Jun 042013
 
When the grid goes down, we will not only need to generate our own electricity but we'll need to store it too.

When the grid goes down, we will not only need to generate our own electricity but we’ll need to store it too.

In our amazing modern life, we seldom pause to consider all the ‘behind the scenes’ miracles that are being worked for our benefit – all the things which could fail, might fail, and probably will fail in a Level 2/3 scenario.

Of all these blessings that we take for granted, perhaps none is greater than the miracle of electricity.  For most of us, nearly all the time, we can plug anything into any wall socket in our house and it will operate, and we can turn on any or all of our appliances and enjoy their normal operation, at any hour of the day or night.

Electricity from our local utility company is always available and amazingly inexpensive and probably has been the greatest lifestyle enhancer of the last 100 years.

You mightn’t think electricity to be amazingly inexpensive when seeing your monthly bill, but try going without electricity for a week or two then ask yourself ‘how much would I pay to get my electricity back?’ and then you’ll appreciate its value.  Or cost out other ways of creating the electricity – for example, electricity from a high-efficiency diesel generator will probably cost 40c per kWhr, compared to a typical cost of about 10c for mains provided electricity.

When the grid goes down and you have to generate your own electricity, you’ll quickly build an even greater appreciation of how amazing our present electricity supply is.  No part of generating electricity in the future will be easy, and because you’ll be using a different way of generating much/most/all of your electricity, one issue deserves particular mention – something you’ve never needed to think about in normal life (although in actuality, it is something the utility companies are very sensitive to).

The chances are you’ll make use of photo-voltaic cells – PV cells or solar cells – for at least some of your energy needs.  Maybe you might use of wind power, too.  These are great energy sources, but there’s an associated problem.  This is the start of a four-part series of articles that considers this problem, and offers ways to optimize your work-arounds and solutions.

The Need to Match Electricity Demand to Electricity Supply

The problem relates to a major limitation of both your likely future energy sources.  In the case of PV cells, you know they only work when there’s reasonably bright sunlight.  So, you never get any power at night, and on short winter days that are overcast, you get very little power even in the middle of the day.

In the case of wind power, the wind turbine only generates power when there is ‘good’ wind – nice steady smooth wind blowing in a reasonably consistent direction at a reasonably consistent speed (wind gusts can destroy a turbine) that is neither too fast (at high speeds, turbines stop working to prevent damage) nor too slow (turbines have a minimum speed below which they no longer generate useful amounts of power).

The problem with both PV cells and wind turbines is that you can’t match their power generation to meet your requirements.  A diesel generator simply starts working harder (and burning more fuel) when its load increases, and if you have a micro-hydro station, you can vary the amount of water driving the turbine, but there’s no way you can make the wind blow more strongly or the sun shine more brightly.

The typical solution is to have a PV/wind system that provides enough power during a realistic typical sort of day of working to both cover your power needs during the period of operation, plus surplus power which can be transferred into some sort of electricity storage system.  Then, when the power being generated becomes insufficient to meet your requirements, you can switch to the stored power and use that until such time as the primary power source can start meeting your needs again.

Hence the need to store electricity.

Storing Electricity is Not Always the Best Solution

In addition to whatever method of storing electricity you might choose to match with your renewable electricity generation program, there is another way of storing electricity which has a huge plus but also a huge minus.

We are talking about simply keeping a large supply of diesel or propane for a generator.  Each gallon of diesel can give you about 10 kWhrs of electricity, and with a typical house using about 1000 kWhr of electricity a month (depending on design, size, and climate of course) at present (with plentiful energy, low-cost, and no need to fanatically conserve energy) this suggests a diesel generator would consume about 100 gallons of diesel a month to give you all the electricity you need.  A few tweaks to your retreat design, some more insulation, and some alternative heat and energy supplements, and you could easily halve this to 500 kWhr of supplementary electricity per month – a mere 50 gallons.

If you have 1,000 of diesel stored, that could see you through 20 months of power needs, which would cover all Level 1 and most Level 2 scenarios.  Those 1,000 gallons of diesel represent something well under $10,000 to purchase, to stabilize with fuel stabilizer for many years, and to store in good quality long life tanks.

As a comparison, if you wanted to have a battery based electricity storage capacity of say 75 kWhr, you’re looking at an investment in batteries and control circuitry of $20,000 or more, and you’ll want to significantly expand the power output of your solar or wind setup so it has sufficient extra capacity not just to meet your regular needs but also to charge up the storage banks – maybe something like an extra 5 kW – 10 kW of power generating capacity – figure on another $10,000 or so for that.

So for solutions extending out a year, two, maybe even three or four, you might decide not to overcomplicate things (and add to the cost as well) and have a system that provides renewable energy during the day and relies on a diesel generator at night.

But, having said that, a key part of preparing includes planning not just for Level 2 situations, but also for ultimate Level 3 situations, and if you base your electricity generation on diesel, you know that, sooner or later, you’ll run out of diesel.  So if you wish to be best prepared for the future, you’ll recognize that electricity storage, while not necessarily the most economical solution for Level 2 events, is essential for Level 3 preparedness.

Any type of preparing of course ideally involves multiple solutions to each single problem, so as to have redundant approaches, and for this reason too, it makes sense, even in planning for shorter term problems, to have at least some way of storing some electricity.

How to Store Electricity

It is difficult to store electricity, with the only ‘true’ form of electrical energy storage being a device known as a capacitor.  While capacitors are remarkable and very useful in some applications, they are sadly not really well suited for storing the large amounts of energy we wish to store, and for the lengths of time we wish to store it.

We’ll spare you the science, but suffice it to say that all other forms of energy storage involve using the electricity to create a different form of energy which can be conveniently stored and converted back to electricity again in the future.  Even a battery, which might seem to be a pure store of electricity, actually converts the electricity to a chemical form of energy.

In considering an electricity storage method, you need to consider a number of factors :

  • System efficiency – for every kWhr of energy you put into the system, how much do you get back again when you convert it back to electricity again?  In the broader scheme of things, efficiency is of course important, but in this application, where you’re essentially storing spare/surplus power, it isn’t quite as important as it would be, for example, for a utility company that is paying for all the electricity it generates and seeking a way to cover the ups and downs of daily demand.
  • Storage losses – does the stored energy slowly – or quickly – dissipate over time, or does it stay unchanging for long periods of time?  In our case, we will have a mix of requirements – some energy needs only be stored for 15 hours or so (ie from when PV cells stop providing power around sun-down until they start again shortly after the next dawn).  But you will want to be able to store some energy for a longer term in case of extended periods of insufficient power supply during the day.  Storage losses are an important factor.
  • Size and other requirements – is anything special needed?  Does the storage thing take up a lot of space?
  • Maintenance and useful life – how many times can electricity be transferred in and out of the storage system?  What types of ongoing maintenance are required, and how easily can the system be maintained in a future situation where you’ll not have high-tech equipment, and sooner or later will run out of replacement spare parts?  How many years until it fails entirely and needs to be replaced?  Clearly these are very important issues for us.
  • Capacity – how much electricity can be stored in the system?  Are there limits to its ability to grow?  Of course we need to have adequate capacity – that goes without saying, and if there’s a low tech way we can grow the system in the future, so much the better.
  • Cost – what are the costs of storing electricity in the system?  Do we need to comment on the fact that, as preppers, we are always confronted with too many different high priority ways to invest our money and insufficient money to invest!

Although there are very many different ways to store electricity (perhaps better to say ‘to store energy’ because the thing we are storing is not actually electricity, but something else which can be converted into electricity), in our case there are only one or two which are practical to the size, scale, budget, and other requirements we are likely to have.

The most obvious storage system involves batteries – probably some sort of lead-acid batteries.  A less obvious form is to store energy in a rapidly spinning flywheel, and a third approach, which may work well for some people but not well for others, is to store energy in the form of pumping water up to a higher elevation, and then to reclaim it as needed by having the water flow down through a micro-hydro power generator.

Continued in Part Two

Please now click on to read part two of this series, ‘Using Batteries to Store Electricity‘, and then continue on to parts three and four (Other Energy Storage Methods and Strategies to Reduce Your Need to Store Electricity).

We also have other articles on the general topic of Energy.

Jun 042013
 
A cutaway view of a typical lead-acid battery.

A cutaway view of a typical lead-acid battery.

This is the second part of a four-part article series about how to store electricity (better thought of as storing energy rather than electricity per se).  If you arrived directly here from a link or search engine, you might wish to start from the first part of the series here, then read on sequentially through this article and the balance of the series.

Lead-acid batteries use a technology that has been around since the mid 1800s.  The relatively recent Lithium-ion technology is showing some signs of promise as a possible replacement to lead-acid, but that is still a way off, and for now, for our purposes, lead-acid batteries, while far from innovative, remain probably the best general purpose way to store electricity in circumstances that typical preppers are likely to encounter.

Batteries offer between about a 50% and a 85% efficient means of storing electricity, making them neither particularly better nor particularly worse than most other forms of storing electricity.  They have acceptably low storage losses, typically losing somewhere between 2% – 15% of their charge each month.

As old-fashioned as they may be, the generic concept of lead-acid batteries masks the fact that there are many different types of lead-acid batteries, designed for different purposes, and with greatly varying suitability for our requirements.

They also have a surprisingly complex series of requirements for how to charge and maintain them so as to get the optimum life out of the batteries – to prolong the amount of electricity they will store, to maximize the number of charge/discharge cycles they can withstand, and to protect against sudden failure.  For optimum use, it is important to be sensitive to many aspects of their care and conditioning that we never consider with our car battery – and the proof of the need to look after our storage batteries should be evident when you consider how quickly car batteries fail!

Lead-acid batteries fall within three general families when it comes to how they are made.  The oldest technology is the ‘wet’ or flooded type battery, then there are gelled batteries and AGM (Absorbed Glass Mat) batteries.  Flooded batteries typically have removable caps and you should occasionally check the level of the liquid inside the cells, adding distilled water as necessary, although some now have ‘fully sealed’ cells (which actually aren’t fully sealed).  AGM and gel batteries are always sealed and in theory need no maintenance.

Some people view gel cells as a transitional technology and suggest you avoid them, preferring either AGM or wet cells.  Gel cells require different charging procedures and voltages than regular and AGM batteries, and are more prone to degradation or failure if not treated optimally.  AGM cells are very low maintenance, but more expensive for the same amount of capacity as wet cells.

The most common measure of a battery’s storage capacity is how many amp-hours of charge it can give.  However, it is important to appreciate that the amp-hour capacity of a battery is dependent on how fast it is being discharged.  The slower the rate of discharge, the more total charge the battery will give you.  For example, a battery that is discharged evenly over 20 hours will typically give 10% less charge than a battery discharged over 100 hours.  A battery that is discharge over 8 hours will typically give almost 20% less charge than one discharged over 20 hours.

Our point is that it is important to understand whether a battery’s capacity is being measured on the basis of a 100, 20 or 8 hour discharge rate.

The lead-acid battery that most people are most familiar with is a car starting battery.  This is designed to store a small amount of charge which can be provided at a very high rate of current for a short period of time, for the purpose of starting the engine.

It has a secondary purpose to power the car’s various electrical loads for a moderately short amount of time while the vehicle is stopped and the engine switched off.

But these batteries are not designed to give up all their charge over a slow gradual period; indeed, they’re not designed to give up all their charge at all.  They are not ‘deep cycle’ type batteries.  Perhaps because of this, they are typically not even rated in terms of amp-hours of storage, but rather quote a ‘cold cranking amp’ current rating – the amount of current it can supply when being called upon to turn a vehicle’s starter motor.

Don’t use car batteries as storage batteries.  They are not designed for deep discharging and don’t last long.

No lead-acid battery should be fully discharged before recharging it again.  The greater the amount of discharge before recharging, the more the battery is stressed and the shorter its future life will be, in terms of additional charge/discharge cycles and capacity of charge that can be stored per cycle.

Deep cycle batteries are designed to allow for the greatest amount of charge depletion per cycle.  Typically these types of batteries (sometimes referred to as ‘golf cart’ or even as ‘forklift’ batteries) are designed to give up perhaps 70% of their capacity per discharge without suffering any severe consequences.  Some batteries allow for an 80% discharge, but it is probably better to go easy on them and not go all the way down to 80%.

Depending on the exact battery design, discharging to 50% is considered the ideal compromise, and you should avoid discharging beyond about 70% of capacity.

You can measure the state of charge of a battery either by testing the specific gravity of its liquid, or by testing the voltage it puts out.  The specific gravity measurement is slightly more accurate, but with so many batteries either sealed or AGM, these days most people use voltage readings as a measure of charge instead.  The voltage steadily declines as the battery discharges, starting from 12.6V when fully charged.  Am offload reading of 12.3V shows about a 50% charge, and a 12V reading (offload) more or less corresponds to a 75% discharged state.

Battery life also depends on other factors such as even ambient temperature (cooler is better than warmer).

Modern batteries such as these or these claim to give up to 2000 or so cycles, with discharge all the way to 80% each time.  That’s almost six years of daily discharging (or twelve if two-daily discharging, and so on for extended cycles).

In terms of actual elapsed time, these types of batteries seem to be talking of lifetimes in the 10 – 20 year range, if the number of cycles isn’t exceeded in a sooner time frame.  That’s starting to become a viable life.

Other highly respected battery suppliers include Concorde/Lifeline and Rolls/Surrette.

If you are building a high-capacity battery, there are several ways to do this to best effect.

The first is not to use a 6V or 12V based system.  Increase your voltage (by connecting batteries in series) to 24V or 48V.  This has several benefits, including reducing the electrical losses through your wiring and/or reducing the need for ridiculously oversized wiring to carry your battery current.

The second is of course to connect multiple batteries in parallel, but this needs to be done with caution.  The more batteries in parallel, the greater the chance that a ‘bad cell’ in one battery unit will bring down the entire set of batteries.  What happens is the battery with the higher voltage then starts ‘charging’ the battery with the lower voltage, and bleeds away its power into the weaker battery.

For this reason, it is always important to match batteries with like batteries, whether connecting in parallel or serial – batteries of similar capacity and similar state of life.

It is best to arrange for each individual battery in your battery array to be of as large a capacity as possible.

Beyond that, rather than to create one huge battery with maybe six individual batteries paralleled together, it is much better to create two three battery units, or even three battery units, each with two paralleled batteries.  That means you can better rotate your batteries in and out of service, alternately charging and discharging each battery in sequence, and stretching out the overall life of all the batteries.

Continued in Part Three

Please now click on to read part three of this series, ‘Other Energy Storage Methods‘, and then continue on to part four ‘Strategies to Reduce Your Need to Store Electricity‘.  If you’ve not yet done so, you might wish to also read the first part of the series, ‘Storing Electricity‘.

We also have other articles on the general topic of Energy.

Jun 042013
 
The fickleness of wind and other renewable energy sources means you need to store power as best you can when it is available, for future use when it is not available.

The fickleness of wind and other renewable energy sources means you need to store power as best you can when it is available, for future use when it is not available.

This is the third part of a four-part article series about how to store electricity (better thought of as storing energy rather than electricity per se).  If you arrived directly here from a link or search engine, you might wish to start from the first part of the series here, then read on sequentially through the balance of the series.

Flowing Water Uphill and Other Gravitational Energy Stores

Another interesting approach to storing electricity is by pumping water uphill.

If you have a hill on your property and sufficient water, you can use surplus energy to pump water up to a large reservoir on the top of the hill, and then when you need electricity, you run the water down the hill and to a hydro-electric plant at the bottom.

This can store energy for a longer term – the only storage loss being evaporation – but involves potentially massive amounts of water and as much vertical rise/fall as possible.  If you double the height differential, you halve the amount of water you need, and vice versa.

Although this might seem like an unusual and strange technology, 93% of all stored power, world-wide, is stored this way.

To put the amount of water needed into perspective, if you wanted to store enough water to be able to generate 5kW for 100 hours – a good reserve for emergencies) you could either have an efficient diesel generator and about 50 gallons of diesel, or if you were able to store water somewhere 100 ft higher than ground level, you’d want to have about three million gallons of water in the reservoir.  That is about 400,000 cu ft of water, so think of a pond measuring perhaps 200 ft by 200 ft and 10 ft deep.  You’d also need another storage area at the bottom to hold the water prior to pumping it back uphill again.

This is of course not impossible, assuming you have a way to get the vertical rise that is necessary, and a source of water to replenish losses from evaporation.

The concept can be extended and slightly modified, indeed, it is merely an extension of the concept found on many cuckoo clocks, where a weight slowly descends, driving the clock mechanism, then is ‘rewound’ when you use energy to pull the weight back up again.  Anything that uses gravity as a way of storing energy can work.

There is a project currently being developed in California that uses rail boxcars loaded with heavy gravel.  Electric locomotives use spare grid power to haul the boxcars up a length of steeply inclined track, and then when the electricity is needed to be returned to the grid, the boxcars are allowed to push the loco down the track, and the loco now acts as a generator feeding power back into the grid.

Such a system can be 80% or more efficient, and will store energy indefinitely with no storage loss.  The boxcar example requires more power to push the boxcars uphill than would be available from a typical private power source, but this could of course be modified (lighter boxcars and/or less steep grade).

These types of systems can require a fair measure of space.  In the water example, if the water reservoirs at top and bottom are ten feet deep, you need almost 2 acres of space just to store the water, plus more space for the pipes and generator/pump.

But their biggest requirement is the height differential.  If you’ve got a fully flat property, you’re either going to have to create a raised portion, which would involve a prohibitive amount of earth working, or else look for other alternatives, which presently tend to invariably circle back to batteries.

Using a Flywheel to Store Electricity

Flywheel technology is becoming more practical, although still a technology that is equal parts experimental and/or not ideally suited for our applications.

With a flywheel, spare electrical energy is used to spin up the flywheel – a huge heavy massive device that spins rapidly – and then when electrical energy is needed, the flywheel is used to run a generator.

Flywheels can store surprisingly large amounts of power, and if in a near vacuum and with magnetic bearings, are slow to lose their energy (by ‘slow’ we mean the energy loss rate is acceptable for a device that charges during the day and discharges at night, but not quite so acceptable if you want to be able to store energy for several days).  They can provide a reasonably efficient means of storing power.

They are also fairly low maintenance, especially if kept in a semi-sealed environment.  But they are also large heavy devices, potentially weighing 5 – 10 tons or more, and require very precise balancing and bearings due to the speeds they spin at.

Flywheels are best suited for applications that require large amounts of sudden energy and/or applications that have large amounts of energy suddenly surplus.  That’s not to say they’re not potentially good for our sorts of applications too, and the good news is that the growth in renewable energy generation is feeding growth in related issues, particularly energy storage.

We expect to see small-sized flywheel installations continue to be developed to a point where they may become practical for storing energy for short-term overnight use, but we’ve not encountered a flywheel that is quite ready for prime time just yet, alas, although there are some hopeful developments underway at present.

There are many other technologies that are either in a development stage, or which are not suited for our sort of scale of energy storage – for example, compressed air.

How Much Electricity Storage Do You Need

Storing electricity is a somewhat wasteful and somewhat expensive process, although it could be convincingly argued that having extra spare electricity being unused at certain times of day to also be wasteful too!

Some electricity storage is both prudent and essential.  The question becomes – how much.

If your only renewable energy source is PV, then you need enough for two purposes :

First, you need enough to get you through a typical night from when the energy flow from the cells diminishes as the sun gets low until such time as the energy flow restarts when the sun rises the next morning.

Second, you need additional ‘spare’ capacity to cover times when the weather is bad, the sky is full of clouds, and the PV cells aren’t generating enough electricity during a normal day to replenish the store for the next night.  Indeed, in a worst case scenario, the PV cells might not even provide enough power to cover the normal needs during the day.

You can of course control this to a certain extent by increasing the capacity of your bank of solar cells.  If you need 20 kWhrs of electricity a day – 10 kWhr for daytime use and 10 kWhr to store for the night, then you’re less likely to run into shortage with a setup that is rated to provide 40 kWhr per typical day than with a setup that is rated to provide only 20 kWhr per typical day.

So the greater your surplus during a typical day, the less an amount of reserve storage you need.  If even a cloudy day sees your PV installation providing enough power for the day and the night, all you would seem to need is a single night’s worth of power to be stored.

We’d still like to increase that capacity to allow for mishaps and emergencies.  What happens if something fails in the solar setup and it takes you a day or more to repair/replace it?  Also, if you only need to recharge your batteries every other day rather than every day, clearly you’ll get twice the life from them, and if you are normally only discharging your batteries down to 50% full, you’ll again get much longer life than if every night you are discharging them down to 20% full.

If you are only using wind power, the first thing we’d recommend would be to rush out and buy some solar cells!  Some days there might be no wind, but some sun (and vice versa); by spreading your electricity generation between two different sources, you are reducing your risks and increasing your resilience.

Beyond that, it becomes harder to predict how much wind power you can expect.  You need to look at detailed wind logs for your location, and approximating the above ground height your turbine will be situated at, so as to get a feeling for average, best case and worst case daily and nightly power generation.

Using a process a bit like that we recommend for working out your water needs, you can proceed to calculate some likely pessimistic scenarios about the amount of wind power you might get, and from that, you can then work out how much stored electricity you’ll need.  Don’t forget to allow for an unexpected several day outage occurring at exactly the worst possible moment, too!

But, wait – before you do these sums, you should first re-examine the question of how much electricity you will need and use, and reduce this amount as much as possible.  The next three sections cover this concept.

Continued in Part Four

Please now click on to read the final part of this series, ‘Strategies to Reduce Your Need to Store Electricity‘.  If you’ve not yet read them, you might also want to read the first two parts of the series too – Storing Electricity and Using Batteries to Store Electricity.

We also have other articles on the general topic of Energy.

Jun 042013
 
Using solar water heating brings two benefits - greater efficiency and an easy way to store energy as hot water for later use when the sun goes down.

Using solar water heating brings two benefits – greater efficiency and an easy way to store energy as hot water for later use when the sun goes down.

This is the final part of a four-part article series about how to store electricity (better thought of as storing energy rather than electricity per se).  If you arrived directly here from a link or search engine, you might wish to start from the first part of the series here, then read on sequentially through the balance of the series.

A Different Sort of Energy Storage – Time-shifting Electricity Demand

Storing electricity is usually both the clumsiest and costliest way of productively using up spare/surplus electricity.  You lose some electricity when you convert it to however it is stored, you lose more during the storage process, and then you lose even more when you convert it back to electricity again.

So it is better to time-shift as much as possible to times when you have spare electricity.  One example of a time-shiftable process would be washing clothes and dishes (assuming you still will use an electric dishwasher in the future, which is unlikely).

With these types of activities, you can wait until a day with lots of electricity coming from the PV cells or wind turbine before washing your clothes (and/or dishes).

If you have an electric range, you should use it to cook food during times of peak electricity production.  Maybe you’ll change your eating habits and have your main meal of the day in the middle of the day (something many societies already do and which many health experts think to be a better approach to eating) so that the cooking energy is sourced when the sun is shining brightly or the wind blowing strongly.

If you are vacuuming, do that when there’s spare electricity, and never when you’re using stored electricity.  There’s almost never an emergency requiring urgent vacuuming in the middle of the night!

Try and match your own sleep and wake times to the sun.  If you’re sleeping during the morning with daylight flooding in to the retreat, but then staying up late at night, using electricity to power lights and possibly heating too, that is more wasteful than using the sun for light as much as possible, and sleeping in a warm bed during the coldest part of the night.

Take your shower/bath in the morning if possible so as to allow the system all day to reheat the water.  Or, alternatively, after using hot water at night, don’t use stored electricity to heat up the replacement water, and instead wait until the morning to do that.

Which leads to another strategy.

A Different Sort of Electricity Storage – Storing the Results of Using Electricity

Another approach to storing electricity is to store the results of using electricity.  We started to get into that in the preceding section – heat your hot water when you have spare electricity to do so, and then deplete it when you do not have spare electricity, and only reheat it again when you have the spare electricity back to do so.

An easy and low tech type of storage is to store heating or cooling energy.  There are special ‘storage’ heaters that will run when you have spare electricity and heat maybe a large vat of oil or even a block of concrete, then at night, you expose this heat source and allow the heat to transfer out and into the surrounding areas of your retreat.

You can also do this for cooling.  When there’s surplus electricity, make large blocks of ice.  Then, when you need extra cooling but no longer have extra electricity, allow the ice to melt, cooling the area around it.

These are low tech but sensible concepts.  Indeed, many large buildings currently use these types of systems for more efficient heating/cooling.  You can do the same.

Replacing Electricity With Other Energy Forms

Electricity is an ‘expensive’ form of energy – it is close to the top of the ‘energy pyramid’, just like beef is close to the top of the food pyramid (in terms of the amount of feed and water needed per pound of meat).

If you can replace electricity with other forms of energy – forms which may be more abundant, and/or lower tech and more sustainable into the indefinite future – you’ll be doing yourself a favor.

One example of this substitution is to mount a solar water heater on your roof.  That way, instead of using solar energy to create electricity and then the electricity to heat the water, you go directly from the solar energy to the hot water, in a much more productive/efficient process, and also in a lower-tech form.

A solar water heater is easy to construct and easy to maintain.  But as your PV cells fail, you’ll absolutely not be able to repair them yourself, and no-way can you fabricate your own additional solar cells in a low-tech future.

Another example is to use wood (or coal or peat) as a heat source for heating your retreat, your hot water, and possibly even for cooking with as well.

Or, if you’re using propane to power a generator, get a propane rather than electric stove and burn the propane in that stove.  You’ll use less propane to directly power your stove than to first convert it to electricity and then to second convert the electricity to heat on your stove.

How Much Extra Electricity Generation Capacity Do You Need

Remember that the first part of an electricity storage system is having ‘spare’ electricity to store!

Once you’ve done what you can to minimize your reliance on stored electricity, the next question becomes how you will get the electricity to store.

Clearly, you will do this by increasing the capacity of your renewable energy sources so they can simultaneously meet your normal electricity needs and also send extra capacity into the storage system you selected.

And, equally clearly, the electricity source(s) you have must be able to generate enough spare electricity each day to be stored to be used each night.

So you need to consider the answer to this question – ‘assuming a less than fully sunny day, or a day with poor rather than optimum wind, how much power do I need generated for the day’s requirements and to recharge for the night ahead as well?’.

Remember that most solar and wind generators are specified as having a certain capacity on a good/close to optimum day.  You’ll need to adjust the claimed daily capacity to more accurately reflect the real-world rather than best-case probability of electricity it will create for you.  Maybe you need to get a system which is apparently twice the capacity you need, just so that in periods of low generating conditions, it still generates enough for both your immediate and your storage needs too.

Now, for an interesting additional factor.  The greater your storage capacity, the smaller your surplus daily generating capacity needs to be.  This is because the extra storage capacity gives you a greater ability to average out the peaks and troughs of actual daily electricity production.

One more consideration.  Most lead-acid batteries require a certain minimum charge rate in order to effectively charge, so you need to be sure that your electricity source will deliver enough charge to actually load electricity into the battery.  Think of a helicopter – it uses a lot of energy just to hover – you don’t want your battery to just hover, you want its charge level to rise, so you need to provide more than this ‘hovering’ amount of energy to actually raise the battery’s charge.

Whatever you come up with, you must have a system that on an average/ordinary day will provide enough electricity during the day for all the daytime needs in your retreat, plus enough left over to replenish a typical night-time’s consumption of electricity, plus perhaps still more left over to replenish one more typical night-time’s consumption, too.

Electricity Will Never Be Cheaper Than Now

Spending $10,000 for a 5 kW solar array might seem like a lot of money, and of course, by any measure, it is indeed a substantial sum.

But – and you can absolutely trust us on this – in a Level 2 and particularly a Level 3 situation – your future lifestyle and ability to survive will be totally linked to your ability to generate your own energy, particularly in the form of electricity.

So get as much electricity generating capacity now as you can afford.  Particularly if it is modular, it can be either used or traded in the future, and you’ll quickly discover the essential nature of energy in a future Level 2/3 situation.

Read the Rest of the Series

If you’ve not yet read them, you might want to read the first three parts of this series too – Storing Electricity, Using Batteries to Store Electricity and Other Energy Storage Methods.

We also have other articles on the general topic of Energy.

Mar 022013
 
The red dots are pumping stations on our national gas pipelines.  The Chinese military may now have the capability to destroy a thousand of these simultaneously through only a few computer keystrokes.

The red dots are pumping stations on our national gas pipelines. The Chinese military may now have the capability to destroy a thousand of these simultaneously through only a few computer keystrokes.

Due to its current abundance and low-cost per unit of energy, the US is becoming increasingly dependent on natural gas.

Already, 30% of all electricity comes from power stations burning natural gas.  Conversion programs to convert buses and trucks from diesel to natural gas are becoming increasingly popular due to the massive cost savings operators can quickly get from their investments.  And if you have gas to your residence, you know that the cost of the gas has dropped over the last few years, while electricity costs have stayed the same or risen, making it more and more appropriate to use gas for heating your water and your house and on your stove top.

An interesting thing about natural gas is that most people perceive it as ultra-reliable and as close to guaranteed to be always available as possible.  We’ve doubtless all experienced power outages from time to time, but when have you ever had an unexpected unscheduled gas outage?  Probably never; indeed some people view their gas supply as so ultra reliable that their emergency generator uses natural gas as its energy source.

Unfortunately, while historically it is true that our gas supply has been ultra-reliable, today it is also true that the gas supply has become ultra-vulnerable to disruption.

Almost all the gas that is used somewhere comes from somewhere else, and travels from where it is extracted/processed to where it is consumed, by pipeline.  For sure, pipelines are physically vulnerable – a stick of dynamite could destroy a segment of pipeline any time and any where, but doing so requires ‘boots on the ground’ – you need people to physically get explosives, travel to vulnerable/accessible stretches of pipeline, blow them up, then escape safely.  None of that is impossible, but it is difficult and requires a substantial number of saboteurs if they are to have an appreciable impact on the supply lines.

We try to make it a little difficult for such attacks to occur; information on the exact location of gas pipelines and the related control stations is somewhat restricted.

But there’s an easier way, which the Chinese military have been preparing.  This article reveals that during a six month period in 2012, cyber-attacks traced back to the Chinese military were detected on 23 pipeline operators (there are about 30 major pipeline operators in the US), and includes the explanation that with the information stolen and access obtained through these cyber-attacks, it would be possible to cause enormous damage, either sequentially or simultaneously, and with the attackers never needing to leave the safety of their bases in China.

The article gives the example of using the access gained to mess up control settings so as to cause a thousand pumping/compression stations to simultaneously explode.  Destroying a pumping station is more serious than just knocking a hole in the side of the pipeline, and takes longer to repair.

Now think about the implications of this.  Not only would we lose the 30% of our electricity that is currently generated from natural gas, but we’d also lose the use of natural gas sourced energy in industry and at home, too, massively increasing our demand for the electricity that would already have become seriously in short supply.

Most households with gas for heating and cooking use more energy from natural gas than from electricity, so household demand for electricity would more than double (in winter, not so much in summer).  The same in many commercial applications, too.

As you may recall from the California electricity crisis back in 2000 – 2001, even a very small shortfall in electricity supply can be enough to massively mess things up.

Maybe this would not destroy our society entirely, but it would sure change our lifestyles substantially.  And all it would take to cause this is a few keystrokes on a computer somewhere in China – and who’s not to say that other countries hostile to the US don’t have similar capabilities or haven’t been given the information obtained by the Chinese cyber-terrorists?

Implications

Our point is simply this.  Scratch the surface of most of the essential underpinnings of our modern-day society and lifestyle, and examine the things we most take for granted, and you’ll find ugly exposed vulnerabilities that are growing rather than diminishing in size and scale and scope.  Barbed wire fences and armed patrols might provide physical security for our nation’s critical infrastructure, but the preferred form of attack these days is not this old-fashioned method involving real people doing real things to real structures, it is a ‘virtual’ attack via computer, a form of attack that we seem to be much less able to defend against.

Your non-prepping friends probably have no idea that a branch of the Chinese military, deploying a team of cyber-terrorists, now has the capability to destroy our natural gas supply system, which is part of the reason they are not preppers.  But you know, and hopefully you continue to prepare for and anticipate potential crises of all forms.

Oh – one last thing.  If a cyber-attack were to be launched against the US, of course it wouldn’t be only limited to our gas pipelines.  These same hacking exploits that created the pipeline vulnerability have been occurring regularly on other elements of our infrastructure, opening up vulnerabilities in many other parts of the fabric which binds our society functionally together.

The overwhelming impact of a cyber-attack would make Pearl Harbor look like nothing more significant than a gnat on an elephant’s rear.  A full-out cyber-attack would destroy just about everything we need to survive currently – energy, water, food, sewer, communications, you name it.  Such an attack, from start to finish, would take less than five minutes, and would have no prior warning at all.

Be prepared.  Be very prepared.