possible to stay SUSTAINABLE let alone even enter into the business of Ethanol production. The capital costs involved in building the production plant are also large.

There are hundreds of operating Ethanol production plants in the US alone. Are we to believe that all of these business people are working with stupid investment bankers who see that they pay out more money in raw material and production costs than they make in revenues from product sales ?!

The price of E85 fuel is always at least 20 cents lower than both regular unleaded gasoline and diesel.

The physics law of Conservation of Energy also prevents these biofuel producers from making the excess energy output (above the energy inputs) from nothing and then allowing them to sell that.

David Pimentel, professor of ecology, needs only to look up into the sky, at that strange ball of fire, to see where the surplus energy comes from.

Now my premise above is entirely specious if farmers work for free, on land they do not own, and pay wildy cheap prices for the fuels they use. The producers also do not pay their employees, work in other people's buildings, with equipment that just appeared one day, and they violate one of the most imprtant laws of physics every day.
Worse of yet, are those silly Europeans, who are paying $4.00 and $5.00 a gallon for fuel used to produce crops like rapeseed for biodiesel.

What you need is a professor of ECONOMICS to make this analysis, Dave!

I cannot stop. Dave, production of biofuels do not contribute to "... air, water and soil pollution and global warming." The crops take CO2 out of the atmosphere and buring the biofuels merely puts it back. That means NET ZERO CO2 emissions! That means no increase in global warming due to excessive green house gas emissions.

There are no benzenes, nor sulfur, nor nitrogen coming from the buring of oxigenated hydrocarbons like ethanol or biodiesel. Those pollutants only come from fossil fuels like gasoline and petroleum diesel. That means no air pollution.