Monday, September 25, 2006
The first lady announced the first commitment - US$10 million from the US government to kick-start a US$60 million public/private project to build children's merry-go-rounds in Africa, which pump clean drinking water into a storage tank.
Is it just me, or doesn't it seem wrong to support a program that uses children to pump drinking water?
I remember how much fun I had on merry-go-rounds as a kid. Because there was little friction, we really got them spinning. But attaching a pump will add friction and the effort required to get the device spinning will make it a chore rather than a fun activity. If it becomes a chore, rather than a choice, then it's definately wrong.
It would be much wiser to use the available funds for solar photovoltaic systems. Such dedicated water-pumping systems are already in use in many parts of the world. Why anyone would want to use kids instead is beyond me.
Thursday, September 21, 2006
Daryl Hannah lives in a teepee…..
Willie Nelson manufactures and sells bio-diesel…..
Schwarzenegger Backs New Solar Power Plan…..
Kennedy campaigns against renewable energy project….
Cameron Diaz Saves the World…..
Pearl Jam Takes On Global Warming…..
Dave Matthews Wants to Lick Global Warming…..
Rams – Eagles in NFL’s First Climate Neutral Regular Season Game…..
So there you go. News stories that include celebrities, conflict, opposing views, and sensational headlines. At the same time all of these stories are related to alternative energy and saving the planet. This, no doubt, is my finest posting on this blog.
Tuesday, September 19, 2006
If you’ve done your homework before purchasing batteries for your solar PV system you’ve likely purchased some sort of a deep-discharge lead-acid type. Your batteries may have been designed for golf-carts, fork-lifts, or perhaps the kind used to run a trolling motor and lights on a fishing boat. If your budget didn’t allow you to buy the best available batteries, you might have chosen batteries with a shorter life expectancy. Whatever the type of lead-acid batteries you’ve chosen, they all have similar characteristics. If you want to know the condition of your batteries at any given time, you need to understand some basic electrical principles and some battery quirks. That is the purpose of this paper.
A battery can be thought of as a storage medium for electrical energy. Just as a glass of water can be nearly full or nearly empty, a battery can be fully charged, fully discharged, or anywhere in-between. If we were to measure the amount of water in a glass with a ruler, it would be easy to determine how full (or empty) the glass is. Since we can’t see electrical energy, we need to use instruments to measure the state of charge in a battery. A hydrometer is the most accurate instrument for state-of-charge measurements, but a voltmeter can also be used.
A hydrometer measures the density of the fluid, known as electrolyte, in a battery. The heavier the fluid, the greater the state of charge. To perform a test, a little of the liquid is drawn from the battery into the hydrometer. A float and a scale within the instrument indicate the specific gravity (density), of the liquid. With that reading, and through the use of a chart, the state-of-charge can be determined. Obviously, a hydrometer test cannot be done on a sealed battery.
Although not as accurate as a hydrometer, a voltmeter can be used to measure the state-of-charge of a lead-acid battery. However, there are a few things you need to know in order to make accurate measurements.
* Batteries have internal resistance.
When a battery is a part of a complete circuit, that is to say one in which current flows, the battery voltage will decrease. The voltage drop caused by the load on the battery will result in an inaccurate state-of-charge determination. Measure battery voltage with no load connected.
* Batteries are charged by applying a voltage greater than the rating of the battery across the terminals.
To charge a 12-volt battery, for example, 14.4-volts dc may be applied to the battery terminals. You cannot determine the state-of-charge of a battery when a charging voltage is applied. Some charge controllers provide pulses instead of a steady voltage, making dc-voltage readings inaccurate.
* The voltage reading across a recently charged battery may be far in excess of the battery’s rated voltage.
This phenomenon is known as a surface charge. To accurately measure the state-of-charge it is necessary to wait until this charge dissipates, or to burn it off by applying a load to the battery for a short time.
Interpreting Battery Voltage Readings:
Intuitively, one might expect the voltage reading of a fully-charged 12-volt battery to be exactly 12-volts. Likewise, one might expect the voltage reading of a half-discharged 12-volt battery to be 6-volts. However, this is not the case. Keeping in mind the information presented above, the chart below can be used to determine the percentage of charge for a 12-volt battery.
Battery Voltage / Percent of Charge
12.70 Volts = 100
12.58 Volts = 90
12.46 Volts = 80
12.36 Volts = 70
12.28 Volts = 60
12.20 Volts = 50
12.12 Volts = 40
12.04 Volts = 30
11.98 Volts = 20
11.94 Volts = 10
11.90 Volts = Discharged
Understanding that overcharging and over-discharging can damage or shorten the life of a battery, this information is very important. Fortunately, your charge controller prevents overcharging. It does so by removing charging current to the battery-bank once it senses that the batteries are fully charged.
Typically, inverters include the ability to turn themselves off when the battery voltage drops to preset level. As a result, the inverter protects the battery from over-discharging. Systems that do not include an inverter should include some method of removing the load when battery voltage drops to a dangerous level. Some charge controllers provide this functionality.
More Battery quirks:
* Battery capacity is affected by temperature.
A cold battery is not able to supply as much power to the load as a warm battery can.
* The discharge rate affects battery efficiency.
As the rate of discharge increases, battery efficiency decreases. An over-sized battery array is more efficient than a smaller-capacity array.
* Battery charging is more efficient at a lower rate of charge.
Just as batteries are more efficient at lower discharge rates, charging efficiency is greater at lower charge rates. In other words, a battery more efficiently stores energy pumped into it when the charge rate is relatively low.
* Batteries are not 100% efficient.
Expect losses in batteries, and other system components for that matter.
* A strange battery quirk.
When connecting a load to a fully charged battery the voltage initially drops as expected, but then begins to increase over time. This phenomenon may be due to the chemical reactions that occur when current flows within a battery.
* Chronically undercharging a battery will result in shorter battery life.
A PV array that does not provide enough charging-power to keep the battery-bank fully charged will result in reduced battery life. If your PV system is unable to maintain a fully-charged battery bank, add solar panels to your array or reduce the load on the battery.
* Allowing a battery to remain in a discharged state for an extended period of time will shorten its life.
Hard crystals of lead sulfate will form on the plates over time, reducing the capacity of the battery. To prevent this, don’t let a battery remain in a discharged state for an extended period of time.
* Avoid battery stratification.
Because battery acid (sulfuric acid) is heavier than water, it tends to settle at the bottom of the battery. This causes a build-up of lead sulfate on the plates near the bottom. This can be prevented by applying an equalizing charge of 14.4 volts to a fully charged battery for a short time, at least once per month. The elevated voltage causes bubbling, mixing the electrolyte. This function is built in to many modern charge controllers.
* Allow a battery-bank to age gracefully.
Do not add batteries to an existing battery-array. If you do, the life-expectancy of the newer batteries will be adversely affected.
* Overcharging can be dangerous.
Batteries produce hydrogen gas when charging. Overcharging, or charging at a high rate, causes an excess of hydrogen gas production. For safety, the battery-bank should be vented to the outside. Since hydrogen gas is lighter than air, an effective system includes a hood above the battery array, and stove-pipe or pvc tubing rising from the highest point.
Unless your batteries are sealed, check fluid levels at least twice per year. Excessive fluid use can be an indication that batteries are being charged excessively. If that’s the case check the rest of your system, particularly the charge controller, to be sure everything is working properly.
Battery bank capacity testing:
The capacity of a battery bank can be measured by conducting a discharge test. At night, when no charging current is present, connect a constant load to the battery bank. Using an accurate digital voltmeter, measure battery bank voltage at regular intervals and record the results. Terminate the test when the battery bank is 50% discharged. The test results can be used as a baseline to be compared with those of future tests. When the capacity of the battery bank falls to an unacceptable lever replace the entire battery bank.
It is also important to note that one defective battery in a battery array can create a load on the rest of the batteries within the array. To locate a defective battery it is necessary to disconnect batteries one at a time from the array and test each battery individually. The defective battery will probably have a significantly lower voltage than the others.
The best way to check the state-of-charge of your batteries is through the use of a hydrometer. It is easier to measure the state of charge with a voltmeter, but you need to avoid measurement pitfalls in order to ensure accuracy.
Avoid battery problems by conducting periodic state-of-charge checks, monitoring the fluid levels, and by avoiding stratification through the application of an equalizing charge periodically. In addition, keep the tops of the batteries and battery terminals clean. Make sure that terminal connections are tight.
To design a PV system you’ll need to understand electrical principles beyond those presented in this paper. For the sake of clarity, technical terms and formulas were avoided.
Wednesday, September 06, 2006
I begin early each spring by double-digging my garden area. In addition to the main area I prepare a couple of raised-beds by deeply loosening the soil and mixing in compost. I don’t use a tiller because I don’t want to chop up worms and beneficial bacteria, or destroy aeration and drainage. My garden is 100 percent organic and I don’t use pesticides or chemicals on my lawn, shrubs, or trees. This practice allows me to use plant wastes as compost. I find that because of composting, my plants don’t seem to need fertilizer. I avoid composting weeds because I don’t want their seeds to sprout, but all other plant matter is composted. Egg shells and waste such as shrimp peelings add calcium to the soil.
Late in July each year I have enough tomatoes to make canning worthwhile. I also freeze tomatoes and other vegetables, but I prefer canning, since those need not be refrigerated, and a long-term power outage will not result in spoilage.
Not being content with what I can grow in the summer, I’m also experimenting with techniques for growing vegetables indoors during the winter. I’ve found varieties of dwarf tomato plants that do well in cool weather, and with limited sunlight. Dwarf plants allow me to efficiently use the limited space that I have available for indoor growing. Some of the plants grow no bigger than 8 inches tall, yet produce clusters of good-tasting tomatoes. I use “free-power” from my solar photovoltaic system to run grow lights and bottom warmers in my sunroom. My plants seem to like a cycle of warm days and cool nights. I place fluorescent tubes and compact fluorescent bulbs very close to the tops and sides of the plants to supplement natural light from windows. Growing veggies in the winter is an interesting project, and I’ll devote another blog post to that subject in the future.
To take advantage of the limited space available in my backyard, I’ve planted raspberries along a section of fence. Each summer I have raspberries to snack on, and enough to freeze for later use. I’ve made some tasty pies and jelly.
I attempted to grow field corn this year to fuel my corn-burning stove but had some problems with squirrels. I salvaged a few ears to use for next year’s seed and bought a live trap. I’m planning to relocate the squirrels I’m able to catch, and hopefully reduce the squirrel population in my neighborhood.
In order to minimize city-supplied water usage, I bought two fifty-five gallon plastic drums. I’m planning to divert rain water from my garage and home roofs to the drums, and then use the stored water as needed in the garden. At the present time I use soaker hoses, and I suspect that I’ll be able to pump water from the drums through them. I’m also considering a more sophisticated system using drip emitters. In the event of a water-supply disruption, this stored water could be filtered and used in my home. Stay tuned as I report my success or failure in this endeavor.
If you’re new to gardening it’s important to understand the importance of open-pollinated seeds and heirloom varieties. By using open-pollinated types you’ll be able to save seeds from your own successful crops for future use, reducing your gardening expenses. Don’t try that with a hybrid, the results are unpredictable. The amazing thing about open-pollinated seeds is that they are able to mutate and adapt to the local ecosystem, where hybrids cannot. Heirloom varieties are those that have been handed down from generation to generation, and are usually better-tasting than hybrid types.
Genetically altered seeds produce crops that are more suitable for marketing than their natural counterparts, but taste and nutrition usually suffer. Plants such as these may cause harmful reactions in those with allergies or sensitivities. In addition, these plants may have lost their ability to prevent cancer. On the other hand, fruits and vegetables produced from plants that have not been genetically modified taste much better than any you’ll ever buy from a grocery store, and they’re better for you. They make gardening worthwhile for me.
Support biodiversity: Because of standardization, all plants of a specific variety share the same strengths and weaknesses. Since they share the same weaknesses, a single fungus or disease can wipe out an entire crop. Growing heirloom vegetables provides humanity with a hedge against future massive crop failures.
It’s also important to understand the dangers of using chemical fertilizer and pesticides in the garden. For more information, visit: http://www.organicconsumers.org/index.htm If you’re as old as I am you might remember tadpoles and crawdads in creaks and streams. Sadly, because of chemical runoff from products such as Monsanto’s Roundup, you don’t see them anymore. I hope you’ll do your part to reverse this trend, and encourage others to do the same. It is unfortunate that we cannot rely on our government, or on agribusiness, to do the right thing.
Although I’ve been gardening for many years, the gardenweb forums have been extremely helpful, especially when it comes to indoor growing. Check them out at:
Here are a few sources of seeds, and other supplies for the organic gardener: