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Wednesday, October 23, 2013

Solar power and the Ratchet Effect

The Ratchet Effect is why solar power won't be worth while for you to invest in --- or at least not as worthwhile as it should be.  For anyone who has true net metering, that is to say a single meter turning backwards when they are generating excess power, forget about this article.  It's not about you*.  But for anyone who is double metered (or stuck with a single meter with a  double read out) monitoring the output from his solar array,  wind turbine or small hydro system, read on.

*Actually, there is a way the power company and the government can still shaft you if you are net metered but it is diabolical.  I hate to mention it in case I give them the idea but, I suppose, it is better out in the open so that we can be prepared.  I have described it at the end of this blog.

The Ratchet Effect is most easily understood, by using the example of a day in which you  generate just exactly as much power as you  use but applies equally to any day in which you generate and use electric power (that is to say, every day).  I have written about it before but I want to put a name to it so from now on we can talk in Short Hand.  We can talk about  the Ratchet Effect without having to go into the whole explanation again.  So let's look at our hypothetical day in which you generate just as much power as you use.

Say you use and generate 60kWh on this day.  That is not what is registered on your meters.  Fortunately, in my jurisdiction (New Zealand) we are allowed to use our home generated power and only top up if we are short or send power to the grid if we generate an excess.  This is not so in all jurisdictions.  In Germany, for instance, every kWh they generate goes through one meter and every kWh they use through the other.  Do the calculations on that little lot and see what a scam it is.  At any rate, let us say, with the ratchet effect, your meters each read 10kWh.  That is the sum of the instantaneous amounts you imported and exported throughout the day.  Remember, that this happens because your meters record any instant that you are importing or exporting and no meter turns backwards..... And you will hardly ever be using exactly what you are generating.

This occurs because of the following.  Firstly, even if it is sunny all day from daybreak to sunset,  the amount of power you generate throughout the day looks like a sin curve.  That is to say, it starts at nothing, rises to a maximum in the middle of the day and falls to nothing in the evening. Your power use does not follow this pattern.

Then, few days will be sunny all the time.  There will be clouds passing in front of the sun, greatly reducing your power generation.  It rises again as the cloud pass by.

Then there is your use.  In a usual use profile, you will have a small peak of use in the morning, a larger one in the evening and automatic devices such as your refrigerator go off and on during the day.   If you are at home, you may turn your computer on for an hour sometime in the day and then turn it off.  So why is all this important.

What it means is that at practically no time will your power use balance your power generation.  In our hypothetical day even though you generate, over the whole day, exactly what you use, at any given moment, one or other of your meters will be running.  Both only run one way and that is up.  Neither of them goes backwards.  In this hypothetical day, at the end of the day, let's say that both of them read 10kWh.

Now you would think on first thought that the power company will simply take note of these two readings and say that, overall,  you have neither generated or used power.  Wouldn't that be nice.  Not on your nelly.   Ever ask yourself why they bother with two meters* if this is what they intend to do.  Why go to the added expense.  All they would have to do is to install a little electronic device to disconnect you if the grid goes down so that you don't electrocute the lineman that comes to repair the broken wires.  Then they could leave the old analogue meter with the rotating disk where it is, at no expense to you.

*which in most jurisdictions, you will have to pay for and also pay for installation.

The various ways  that the government and the power company can set up  the system are numerous.  Just remember, though,  that once you have installed your system, the power company (and the government) has you by the short and curlies (in politeze 'can change the rules any time they want').  They may tempt you into installing your system with a promise simply to subtract one meter from the other for billing purposes, and the government may say the same for tax purposes.  They may even do as in Germany and promise you a greater rate for excess that you generate than for extra you use.  This will generally be for a specified period*.  Ever get suspicious when something seems too good to be true.  It usually is.  Let's look at one variation.  There are many and each jurisdiction will have their own scam.  Remember that one or other of your meters is ratcheting up at any given moment.

* 20 years from installation in Germany, for instance.

Suppose that the power company gives you less for power you buy than for power you sell. That is fair and right.  The power company has to earn a profit from their business*. Let's say in our example they charge you 20c per kWh and pay you  10c per kWh.  In our example you have used a make up of 10kwh and sent d 10kWh to the grid.  You pay $2 and get $1 for that day and despite having generated just exactly what you have used,  you still pay a dollar. If that is the daily average over the year, your yearly bill is $365**.  Remember, this is the excess sent and received due to the fact that both your meters ratchet.  They record the instantaneous export and import and meters only go upward.  No meter turns backward.  Of course the situation will be worse than this.  We still haven't talked about summer vs winter or about totally overcast days vs totally sunny days.

*Note that the way the power companies structure their costs is to charge you some fixed costs, correctly characterized as Line Charges, theoretically for the maintenance of the lines, and charges per kWh you use.

** Plus, of course your line charge which is a fixed charge for the privilege of being connected to the power company.

A second possibility is that they give you exactly the same price for the 10 in and 10 out.  Your bill is zero but hold on.  The government is something else again.  They will charge you tax at your marginal rate (say 33%) for the power you sell to the power company and GST at 15% (in New Zealand) for the power you buy from them.  If again power costs 20c per kWh, you will pay 66c and 30c = 96c to the tax office for the power you used and generated that day.

What is more likely is that you will pay the dollar to the power company and the 96c to the government despite having generated all the power you used that day.  In actual fact, in my jurisdiction, the typical price the power company pays is nearer to 5c

I'll leave you to work out other possibilities.  They depend on the system which is in place in your bally-whack and there are many  possible variations.

Just remember, with your twin meters ratcheting up - the Ratchet Effect - small renewable power becomes far less attractive.

The Net Metering Ploy
I mentioned at the start that the power company and the government can still "pull one" even if you are net metered.  It goes like this.  With the advent of small power generation and the installation of new meters, it is likely that "smart meters" will be deployed.  This is for, the most part, to the benefit of the consumer since the smart meter should be able to talk to your devices and turn them on and off to take advantage of less expensive power when there is excess generation.  However the smart meter will also talk to the power company.

There will no longer be any necessity for meter readers since the company can read your meters remotely whenever it wants to.  Suppose your power company sets up its computer to read your meters as often as possible.  It should be possible, for instance, with today's computer power to read them every minute if they so desire.  You see where we are going with this.  In one particular minute interval your single meter increases from X to X+x.  The x is how much net power you have used, above your home generation, in that interval.  This is accumulated with all other x's in your power import file.  In a different one minute interval, your  meter decreases from X to X-y.  The ]y[* is how much you have sent to the grid in that meter.  These are accumulated in your export file.

*The absolute value of 'y'

We are now, essentially in the same situation as we were with double metering and the company can charge you as they decide.  The government, will, of course charge you both types of tax.

Watch out.  Any scheme a government puts in place is rarely as attractive as it seems and the more attractive it seems, the more likely that it is a scam.  It may be a scam now or in the future when they change the rules.  A good first blow for the consumer is to have true net metering but even then you have to keep your guard up.

Saturday, October 19, 2013

The ice recovery of 2013

Much has been made, especially amongst the climate change deniers, of the recovery of Arctic ice in 2013 when compared with 2012.  The ice extent (area covered) in the middle of September 2013 is approximately 60% greater than the ice extent of 2012.  A few comments are in order.

Firstly, this a recovery from a very low level.  This is 60% above the totally unexpected (at least by climate change deniers), exceedingly low ice extent of 2012.

The second point is that even though this was a big increase above this low level, if you look at the trend line (linear regression) in the following graph, you see that the ice extent of 2013 is only just above the trend line.  The September ice extent since 1978 has been decreasing at 13.7% every 10 years and the value for 2013 is very much in keeping with this trend.  Looked at another way, the ice extent for 2009 which you will see is just above the trend line was 5.63 million square km while for 2013 it was 5.35 million square km;  a slight decrease. There have also being other "recovery" years, notably from 1995 to 1996 without any lasting effect.  Looked at still another way, if this was really a recovery of the ice, you would expect the 2013 dot to be as far above the trend line as the 2012 dot was below it.

September 2013 compared to previous years

Figure 3. Monthly September ice extent for 1979 to 2013 shows a decline of X.X% per decade.||Credit: National Snow and Ice Data Center |High-resolution image
Figure 3. Monthly September ice extent for 1979 to 2013 shows a decline of 13.7% per decade.

Credit: National Snow and Ice Data Center 

Going out on a limb here, it would appear, looking by eye, that a downward curving, exponential line would fit the data points better than a linear regression (straight line).  In which case we can expect, in the coming years, some very low ice extents  in September, rivalling and exceeding the 2012 values.  In other words, ice melt is accelerating.  Even if the decrease in ice extent only continues as per the linear trend line, the Arctic will be ice free in a couple of decades.  If ice decrease is actually accelerating, we only have a few years to go.

Note that here we are talking about the ice extent in the middle of September when it is its lowest.  Following a zero ice extent on September, with small ups and downs, the ice free period will increase year by year.

If you want to see what ice volume has been doing click here

One further point.  In a previous blog, I described how Coriolis tends to concentrate surface water and ice into the centre of high pressure (sunny weather) systems while low pressure systems (cloudy weather)  spread things out that are floating on the surface.  2013 has had predominately low pressure systems and the ice extent could, to some extent be an artifice.  NSIDC measures ice coverage above 15% as complete ice coverage so spread out ice would appear as more ice even if it is not.  But let's say, for the sake of the argument that the 60% increase in ice extent is real.

The check on this should be the results from ESA (European Space Agency) satellite, Cryosat2.  By measuring free board (the height of the ice above the water), it can calculate the volume of ice in the Arctic.  As has often been mentioned, ice volume is a better measure of the true amount of ice floating on the Arctic ocean than ice extent.  It may be that I just can't find the data but if not, I would urge the ESA to release the information.  Then we could see if the ice really has increased 60% from Sept 2012 to Sept 2013.

ps.  Gaia has many mechanisms to try to keep the temperature constant on the earth (sorry about the anthropomorphism) We apparently are seeing one of them here.  With warmer Arctic water, air rises and gives rise to clouds which shade the Arctic ocean and reduce ice melt.  I wish Gaia luck in the attempt.  We are pushing her pretty hard.

This is one of the best graphs I have seen.  It shows that this year is only just a line width above the 2010 to the present average.  Not much of a recovery.  Sorry about the size. Click on the image to see a decent sized version.

You will notice that the space between successive decade averages gets wider and wider.  In other words, ice melt is not increasing linearly but is accelerating.

Just an amusing thought to finish with.  There will come a year when the ice extent is zero.  The year after that, there is likely to be a recovery.  Look at the graph.  It is a ever decreasing saw tooth pattern.  On the year after the zero ice extent, no matter what the level of the recovery, the climate change deniers will be able to claim an infinite increase in ice extent.