The house is on fire.

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
boji said:
Note that:
Only about 15 percent of the energy from the fuel you put in your tank gets used to move your car down the road or run useful accessories, such as air conditioning. The rest of the energy is lost to engine and driveline inefficiencies and idling.

That means a majority of the gasoline in cars is being used to heat the environment. I don't know of any studies on car temperatures and AGW, but everyone talks about CO2 as the main worry, but what about the problem of heat itself being produced by over a billion cars, trucks, factories, industries each day?

Basic physics tells us that ALL the energy from burning ANY fuel (fossil, nuclear, renewable) ends up as heat energy all of which is eventually radiated into space as infra red. I don't know how much this totals but you need to compare it with the average 342W per square metre that the sun inputs to the earth every day on the 510 million square kilometres of the earth's surface which my calculator says is about 1.7x10^17 watts every second.

Cheers

Ian
 
None of this even speaks to the use of electricity as population and temperatures increase.
https://www.theverge.com/2017/9/14/16290934/india-air-conditioner-cooler-design-climate-change-cept-symphony

Part of me feels like were arguing about the numbers of angels on the head of a pin. As I've said before, I'll sign whatever deferred paybacks are needed for corporations to chance the strict emissions rules.  Put it on me, the uneducated tree-hugger.  I'm fine with that, as I owe nearly all my understanding of physical reality to the scientific community. I really really don't get why we're supposed to suddenly break faith with them concerning climate projection.
 
[All fuel] ends up as heat energy all of which is eventually radiated into space as infra red
Thank you. At what rate? Certainly CO2 plays a part, so I can see why it's a main point of contention.
342W per square metre
Something doesn't feel intuitively right about that figure. For example albedo, or reflectivity, and the fact that at any one snippet of time, only half the earth is being beamed upon. I wish I could do the math, but I can't. :/  Has the 342W figure already taken that into account?  I gotta sleep Ian, I'll try looking that up tomorrow.
 
Basic physics tells us that ALL the energy from burning ANY fuel (fossil, nuclear, renewable) ends up as heat energy all of which is eventually radiated into space as infra red
Infra red, like visible light, has a range of "colours".  The various gases in the atmosphere are transparent or reflective at different wavelengths of infra red like colour filters.

Carbon dioxide and water absorb long wave radiation from 12 to 19 microns. Methane absorbs wavelengths 6 to 8 microns. Water blocks radiation below 7 microns from being reflected out to space.  This is how clouds keep us warm overnight, wheras a clear sky does not.  This is also the reason why some telescopes have to be on satellites outside the atmoasphere in order to detect the full range of radiation fron space.

DaveP
 
Something doesn't feel intuitively right about that figure. For example albedo, or reflectivity, and the fact that at any one snippet of time, only half the earth is being beamed upon. I wish I could do the math, but I can't. :/  Has the 342W figure already taken that into account?
The Earth receives 1,370 watts per square meter at the top of the atmosphere directly facing the sun.  Some of the solar energy that arrives at the Earth bounces off the atmosphere and clouds and back into space.  The Earth does not heat evenly, chiefly because some areas receive more solar radiation than others. The differences in energy drive the winds and ocean currents across the entire planet.

The Earth radiates heat back into space, preventing the planet from overheating. The amount of re-radiated heat is sensitive to the type of gases in the atmosphere; some gases absorb heat more effectively than others and interfere with re-radiation. One of these gases is carbon dioxide. As atmospheric carbon dioxide concentrations increase, the Earth's heat budget is altered, with more energy stored in the atmosphere and less heat radiating back into space, This is the greenhouse effect.

DaveP
 
boji said:
None of this even speaks to the use of electricity as population and temperatures increase.
https://www.theverge.com/2017/9/14/16290934/india-air-conditioner-cooler-design-climate-change-cept-symphony

Part of me feels like were arguing about the numbers of angels on the head of a pin. As I've said before, I'll sign whatever deferred paybacks are needed for corporations to chance the strict emissions rules.  Put it on me, the uneducated tree-hugger.  I'm fine with that, as I owe nearly all my understanding of physical reality to the scientific community. I really really don't get why we're supposed to suddenly break faith with them concerning climate projection.

Because conservatives are only concerned with conserving exactly one thing: their wallets. Common sense and greater good are no factors in that equation.
 
Here are some relevant figures.

Total energy consumption in the US is roughly 4 PWh (peta-watt-hours) per year, split roughly 1 PWh residential versus 3 PWh industrial/commercial.  This is roughly 10 MWh per year for each of the roughly 130 Million households.

A modest solar installation of 12, 350W panels provides a maximum output of 4.2kW, and assuming the average of 150 hours per month means that each installation can generate approximately 7.5 MWh per year.

Assuming zero economies of scale, a typical 4 kW solar panel system costs about $2k per kW installed, which means it would cost each household approximately $8k to install such a system.  Installing such a system (again, assuming no economies of scale) would cost roughly 1 Trillion dollars for every household.

Notice how close those numbers are to lining up? 
 
abbey road d enfer said:
This is without the batteries, isn't it?
I recently had a quote for €13k for a similar installation.
Yes, no local storage, and no back-link to send excess back into the grid.

DaveP said:
What numbers?

DaveP
A modest installation versus the total energy used in residential applications.  Meaning a 4kW installation in every household virtually eliminates residential energy usage from the national equation.
 
Matador said:
A modest installation versus the total energy used in residential applications.  Meaning a 4kW installation in every household virtually eliminates residential energy usage from the national equation.
Although I'm convinced of the validity of the concept, I still have some doubts.
Basing my estimation on €13k ( 3kWp with storage but no return to the grid) and the current kWh price, return-on-investment time is about 15-20 years. By then, I'll probably be dead or living in elderly home.
What is the long-term maintenance cost?
Should I aim for a larger system, considering the risk of needing more energy for A/C with global warming?
 
If everyone has electric cars, then they will be recharging them overnight when there is no sun, there are massive amounts of energy required for this alone.

To get a rough idea we have to know the calorific value of diesel and petrol used in cars and multiply that by the total sold.  I believe that the efficiency is only about 20% from thermal to movement on the road.  The rest is lost to the coolant, the oil and mechanical losses in the drive train.

The UK uses about 47 billion litres/year which is 129 million litres/day.  With a density of around 0.8 that's about 103 million kg
There are 45MJ/kg which equates to 12500Wh/kg
This is roughly 1.3 MWh but only 20% of this is used so it's  257,500 Wh/day assuming 100% efficiency in an electric car.  In practice there are considerable electrical losses mainly in the conversion of DC to AC for the motor which is only about 90% efficient in any case, so I estimate is that the UK would need around 0.5MWh extra capacity just to charge its electric vehicles every day.

Someone should check my  methodology!

DaveP
 
DaveP said:
The UK uses about 47 billion litres/year
France reports only about 30 billion litres for passenger cars.

There are 45MJ/kg which equates to 12500Wh/kg
One source claims about 30 MJ/kg (https://fr.wikipedia.org/wiki/Pouvoir_calorifique)

In practice there are considerable electrical losses mainly in the conversion of DC to AC for the motor which is only about 90% efficient in any case,
Actually, the main losses are in the charging processs; even with modern chargers, a lot of energy is lost in Joule effect (heat). Although Tesla optimistically claims 92%, users report an average of 70% efficiency.

Someone should check my  methodology!
Nothing wrong with your methodology IMO, although one can always argue about numerical values, but the orders of magnitude are there.
I have a different (albeit convergent with yours) analysis. Most  cars are used for commuting, the average being compatible with a 22kWh battery. That's about 30kWh/day, which is about the limit of a basic domestic subscription for overnight charging.
 
One of the largest complications with providing power is handling over provisioning, or large demand swings.  Power is already cheapest in the middle of the night, and if the residential grid was exchanged from powering homes during the day to charging cars overnight the economies involved would be quite different.

I think my larger point is the calculus of a major infrastructure project to radically change the way we deliver and use energy isn't based in the lands of unicorns and fairies. What is especially crappy is the idea that for the price tag of the Iraq war, we probably could have eliminated residential grid power needs, and given every household a plug in electric car (or two!) to boot!
 
Matador said:
What is especially crappy is the idea that for the price tag of the Iraq war, we probably could have eliminated residential grid power needs, and given every household a plug in electric car (or two!) to boot!
Tell that to the Halliburton shareholders.  :eek: :-[
 
What is especially crappy is the idea that for the price tag of the Iraq war, we probably could have eliminated residential grid power needs, and given every household a plug in electric car (or two!) to boot!
The problem is knowing which wars are worth fighting and which are not.

Let's see, WW1, WW2, Korean, Vietnam Iraq Afghanistan IS?

Usually we only know after the event.  WW1 was essential for the survival of France and the UK, but should have been followed by something like the Marshall plan, but that was born out of the failure of WW1 after-planning.  Too many were too bitter.

WW2 was essential for the survival of the free world.

Korea and Vietnam were part of the "Domino" wars, no-one knows what would have happened if they had not been fought, maybe more  Pol Pot type countries?

Iraq and Afghanistan and IS are all part of the Islamist wars which were bubbling under around the first world trade centre  event on Clinton's watch.

I would not want the responsibility of making the call on these, but I do know that history teaches that percieved weakness is always exploited by those that want to dominate the world, whether in the name of ideology or religion.

America spends a lot of defence so that it does not have to fight wars , that's the theory anyway. :-\

DaveP
 
Matador said:
A modest installation versus the total energy used in residential applications.  Meaning a 4kW installation in every household virtually eliminates residential energy usage from the national equation.
I am not so sure about this. The problem with solar is that it only works when the suns shines brightly. In the winter when you need most energy, there is little sun - certainly not enough to heat the home and cook with.

Cheers

Ian
 
Only skimmed through above.

We have solar on our house. Somehow the electric bill went up.  Can’t figure it out ..

For the amount of recycling and reusable bags we  use I’m sure a half a days drive nulls that back to negative something..

What I’m  wondering and know nothing about is, who is actually leading the way in realistic climatate changing green energies?

Is it Tesla?
I can’t afford his car even if I wanted one..

 
ruffrecords said:
I am not so sure about this. The problem with solar is that it only works when the suns shines brightly. In the winter when you need most energy, there is little sun - certainly not enough to heat the home and cook with.

Cheers

Ian
In winter, in northern Europe (think Hamburg), a 3kWp installation can produce an average of 2kWh per day. Compare to about 12kWh/day in summer. No way an ordinary home can be turned into an eco-neutral one.
 
Back
Top