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Author Topic: Mankind's Heat/Energy increase  (Read 6251 times)

jonthed

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Mankind's Heat/Energy increase
« on: July 06, 2013, 03:57:53 PM »
Hello,

Please forgive my ignorance here, but I have been puzzled about the effect of all this heat and energy that mankind has been making for the last several decades.

Besides the carbon emissions increasing the greenhouse effect and trapping more heat on earth, aren't we actually 'making' a lot more heat than used to be made on earth as well? Wouldn't this also contribute to warming? Or is the amount of human generated heat negligible?

I mean all the fossil fuels we're burning contain a lot of energy, and besides all the GHG effects the emissions make, that energy always ends up as heat in the system surely? That's got to be a lot of extra energy that had been locked away. All the car engines we have running, heating systems, hair driers, refrigerators, everything we use ends up putting more heat into the system. If we're using something that's using energy, then it's adding heat to the system, right?

So sure, I know about conservation of energy, so I think Hydro, Wind, tidal energies all have no net effect. Fossil fuels most certainly do, and solar might depending on how much extra energy is extracted by a solar panel than would otherwise be reflected? and as solar panel efficiencies increase, might that change too? Geo-thermal takes heat from deep underground and let's it into our the biosphere (after conversion between energy forms and being 'used'). Nuclear is taking huge amounts of locked away energy and releasing it into our biosphere.

My point it this: Surely, on top of the increased greenhouse effect from the carbon emissions, all this previously-locked-away-energy will also be increasing temperature, and also driving the climate to need to adjust to reach a new equilibrium to cope with the added energy before achieving energy balance again?

Does anybody know anything about this? Has mankind's energy release been calculated?

Does it need to be considered?

I for one would be put off by geothermal and nuclear power if they were actually contributing to the temperature increase. (Although their lack of carbon emissions still might make them beneficial overall.)

Any thoughts or info? How many Hiroshima bombs per day are human's releasing from locked away energy?

Richard Rathbone

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Re: Mankind's Heat/Energy increase
« Reply #1 on: July 06, 2013, 04:31:49 PM »
Humans run at the order of 0.1-1 kW. (0.1 is typical metabolic rate, 1 is where it gets to once you factor in things like cars, TVs, showers and washing machines.)  The earth gets about 1 kW/m2 from the sun when its directly overhead.

You'd have to have about one person per square metre (of projected rather than total surface area) to get the same energy usage from humans as from the sun.

Actually its about 1e10 humans and 3*6.4^2*10^12 = 1e14 m2.

If there were a hundred times as many people using just as much energy each as we do now, it would be at the % scale and start to make a difference, but at the moment the direct effects are at the parts per ten thousand level and negligible.

This is a reason why SF scenarios of orbiting solar panels providing energy to support a world of trillions wont work, but 10 billion is manageable if the side effects of our energy usage are brought under control.

pikaia

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Re: Mankind's Heat/Energy increase
« Reply #2 on: July 06, 2013, 04:35:39 PM »
Let's do a calculation using ball park figures. Suppose each person uses 1 Kw of power from fossil fuel. that is roughly the amount we get from the Sun on one square metre. So, since the global population is 7 billion we would need about 7 billion m2 to collect all of our energy usage, or 7000 Km2. Since the cross-sectional area of earth is 128million KM2, you can see that our consumption is probably less than 0.01% of the energy we get from the Sun. This would produce less than 0.01 degrees of warming, which is rather negligible.

jonthed

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Re: Mankind's Heat/Energy increase
« Reply #3 on: July 06, 2013, 05:09:39 PM »
@ Richard

@Pikaia

Where does the 1kW figure come from?

And why do it based on what one person might use? why not based on how much energy a ton of coal contains, or how much a million barrels of oil contains, and then work out how much we're releasing each year, and how much we've released to date?
« Last Edit: July 06, 2013, 05:29:53 PM by jonthed »

pikaia

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Re: Mankind's Heat/Energy increase
« Reply #4 on: July 06, 2013, 05:44:55 PM »
The 1kw figure is my guess at the total amount we use per person. Actually, according to Wiki it was 21,000 kWh per capita in 2008, which works out at 2.4kW per person, but my figure was only a ballpark estimate.

You could do it your way, but you would have to include nuclear and renewables, and the answer would be the same!

Vergent

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Re: Mankind's Heat/Energy increase
« Reply #5 on: July 06, 2013, 06:12:40 PM »
Excuse me for introducing some facts.

The average insolation of Earth is 250 W/m^2

http://en.wikipedia.org/wiki/Insolation

A 100 hp engine produces 75,000 watts of power and with 20% efficiency, 300,000 watts of waste heat.

http://en.wikipedia.org/wiki/Internal_combustion_engine

There are 254,000,000 cars in the USA

http://en.wikipedia.org/wiki/Passenger_vehicles_in_the_United_States

15,000 miles/year is average usage

http://wiki.answers.com/Q/What_is_the_average_car_mileage_per_year

@ 50mph that is 300 hours of usage.

The average per capita energy consumption in the USA is 9,500 watts.

http://en.wikipedia.org/wiki/List_of_countries_by_energy_consumption_per_capita

The sustainable average per capita energy usage globally is 2,000 watts.

http://books.google.com/books?id=u-g1ud3ZtfkC&pg=PR17&lpg=PR17&dq=average+per+capita+energy+usage+watts+world&source=bl&ots=C2cYVkmywM&sig=ohWhyetIyOgPqregxJdDfRA2UQc&hl=en&sa=X&ei=dD_YUdDaNKGpigLE6IHYBQ&ved=0CHwQ6AEwCQ#v=onepage&q=average%20per%20capita%20energy%20usage%20watts%20world&f=false

Vergent


jonthed

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Re: Mankind's Heat/Energy increase
« Reply #6 on: July 06, 2013, 06:17:04 PM »
@pikaia

I thought my way would be simpler to get the figures we need, and would account for the inefficiencies of power production, capturing ALL energy released, not just the energy that reached and was used by the end user.

Also, you wouldn't have to include renewables, as they are taking energy that was already in the system.

I have found some stuff on wikipedia about it, and also a journal article (here http://energyresources.asmedigitalcollection.asme.org/article.aspx?articleid=1556807) that I can't access whose abstract states they found the anthropogenic contribution to heat increase to be between 3.5%-5%.


EDIT:

OK, I've found a few more articles and discussions of articles to do with the human contribution to the Earth energy budget. and as i thought they would skeptical science have a bit on it, real climate too. Seems the calculations show it is pretty much negligible. So I'm happy to leave it at that.  A little surprised though, I thought we'd have burned through a load of energy.

If anyone can find a clear explanation of how they calculated it I'd be grateful though.

Thanks.
« Last Edit: July 06, 2013, 07:00:26 PM by jonthed »

Richard Rathbone

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Re: Mankind's Heat/Energy increase
« Reply #7 on: July 06, 2013, 08:54:37 PM »
Try the CIA factbook if you want to get the data to do it yourself.

e.g. world electricity consumption estimated at 19.54e12 kwh for 2009.

At 8e3 hr/yr and 7e9 people thats about 0.3 kW per capita. Americans use rather more and Indians rather less.

You can add up contributions of different fuels if you want an accurate figure, but if you just want an order of magnitude estimate, then you can look at that and say its clearly going to be more than 0.1 and less than 10 and base your calculation on 1.

The BP statistical review is another source for energy statistics. A good way to view the BP data is in the energy export data browser.

http://mazamascience.com/OilExport/

Reading off their graph gives total world energy consumption for 2012 of about 500 exajoules.
5e20 J, 3e7 s/yr 7e9 people gives about 2.5 kW per capita.

Thats a nice round number and you might as well use it rather than 1 kW if you have gone to the trouble of digging it out, but the order of magnitude is still the same.

250W of insolation is obtained by dividing 1 kW by 4, since the surface area of a sphere is 4 times its cross sectional area.

Laurent

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Re: Mankind's Heat/Energy increase
« Reply #8 on: July 07, 2013, 11:13:44 PM »
By comparing what the humans are consuming with what the earth is receving is not really fair. The earth is (was) at the equilibrium with what it does receive from the sun with or without humans. So if you want to compare, it is with the variations of the sun so around +- 2w/m2 !!!

Glenn Tamblyn

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Re: Mankind's Heat/Energy increase
« Reply #9 on: July 17, 2013, 09:15:20 AM »
The numbers I have heard are that total energy production by humanity, from all sources is around 16-17 TeraWatts.

Contrast that with total Geothermal energy, the largest terrestrial energy source, which the Geologists estimate at around 44 TeraWatts. If energy consumption keeps growing on current trends, whether that be from Fossil Fuels or Renewables, we will produce/consume as much energy as total Geothermal within around 40 years.

Also in contrast, heat accumulation in the oceans, measured from 0 to 2000 meters, is running at just over 250 TeraWatts. That simple number says a great deal about what is causing the Earth to warm. It isn't ant redistribution of terrestrial energy. There is no heat source on Earth large enough to be supplying the heat that is going into the oceans. We are in a state of energy imbalance with space - nothing else fits the evidence.

Laurent

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Re: Mankind's Heat/Energy increase
« Reply #10 on: September 30, 2013, 08:59:11 PM »
I though that the lower atmosthere is increasing more (temperature) than the upper atmosphere ?

Quote
With the help of this system, the researchers found that the changes taking place in the upper atmosphere is dramatic, when compared to the lower atmosphere. They found out more about ionosphere and stated that earlier it was difficult to observe the changes taking place in this zone

http://www.idigitaltimes.co.uk/articles/496419/20130805/radio-waves-measure-climate-changes-atmosphere-research.htm

ccgwebmaster

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Re: Mankind's Heat/Energy increase
« Reply #11 on: October 05, 2013, 07:22:28 PM »
I though that the lower atmosthere is increasing more (temperature) than the upper atmosphere ?

I'm not sure global warming doesn't actually act to cool the stratosphere by retaining heat closer to the surface:

http://www.wunderground.com/resources/climate/strato_cooling.asp

Counter-intuitive at first perhaps, but also one of the reasons we know global warming is indeed caused by greenhouse gases and not by other factors proposed by deniers.

Tom_Mazanec

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Re: Mankind's Heat/Energy increase
« Reply #12 on: April 19, 2019, 03:24:48 AM »
American energy usage surges:
https://phys.org/news/2019-04-americans-energy-surges-climate.html

EDIT: Let me mention that an energy growth rate of, to make the math easy and be conservative 3.6% per annum is equivalent to doubling every 20 years. Or growing 1024-fold in 200 years. No matter how sustainable the energy source, this cannot go on. If you use fusion, you have effectively turned Earth into a star. If you use solar power satellites, you have effectively put the Earth under a burning glass. Exponential growth will stop in a historic eyeblink. If we colonize the solar system (a big if), this will just change a couple centuries into a couple millennia. If we reach other planetary systems, that would be nice but it won't grow our own civilization...they would be separate civilizations, many years away at best. This will end one way or another.
« Last Edit: April 19, 2019, 04:53:47 AM by Tom_Mazanec »
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