IEEE Spectrum: Biofuels Aren't Really Green Their model suggests photovoltaics are a better answer than a biofueled world economy. I have no opinion one way or the other but it is an interesting hypothesis and model. So this begs a question ... Is enough solar energy impinging upon streets and highways to power electric vehicle transportation? Bob Wilson
There is clearly enough solar energy landing on the streets and Hwys, but that begs the question of being able to usefully capture it. I'm not sure that trying to capture it through the pavement is the best/most efficient alternative. On the other hand, it is increasingly clear that bio-fuels are not the solution, although they might be a tool in a stop gap. I read a stat once that stated that we collectively burn ~ 16 terrawatts (tw) of energy per year world wide. ALL biomass grown on the earth's surface, ALL OF IT, creates ~20 tw worth of biomass. Can you imagine a scenario where we burn ~70% of every tree, every algae, every plant? I don't think so. (Source: Dennis Hayes, founder of Earth day, current President of the Bullet Foundation) Icarus
CLANG CLANG CLANG ... ERROR DETECTED ... INVALID UNITS 'Terawatts of energy per year' is not a measure of energy, it is a confused mishmash of three measures. A corrected sentence could read: "We collectively burn an average of 16 terawatts worldwide. Every second, every day, all year." For the masses, this is usually changed to 'terawatts of power', though to the engineers, 'of power' is a redundancy of needless extra words. Wikipedia - energy consumption.
Let me get this straight. A 1 watt light bulb, burned for an hour is 1 watt/hour (wh) A 1000 watt light bulb burned for the same hour is 1 kilowatt/hour (kwh) So you are absolutely right, that talking about watts with out talking about time doesn't mean much. Understanding that a KW doesn't mean anything with out knowing the time factor. So to restate my point, we burn 16 twh of power in a year. So, I stand corrected, thank you, Icarus PS. I believe that my point still stands. The bottom line is that we burn way more energy per year than the biomass that grows can sustain.
Corrections below. A 1 watt light bulb, burned for an hour is 1 watt*hour (wh) To get energy, the time is multiplied in, not divided in. Watt is a stand-alone measure of power (i.e. rate of energy flow). Time is already included within the unit, and needs no additional reference. We burn 16 Tw of power at an average instant. We burn 140,000 Twh of energy in a year. Tw is power. Twh is energy. For those who use calculus, power is the first derivative of energy, with respect to time. For those who do not use calculus, power is the rate of energy burned, per unit of time. For any unit including the word 'watts', this is joules of energy per second.
The common news outlets scramble this detail most of the time, often providing a confused mishmash that can be interpreted three different ways. Unfortunately these three interpretations are mutually incompatible, usually by several orders of magnitude. As for your original point, that our energy consumption is very large compared to the available biomass, I haven't reviewed this. But it is consistent with comments I've heard, and with statements that the entire potential corn ethanol supply in the US would replace only a fraction of our transportation gasoline, which in turn is only a fraction of our total energy consumption.
The amount of carbon photosynthesized by plants (after subtracting their respiration) is approximately 60 petagrams = 60 billion metric tons annually. The amount of fossil fuel carbon burned annualy is now about 8 petagrams. Presuming the energy extractable from a gram of 'plant' is similar to that from gram fossil, there is enough plant energy being produced. However, the idea strikes me as not wise at all.
I would posit that the energy density of fossil fuel is very much greater than that of a similar weight of biomass. Take 6lbs of gasoline, light it on fire, count the BTUs. Light the gasoline,,,,, Icarus
That balance won't work for 2030 or 2050 with the article assumptions that other nations will begin to use energy at a similar rate to the U.S./West at present. This latter part of course is the key point that conservatives have failed to understand about Kyoto and such.
He is comparing carbon to carbon, not a unit of raw (or dried) biomass to a similar mass of fossil fuel, so the disparity is not likely as wide as one may first think. Oil and gas will have a substantial portion of additional energy in hydrogen too. Coal and biomass likely don't.
It can be considered more than a stop gap as it also provides a means to reduce our waste stream as well as the global warming gasses in our atmosphere. There are a number of companies that are producing biodiesel for transportation diesel and for heating oils. This reuse provides a kinder environmental balance than other disposal methods. Biofuels reduce net CO² emissions by 78 percent compared to petroleum diesel. This is due to biodiesel’s closed carbon cycle. Biodiesel emissions have decreased levels of polycyclic aromatic hydrocarbons (PAH) and nitrited PAH compounds that have been identified as potential cancer causing compounds. Test results indicate PAH compounds were reduced by 75 to 85 percent, with the exception of benzo(a)anthracene, which was reduced by roughly 50 percent. Targeted nPAH compounds were also reduced dramatically with biodiesel fuel, with 2-nitrofluorene and 1-nitropyrene reduced by 90 percent, and the rest of the nPAH compounds reduced to only trace levels. Ref: Newport Biodiesel Company FAQs. To be a technical nitpicker, the unit Watt should also be expressed as a capital W since it is named after a person (The watt is named after James Watt for his contributions to the development of the steam engine, and was adopted by the Second Congress of the British Association for the Advancement of Science in 1889 and by the 11th General Conference on Weights and Measures in 1960 as the unit of power incorporated in the International System of Units (SI). Ref: [ame="http://en.wikipedia.org/wiki/Watt"]Wikipedia[/ame]).
In terms of a solar power, transportation grid, I was thinking along the lines of a cover using 16% efficient photo cells. The vehicles would have a rolling contact to a 'ground rail' and an upper conductor. Since everyone is limited to their lane, vehicle staging and automatic controls would be mandatory. This would allow 'bumper-to-bumper' operation and further reduce air drag. Best of all, I could take a nap going to grandmother's house. Once you get to your exit, everyone 'makes space' and you drive off the highway and proceed on other power (or charged battery.) <sigh>Too much pie-in-the-sky ... Bob Wilson
Yep. Darell's solution is more practical, at least here in Calif and the Southwest. Install solar on your rooftop, use electricity to charge your car at night, in the daytime you produce power and sell it back to the utility. You run your vehicle and power your house at the same time.
Like when we were kids and dreamed of driving the bumper cars off the platform? Would a skinny bloke with tattoos stand on the back of the car and steer if we messed up?
