Natural Gas Price Drop, and Natural Gas Electricity!

Today’s post is about the shift in US primary energy use from coal to natural gas (AKA methane). Hydrofracking, the hydraulic fracturing of rock to subsequently produce natural gas, is a new favorite pass-time in the US. Natural gas prices used to track oil prices per unit of heat. They now roughly track coal prices per unit heat. As a result, it is now economical to produce electricity from methane rather than coal. As we discussed before, coal produces a whole bunch of dirty pollution, and methane does not. All good, right?

This is very important for both CO2 emissions reduction and for reduction of other pollutants. The math section is chemistry heavy. If you are going to skip a math section, this is the one.

The highest grades of coal have composition C_{240}H_{90}4NS , and lower grade coal is C_{137}H_9O_9NS. All coal is tainted with mercury and other heavy metals. Lower quality coal has more pollutants per unit heat, and this produces more pollution for the same amount of electricity. From the last post, we learned burning coal has quite the array of negative health effects.

The chemical composition of natural gas is CH4. It contains almost no other pollutants. It doesn’t produce particulate matter. When it is burned to produce electricity, we do not have the direct adverse health effects associated with coal. What about the CO2 emissions? These are reduced. Cause of math.

The Math of Chemistry! This is bond enthalpy chemistry. (Feel free to skip ahead if you don’t like the math parts)

Let’s look more closely at the composition of these two things. When any substance burns, it produces heat by converting everything to H2O and CO2. The resulting H2O and CO2 have lower internal energy than the coal or methane that formed them. The difference in energy from the coal to the H2O and CO2 has to be given off as heat.

Before the math: First, what is a mol? It is short for mole. Pretty bad abbreviation, eh? A mol is the number of molecules it takes to make one g times the molecular weight of the molecule. It is 6.022 \cdot 10^{23} molecules. This is confusing. Lets use examples to make it less confusing. Hydrogen has a molecular weight of 1. A single mole of it weighs 1 gram. CH4 has a weight of 16 (12 for the carbon, 4 for each hydrogen). A mole of it weighs 16g. CO2 has a molecular weight of 44, and a mol of it is 44g. Done.

The amount of energy used to hold atoms together to make molecules is the bond energy. Chemical reactions happen, chemical compositions are changed. If the overall energy of bonds are lower after the change, heat has to be released. This creates fire.
Bond energies: C-C bonds (aromatic, the ring-type found in coal) have 519 KJ/mol. C-H is 410. H-O is 460. C=O (double bond) is 799. O=O are 494 KJ/mol.

We simplify coal as aromatic bond chains of 4(-CH-) (this is generous in terms of calculating CO2 produced per unit coal, as all my prior calculations have been) (I stole this clever approach from my advisor, Jim Anderson, to simplify things). CH4 is pretty easy as CH4.

We can write these as:

4(-CH-) \longrightarrow 4CO_2 + 2 H_2O
CH_4 + 2 O_2 \longrightarrow CO_2 + 2H_2O

The molecular weight of our coal is 4*(12+1) or 52. Methane: 12*1+1*4 = 16

Coal: We break four C=C aromatic bonds (only four cause we would be double counting if we did each side of (-CH-), four C-H bonds, and 5 O=O bonds. We form 8 C=O and 4 H-O bonds.
Methane: 4 C-H bonds are broken, as well as 2 O=O bonds (the two O=O bonds are from converting the 4 H bonds into H2O). 2 C=O, and 4 H-O bonds are formed.

Coal:   4 \cdot 519 + 4 \cdot 410 + 5 \cdot 494 - (8 \cdot 799 + 4 \cdot 463) = 2058 \frac{KJ}{mol} = 514 \frac{KJ}{Mol-CO_2}

Methane:   4 \cdot 410 + 2 \cdot 494 - (2 \cdot 799 + 4 \cdot 463) = 810 \frac{KJ}{mol} = 810 \frac{KJ}{Mol-CO_2}

Math done!

The changing landscape of energy production based on cheap NG

Back in the day (pre-2010 or so) natural gas was much more expensive per unit heat than coal was. If you were going to burn something to produce electricity, coal was much cheaper and so produced cheaper electricity. The fact that it was pretty dirty didn’t matter as much. Then hydrofracking happened. Natural gas got cheap. Its price once roughly tracked with but below oil. Now it tracks with coal. This makes it a viable alternative to coal in power production. This fundamentally alters the primary energy landscape in the US. Once more data is available, we will revisit this.

Hydrocarbon Prices 86-12

Historic hydrocarbon prices per million BTU. Natural gas roughly tracked with oil, until hydrofracking made a glut in the market

Hydrocarbon Prices 07-12

Zooming in on the recent few years, the divergence of oil and gas and convergence of coal and gas becomes evident

 

Let’s discuss policy and environmental implications. They are pretty huge.

The math shows that in energy per unit CO2 produced, methane is about 60% more efficient than coal. This means that if we have to burn either methane or coal, and we seek to limit CO2 production, methane is the natural choice. Historically pricing prevented this from happening.

Natural gas is now only slightly more expensive per unit heat than coal. It makes sense to make electricity from natural gas, cause it produces far less pollution per unit heat. Since 2008, the US has reduced the amount of CO2 is produces for the first time in a long time. The reduction of CO2 produced by the US is partially based on this change in natural gas price. We now produce more electricity from methane than we used to. Since methane is more efficient at producing energy per unit CO2 produced, we produce less CO2 as a country.

Many staunch environmentalists argue this is a bad thing. Natural gas is still a hydrocarbon and still produces greenhouse gases. It kills far fewer people directly than coal does. The deaths that came as a result of coal might have pushed us towards a much greener economy. Methane is the lesser of two evils. It produces energy like coal. It produces CO2. It is still a finite resource. It is much better than coal.

Coal: The great of two evils between coal and methane. A picture of anthracite coal to break up the monotony of a text well. From Wikipedia.

Barring legislation to prevent hydrofracking, this trend of cheap NG will continue for a long time in the US. We have massive reserves of natural gas in our shale, and hydrofracking can get it out. This is not limited to the US, but there are only a few countries in the world that will be able to do this.

Before closing, we have one last thing. Many of you looked at the graphs of natural gas prices, saw that they were historically not much higher than coal for many years, and wondered why we didn't have natural gas electricity plants then. There are two answers. The first is that we did. It is why we have so many right now that can instantly go online. The second answer is that the EPA really only started getting strict on coal plants in 2004. The emissions from coal plants add many costs that go beyond the price of coal. Natural gas is pretty clean, so it doesn't face these costs, making it more competitive with coal.

Summary: Hydrofracking in the US has changed the natural gas price to be much lower and has made it a basic energy feedstock rather than a premium one. The US has natural gas power plant capacity, and has started shifting to electricity from natural gas. These power plants produce less harmful emissions as a result. CO2 emissions are reduced for the same amount of electricity. Harmful pollutants that cause heart attacks, asthma, and early death are also reduced. This is pretty huge.

Thanks for reading again, and sorry for the huge length

Jason Munster

* Will pointed out that I had Avogadro's # off by a factor of 10. Fixed

Coal Power Plants

Expect a lot of updates on this post. Thanks to Buck Farmer, who told me that I needed to learn LaTeX to make this prettier.

COAL FIRED POWER PLANTS

A coal fired power plant.

Coal fired power: it provides a lot of our energy, is less expensive than petroleum by far, makes cheap electricity, and causes all sorts of health ailments and pollution. Coal power plants produce particulate matter, sulfur pollution, and other pollution, resulting in deleterious health effects.

Coal fired power plants provide a huge chunk of the world’s energy. It provided almost 50% of US electricity in 2009. Today, the math section is a review of how much energy is in coal, how much coal we need to operate a single power plant, and how much coal we need to operate all the coal fired power plants in the US and China.

The topic of coal fired power plants used to be simple. Thanks to fracking, natural gas prices are now approaching coal prices. This post is written with 2009 information. It is largely relevant today, but this landscape may change in a few years as more power is produced via natural gas in the US. Suffice it to say that natural gas has become considerably cheaper in the US:

Oil be getting expensive, NG be getting cheap!

The price ratio per unit of heat in natural gas prices compared to oil in the US. The ratio used to be around 1. Now you get a lot more heat out of natural gas per dollar, thanks to the abundance from hydrofracking.

We will discuss this more in a future post.

Maths! Warning, this is pretty shocking!

High grade coal has an energy density of about 32MJ/kg (For our math, lets assume the best coal is used everywhere. In reality it is about 24, so my world with coal is 33% nicer than the real world). Compare this to a gallon of gasoline, from my very first post, at 120MJ. A gallon of gas weighs about 3kg, with an energy density of 40MJ/kg, slightly higher than coal, or nearly twice as high an energy density of a majority of coal.

A watt is a joule per second. A megawatt is a megajoule per second. A coal fired power plant can produce 1GW per second, which would be a gigajoule expended per second. But remember from our thermal efficiency post, these powerplants are not all that efficient! Let’s say a coal one averages 35% for thermal efficiency.

 

Coal_eqn1

31.25kg of coal used per second to produce 1GW of heat! But remember from the thermal plants post, thermal plants tend to only be about 35-40% efficient!

Coal_eqn2

A 1000MW coal fired power plant burns nearly 200 lbs of coal PER SECOND to provide power. That is my weight in coal for every second.

Let’s continue blowing your mind. There are 86,400 seconds in a day, yes? (yes).

Coal_eqn3

2.8 megatons of coal per year for a single coal-fired powerplant! Okay, 200 lbs. per second leaves a bigger impression. Here is another way to look at it. How much coal does it take to keep a 100W lightbulb lit for a year?

Coal_eqn4

 

280kg! Per year! This is about 2 lbs. of coal per day to power a 100W lightbulb. “But Jason,” you say, “We don’t get all our electricity from coal!” This is also true. We get almost ½ of our electricity from coal. But say ½ is from coal, the other ½ is from hydro power. If you turn off your light, we get back the ½ from coal, saving a pound of coal from being burnt. What about the ½ from hydro? Welp, that can go and power another light. The ½ of the light that would have been powered by coal. So yeah, even though ½ of our power comes from coal, the opportunity cost of using that light is the equivalent of getting all of it from coal.

Let me repeat that. If you have a 100W incandescent bulb, and you leave it on for a day, you just burnt 2 lbs. of coal. Good job. If turning off your lights to save on electricity is not enough to get you to shut em off, just picture that much coal burning to keep that light on. Your laptop computer uses about 2-3 pounds if it runs the entire day. Your TV, if left on, will burn more like 10 lbs. of coal a  day.

One last part. China provided 500GW of coal power provided in 2012. The US provided 200GW in 2009 (note: thanks to shale gas and fracking and using the gas to produce electricity, the amount provided by coal has dropped!). 200GW of coal power in the US means 600 megatons of coal per year in the US using our numbers, and 1500 megatons of coal in China. And remember, my numbers are rosier than the real world.

Turn off your lights.

The qualitative stuff!

Emissions from coal-fired power plants, and health trade-offs

Smog. Not fun to breath.

Burning coal emits sulfur (which can be mitigated through special filters, but often is not), CO2, NO and NO2, mercury (also can be mitigated, usually is in the US), other metals, and fine particles (called PM2.5 and PM10 for Particulate Matter of radius 2.5 microns and less, and radius 10 microns or less, respectively). Sulfur causes irritation and lung problems, smog, and acid rain. CO2 and NOx contribute to global warming, NOx also to smog. Mercury emissions are the reason we can no longer eat fish every day. PM2.5 causes cancer, asthma, and severe lung problems. Coal power plant emissions can lead to ozone at ground level, which causes smog and serious respiration issues.

Later we will discuss black carbon vs. sulfur here, since they have opposite effects on regional warming vs. cooling. Today we discuss the health effects of a coal fired power plant.

In the US, where coal-fired power is relatively clean, it causes tens of thousands of deaths per year. It causes hundreds of thousands of heart attacks, asthma attacks, ER visits, and hospital admissions per year. A compilation of EPA and heavily peer-reviewed articles estimates 13,200 deaths and 20,000 heart attacks were caused by coal-fired power plants in 2010. In 2004, before the EPA starting getting aggressive, these numbers looked like 24,000 deaths per year in the US.  The rate of asthma is drastically increased in the area of coal fired power plants. The US even then had relatively stringent requirements on power plants. When you factor in the population and lax controls of countries like China and India, I have heard estimates of premature deaths caused globally by coal fired power to be in the millions, and even larger numbers for asthma.These adverse effects are much more likely to be caused by the wealthy regions that use more electricity per capita than the poor regions that host the power plants and the adverse effects. In other words, the electricity used by large mansions in wealthy neighborhoods often comes from powerplants placed near poor neighborhoods.

The coal used by the US and China directly contribute to global warming on a huge scale. In a future post that describes the composition of the atmosphere and how greenhouse gases work, we’ll get directly into those numbers.

Satellite image of pollution in China. From: http://earthobservatory.nasa.gov/IOTD/view.php?id=76935

Beijing's got a bit of a particulates in the air in the winter. I was in an airplane in Beijing on this day. They announced "The fog is too thick to take off." Except it was below freezing and the air was dessicated, making fog unlikely.
A more clear day near Beijing

 

Let’s be pragmatic for a second.What’s worse than deaths and heart attacks caused by coal-fired power? Not having electricity to power your hospitals and other vital services. If you are a poor or developing country that can’t afford fancy nuclear or renewable electricity, and you don’t have access to hydro power, putting up a coal plant to power cities enough for basic services is a no-brainer.  Wealthier countries have a choice: suffer the pollution, or spend more money and avoid it by building more expensive yet cleaner electricity sources. The US as a whole can easily afford to do this. Pakistan and India? Not so much.

Take-aways: Turn your lights off, they require a lot of coal. Avoid breathing or raising children near coal-fired reactors.

-Jason Munster

Base load electricity vs Peak Load

Base load Electricity vs. Peak Electricity

I was writing a post about how a coal fired power plant works, and then realized that I needed to describe more about our electrical power grid and how each power component fits into it. Also, speaking of power grids, there is an excellent game called Power Grid that anyone who knows me should come over and play.

Base load electricity!

Electricity_demand_profile_NE

Pictured above is the electricity demand for an October day in New England. Notice that throughout the middle of the night, the electricity demand is roughly 10GW. Throughout the day it ramps past 15GW. Base load electricity in this case is 10GW. It is the minimum amount of electricity needed at any point. All power plants that provide base load electricity will run 24 hours a day. Base load power plants need to be very reliable so they don’t shut down unexpectedly.

Base load electricity requirements do change throughout the year. During the sweltering summer in southern states, air conditioners are constantly on, drawing more electricity in the summer. In some countries, there is not enough base load electricity to provide electricity in the worst months. In Pakistan, for instance, there will not be viable electricity more than 4 hours per day for several months. We will return to base load electricity soon.

Peak electricity is whatever is above base load. In the above figure, it is the all the extra stuff from 10GW to 15GW. Peaking power presents special challenges, because it can be unpredictable. If the temperature is several degrees warmer in a summer afternoon, the peak electricity requirements can be greater than predicted. Power plants that are capable of ramping up power quickly will compensate for peak electricity demand. “Ramp Rate” is the MW per minute a turbine can spin up at. This ramp rate is important, and we will get back to that almost immediately.

A brief interlude on cost! Base load electricity tends to be pretty cheap. A base load plant will not get paid as much for electricity. Peaking plants are designed to turn on only when electricity is more in demand. This means they get to charge more! A peaking power plant will figuratively not get out of bed in the morning for less than 50% above base load electricity rates.

Okay so here is where things get somewhat more complicated. Some power plants can never be taken offline in short order (think nuclear). Thermal power plants tend to take longer to create enough heat and steam to spin up their turbines, including both coal and nuclear, and some types of natural gas. Anything that takes a long time to spin up is meant for base load power.

A nuclear power plant with the nuclear plant (small rectangle buildings and one cylindrical building) and a cooling tower (big steaming parabolic-shaped tower). Nuclear power plants never shut down, except to change fuel rods.

A nuclear power plant with the nuclear plant (small rectangle buildings and one cylindrical building) and a cooling tower (big steaming parabolic-shaped tower). Nuclear power plants never shut down, except to change fuel rods.

Other types spin up very quickly. For some, like natural gas plants that are designed to deal only with the peak electricity use, a typical turbine can ramp at a massive 20MW per minute (most plants have several turbines, and can ramp at multiples of 20MW!). Why don’t we use these for base load, since they seem so flexible? These fast-ramping systems are not designed to be always-on. They accrue damage if they do not have downtime.

Let’s talk about renewables. A power plant has to produce either base load or peaking electricity on demand to be useful. We have the magic of hydro electricity. It combines a very high ramp rate, and also capable of maintaining base load electricity.  Wind and solar at first seem terrible. They only work when the wind is blowing or when the sun is shining. So they cannot provide either base load or peaking electricity, right? Fortunately, this is not correct. Due to complexities we will discuss in later posts, wind and solar can be installed and paired with each other and with other tech to produce somewhat reliable base load electricity or peak electricity.

One example? When does electricity demand peak in the summer?

If you said when it gets hot and air conditioners work harder and draw more electricity, you are onto something. And it gets hot when the sun shines. Put some solar panels on your roof, and you see your solar panel electricity production rise coinciding with your need for more electricity for house cooling.

Every power plant type has important considerations for peak load vs. base load. As we look at each in turn, it will become apparent how important this distinction is.

One last thing before closing. How do power plants figure out when to turn on? In New England, we have a group called ISO New England. It projects electricity demand based upon yearly trends (people consume a ton of electricity over holidays, and at different time periods!) and upon weather forecasts. Each day, every power plant puts in a bid for how many cents per kilowatt hour they need to turn on. In other words, it’s the figurative “price per kwh to get out of bed.” If demand is projected to rise to such a point that the bid for a plant is met, that plant will turn on once the price hits that. This is confusing. Let’s use an example.

We have three power plants in our imaginary tiny country. Since I keep bringing up this country, I am going to call is JasonLand (for now). JasonLand currently has a coal fired plant, a nuclear plant, and a natural gas plant designed for peaking. The nuclear plant cannot shut down. It will literally bid -$0.50/kwh to  ensure that no matter how low the price is, it will produce electricity. Our coal-fired power plant is baseload, but will shut down on days when it is not needed. It will bid $0.07/kwh. As soon as the price rises above this, it will start up (this is simplified, starting a coal power plant takes a long time). Our peaking gas plant will bid in at $0.11/kwh. Once people get home and need more power, or when it is a really hot day, our peaking gas plant will spin up its turbines rapidly.

So how do these bids work? How much does each plant get paid? As demand rises, price rises, and the power plant earns more for every kwh. Our nuclear power plant will make a small amount in the middle of the night, and make more during the daytime. I’ll leave you to ponder why a power plant would choose to not run until a certain payment threshold is hit.

Because I can’t help myself, let’s close with a tiny bit of math. A realistic price for energy in New England is about $0.15/kwh. To make it easy, let’s convert to $150,000/gwh*. A nuclear plant is about 1gw. It will produce 24 gwh of electricity in a day. That is $3,600,000 in revenue per day. Every week it earns nearly $25 million. I hope at this point any regular reader is beginning to get a sense of how staggering numbers associated with energy use are.

Thanks for reading again!

Jason Munster

*Correction: original post was a factor of 10 short.

Powerplants, Primary Energy, and Electricity!

Power Plants! Primary Energy vs. Electricity!

Energy and electricity are the backbone of our civilization and economy, right?  (Hint: the answer is yes) How do we get all this electricity we got kickin’ around? That’s a pretty complicated topic. This is gonna take a few posts, but we’ll get there. Today is energy and electricity, and how they relate. Later will be a more detailed look at some power plants. I don't think most people will want to skip the math section this time, as it is both interesting and kind of fun.

First, The Math!

The great bulk of our electricity generation amounts to complicated ways to boil water. Even nuclear plants generate electricity by harvesting the heat of a nuclear reaction to boil water. In all these power plants, application of heat turns that water into steam. That water to steam thing expands the water a whole lot and creates positive pressure (and thus wind) to drive a turbine. Driving a turbine spins a coil of metal in a magnet, converting mechanical energy into electric energy.

Picture!

Block diagram of a coal / thermal / steam / fossil fuel power plant. Source is TVA website (government authority that built powerplants in a huge chunk of the south)

Nuclear plants, coal plants, and natural gas plants all produce electricity via boiling water. For this reason, these powerplants are called thermal plants. Thermal --as in heat. Right? Cool.

Hokay, so how efficient are these thermal plants? The maximum efficiency of a heat engine (which a thermal plant is) is 1 - \frac{cold temp}{hot temp} (temperature in Kelvin!). Kelvin is the celcius scale, but is always positive. Absolute zero is 0 kelvin. 273.15°K is 0°C. Using Kelvin makes it way easier to do science.

The hot temperature is the temperature of our steam that drives the turbine. The cold temperature comes from whatever cold water they have handy. Often it is seawater, a lake, or a river. The cold water will probably be around 20C, or 293K. The hot temperature is the temperature of the steam in the thermal plant. Lets say that is 650K (roughly 377 celcius, quite a bit above the boiling temperature of water at 100C! This is very hot steam!)

1-\frac{293^\circ}{ 650^\circ} = .55 or 55% efficient.

This is the maximum theoretical efficiency of a thermal power plant. It is how much heat can be converted to electricity. So say that our gallon of gasoline with 33kwh of power was burnt in a perfectly efficient power plant with 650°K steam. We would only obtain 33*.55 or roughly 18kwh of our 33kwh. The other 15kwh will just become waste heat. This maximum efficiency is never attained. There are always extra heat losses and efficiency losses throughout the power plant. Many coal-fired power plants only achieve 35% efficiency. The same gallon of gas would actually only be able to produce closer to 12kwh of electricity from our 33kwh of energy in the gallon of gasoline.

More math! (only slightly related, cause I want to do more math). Calculating how much heat is produced from stopping a bicycle is a fun way to get an idea of how heat and motion relate. For the setup, assume that I weigh 90kg and am bicycling at 10 meters per second.

The amount of kinetic energy (the energy just from moving) that I have is .5*mass*velocity2

.5 \cdot 90kg \cdot (10 \frac{m}{s})^2=450 J . This is all of .125 watt hours. Not much at all. All of this kinetic energy is converted to heat energy in the brakes. Compare this to the energy from the first post about heating up a cup of tea, which took 31kj, or nearly 100 times as much. How bout a car? It travels at about 30m/s on the highway (about 70mph). It weighs 1000kg.

.5 \cdot 1000kg \cdot (30 \frac{m}{s})^2=450kJ , or 125 watt hours. Stopping this car requires dissipation of a lot of heat at the brakes! That’s like 15 cups of tea worth of heat. Another way to look at this is that stopping this car would provide only enough energy to power a 100 watt lightbulb for an hour and 15 minutes. So that is how much energy the car has in its motion. It takes a lot more energy to get the car going that fast, though. Why? Cause the engine in our car is also a heat engine. It’s not very efficient at converting energy. A car is about 25% efficient. The other 75% is all converted to waste heat. The energy it takes to accelerate your car to 70mph could power a 100 watt incandescent lightbulb for 5 hours.

Okay! Back to the big picture!

Electricity Generation and Primary Energy

What is primary energy? Let’s step back and figure out all the way we use power plants and fossil fuels to make our lives easier. The first one is obvious: electricity. It powers our houses, lights, electronics, etc., and sometimes even is used for heating our houses. And it is definitely used to cool our houses with an air conditioner. The next obvious one is your car, which doesn’t run on electricity. We pour gasoline in, and then the engine converts the gasoline to kinetic energy and the car moves. After electricity production and transportation, what we have left is heating for home and industrial purposes. This can be done with coal (many poorer countries use low-quality coal to cook with), wood, natural gas, or any other combustible. As discussed above, electricity is produced by burning fossil fuels to produce heat. Electricity is a byproduct of primary energy.

So that is what primary energy is. All that stuff added together. When most people think “Energy” they equate it with electricity. Now you know differently! A great example of this error was the reporting on the Fukushima nuclear meltdown in Japan. During the reporting, news organizations would regularly say that 20% of energy supplied in the US is from nuclear power. This, however, is wrong! Only about 10% of energy supplied in the US is nuclear. The 20% number is how much of our electricity comes from nuclear. First, what causes these two numbers to be different? And second, why do we even care?

That difference in between resource inputs and electricity output is part of the difference between primary energy and electricity. If we live in a tiny country that uses only one power plant to provide all of its electricity needs, and it uses only electricity for everything. It burns 100 gallons of gasoline an hour (this would never be a power plant input, but let’s keep it simple with numbers we know). It would burn 3340kwh of energy in that hour, and produce 1200kwh of electricity in that hour. Since this is our only energy use in the entire country, the former is primary energy use (3340kwh), and the latter is electricity use (1200kwh)!

This pretty picture from the DOE pretty much explains it all. And now you can explain it to others!

Primary Power is all the things that produce energy, whether it is burning coal in a power plant or gasoline in your car. These are our sources of energy, and where they end up.

Primary Power is all the things that produce energy, whether it is burning coal in a power plant or gasoline in your car. These are our sources of energy, and where they end up.

What about power plants that don’t use fossil fuels, like hydroelectricity? Easy! A 10MW hydro plant run for an hour registers as 10MWh both primary energy use and electricity use. An important takeaway here: if we lived in a 100% renewable and 100% efficient economy, primary energy use could nearly equal electricity use.

So this is one reason we care about the difference between primary energy use and electricity use. It is a measure of how efficiently we are using our resources, and how much we are getting for all that CO2 we are shoving into the air when we make electricity.

Let’s go back to everything that is primary energy. We have the inputs of heating, cars, and electricity production. Cars and heat are entirely primary energy use. We don’t really use electricity in many places to run either. So now we have everything we need to know to analyze primary energy vs. electricity, efficiencies of power plants, and energy efficiencies of whole economies! Pretty sweet, eh?

Okay, we are pretty much done here. I want to mention one last thing. That small powerplant we had, the one that burned 100 gallons of oil in an hour to produce 1200kwh? A real powerplant in the US produces in megawatts. Like 600 to 1000 MW. 600 times the size of our small powerplant. Even a small 600MW powerplant one would require 60,000 gallons of oil per hour. This is the scale we are talking when we have power plants.

-Jason Munster

Disposable Cups, part 2!

Hi again! Apologies for the lack of quantification in this post. It will be largely qualitative. I know how much everyone hates that.

Last time we discussed the energy use of reusable vs. disposable cups, and showed that the reusable cups require a significant number of reuses before they break even in regards to energy requirements when compared to single-use cups. This time we discuss pollution and disposal. When factoring in the pollution from production and the space required for disposal, reusable cups become more attractive.

Producing ceramic and glass cups is straightforward. It is only slightly more complicated than heating up dirt and making it into the shape you want. It takes a lot of energy to produce that heat, but few chemicals are used. There are some potential pollution issues associated with the dusts and powders used to create glass and ceramics, but proper techniques that are used in the developed world largely mitigate these.

Making paper requires pulping of the wood. Paper can use a chemical or mechanical process for making pulp. The chemical process can release some pretty gnarly chemicals and volatile organics. Ever been downwind of a paper mill? Paper production produces quite a bit of pollution. The mechanical process produces less pollution and ultimately costs less, but produces a lower quality paper. Wax or plastic is often added to the cup to make it water-tight, preventing decomposition. As far as disposal goes, most of it ends up in a landfill.

Styrofoam cups were manufactured with a method that produced CFCs for a long time, which rip apart the ozone layer. Emissions of CFCs were supposed to be arrested, so we didn't wreck our home planet. The process has since converted to HFCs; safer for the environment, but a significantly powerful greenhouse gas, with a per-molecule greenhouse strength about 1300x of CO2. Moreover, the production of Styrofoam releases volatile organic compounds. These ultimately help produce ground-level ozone and smog. We like ozone in the stratosphere, about 15km above our head, as it blocks harmful UV radiation from reaching us. We do not like it at the ground. It causes breathing difficulty and smog, and can contribute to rising asthma rates. In other words, Styrofoam production creates air pollution. When it comes times for disposal, like paper, most of this ends up in landfill.

It is clear that the energy used to produce and clean reusable cups is the largest negative environmental factor, which, as discussed in the prior post, is mitigated after many reuses. The production of disposable cups creates pollution, and the disposal requires a significant portion of landfill space. These factors contribute to a lower number of reuses of reusable cups before an environmental break-even it obtained.

-Jason Munster