Is anything really green?

[Not half- but whole!]

I have pondered some issues concerning renewable resources. For many of the renewable sources that involve siphoning off some of the naturally occur systems (Wind, geothermal, tidal, solar, etc), would there actually be detrimental effects to the global systems in the long run.

 

For example:

Wind- If we are pulling out mechanical energy from wind systems; what impact could it have on weather patterns?

 

Geothermal seems pretty harmless, but tinkering with such volatile areas surely could have some detrimental side effects.

 

Tidal- While there are countless factors that drive ranging from various physical gradients, apply a turbine to drive for example might push the gradients into a different cycle or stall them completely.

 

 

What truly are the risks of tinkering with these systems?

[CraigD]

What truly are the risks of tinkering with these systems?

As best I can figure, the risk to the gross mechanical energy of these systems is insignificant, the smaller-scale ecological risks significant, but, with research and planning, manageable.

 

It’s always a good – nay, essential – idea to determine as accurately as possible the consequence of any act of engineering. That said, the impact of most of the alternative energy technologies NHBW mentions – wind, geothermal, and tidal (which I think should be consider more broadly as ocean currents in general) – appears to be low, because the maximum human power requirements are very small compared to the available power and its natural variation, and because these supplied of energy are effectively inexhaustible.

 

At first order approximations, a major ocean current system such as the gulf stream has about [math]2 \times 10^{15}[/math] J of kinetic energy, while the atmosphere has about [math]2 \times 10^{18}[/math] J. The Earth’s total power (energy/time) from the Sun is about [math]1.74 \times 10^{17}[/math] W. All artificial energy consumption by humans – transportation, electric, etc. - is about [math]1.5 \times 10^{13}[/math] W. (sources: wikipedia articles “Earth’s Energy budget”, “Orders of magnitude (power)”)

 

So, human currently consume only about 1/10000th of the available non-exhaustible energy on Earth. If the Sun were to stop supply the Earth with power, and all of the world’s energy were obtained from a natural source which were somehow freed of natural sourced of drag (an unrealistic scenario, but useful for this illustration), the Gulf stream would last about 2 minute, wind about 2.5 hours, illustrating that these systems have a considerable amount of “inerta”.

 

Intuitively, one should consider natural features that currently have an effect indistinguishable from artificial ones that could provide human-usable power. For example, the aerodynamic effect of a large tree is about equivalent to that of a 10 m, 10000 W wind turbine. If all human energy needs were met with wind turbines (another unrealistic, but illustratively useful scenario), about 150 million such turbines would be required. I’m unable to find an estimate of the number of large trees in the world, but extrapolating from my neighborhood, where there seems to be one at least every 10000 m^2, there should be on the order of 10,000 to 100,000 million worldwide, or about 100 times as many as the number of number of equal-effect wind turbines required to supply all human energy needs. (source: wikipedia article “Wind turbine”)

 

The main difficulties with these technologies, IMHO, are economic – with rare exceptions, they are more costly than fossil fuel burning, so until fossil fuel becomes much more expensive, can’t be afforded in our current market-driven economy.

 

Adverse ecological impacts, although insignificant in terms of effecting the large scale energy dynamics of natural systems, can be considerable in terms of impact on local fauna and flora – eg: killing fish in water turbines, killing birds in wind turbines. Tidal power systems, attractive because they permit water current power generation near large coastal power consumers (eg: cities), can upset local ecologies by changing the normal tidal patterns. Geothermal power generally is a closed heat engine with nearly no ecological impact other than waste heat, but is a small resource compared to these others.

 

In summary, on a gross mechanical level, we humans should be able to increase our power use by about a factor of 10,000 without exceeding the amount of effectively inexhaustible energy on Earth.

[Govind]

I have pondered some issues concerning renewable resources. For many of the renewable sources that involve siphoning off some of the naturally occur systems (Wind, geothermal, tidal, solar, etc), would there actually be detrimental effects to the global systems in the long run.

 

For example:

Wind- If we are pulling out mechanical energy from wind systems; what impact could it have on weather patterns?

 

Geothermal seems pretty harmless, but tinkering with such volatile areas surely could have some detrimental side effects.

 

Tidal- While there are countless factors that drive ranging from various physical gradients, apply a turbine to drive for example might push the gradients into a different cycle or stall them completely.

 

What truly are the risks of tinkering with these systems?

 

First, going green does not really mean doing things that will not affect the environment at all!! For....the moment we breathe...we put in a little more CO2 in the atmosphere!

 

The lets go green movement was started first..after the highly polluting industries and things like coal-power, petroleum, etc. were doing large scale damage to the planet. It was then, that an urgent need was felt to shift to "less polluting" sources of energy generation, etc....and those were the green sources...for they certainly caused much less problems.

 

As for is there anything really green...well if you grow vegetables and foodstuff in your backyard for your own consumption, I think that comes pretty close to being very green!,...n that's like just one example!

[UncleAl]

Keep it simple with thermodynamics: All desired output less inputs and waste over the lifetime of the generator. A solar cell makes no net energy until its manufacturing inputs (energy, materials, waste; eventual disposal) are covered. A fossil fuel power plant, wind generator, nuclear power plant, fuel ethanol... are no different. Area necessary to generate 1 GW electrical, theoretical minimum,

 

mi^2

Area Modality

============

1000 biomass

0300 wind

0060 solar

0000.3 nuclear

 

Text formatting aside, who's your daddy? Now look at fuel from crops ignoring ALL inputs like fertilizer, insecticide and herbicide, tractor fuel, etc. Iodine Number measures unsaturation - bad for fuel for causing sludge in the tank and varnish in the engine as oil paint cures in air. Corn will give you 18 gal/acre IN=125, olives (and opium poppy) 129 gal/acre with IN~100, avocado 282 gal/acre IN=85, oil palm 635 gal/acre IN= 37-54 (35 times better than corn). Why isn't Louisiana planted into multi-$billion/year wealth?

 

How do we know fuel ethanol from corn is corrupt crap? All fermentation facilities run on fossil fuels, every one of them. Why don't they use cheap fuel ethanol instead? Because fuel ethanol costs a fortune and is a net 40% energy LOSS.

 

Pulling few hundred or thousand gigawatts out of the Earth's winds worldwide will slow its planetary spin (momentum exchange). Remember that the typical wind turbine output averages less than 1/3 its nameplate capacity. A fossil fuel power plant is about 90% efficient.

 

Civilization knows what it is doing, Luddite Enviro-whiners do not.