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Tuesday, February 5, 2019

Flooding

It would appear that we are going to have ever increasing flooding on into the future.  On land, rain is coming in more extreme bursts and, as warm air can hold more moisture than cold air, it is likely that in many locations there will be more rain.

On the sea shore, the sea is rising and storms are becoming more intense so higher storm surges will be added to an ever higher sea level.  Areas that were never flooded before will be..

In addition we are seeing a further effect of climate change.  Weather systems are sometimes getting stalled over certain geographical areas instead of continually moving around the globe.  If this is a 'ridge' you are likely to have prolonged drought.  If it is a 'trough', you are likely to have prolonged rain.  We saw this in Townsville in Australia (beginning of Feb, 2019) where they had almost 400mm of rain on each of 4 consecutive days.  I can't even imagine that much rain.

So what are we to do.  We can build up levies to hold rivers in their beds and build walls to keep out the sea but just look at the cost.  There is a far better and less expensive solution.

In areas that get flooded, the insurance companies should be held to account by the government and forced to honor their commitments.  We saw in the Christchurch earthquake how reluctant insurance companies are to pay up and how they delay any way they can.  In addition to the insurance the government should top up the pot so that the victims are generously compensated but that is it.  The area is declared un-insurable.  The people can stay if they want but they have had their one time pay out.  If they get flooded again, (and if it happened once, it will only be worse in some future event), they are on their own.  They had the option to take the money and move to higher ground.  If they didn't take it, too bad.

Of course, areas that are flood prone but haven't yet been built on should be declared un-insurable for floods and no buildings ever allowed on them.

This is a far less expensive option than trying to hold back the floods and the tide.

Better still, the expense is spread over time rather then having to come up with huge tranches of money to do major civil engineering works, engineering works that will be obsolete sooner or later.

So what about the land that remains empty.  If it is on a flood plain (where we never should have built in the first place), it can be used for agriculture, turned into a park or left to regenerate native vegetation.  Incidentally, allowing a river to spread over it's flood plain, reduced the height of the flood downstream and so protects other properties.  This is even more effective if the area is well vegetated with shrubs and trees.  Shore areas can become nature reserves too. Shore areas, if vegetated, will tend to collect silt and build up over time, aiding in the defense of landward properties.

If it is on the sea shore, salt tolerant plants can be introduced.  They hold the soil, reduce wave damage and moderate the force of subsequent storms.  They can become mud flats with all the benefits this brings to the bird life of the area. 

It doesn't seem likely that we will take the necessary measures to reduce our carbon output to the atmosphere.  In fact, following a few years of steady output, in 2018 we actually increased Carbon dioxide production once again.  This in spite of more and more renewable energy coming on line and ever increased efficiency in lighting and powering our machinery.

We are so clever individually but so abysmally stupid in the collective.  Let's at least be sensible in reducing the cost of flooding.

Friday, January 18, 2019

Nano-Aluminum-New Energy Source

Sorry, but it is complete BS - at least the way it's being presented.  I'm not saying that there is no place for nano-Aluminum in the pantheon of energy systems but not as implied.

I get this investment advice site on the web and they are promoting nano-aluminum as the energy source that will soon be found powering virtually everything in our modern society.  They don't say it in so many words but leave the impression that nano-Aluminum - very small particles of Aluminum. is a catalyst which causes water to disintegrate into it's component parts, Hydrogen and oxygen, and that it does this at room temperature.  Either they are ignorant of the most basic chemistry and physics or they are trying to play the market so that they can make a buck on it's ups and downs.  Let's start by looking at what it would mean if Nano-Aluminum was such a catalyst.

As anyone who has taken first year chemistry in High School or even basic science in year 9 knows, a catalyst does not take part in a reaction.  Rather, it enables a reaction to proceed and quite often at lower temperatures than would be necessary without the catalyst.  In some cases the reaction would not occur at all without the catalyst.  So let's pretend, for a moment, that nano-Aluminum is such a catalyst.  What would bubble off.

You are probably way ahead of me.  We would have bubbles of the perfect stoichiometry mix of Hydrogen and Oxygen  in the exact proportions to convert back to water with one mother of a bang with the slightest spark. And you certainly wouldn't want to try to compress this mixture into a high pressure tank.  Let's look at the claim that this is a source of energy.  Clearly the reaction would be endothermic.  It takes energy to split water and if this reaction took place at room temperature, the reaction vessel would cool down, creating a 'delta T' (temperature difference).  Heat from the environment would move toward the cool reaction vessel and continue the reaction.

Of course you could add heat from, say, solar panels, to speed up the reaction but my investment-advice-web-site is presenting this as a source of energy.  Mind you it would be pretty neat and you would have found a way of absorbing surrounding low level heat energy and converting it into a high energy mix of H and O. 

What the reaction between nano Aluminium and water actually produces , is pure hydrogen which can be used in a fuel cell which  by the by, also work at room temperature. What is actually happening here chemically.

The Aluminum is pulling the oxygen off the water, forming Aluminum oxide and in the aqueous environment of the reaction, probably Aluminum Hydroxide and releasing the Hydrogen.  Nano Aluminum is not a catalyst but a reagent which is taking part in the reaction and is used up.  So let's look at how we got our Nano Aluminium in the first place and particularly how much energy went into the process..

First you ship the Aluminum ore, Bauxite, from where it is mined to somewhere that has abundant electricity.  First energy cost.  Aluminum is a tri-valent element.  That means for every atom of Aluminum released from the Bauxite, three electrons are needed. Second energy cost. It is an electrically hungry process but this is not all.  The process takes place in molten reagents.  You have to heat up the Bauxite and other reagents to 1000 degrees centigrade.  No matter how well insulated your reaction vessel, it looses heat and energy must be constantly added to keep the temperature up. Third energy cost.  Then you have to ship the ingots of Aluminum to where they are turned into nano-Aluminum. Fourth energy cost.  And finally it takes energy to convert a block of Aluminum into nano Aluminum. Fifth Energy cost.  We could add one more.  The energy cost of shipping the nano-aluminium to where it is to be used.


But this is all moot.  In fact, as noted above, the Aluminium is not a catalyst.  If it was a catalyst, all the above energy costs would be worthwhile since the Aluminum would remain for a very long time or perhaps for ever without being used up and you would have a continual source of hydrogen (mixed with Oxygen)

The Aluminum pulls the oxygen off the water making Aluminum Oxide (Bauxite basically) which probably converts to Aluminum Hydroxide in the watery environment of the reaction.  The Hydrogen is released.  The hydrogen can then be used in a fuel cell.  You can never get more energy that the amount that actually split the bauxite in the first place and actually there are inefficiencies in this process.  You certainly do not recover the other 5 energy inputs listed above.  So you have used a lot of energy to get a relatively small amount where you want to use the energy.

At the very most, the use of nano-Aluminium is a sort of battery or if you like an energy storage device and not a very efficient one and one at that.  It is not chargeable.  In that sense it is comparable with the old Zinc batteries.  Of course you also need a fuel cell as part of the package in order to produce electricity.  At the most, nano-Aluminium could serve as an emergency source of electricity in a pretty safe and compact form for specialist applications where it is worthwhile to go to the expense of the whole process.  It is not a source of energy but at best an energy storage mechanism which could use wind, hydro or solar to product it in the first place and not very efficiently when you consider the total energy input and the final energy output.

It might, for instance, be used for the military in remote areas.  Getting their fossil fuel to their tanks, trucks and generators is not only expensive but highly dangerous.

Sunday, December 30, 2018

Energy storage

Despite what you hear, we have already cracked the energy storage problem which is needed to make intermittent sources of renewable power such as wind and solar-electric a practical reality.  And it is not a single solution but a whole range of solutions.  Let's have a look at some of them.

1.  The clothes in your clothes cupboard and the dishes in the kitchen cupboard

Clean dishes and clean clothes are potentially energy storage devices.  All that is needed is a smart grid and smart meters.  I'm not talking about what many electrical companies have taken to call smart meters.  All these pitiful machines are designed to do is to eliminate meter readers and hence make more profit for the electrical distribution company. These so called smart meters send the company information on how much power you have used.  That's all they do.

No, I am talking about a smart grid with smart meters in which the price of electricity varies according to availability and a smart devices in the home that detect the current electrical price and controls  your smart appliance.  In the case of your clothes washer, you dial in the price you are willing to pay to wash your clothes and the machine comes on when the price falls to this level (because the sun is shining, the wind is blowing and electricity prices have fallen or because it is night and everyone has turned off the lights and gone to bed).  After a while, you will become pretty canny about not setting the dial so low that your clothes stay dirty but low enough to save you a nice bit of change.

One thing to consider, though, is that in the case of washing clothes or dishes, once the process starts, you don't want it to stop even if the price of electricity increases.  Clothes and dishes won't get clean if the power keeps going on and off.  There are even better applications.

2.  Charging your car battery or heating your water.

Everything said above about washing your dishes and clothes applies but here it doesn't matter if the electricity goes on every time the power price has got down to what you dialed on your battery charger or water cylinder heater, and goes off when the price rises above that level. Here though, we need another feature on our smart device

You need to be able to dial in "if the water isn't up to a certain temperature or the battery up to a certain level of charge when 5 in the morning rolls around, turn on the power regardless of price.  After all, you want to take a shower in the morning and have enough power in your electric car to get to work. You have gained charging or heating at a highly beneficial price through the night and just top up with more expensive power.

All the above is what is known as 'demand balancing' of the grid as opposed to the present supply balancing.  At present, the electric companies have multiple generating stations and they cut them in and out according to the momentary demand.  That will not change but now they have an additional tool.  By signaling when their base generation is in excess to demand, they can bring on more demand.  Then when demand rises, mainly in the morning as everyone gets ready for work and in the evening when everyone has all the lights on and is watching television, a whole bunch of electrical devices will not be demanding power.  Your dishes and clothes are already washed and your water is heated.

This has a real 'up-side' for the power companies.  To build another power generation station which will only be used for peak shaving is bloody expensive.

Another up side is that they will pretty well always have a market for excess power.  Instead of letting water go over the spillway, they can run it through the generators and no need to feather their wind turbines.  Most of the time there will be a market for the excess.

3.  Pumped Storage
This is already done in many jurisdictions.  When you have excess power from a cheap source, you can use it to pump water up into a reservoir.  When power demand exceeds supply, you can run this water through a generator for 'peak shaving'.  Water power is probably the most useful source of power for peak shaving as it can respond instantly to increased  or decreased demand.  While you only get, say, 75+% of the power out that you put in, this system is economically worth while.  It becomes even more so when you have wind and solar which will  often be generating far more power than is needed.  The more of this stored energy you have, the less coal you have to burn.


4.  Power walls
Tesla already produces a 6.4 and a 13.5 kWh battery pack that you can hang on your wall.  It uses lithium ion technology and a very good power management computer.  Even if you do not have solar panels or a wind generation, this could be worthwhile for you but only if we have smart grids and smart meters.  You could then charge your power wall when electricity is inexpensive and use it when power prices are high.  If you have your own renewable energy generation device, any power which is in-excess of your instantaneous demand goes into your power wall.  This is a great advantage.

Many power companies give abysmal returns for power you send to the grid.  Unless you have an enlightened power company, you don't want to be sending them power but rather using it yourself.  A further possibility opens up here.

5.  Private peak shaving
  At some point the power company may need power for a peak demand and decide, OK, just now we will pay a fair return.  They could then draw on the power walls of the country until the peak passed.  The interval in a rugby game comes to mind when everyone puts on the jug for a nice cup of tea.  The owner of the power wall dials in the price he wants to get for sending power to the power company.  The power company can up the price until they have enough power to balance the system.  The power wall owner gets a nice little bonus any time this occurs.  Again, it all boils down to truly smart grids and smart meters.


6. Liquid metal batteries
Liquid metal batteries are not likely to be useful for home use although small units have been built.  These were invented by Donald Sadoway and his team of students at MIT.  They work at temperatures high enough to melt the metals that form the electrodes and the salt that forms the electrolyte.  The flow of current through the battery creates enough heat to keep the materials molten.  The trick is in a very well insulated container.

One of the metals is denser than the salt they use, the other less dense so they automatically form horizontal layers.  As the battery discharges metal migrates through the salt to the other layer and the reverse when the battery is being charged. (Sorry, that was a bit simplistic)

In terms of the cost per kWh stored, they are projected to be very cheap. They are also said to be very long lasting and very safe.  If I had one at home, I would still want it in an outbuilding.  They have had some start up problems but have gone through a re-design phase and apparently have solve these.  They say that they have also developed an alternate chemistry using even less expensive materials than with the initial batteries.  They are projected to be available by 2020.

There are over 90 elements in the periodic table and thousands of different salts.  Now that the basic system has been proven, we can expect an exploration of different chemistries to make liquid metal batteries with other chemistries. 

7. The Vanadium Battery
The vanadium battery is a very clever innovation.  It is known as a flow battery.  Instead of using two different elements, it uses solutions of Vanadium in two different oxidation states.  This way, if some of one solution leaks into the other one through the semi permeable membrane, all that happens is that the battery operates a little less efficiently.  And you can have tanks of any size of the solutions of Vanadium in the two different oxidation states.  Thus the storage capacity of the battery is only limited by the size of the tanks.  The Vanadium battery therefore has a huge potential for storage capacity.  It also apparently has a very long life and a very fast response time to varying loads.

It is doubtful if it could be used in a car but one can imagine a train with the first car consisting of a giant battery of this type.  (or for that matter, a liquid metal battery).  If part of the rail line was electrified, the battery could be charged while the train was in motion over the electrified part of the track giving it enough power to bridge the gap between electrified portions of the track.  Large semi trailers might be similarly powered. However, at present these batteries are only used in static energy storage applications.

Again, there are over 90 elements in the periodic table, many of them with more than one oxidation state.  Now that the basic principle of a redox, flow battery has been proven and brought to commercial application, we can expect further exploration of the elements of the periodic table.

8.  The Iron Battery
The Iron battery is another flow battery although I am puzzled about how it could work.  True, Iron exists in two different oxidation states, ferric and ferrous but the more oxidized ferric state is quite insoluble.  It seems to me that it would go one way and that would be it.  I am clearly wrong since this type of battery exists.  Apparently they use Iron chloride which may explain the fact that it does indeed work.

9. Ultra Capacitors
Ultra Capacitors don't hold huge amounts of power compared to batteries but their great advantage is that they can take up and deliver huge fluxes of energy as needed.  In many applications, this makes the delivery of stable power levels and frequencies feasible and by avoiding large fluxes of energy through batteries, greatly extends their life.  They can, for instance, take up the regerative power during hard braking of an electric car and either hold this for acceleration or dribble it into the battery at a rate that is good for the battery.  They are vital components of renewable energy systems.

10.  Air pressure
Disused caverns created by mining, notable salt mines which tend to be air tight, can have air compressed into them in times of excess renewable electricity which can be used to power a turbine for peak shaving.  The walls  of these caverns tend to be good insullators so the heat of compression is not lost but is stored in the walls of the cavern, increasing their over all efficiency.

11.  Gravimetric
Energy can be stored using gravity.  Some mines go down kilometers. they have elevators to take miners up and down.  In such a disused mine, a large weight can be suspended from a the elevator reel, and connected to a motor/generator.  The weight is raised when electricity is available allowed to descend when power is needed.

12.  Fly Wheels
Fly wheels can store large amounts of energy.  If I remember my physics correctly, the best sort of fly wheel is similar to a bicycle wheel rather than a solid disk.  Whatever the best shape, with modern materials, fly wheels can be made enormously strong and hence spun up to high speed, storing more energy.  I seem to remember that a simple DC motor is the way to go since it just keeps increasing in speed as power is applied (not frequency modulated) 


13.  Hydrogen production
When excess energy is available, Water can be split into Hydrogen and Oxygen.  Despite being vaunted as a fuel for transportation, batteries are most likely a better, more efficient option but Hydrogen should be great for static applications.  For these, you can store the hydrogen at low pressure in those up side down tanks such as they used to use for producer gas.  Avoiding liquefaction or compression makes the whole system more efficient. If the Oxygen is collected and compressed into tanks, you have a valuable much used by product to make the system more economically viable.  The hydrogen is used when needed to make electricity in a fuel cell.  The hydrogen can also be used directly in heating and welding.

14.  Energy Transmission
This is not strictly speaking a method of storing power but rather a method to reduce the amount of energy you have to store.  Look at the map of British Columbia.  Power is transmitted by very high voltage power lines (less line losses at high voltage) all the way to Vancouver.  Lay such power lines East and West and you see that as the sun is felt in one location, it can be transmitted a considerable distance east and west.  In other words from where it is noon to where it is early morning or afternoon.  In this way, the solar generating day can in essence be greatly extended.  In addition, using DC, power can be transmitted under water from, for instance, the Sahara desert to Europe and other similar combinations of locations.  The same applies to wind power.  Electricity is transmitted from where it is windy to where it is not.
 
15. Increased Efficiency 
This is not an energy storage system but is vital for the passage to renewable sourced of energy.  Think of lighting that in the USA uses about 10% of the power generated.  Florescent lights use about a tenths of the power of incandescent lighting and LEDs about one percent of the energy used for incandescent bulbs for the same amount of light.  Other effects such as the Halbach effect for electric motors can also make electric motors lighter and more powerful.  This is especially useful for transport applications.

Buildings use huge amounts of power and have huge surface areas to collect solar radiation.  The more we take advantage of their characteristics and use them to collect energy, the lower our electric demand will be and the easier it will be to meet it with renewable sourced of energy.

The key to energy storage is truly smart grids.  The sooner we have them, the sooner we will wean ourselves off fossil fuel.  In this context, the vital path is to eliminate vested interest money in politics.  Who Pays the Piper Calls the Tune.  Never was this more true than in politics.

Friday, November 9, 2018

Greenland melting and Latent Heat

Possible effects of Latent Heat with regard to the melting of Greenland are interesting.  As usual, this is speculation but based on old established physics.  So what is Latent Heat.

When you add heat to an object it gets warmer.  We will use the old imperial measurement since in this instance it is easier to understand.

A calorie (with a small 'c') was defined as the amount of heat needed to raise one gram of water by one degree centigrade.  This is not Latent Heat. The term used is Sensible Heat - possibly because we can sense when something gets warmer.  And, of course,  it will take 100 calories to raise one gram of water, from zero degrees to the boiling point.

There are two types of latent heat.  Lets start with the phase change from ice at zero degrees to water at zero degrees.  For this transformation, it takes 80 calories to melt one gram.  That is to say, the amount of heat to melt a gram of ice is the same as is needed to raise a gram of water from 00to 80 degrees Centigrade.  This is the latent heat of the phase change between ice and water.

Importantly, when water becomes ice, exactly this amount of heat is given out.  You might be tempted to say - "but won't this heat up the water".  No.  But it will keep the temperature at zero degrees centigrade until the water is all frozen.  When ice is melting (say in a styrofoam cup) it will remain at zero degrees until all the ice is melted at which time the added heat from the environement will cause the water to warm.

The second  latent heat is the phase change from water to water gas (water vapor).  To convert a gram of water to water vapor takes 540 calories.  This is 6.75 times as great as the phase change between ice and water.  This will be important below.

Let's see what the importance may be of latent heat with respect to the great big ice cube which is Greenland.

At some time in the not too distant future, all the ice will be gone on the Arctic ocean.  Initially it will only occur in mid September when the ice minimum occurs but the period of no-ice will widen in subsequent years.  Without ice, the heat absorbed by the open water will go into warming the water*.  Here is our first effect of Latent heat, in this case the Ice-Water Latent heat.  The ice will keep the water cold until it is all gone. When the ice is gone, the water begins to warm up.
Actually this is a bit of an exaggeration.  If you draw a cross section of the Arctic ocean to scale, it is a very shallow body of water in comparison to it's width.  Already, for a considerable portion of the melt season, large areas are ice free.  These are warming already since the ice that could keep them cool is far away across the ocean, but you get the idea.

As more and more of the water is ice free, we have ever warmer water on the surface of the Arctic ocean, heating the air from below and evaporating water vapor into the air.  Since the solar radiation penetrates into the water, the warming occurs over one or two tens of meters of the surface, depending on the clarity of the water.  It takes a lot of heat to warm water so the temperature only gradually increases but a very large amount of heat is stored in this surface water.  It heats and humidifies the air blowing across the ocean.  What happens when this air blows across Greenland.

First we must define The Lapse Rate.  The Lapse Rate is the change in temperature if you take a body of air and increase it's altitude without the addition or removal of heat.  For reasons, I won't go into, as air expands, it cools.  Conversely as it is compressed, it warms.  You can feel the practical effect of this if you pump up your tire with one of those cylindrical hand operated air pumps that you hold near the flexible tube that connects with the tire and pump with the other hand.  The hand holding the tube gets hot.  

Lapse rate is 9.8 degrees per km of altitude.  That is to say, if I took a perfectly insulated balloon full of air and raised it up a kilometer, it would be 9.80C cooler at the top then when I started up.

 Little boy inflatingf bicycle tires : Stock Photo


It gets a tad more complicated when there is water vapor in the air (as there always is) but we will leave that for now.

Now, for the sake of the argument let's assume that we have fully saturated air at 100C blowing onshore in Greenland.  The air hits the ice.  Look at the following table.  That 10 to the minus 3 kg/m cubed in the third column is their way of saying grams so a cubic meter of saturated air at 100c contains 9.39 grams of water in the form of water vapor.


TemperatureMax.
Water Content
(oC)(oF)(10-3 kg/m3)(10-3 lb/ft3)
-25 -13 0.64 0.040
-20 -4 1.05 0.066
-15 5 1.58 0.099
-10 14 2.31 0.14
-5 23 3.37 0.21
0 32 4.89 0.31
5 41 6.82 0.43
10 50 9.39 0.59
15 59 12.8 0.8
20 68 17.3 1.07
30 86 30.4 1.9
40 104 51.1 3.2
50 122 83.0 5.2
60 140 130 8.1


This saturated air contacts the ice at 00C and the ice cools the air and causes water to condense out of the air.  Remember that as water vapor changes into water, it gives out 540 calories per gram of water.  Each gram of water condensed from the air gives out enough heat to melt six and three quarter grams of ice*.

*Incidentally if you want to read a dramatic account of a warm wind blowing across ice, read the book Plains of Passage by Jean Auel.  True it is a novel but Jean did her homework and reports what generations of glaciologist have observed.  It is somewhere around chapter 42 or 44.  I can't find my copy of the book.   

Let's back up a step. Where did this heat actually come from.  The wind blowing across the open water is picking up the water vapor from above the ocean.  Each gram of water that evaporates from the ocean takes this 540 calories from the ocean.  So the air is cooling the ocean and the heat is being contained in the air as latent heat.  If you have a wind that is blowing for some time from the water to the ice, a considerable amount of heat can be transferred.

You remember, I said that the top ten or twenty meters of water are heated by the sun.  As the surface water is cooled by the wind, it sinks and warm water comes to the surface.  If the water has been open for a good portion of the summer, there is a lot of heat available.

Note that sun shining on snow isn't very good at melting it.  Most of the radiation is reflected back to space without warming the snow.  Clear ice or ice with a pool of water on its surface is a little different.  The radiation penetrates but has to heat a considerable layer of ice up to zero degrees C before melting starts.  

A warm wind or a wind with lots of water vapor is something else again.  The heat is applied on the very surface of the ice and is constantly replenished from the sea.  If there is considerable water vapor in the wind, latent heat of condensing water vapor is added to the sensible heat of the wind. 
 Sea ice reflects as much as 85% of solar radiation hitting the surface, hence absorbing only 15%. Ocean water, by contrast, reflects only about 7% of solar radiation, absorbing 93%.

If this was dry wind blowing across  Greenland, it would only contribute sensible heat to the ice.  The air would cool both by contact with the ice and the expansion of air as it rose up the slope.  However with a high water vapor content, some of the latent heat of the condensing water vapor stays in the air.  

You remember, in our example we started with 10 degrees C, fully saturated air.  At a little over a km in altitude, it would have cooled to zero degrees and would stop melting the ice.  However some of the latent heat which is released as water vapor condenses into droplets (fog), the air will remain above zero degrees to a higher altitude, all the while melting the ice.

Of course the situation get's rapidly worse as the air becomes warmer than the 100 C we took as our example and the water vapor content of the air increases.  Have a look back at the table. 

While we are at it, there is another scenario that may be relevant to the story of a melting Greenland.  

Suppose there isn't much wind but Greenland is bathed in war moist air right to the top.  This air is light (relatively) due both to it's temperature and it's water vapor content.  That's right.  Humid air is lighter than dry air.  The reason is interesting and explained below.  It is in contact with the ice.  The ice cools this air and condenses out some of the water vapor making it heavier.  If the droplets of water stay in the air as fog, this exacerbates the effect.  This air now begins to flow down the slope as a density current.

You remember the lapse rate.  It works in the other direction too.  For every km that this air flows down the slope (vertical kilometer), it warms by 9.8 degrees C.  by compression.  Of course, it doesn't actually warm.  It transfers this heat to the ice, melting it.  These are the the famous Piteraqs that are seen around the shores of Greenland.   

A body of air flowing from the very top of Greenland to the sea would warm almost 30 degrees if it didn't gain or loose heat.  This heat plus the latent heat of water vapor condensing on the ice is available to melt the ice.  We should see some rather extreme melting events in the future.

Relative density of gases  
Gases have some interesting properties.  The volume of a gas is inversely related to pressure (if you keep temperature constant).  That is to say, if you double the pressure, you half the volume.  The volume of a gas is directly related to temperature.  Not Centigrade but Kelvin temperature otherwise known as absolute temperature.  This is temperature measured from absolute zero.  If you increase the temperature of a liter of a gas, for instance, from zero degrees centigrade (2730K) to 100 degrees centigrade (3730K) then the volume will increase by 373/273 =  1.37liters.

Leaving all this aside, let's get on to the really interesting aspect of gases.  It turns out that a given volume of any gas at the same temperature and pressure contains the same number of particles.  I say particles rather than atoms since many gases exist as molecules of two atoms such as N2, O2 and H2.  This has an interesting implication.  If you know what gas you have, you can work out it's relative density to, for instance, air.

Now air is a combination of mainly Nitrogen and Oxygen.  An atom of Nitrogen has an atomic weight of 14 so each N2 atom is 28.  Oxygen, similarly has an molecular weight of 32.  So air is approximately 30 (I should have done a weighted average but we are just illustrating the principle).  Water vapor consists of two hydrogen atoms and one oxygen atom so has a relative weight of 18.  Water vapor is only 18/30 = 3/5ths or 60% as dense as air.  Now we need one more property of gases.

When you put sugar into water it dissolves and  to some extent the sugar fits between the water molecules.  The volume of the sugar and the water is somewhat less than the volume of the water and the sugar added together.  Gases are not like this.  Each molecule occupies the same volume as any other molecule.  So if you add a tenth of a liter of water vapor to a liter of air (with no condensation, of course) you end up with 1.1 liter of gas.

You can see, therefore, that humid air which is a mix of water vapor (relative density 18) and air (relative density 30) is lighter than dry air.

All bets are off, of course, if the water vapor condenses into fog.  Now you have a suspension of water droplets in air and it is heavier than dry air.

So we have a couple of mechanisms that could cause a rather striking acceleration in the melting of the surface of Greenland.

 

Thursday, October 25, 2018

The End of the Ice Age

Sorry to rain on your parade but it ain't over.  We are still in the middle of an Ice Age.  It has been going on for about 2.8million years and is not over.  It is actually, if named  correctly, an epoch.  Namely the Pleistocene Epoch.  This Epoch is colloquially called the Ice Age.

During the Pleistocene Epoch (Ice Age)  there have been many icy periods (Glacials or glacial periods) and relatively ice free periods (Interglacials or Interglacial periods).  We are at present in the Holocene Interglacial and the previous one around 125,000 years ago was the Eemian Interglacial.  You could say that the Holocene Interglacial started 20,000 years ago since that was the peak of the previous Glaciation but melting really got underway a little less than 12,000 years ago so that is usually taken as the beginning of the Holocene Interglacial.

We should already be beginning our slide into the next Glacial period (not Ice Age - remember, we are still in an ice age) but the plow, rice paddies and the destruction of forests slowed our slide into the next galcial just long enough for the Industrial revolution to kick in and send us into a warming phase.  Read Plows, Plagues and Petroleum by Ruddiman for chapter and verse on the plow, plagues and rice paddies.  Despite early (6000 to 8000 years ago) human influence delaying our slide into the next glaciation, we apparently were just starting into the next glacial period when the industrial revolution reversed the trend.

The final straw in our slide into the next Glacial was the demise of the population of North America due to European diseases and the black death in the 'Old world'  Both resulted in forests regrowing and the suck down of Carbon dioxide just enough to start the accumulation of snow way up on the high lands of Baffin Island.  Apparently there is still a halo of dead lichens around this area where the expanding permanent ice and snow killed the lichen.  Green house gases then increased enough to reverse the accumulation of snow.

Some scientists are predicting that we are going into a sort of Maunder Minimum in which sun activity decreases.  No way, though, that this will reverse our warming.  We have put way too much Carbon dioxide into the atmosphere.

Our output of green house gases, by the by, long before the industrial revolution, is the explanation of why this interglacial has been so much more stable, weather wise, than previous interglacials.

With our output of Green House Gases and especially Carbon dioxide, we have put off the next glacial and with a little luck we may put it off until the next Interglacial.

However, we now have too much of a good thing and it is time to put carbon back into the soil, into trees and to stop adding more to our atmosphere.  We have the technology.  Any reasonably bright year 12 student could tell the politicians exactly what they should be doing but the politician won't listen.  They want to be elected next time and need the money from the vested interests to succeed.  Until we make it illegal for anyone to contribute anything to any politician for any reason whatsoever, we will be pushing the brown stuff uphill with a spoon.  Never was the old adage, Who Pays the Piper Calls the Tune more true.

One of the barriers to the use of renewable energy is it's unpredictability.  In the long term, you know more or less how much wind and sunshine you will get at any location but it comes in unpredictable booms and busts.  There are may fixes including notably,  demand balancing of our grids (electricity priced to reflect the extent of availability over  demand and devices that use electricity selectively when it is most available and hence least expensive).  However, a really good battery for stationary applications would go a long way to help.  Fortunately there is a technology in the wings, which could fill in the gaps left by other methods and systems.  It is the Vanadium Battery.

You might ask yourself, why I get so up tight over terminology - namely the misuse of the term Ice Age.    You will see in the popular literature and even in scientific papers, the use of the term Ice age to mean the glacial period between the present Holocene interglacial and the previous Eemian interglacial.  Why is this important.  We as humans are prone to lie to ourselves.  For instance, we note that the megafauna of North America disappeared when the Ice Age ended.  And we admit that man might have had something to do with it but it was probably climate change.  Nonsense.

First, as I said, we are still in an Ice age.   (The Pleistocene Epoch to be totally correct) so it hasn't ended.  But that is the least of the deception.  The Mega Fauna survived repeated cycles of glacials and interglacial and depending on how you define them, there have been between 30 and 50 such cycles within the present ice age (Pleistocene epoch).

No, the NA mega fauna disappeared at the end of the most recent Glacial period.  They survived quite happily the end of many previous Glacials and the subsequent interglacial and only the recent one caused their demise.  The only difference was the arrival of the first people who ate their way through these animals from one end of the Americas to the other.  If you don't think that primitive hunters could wipe out the mega fauna of the Americas, just look at the extinctions in Australia (50,000 years ago) and New Zealand (700 years ago) or in  any other  area when man first arrived.   Now we are finishing the job with habitat destruction.  Soon we will be alone in the world and then pooooof.   We are Gone Burgers. Evolution can begin again from whatever remnants remain.

The Anthropocene actually started at different times in different locations with the arrival of man.  So much for first people being the guardians of nature.  In actual fact, they eliminated any animal that they could hunt faster than it could reproduce. Now modern man is finishing the job.