Breaking News
Blog

Energy Availability vs. Power Needs

NO RATINGS
View Comments: Threaded | Newest First | Oldest First
Bert22306
User Rank
CEO
Out of balance
Bert22306   12/2/2013 5:02:04 PM
NO RATINGS
In a sense, that's what "sustainable energy" is all about.

Most of our sources of energy have used long term, low power "charging" in developing themselves, and we are depleting them a lot faster than it took to build up that energy content.

Battery-powered EVs are a less dramatic example of the same phenomenon. The power needed to move vehicles is quite a bit higher than the power available in battery charging circuits, which means that the battery is depleted a lot faster than it can be replenished. But the delta time is not close to being as dramatic as it is for making coal, oil, or natural gas.

To bring this back to harvesting RF power for your smartphone, since smartphones tend to be on most of the day, and RF harvesting yields very low power in most environments suitable for human habitation (unless you render that RF system useless by capturing most or all of its energy with large, encompassing receive antennas), I don't think it's a practical solution.

Bill_Jaffa
User Rank
Blogger
Re: Out of balance
Bill_Jaffa   12/2/2013 5:15:31 PM
NO RATINGS
I suppose you can think of oil etc as solar energy collected over the eons, converted to biomass, then tranformed into fuel.

Consider how much solar energy flux and solar power impinges on Earth--that's an upper limit of what we can get from most renewable sources (not counting geothermal, for example, which is likely due to radioactive decay deep within the Earth and is solar-independent). The Wikipedia entry is a starting point at http://en.wikipedia.org/wiki/Solar_energy, Warning: I don't know how good those numbers are--but they do make you stop and think.

 

Bert22306
User Rank
CEO
Re: Out of balance
Bert22306   12/2/2013 5:39:03 PM
NO RATINGS
Harvesting power from the sun follows the same model as harvesting power from RF sources. If you expect to harvest a large percentage, you're going to destroy whatever system is using that power now. In the case of solar, you can't come close to harvesting all of the solar energy impinging on the planet, if you expect the ecosystem to continue to function!

Ditto with any other "renewable" source. Power harvesting only makes sense if its impact is "in the noise."

Perhaps we should do the harvesting on the moon, then find some safe way to bring that power to earth.

Bert22306
User Rank
CEO
Re: Out of balance
Bert22306   12/2/2013 5:48:12 PM
NO RATINGS
"Perhaps we should do the harvesting on the moon, then find some safe way to bring that power to earth."

Hmmm. Even that idea is full of risk, come to think of it. Even if the human contribution to global warming is ambiguous now, the human contribution would be much more obvious if we bring down energy from other celestial bodies, eh?

That's why I think demanding ever increasing efficiencies from our machines makes a lot of sense, even if global warming is not primarily our own doing, as of now.

Bill_Jaffa
User Rank
Blogger
Re: Out of balance
Bill_Jaffa   12/2/2013 6:42:28 PM
NO RATINGS
Good point--solar arrays occupy lots of land (unless they are on the roof). That land can't be used for food or habitation. Some of the solar setups in the desert are huge, makes it hard for native flora and fauna to succeed, they have evolved to live in that environment.

Sheetal.Pandey
User Rank
Manager
Re: Out of balance
Sheetal.Pandey   12/3/2013 9:47:21 AM
NO RATINGS
Energy and power normally gets interchanged in casual conversation unless we have technical datasheets reference. In a project team there are individuals with different educational backgrounds so quite possible. Problem happens when in design phase data gets calculated wrongly espcially when the product have crossfuntional areas like mechanical, software and electronics.

Jack.L
User Rank
CEO
Re: Out of balance - Sun Harvesting
Jack.L   12/3/2013 11:16:59 AM
NO RATINGS
Except it is highly unlikely we would ever need to capture a large portion of the solar energy that hits the earth. On the magnitude of 0.01%. Given that energy is only converted, never destroyed, it is questionable that capturing that "sunlight" and repurposing it would have any impact at least on a global basis. If anything, we are more likely to capture more energy that would be reflected, so the effects would be similar to burning fossil fuels ... i.e. adding energy.

 

In terms of energy and power, Engineers know the difference and only get hung up on the semantics of which is the right term when it matters for the most part and always when formal writing.

Bert22306
User Rank
CEO
Re: Out of balance - Sun Harvesting
Bert22306   12/3/2013 4:36:48 PM
NO RATINGS
"Given that energy is only converted, never destroyed, it is questionable that capturing that 'sunlight' and repurposing it would have any impact at least on a global basis."

If we're collecting that energy with solar panels on earth, I would agree. As long as the amount is down in the noise level, so it aren't darken huge expanses of our planet, the rest of the ecosystem should be mostly unaffected.

But if we're collecting that energy with solar panels on the moon, or asteroids, and then beam it down to earth somehow or other, that's a different matter. If releasing the energy that was previously trapped in fossil fuels is creating appreciable global warming, imagine what happens if humans start to believe that shipping in extra energy from extra-terrestrial sources constitutes "free energy."

Jack.L
User Rank
CEO
Re: Out of balance - Sun Harvesting
Jack.L   12/3/2013 4:42:32 PM
NO RATINGS
It is not the energy released from fossil fuels that is the main contributor of global warming. What is creating the warming is the trapping of energy from the sun due to the insulating properties of the gases that are released from that burning.

Bert22306
User Rank
CEO
Re: Out of balance - Sun Harvesting
Bert22306   12/3/2013 5:04:56 PM
NO RATINGS
"It is not the energy released from fossil fuels that is the main contributor of global warming. What is creating the warming is the trapping of energy from the sun due to the insulating properties of the gases that are released from that burning."

So, let us assume for a moment that the greenhouse gases remain as is, and that we import large amounts of solar energy from collecters on the moon.

What happens to global temperatures, if that extra energy is also trying to (eventually) find its way back into space?

Greenhouse gases also keep solar energy out. If we create some sort of concentrated beams to force more energy in from outside, this can't help but create another source of imbalance.

Wilco1
User Rank
CEO
Re: Out of balance - Sun Harvesting
Wilco1   12/3/2013 9:25:03 PM
NO RATINGS
Greenhouse gases do not keep solar radiation out - that's key reason why they are called greenhouse gases. They have a very specific absorption spectrum that allows most sunlight (70%) to pass through the atmosphere, but block IR radiation from escaping back into space.

The earth receives more solar energy in one hour than the total amount of energy we consume in one year. Being just 0.01% of the solar radiation, the heating effect of burning fossil fuels, splitting or fusing atoms etc does not cause noticeable warming. So if instead we imported all our energy from outer space, the heating effect would be equally insignificant.

However if we increased our energy consumption 10-50 times then the heating effect might well become a contributing factor to global warming. But if this would also imply a huge increase in CO2 emissions then the greenhouse aspect of global warming would continue to dominate of course.

Bert22306
User Rank
CEO
Re: Out of balance - Sun Harvesting
Bert22306   12/3/2013 9:41:51 PM
NO RATINGS
"Greenhouse gases do not keep solar radiation out - that's key reason why they are called greenhouse gases."

The atmosphere in general does both, actually. Look at the picture in this:

http://earthguide.ucsd.edu/virtualmuseum/climatechange1/02_1.shtml

Water vapor is a greenhouse gas. Clouds keep heat out. But that wasn't my main point. My main point was that concentrating even more solar energy on earth, than what impinges on earth now, can only worsen global warming. EVEN IF the greenhouse gas levels stay the same.

"However if we increased our energy consumption 10-50 times then the heating effect might well become a contributing factor to global warming. But if this would also imply a huge increase in CO2 emissions then the greenhouse aspect of global warming would continue to dominate of course."

Yes, true, but even without any increase in CO2, you'd get warming. So there's no free lunch there either. Just because in 2013 we obsess over the CO2 humans generate, rightly or wrongly, does not mean that global warming only obeys the environmental mantra popular in 2013. :)

Wilco1
User Rank
CEO
Re: Out of balance - Sun Harvesting
Wilco1   12/3/2013 10:59:28 PM
NO RATINGS
70% of solar radiation reaches the surface, so there is some reflection indeed, but the fact is the greenhouse gases keep us warm during the night by blocking IR radiation. That is why the surface does not cool down to -150C like on the moon.

Let's consider importing additional energy by harvesting solar energy from outer space. It doesn't matter whether this is by using giant solar panels in space, on the moon or some other way of energy harvesting. What I am saying is that if we displaced ALL our energy needs by this new imported form of energy then the direct heating effect is negative (cooling). That's because the additional heating from this new form of energy would displace the burning of fossil fuels and thus avoid not just the resultant heat output but more importantly CO2 emissions. 

Interestingly this scenario is exactly what would happen if we planted lots of solar panels and/or wind turbines on earth itself (the area required to provide all our energy needs is actually very small). This is effectively already happening today - for example a significant proportion of the UK's electricity is provided by wind turbines (right now about 16%).

Bert22306
User Rank
CEO
Re: Out of balance - Sun Harvesting
Bert22306   12/4/2013 5:05:24 AM
NO RATINGS

"That's because the additional heating from this new form of energy would displace the burning of fossil fuels and thus avoid not just the resultant heat output but more importantly CO2 emissions."

Remember first that the CO2 emissions from all of human activity amount to barely over 3 percent of the daily total. So it's not a given that one form of pollution would exactly counterbalance the other one. Especially since we would most likely be tempted to overcompensate, having found this supposedly unbounded source of energy.

And, the energy we bring down as some magical concentrated beams of microwaves, or whatever form it takes, will eventually become waste heat. (Assuming it doesn't  wreak havoc just by being beamed down through the atmosphere.) Energy cannot be destroyed. So there will indeed be a heating effect, even if this other heating phenomenon is not in today's popular "global warming argot."

"Interestingly this scenario is exactly what would happen if we planted lots of solar panels and/or wind turbines on earth itself (the area required to provide all our energy needs is actually very small)."

I'm not so sure the effects are the same. If we plant solar panels here, we are not importing more energy from outside, and we are depriving some amount of the earth's surface from that energy. So some amount of plant and animal life will be impacted, not to mention winds and other natural phenomena. Importing the solar energy from outside, instead, does not theoretically deprive these other natural systems from that energy.

I don't see these as identical effects. Also, importantly I think, ALL of these effects are "small," at least until now. INCLUDING the human contribution of the daily total CO2 output into the ecosystem. Yet, that doesn't stop anyone from accepting that the human contribution is already irreperably catastrophic, right?

Wilco1
User Rank
CEO
Re: Out of balance - Sun Harvesting
Wilco1   12/4/2013 10:10:17 AM
NO RATINGS
Bert, you don't seem to grasp the magnitude of the numbers. If for example we imported 200W per m^2 of earth, then yes we'd be starting to fry ourselves. But that's also more than 1000 times the energy we actually use. What would we use all that energy for unless it is to fry ourselves? That's assuming it is even technically feasible to import that much energy!

So you can't use such an unrealistic scenario to make the claim global warming isn't happening or is not significant. The fact is that the climate forcing due to CO2 is many times more than the current energy we use - and the forcing due to CO2 increases faster than our energy use. So the indirect heating effect due to our energy use is insignificant compared to that.

"Also, importantly I think, ALL of these effects are "small," at least until now. INCLUDING the human contribution of the daily total CO2 output into the ecosystem. Yet, that doesn't stop anyone from accepting that the human contribution is already irreperably catastrophic, right?"

The effect of CO2 is far larger than the heating effect of burning fossil fuels and lasts for many decades due to being accumulative. Given humanity doesn't appear to want to reduce CO2 emissions, it seems we are indeed heading for a catastrophic change of our climate. Even if 3% extra CO2 causes just 1% increase in temperature, then that is 3 degrees Celsius hotter and well into catastrophic territory...

 

Bert22306
User Rank
CEO
Re: Out of balance - Sun Harvesting
Bert22306   12/4/2013 4:37:23 PM
NO RATINGS
"The effect of CO2 is far larger than the heating effect of burning fossil fuels and lasts for many decades due to being accumulative."

Who says it's cumulative? We've been through this on another thread. The natural CO2 sequestration mechanism in the ecosystem is not open loop, such that a fractional increase in CO2 accumulates over time. We already know that plant growth in greenhouses is stimulated by injecting a far higher concentration of CO2 than what is in the atmosphere. This idea that human contribution has been accumulating ever since the Industrial Revolution began is a first order approximation that is less than totally credible. More likely is that a slightly different equilibrium point will be reached (and reforestation in large scale would help reduce the risks without being destructive in other ways). Yet, thanks to luminaries such as Al Gore, we are all happily reciting the popular simplistic formula.

Todays' mantra is CO2, even though it is far from being the most abundant or potent greenhouse gas. If we become reckless and import large quantities of energy by focusing sun beams not originally directed here, tomorrow's mantra on global warming will be something else.

I don't know about something as undefined as "humanity" not wanting to reduce CO2 emissions, but I see specific individuals all around me driving totally irresponsible behemoths, pickups, SUVs, crossover vehicle blobs on the road, with reckless abandon, all day long. And they complain about the price of gas, to add insult to injury.

Wilco1
User Rank
CEO
Re: Out of balance - Sun Harvesting
Wilco1   12/4/2013 5:25:11 PM
NO RATINGS
We know for a fact that CO2 accumulates as the CO2 concentration has been rising fast due to our use of fossil fuels. About 50% of the CO2 we emit stays in the atmosphere for many decades, the rest is absorbed by the ocean (which is less and less able to take up CO2 due to the heating). CO2 is the most important greenhouse gas precisely because it accumulates (unlike water vapour). The result is that it drives global warming.

If you could prove that CO2 is not accumulating then it would make you rich and famous.

At the moment forests are shrinking fast due to human activities and so we actively work to obliterate CO2 sinks:

"The forests are being destroyed at a rapid pace.[30][31][32] Almost 90% of West Africa's rainforest has been destroyed.[33] Since the arrival of humans 2000 years ago, Madagascar has lost two thirds of its original rainforest.[34] At present rates, tropical rainforests in Indonesia would be logged out in 10 years and Papua New Guinea in 13 to 16 years.[35] "

If we can't even manage to stop the rapid deforestation, I don't think the idea of reforestation will work...

Again, if we somehow created all our energy from a different source (fission, fusion or solar panels on the moon), it would have a cooling effect - because it would reduce our CO2 output dramatically. The indirect heating effect from our energy usage is insignificant today and would be equally insignificant if we switched to a different source.

"I don't know about something as undefined as "humanity" not wanting to reduce CO2 emissions, but I see specific individuals all around me driving totally irresponsible behemoths, pickups, SUVs, crossover vehicle blobs on the road, with reckless abandon, all day long. And they complain about the price of gas, to add insult to injury."

That exactly describes the average human indeed, particularly US citizens which already benefit from ridiculously low gas prices compared to Europe.

 

 

Bert22306
User Rank
CEO
Re: Out of balance - Sun Harvesting
Bert22306   12/4/2013 8:11:22 PM
NO RATINGS
"If we can't even manage to stop the rapid deforestation, I don't think the idea of reforestation will work..."



Perhaps this is the crux of the matter. It seems to me that IF climate scientists believe that human activity has been increasing CO2 levels in an uncontrolled manner (i.e. cumulative), THEN my bet is that the effect is caused by deforestation. Not because our tiny contribution of CO2 puts the entire ecosystem out of kilter, but because we are simultaneously breaking down nature's CO2 sequestration mechanism. That would make sense.

As I said in another thread, it is totally inconceivable to me that the natural CO2 control system is operating on such a hairy edge, that CO2 contribution from humans has been accumulating for 200 years, as they claim. What was our contribution 200 years ago? Maybe 0.003 percent? And yet, supposedly, that was enough to start showing an irreversible increase? Why wouldn't such tiny increases in CO2, especially back then, simply stimulate more plant growth, which in turn would sequester some of that CO2? (We're supposed to be engineers, right? We're supposed to know how auto-regulating control systems work. Even if Al Gore has no idea.)

Here's a web site that explains about CO2 injection into greenhouses:

http://www.omafra.gov.on.ca/english/crops/facts/00-077.htm

Here's a web site that gives the human contributions in different greenhouse gases:

http://www.geocraft.com/WVFossils/greenhouse_data.html

Furthermore, rather than concocting less than credible schemes of channeling solar energy from Mars to earth, or burying human-generated CO2 in deep caves, I suggest that a campaign of massive reforestation would be far more practically achievable, with no negative side effects, and that it would make this a more beautiful place besides.

We have to do something. Seems to me we should talk about doing sensible things, instead of assuming anything sensible is impossible, and discussing the most outrageous hair-brained schemes as if they made sense.

Wilco1
User Rank
CEO
Re: Out of balance - Sun Harvesting
Wilco1   12/5/2013 6:08:50 AM
NO RATINGS
"Perhaps this is the crux of the matter. It seems to me that IF climate scientists believe that human activity has been increasing CO2 levels in an uncontrolled manner (i.e. cumulative), THEN my bet is that the effect is caused by deforestation. Not because our tiny contribution of CO2 puts the entire ecosystem out of kilter, but because we are simultaneously breaking down nature's CO2 sequestration mechanism. That would make sense."

Deforestation is definitely a significant CO2 contributor. Yes we made things worse for ourselves by killing part of the CO2 regulating system. Reforestation would certainly help buy us more time to lower our carbon intensity and adapt. Unfortunately it seems unlikely we will give up our farmlands and change them back into the forests they once were. So while deforestation should be high priority, significant reforestation doesn't seem feasible without creating food supply issues. Therefore it will be one of several methods (reducing coal use, improving efficiency and recycling, increasing renewable and nuclear energy, carbon capture).

"Why wouldn't such tiny increases in CO2, especially back then, simply stimulate more plant growth, which in turn would sequester some of that CO2?"

Plants can and do indeed grow faster if the CO2 concentration is higher, and that is already happening today as CO2 concentration is 40% higher. And yet CO2 concentration is still increasing ever faster. So clearly we emit many times more CO2 than plants can use as food... It is true that if we stopped emitting CO2 altogether right now that CO2 will stabilise (not necessarily to 280ppm) due to these sinks. However that may take centuries. So it certainly is a complex auto-regulating system but it is slow acting and so can't deal quickly with sudden surges on its inputs.

August Cartoon Caption Winner!
August Cartoon Caption Winner!
"All the King's horses and all the KIng's men gave up on Humpty, so they handed the problem off to Engineering."
5 comments
Top Comments of the Week
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Times on Twitter
EE Times Twitter Feed
Flash Poll
Radio
LATEST ARCHIVED BROADCAST
David Patterson, known for his pioneering research that led to RAID, clusters and more, is part of a team at UC Berkeley that recently made its RISC-V processor architecture an open source hardware offering. We talk with Patterson and one of his colleagues behind the effort about the opportunities they see, what new kinds of designs they hope to enable and what it means for today’s commercial processor giants such as Intel, ARM and Imagination Technologies.