Wednesday, January 16, 2008

On Energy Conservation

I'm an engineer. As an engineer, when you think about optimizing something or fixing something, you think about the 80% case. Its nice to think of the tiny micro-optimizations that will gain you a percent here, a percent there, but for the most part, they're futile academic exercises. Applying the same logic to energy, I think the 80% problem is energy *harvesting* not conservation.

Note: harvesting not production. Why? The sun is the closes source of infinite energy (by todays consumption rates). Various nuclear reactions on the sun are going on and are expending the energy stored there (as a result of the big bang, or God, depending upon your choice in these matters) and blasting this energy out to us. The amount of energy that sun blasts out does not change irrespective of how much you or I use. It is available for harvesting and if you don't harvest it, its gone.

Note again: I lied. Energy coming from the sun is clearly not infinite. Its a finite resource. However, it is more, by several orders of magnitude (unverified, pulled-out-of-thin-air stat here folks!) than the energy that we consume as a planet.

Hence my conclusion: Conservation is not the 80% problem. Better harvesting is the 80% problem and that's what we should be focusing on.

Now this is clearly untrue for known finite energy production resources such as nuclear fuel, coal, natural gas and of course, oil. The known capacity of these resources is within the same order of magnitude as our current energy needs x several decades or centuries. Which is worrying given that as our society evolves, our energy needs will go up and thus the known period of time for which we can survive on these resources will go down.

There is another, non-trivial argument for conservation: Energy costs. *Because* we get energy from increasingly expensive finite resources, the cost of energy keeps going up. Right now, its bordering on the edge of becoming a non-trivial part of living expenses, I think sooner or later, it will become this. Some percentage of our living expenses will be the energy. Cities will be able to attract or repel people based on how much energy they can supply and how much it costs (this already happens for industry which requires a steady supply of clean electricity at relatively low costs). So for purely monetary reasons, I think conservation is fine - even necessary in order to keep our daily costs down.

However, for anything else, we're attacking the wrong problem. Lets focus on harvesting, not on conservation. Go after the 80%.


Andrew said...

Even from an engineering perspective, I'm not sure if your argument makes much sense.

Let's take man's greatest achievement of the 21st century - the iPhone - as an example.

Apple's engineers knew that they had some strong battery life requirements that they needed to meet - 8 hours of talk time, 24 hours of music playback time, etc. Was the solution to these challenges to go off and invent some totally amazing new battery that has amazing power density - enabling the rest of the iPhone to waste energy with reckless abandon?

No! Apple's engineers had to approach the problem of battery life in the iPhone from both sides of the equation. They had to pick the most power dense battery technology that they could fit with in the design requirements (and operating environment) of the iPhone. But simultaneously, they had to work the problem form the other end, and ensure that each component of the iPhone used as little power as possible in order to accomplish its task.

I'm sure that Apple spent months optimizing power draw from the CPU, the cellular radio, the WiFi radio, and on down the line, in order to make the iPhone reach its intended battery life targets.

As an engineer, you have to solve the problem in such a way that the requirements are met - and most of the time, this is going to require a combination of techniques - not just a dogged pursuit of one part of the solution.


Mark said...

i'll post a real response in a bit but for perspective here's the amount of power hitting the sun facing side of the earth at any time

radius of earth = 6 378.1 km or 6,378,100 meters

surface area of sun-facing circle = pi*r^2 = pi*40680159610000 = 127,800,490,577,636 m^2

about 1000 watts of power hit a square meter of noontime ground so figure 127,800,490,577,636 kilowatts hitting earth round the clock.

according to the CIA worldwide electricity consumption is 17.42 trillion kWh which given 365*24 hours in a year gives 1,988,584,474 kW. So sun power is about 64 thousand times more than electricity production.

I did some fast math with oil production and came up with 5,879,166,666 kilowatts so if you add that up the sun's only putting out 16,000 times more than we're generating.

check my math. I have a bad habit of being off by 3 orders of magnitude now and then.

Mark said...

Quick followup. I forgot to include natural gas production which would probably decrease the ratio of sun to human power a bit. I don't feel like doing any more math though.

I'm also assuming above that there is no cloud cover and that the entire surface of the earth is covered in 100% efficient solar panels which don't exist. It would also end all life on earth except for those cool crab things that live by those geothermal vents on the ocean floor.

::rushabh:: said...

Mark: Your math is a bit off. I know you love wikipedia (har har) so I'll quote it to start off:
* The total solar energy available to the earth is approximately 3850 zettajoules (ZJ) per year.[12]
* Oceans absorb approximately 285 ZJ of solar energy per year.
* Winds can theoretically supply 6 ZJ of energy per year.[13]
* Biomass captures approximately 1.8 ZJ of solar energy per year.[14][15]
* Worldwide energy consumption was 0.471 ZJ in 2004.[16]

Please note that this is energy available to earth. We could build solar panels that orbit the sun thus greatly increasing harvested energy. Who knows.

The sun definitely provides several orders more energy than we currently consume. Most of it is wasted (only high-40%s of it hits the surface). We can do better. Put solar panels in LEO. I don't profess to know if these ideas are viable, just strongly believe that we're attacking the wrong problem with conservation.

::rushabh:: said...


Here is some more math to back it up:
1000 watts is peak power, typically available only for an average of 6 hrs / day. That's 6kWh / day / sq-mt.
Earth's surface area (4*pi*r^2) = .51 * 10^9 sq-km = .51 * 10^15 sq-m
Landmass = 29% total = 1.48 * 10^14 sq-m.
Theoretical production capability =
landmass * energy/sq-mt/day
= 8.875 * 10^14 kwh / day
= 3.24 * 10^17 kwh / year
= 324000 trillion kwh / year.

At current estimates, 25 trillion kwh will be consumed in 2025.

Please note that I corrected above for landmass vs not. This is an important distinction since by putting panels in space we would gain much larger exploitable surface area and double the efficiency.

Have I convinced you yet?

::rushabh:: said...


The iPhone is most definitely not the greatest achievement of the 21st century in my book. It is a marvelous device, does some things extremely well and is a joy to use. That does not make it the greatest achievement in the 21st century. There are a lot of other contenders ranging from microloans to autonomous vehicles to putting men in space for very little cost... the list goes on. I presume that this was not the argument.

I believe you are misrepresenting my argument. I do not believe in a dogmatic approach from one direction. I believe in doing what will get me the biggest bang for the buck (in the sense of the phrase not real $$$). If it was clear that conserving energy meant solving, say, 40 or 50% of the problem, I'd be all for it. However, even if everyone conserved like crazy and we didn't see *any* energy consumption growth, we'd be at 17 trillion kwh / year. If we allowed people to keep consuming, we are projected to grow to 25 trillion by 2025. Doubling these estimates, say we grew to 50 trillion. The sun blasts out 300,000 trillion kwh/sq-m of land. We are not even close to consuming what we throw away every day. Hence my point about lets focus on keeping more of that energy that simply gets dissipated into the atmosphere (creating more issues) reduce coal burn, reduce oil dependence (get rid of it), and not worry about how much energy we consume, because that's a-okay.

Besides, harnessing and generating more energy is an engineering problem (more than a political problem). Conservation is the latter. Its more headache and much harder to do and at the end of the day will not have the same effect as harnessing more power.

You cannot convince India and China to use less energy. Its simply not going to happen because the US has been the world's #1 energy consumer for several decades and it simply feels like the bully bullying the rapidly growing economies out of what they believe is their right (why can't we consume as much, heck, even more, than *you*). What you *may* be able to do is convince them to not use coal to get there. The damage is *not* in consumption, it is in burning coal/oil or some other horrid resource that wreaks havoc in the atmosphere. So lets focus on the renewables and other clean energy sources. Let the US lead the way in going clean and then it can pressure everyone else to do the same.

Mark said...

It's entirely possible that my math is off. I was assuming a circle with the diameter of the earth facing the sun all the time. No water, no clouds, no plants. That might be the source of the differences in our calculations. One counter nitpick though.

"The sun blasts out 300,000 trillion kwh/sq-m of land."

In how long? Don't forget the all important distinction between kW and kWh. One's power and the other is energy. the 1kW/m^2 is a number I've seen from a number of sources so in a year a square meter of all-noon land would get 8760 kWh or energy.

Anywho, you and I are on the same side here. The side that's optimistic about our massive growth potential and limited enthusiasm for conservation. Whatever my figures are we're underutilizing solar power by at least 5 orders of magnitude.

The rub is that we can't really use it effectively yet. There are a couple technological limitations that prevent it. That's not to say that they can't be overcome or won't be in the near term, but there's a reason we can't just go to Home Depot and buy solar shingles for a dollar a sheet.

Here's what's got to happen:

Carbon nanotubes need to mature.

Among other cool things they will get us 1) cheap, efficient solar collection and 2) the space elevator (stay with me here).

Once you get cheap access to space and efficient solar collection you can start the process of building orbital collection stations, stations at the LaGrange points, all leading up to the partial Dyson sphering of the sun.

Right now solar cells are shitty, expensive, heavy, resource and energy intensive to make. Also space access is very expensive and energy intensive to achieve. So if you launched a rocketfull of silicon solar panels into space you'd have to have them working for thousands of years before any kind of payback.

So I'm all about beaming back microwaves to the surface from space based collection. I just think we simply won't be able to do it until we work out the kinks on a couple technological issues. I also think that working out those kinks are inevitable and will come before we expect so I feel we have a sunny (haha) future.

The dark side of this is that you replace the wimpy climate change we've got now with the equivalent of placing a massive magnifying glass between us and the sun. Indeed some Martian terraforming plans call for the construction of a massive fresnel lens at the Martial L1 point. 1 degree in 100 years? With lots of space based collection beaming new energy to the surface you could get 1 degree a minute. Then we have to start thinking of off-planet manufacturing and asteroid mining and refining but that's all in la-la land.

I also feel I took the wrong thing from your original post, that conservation is utterly futile. The attitude of simply waiting for more recourses to make themselves available and then gobbling them up is the reason Windows will boot up and grab hundreds of MB of memory just to sit idle.

I believe in inward as well as outward growth. While we're building shells around the sun and fusing the hydrogen of Jupiter we should also be perusing more efficient motors and reversible computing. If we waste 20% of the resources we use now, imagine how much goes to waste when we're gathering a million times more but still wasting 20%.

Back down to earth and the present if I can save 10% on my energy bill by conserving you bet you ass I do. That's why as a Midwesterner if it's cold I put on more clothes and get a blanket. I set the heat low (68F-70F) in the winter and the AC high (76F) in the summer. I'm also researching the payback from getting a fireplace put in as well as an insane geothermal AC system in the back yard. Me leaving the fridge open or the lights on isn't going to accelerate the carbon nanotube industry.

You might be surprised. If you look hard enough you might save a lot more than 20% through conservation.

Still, Dyson Sphere FTW.

batticdoor said...

How To Reduce Your Energy Bills / Energy Conservation Begins at Home

Imagine leaving a window open all winter long -- the heat loss, cold drafts and wasted energy! If your home has a folding attic stair, a whole house fan or AC Return, a fireplace or a clothes dryer, that may be just what is occurring in your home every day.

These often overlooked sources of heat loss and air leakage can cause heat to pour out and the cold outside air to rush in -- costing you higher heating bills.

Air leaks are the largest source of heating and cooling loss in the home. Air leaks occur through the small cracks around doors, windows, pipes, etc. Most homeowners are well aware of the benefits caulk and weatherstripping provide to minimize heat loss and cold drafts.

But what can you do about the four largest “holes” in your home -- the folding attic stair, the whole house fan or AC return, the fireplace, and the clothes dryer? Here are some tips and techniques that can easily, quickly and inexpensively seal and insulate these holes.

Attic Stairs

When attic stairs are installed, a large hole (approximately 10 square feet) is created in your ceiling. The ceiling and insulation that were there have to be removed, leaving only a thin, unsealed, sheet of plywood.

Your attic space is ventilated directly to the outdoors. In the winter, the attic space can be very cold, and in the summer it can be very hot. And what is separating your conditioned house from your unconditioned attic? That thin sheet of plywood.

Often a gap can be observed around the perimeter of the door. Try this yourself: at night, turn on the attic light and shut the attic stairway door -- do you see any light coming through? These are gaps add up to a large opening where your heated/cooled air leaks out 24 hours a day. This is like leaving a window open all year round.

An easy, low-cost solution to this problem is to add an attic stair cover. An attic stair cover provides an air seal, reducing the air leaks. Add the desired amount of insulation over the cover to restore the insulation removed from the ceiling.

Whole House Fans and AC Returns

Much like attic stairs above, when whole house fans are installed, a large hole (up to 16 square feet or larger) is created in your ceiling. The ceiling and insulation that were there have to be removed, leaving only leaky ceiling shutter between the house and the outdoors.

An easy, low-cost solution to this problem is to add a whole house fan cover. Installed from the attic side, the whole house fan cover is invisible. Cover the fan to reduce heating and air-conditioning loss, remove it when use of the fan is desired.

If attic access is inconvenient, or for AC returns, a ceiling shutter cover is another option for reducing heat loss through the ceiling shutter and AC return. Made from R-8, textured, thin, white flexible insulation, and installed from the house side over the ceiling shutter with Velcro, a whole house fan shutter cover is easily installed and removed.


Sixty-five percent, or approximately 100 million homes, in North America are constructed with wood or gas burning fireplaces. Unfortunately there are negative side effects that the fireplace brings to a home especially during the winter home-heating season. Fireplaces are energy losers.

Researchers have studied this to determine the amount of heat loss through a fireplace, and the results are amazing. One research study showed that an open damper on an unused fireplace in a well-insulated house can raise overall heating-energy consumption by 30 percent.

A recent study showed that for many consumers, their heating bills may be more than $500 higher per winter due to the air leakage and wasted energy caused by fireplaces.

Why does a home with a fireplace have higher heating bills? Hot air rises. Your heated air leaks out any exit it can find, and when warm heated air is drawn out of your home, cold outside air is drawn in to make up for it. The fireplace is like a giant straw sucking the heated air from your house.

An easy, low-cost solution to this problem is to add a fireplace draftstopper. Available from Battic Door, a company known for their energy conservation products, a fireplace draftstopper is an inflatable pillow that seals the damper, eliminating any air leaks. The pillow is removed whenever the fireplace is used, then reinserted after.

Clothes Dryer Exhaust Ducts

In many homes, the room with the clothes dryer is the coldest room in the house. Your clothes dryer is connected to an exhaust duct that is open to the outdoors. In the winter, cold air leaks in through the duct, through your dryer and into your house.

Dryer vents use a sheet-metal flapper to try to reduce this air leakage. This is very primitive technology that does not provide a positive seal to stop the air leakage. Compounding the problem is that over time, lint clogs the flapper valve causing it to stay open.

An easy, low-cost solution to this problem is to add a dryer vent seal. This will reduce unwanted air infiltration, and keep out pests, bees and rodents as well. The vent will remain closed unless the dryer is in use. When the dryer is in use, a floating shuttle rises to allow warm air, lint and moisture to escape.

If your home has a folding attic stair, a whole house fan, an AC return, a fireplace, and/or a clothes dryer, you can easily, quickly and inexpensively seal and insulate these holes.

Mark D. Tyrol is a Professional Engineer specializing in cause and origin of construction defects. He developed several residential energy conservation products including an attic stair cover, an attic access door, and is the U.S. distributor of the fireplace draftstopper. To learn more visit