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1. Browse through articles by clicking on "Older Posts" below each article in the center column.
2. Search through the Blog Archive at the lower right-hand column.

3. Read Editor's articles to the right.
4. Get Technical help in the lower left hand column.
5. Efficiency and low-waste strategies in the lower right column.

Monday, March 31, 2008

Do it now!

I have lived on photovoltaic systems for 25 years that are not grid-intertied. These systems include long-life batteries which means that if the grid goes down you still have power. Properly designed and installed solar electric systems with backup do not normally experience power outages. It also means that your electrical equipment lasts longer without the high voltage transients and brownout conditions that effect the grid. I strongly recommend this approach.

For people who are already on the grid they can use the electric company as their backup.

In Hawaii, such an energy system for a single person household would typically run about $15-20,000. Add a person and it will cost another $7-10,000. Household members after the first 2 are maybe about $5000 additional. The solar panels that run these systems can last up to 40 years. They typically have 25 year warranties! The most robust, active, manufactured product ever developed by humans!

In such a system you need to make an investment as well in Energy Star equipment because these system's effective use requires not wasting energy. The costs of these systems can typically be financed with home equity credit lines. If you shop around for equipment and be your own contractor, you should be able to save a lot in terms of equipment costs. Plus there are lots of tax incentives if you have taxable income. The payback would generally be less than 10 years. After that your power becomes very cheap.

And you have helped to avert the destruction of life on earth. Its not just the CO2, but a very wide range of toxic contamination deriving from a fossil fuel energy regime. All those people in Asia want the same standard of living as most westerners enjoy. But if everybody is made comfortable using fossil fuel technology, the planet will rapidly become inhospitable to life. So if you can afford to switch to solar, do it now. To wait is a fools game, since no one can say for sure when it will be too late!

Saturday, March 29, 2008

Storage is Essential for Photovoltaic Systems

A few basic terms can help to understand and visualize electrical energy storage devices.

Specific Energy is the kwHrs/Kg.
Specific Energy is important, because you want as much energy stored with as little weight as possible. However, compared to an automobile a boat can much better tolerate weight.

Volumetric Energy Density is the kwHrs/unit volume.
Volumetric Energy Density is important because whatever the weight, the smaller the package size, the easier it is to integrate into the space you have available.

Power (watt or kw) is the rate at which a device can accept or discharge its energy.
Power is important for the rate of charge and how much you can draw in a short time for a rapid acceleration for example. High power rates can allow the instantaneous drawing of huge amounts of energy when required. Low power rates cause inefficiency because when you try to draw it, the energy is converted to thermal energy which can actual damage the device and reduces the amount of energy available.

Energy (kwHr) is the actual amount of energy stored.
Energy is the amount of power you have over time, which relates to the time and distance that you can run. But you have to calculate the total efficiency of the system in order to determine how long your storage device will actually run your electric motor or what have you.

Deep Discharge Cycles are the number of times you can fill and empty the storage device before it fails or falls below a certain percentage of its original capacity.
Deep discharge cycles relate to the life of the storage device. This is complicated somewhat by the fact that in some storage devices (such as deep cycle lead acid batteries) a partial discharge/charge of the device can be more efficient than full discharge. In a situation in which one deep discharge is anticipated on a daily basis, you can calculate the life of the storage device.

Efficiency is the ratio of the energy put into the device compared to what comes out.
Efficiency is very important, especially throughput efficiency or in/out efficiency. This tells you how much of the energy you put into a device will be retrievable. The amount that is not retrievable is generally lost as thermal energy which also generally shortens the life of the device.

Shelf Life is how long the device can endure when not in use or with a minimal maintenance charge.
Shelf life relates to how long the device can sit unattended without self-destructing. This is very important in uses which are occasional as in recreational boats.

Maintenance is the amount of effort, expense, and risk that is required to utilize the device over its life. Obviously the less maintenance required, the more useful the device.

The Self-discharge Rate is what percentage of the energy is lost over time when the device is charged but unused. The only type of energy storage that does not appreciably self-discharge is the potential difference created by gravity. If you lift a weight away from the earths center, you have stored energy in that mass which can be released when it falls back to its original position. This is why pumped hydro storage is very attractive on a large scale, although impractical for vehicles because of the scale of the device. Lead acid batteries discharge at about 3%/month when fully charged. Super capacitors can self-discharge that much in a day, depending on the technology. The Lithium titanate technology from Altairnano self-discharges at about 10% per month. The self discharge rate of a device is sometimes gradually reduced as the voltage goes down. So for example a fully charged 5 volt supercapacitor may self-discharge more rapidly until 75% of its energy remains at which time the rate is rapidly reduced.

These issues are what make the Altairnano technology a real breakthrough in batteries. But right now the company seems to be going through some difficulties as the CEO has stepped down and they have had to have a recall of their earlier battery packs from Phoenix Motorcar Company because of a heating problem. If these people can work out their problems, their technology represents a quantum leap in electrical energy storage technology.

Jonathan Cole

Thursday, March 27, 2008

Clean Energy - Best Investment for the 21st Century

March 26, 2008

The Future Ain't What Is Used to Be

Anyone still not convinced about the economic strength and viability of clean energy need look no further than the latest numbers in our annual Clean Energy Trends 2008 report.

Against the backdrop of a contracting economy, record-high oil prices, rising home foreclosures, and consumer uncertainty, clean-energy markets grew by 40 percent from $55 billion in 2006 to $77.3 billion in 2007. We project that these same technologies will reach $254.5 billion by 2017.

For the past decade, solar and wind have been averaging growth rates in excess of 30 percent per annum. That's a compounded annual growth rate that most industries would be envious of.

Clean-energy naysayers complain that the cost for clean energy is still too high, but they just aren't looking at the numbers. The cost for solar and wind have both dropped by an order of magnitude over the past 30 years, bringing the cost of both sources within striking distance of, and sometimes even cheaper than, conventional energy sources.

In fact, the average upfront capital cost for a new 1-gigawatt (GW) nuclear plant — often lauded as one of the cheapest sources of energy — is between $2 billion and $6 billion. Compare that to the cost of 1 GW of geothermal and wind power at less than $2 billion and 1 GW of solar at between $5 billion and $10 billion. Not to mention the fact that it can take years to bring a new nuclear power plant online (the U.S. hasn't had a new nuke plant in more than two decades).

Admittedly, these aren't apple-to-apple comparisons. Whereas coal, nuclear, natural gas, and geothermal plants are able to provide baseload power, solar and wind are intermittent resources. In order to compete head-to-head with conventional sources, solar and wind have to be paired with baseload power sources or require the implementation of energy storage/smart-grid capabilities.

But clearly, the pendulum is shifting in favor of a range of renewables.

Europe provides a great example of this transition. Since the beginning of the decade the EU has added 47,000 megawatts (MW) of new wind energy compared to just 9,600 MW of coal and only 1,200 MW of nuclear, according to Platts Power Vision and the European Wind Energy Association. Perhaps even more telling, 2007 saw net capacity additions of 8,505 MW of wind, whereas both coal and nuclear saw net capacity reductions of 750 MW and 1,023 MW, respectively.

This trend toward renewables isn't just happening in carbon-constrained, Kyoto-signatory Europe.

In the United States more than 50 new coal plants are on hold because of concerns about greenhouse gas emissions and some Wall Street luminaries have put the kibosh on investments in coal power in anticipation of federal carbon emissions caps under the next presidential administration. Nearly 800 cities in the U.S. have pledged to meet Kyoto protocol targets and more than two dozen states now have renewable portfolio standards calling for significant portions (often up to 20-30 percent) of their electricity supplies to come from renewables within the next decade or two.

Investors are taking aim at this opportunity. New global investments in energy technologies — including venture capital, project finance, public markets, and research and development — have expanded by 60 percent from $92.6 billion in 2006 to $148.4 billion in 2007, according to research firm New Energy Finance.

High-tech giant Google has no doubts about both the opportunity and the necessity of renewables. The company is hiring dozens of engineers to push the clean-energy envelope like it has within the world of online search and information. Google's goal: Nothing less than bringing the cost of renewable energy to less than the cost of coal power. And according to the company, it hopes to achieve this goal not within decades, but years. Google has the cash to back high-risk, high-return, clean-energy investments - and the company has zeroed in on solar-thermal, advanced wind, and geothermal projects as some of the sectors to bet on.

The clean-energy opportunity hasn't escaped the attention of legendary oil and gas investor and prospector T. Boone Pickens either. He recently announced plans to build the world's largest wind farm at 4,000 MW with an estimated development price tag of around $10 billion. "I have the same feelings about wind," Pickens told the New York Times, "as I had about the best oil field I ever found."

Critics of clean energy like to point out that without subsidies and regulation, clean-energy sources would never be getting a foothold in the market. But that misses the critical point that all energy industries are subsidy and regulatory dependent. Coal, oil, natural gas, nuclear power and other sources have been supported with the direct and indirect financial support of governments that want to encourage them. Clean-energy sources shouldn't be expected to operate without similar regulatory support and incentives.

Indeed, governments that support the growth of clean-energy industries are already reaping the benefits with tens of thousands of jobs, reduced carbon footprints, and the creation of a competitive 21st Century industry.

As American baseball icon Yogi Berra put it, "The future ain't what it used to be."

That certainly seems to be the case when forecasting the energy industry. Instead of the once conventional wisdom of cheap coal, inexhaustible supplies of oil, and unlimited nuclear power, we now have cities choking on power plant emissions, $100 barrel crude, and nuclear proliferation and radioactive nightmares. The future doesn't belong to the incumbents, but to a range of emerging efficiency and renewable energy technologies that are reshaping the global economic and environmental landscape.

Over the next two decades, this transition will offer untold opportunities to the companies, individuals, and governments that exploit it.

Ron Pernick is co-founder and principal of clean-tech research and publishing firm Clean Edge, Inc. and co-author of The Clean Tech Revolution (Collins, June 2007). Clean Edge's annual Clean Energy Trends 2008 report is available for free download at

Friday, March 7, 2008

Intelligent Energy Systems

Excess Energy - what to do

The first of our pieces from contributors we take a look at a view on Energy from New Zealand

If we continue to install wind turbines, solar panels, tidal generators and hydro dams, we will find ourselves more and more often in the beatific state of generating more power than we know what to do with. There will be times when a nor-wester is blowing, the sun is shining ( they occur together here in NZ), a spring tide is running and the reservoirs are bursting from recent rains. What should we do? We could feather the wind turbines, let the tidal generators free-wheel, and allow the excess water to flow over the spill-way without going through the turbines but it seems like such a waste. With the advent of excess power the possibility opens up to use demand balancing of our grid rather than supply balancing.

Line Signals
We've long had a system in New Zealand of heating our water at night. In the evening, at a given time, the generating company sends a signal down the lines. If you are set up for it, this turns on your water heater. Because you are using power when demand is low, you get a better rate. In the morning at a set time, a second signal turns off your water heater. This is the horse and buggy demand-balancing-system. We could have the space shuttle.

Instead of sending the signal at a given time, it could be sent when power generation exceeds demand. Even better there is nothing to stop the power company from sending a number of different "turn on" and "turn off" signals. The company could send Priority 1 when there is a little excess power, priority 2 when the take up by priority 1 isn't sufficient to balance the supply and Priority 3 when generation is really humming along. The customer chooses (dials) which priority they want for a given function. Of course, the lower the priority (priority 3 in this example) the cheaper the rate. The sort of loads that these power options would be useful for would be pumped storage, heating your water, charging your electric car, and generating Hydrogen for later power use.

The flip side of such a system is less demand in times of lower power production. If you already have a tank of hot water or if your electric car is already charged up, you won't be using power when it is in short supply. The vehicle charging points at your place of work could be on this system. You may have enough power in your batteries to get home after work but, given a choice, you would rather have your car fully charged. You select the most conservative, least expensive option on the dial on the office plug-in point and swipe in your credit card. During the day, if the lowest priority signal is sent, your car gets some extra charge at the best rate. If not you charge your car when you get home utilizing the night rate.

On the other hand, if you arrived at work without enough power to get home, you might choose the less conservative option or even the most expensive "charge now" option and pay a little more to have your car charged. You might even choose "charge now" for $10, which would be enough to get home where you could access a more favorable night rate. This is only one option for balancing demand against available generation.

Pumped storage
Another system which is used by some generation companies is pumped storage. When excess power is available, water is pumped into a reservoir to be used for "peak shaving" when power demand is high. This seems counter-intuitive, since, as everyone knows, no system is 100% efficient. You lose power at each stage. You are probably lucky to get back 60% of the power you used to pump the water. The reason the system is feasible is largely financial. To build a separate power plant that is on standby most of the time is expensive, especially when you factor costs such as the interest on the loan to build the plant. Such a plant is not generating most of the time so the return on the investment is poor. It turns out that in some cases, even with the inevitable power loss, it is financially more favourable to use pumped storage for peak shaving rather than building another power plant. With excess (cheap) power, pumped storage is likely to be even more attractive for some power companies.

Production of Hydrogen
Hydrogen has long been touted as the fuel of the future. It is of course not an energy source. There are no underground pools of Hydrogen we can tap as we do with oil. However it has some very attractive features as an energy-transfer mechanism. Firstly it can be used to fuel a special "battery" called a fuel cell. Hydrogen is particularly attractive in this regard since hydrogen fuel cells operate at room temperature. These fuel cells are pretty efficient and you get a large portion of the energy back that you used to split the water molecule. You also get very pure Oxygen as a by-product of the electrolysis process, which, in a commercial operation, has a market for medical purposes, for welding, and for steel production.

Besides powering fuel cells, hydrogen can be used in internal or external combustion engines and can be used to reduce metal ores in place of coke. It can also be combined with coal to make petrol and diesel. In this application, there is still a carbon footprint as some fossil fuel is being used but it is much reduced over the use of pure coal and it produces a liquid fuel which is useful for transport.

Arguably, though hydrogen is best use in static facilities rather than as a transportation fuel. This is because it takes a lot of energy to compress or liquefy hydrogen for use in a vehicle. In a static facility there is another way of storing hydrogen.

As a boy in Vancouver, I remember the huge tanks used to store producer-gas. For those of you too young to remember, producer gas is a nasty mix of hydrogen, methane and carbon monoxide which is produced by passing a stream of steam through burning coke or coal. Have a gas leak in your home and the carbon monoxide in producer gas will kill you long before a similar gas leak of propane would have smothered you. The producer gas was piped from the storage tanks to businesses and domestic locations around Vancouver. So how did the tanks work?

The storage tanks resemble the tanks you see in petrol refineries but they are open-topped and contain water. A second open-bottomed tank, slightly smaller in diameter, is floated inside the main tank. The gas is let into the bottom of the tank and as it flows in, the inner tank floats higher and higher. Gas pressure is determined by how much the inner tank weighs and by how much extra weight is put on it. Such a system is only suitable for a static application but is perfectly amenable to small scale domestic use if electricity can be accessed at a suitable price to produce the hydrogen (priority 2 or 3in our example)

A problem with hydrogen is that the hydrogen molecule is very small. It will get through the smallest gap in a joint and hydrogen even soaks into some substances and actually leak out through the material itself. However technical fixes have been found for these problems.

This property of Hydrogen is leading to a new way of storing it. Hydrogen is adsorbed by certain metal alloys. It is absorbed so efficiently that in, say, a diving tank full of the alloy, you can store more hydrogen than would be the case if you compressed the hydrogen to 200 atmospheres into the same tank. Moreover, the storage takes place at very modest temperatures and pressures. Heat is given out when the hydrogen is absorbed and heat must be supplied to release the hydrogen, so there are some energy costs. See:

So hydrogen is an attractive option for using excess power when power is cheap. The hydrogen then represents an energy store which can be used when renewables are at an ebb. For some reason, possibly because of the Hindenburg, Hydrogen is considered a dangerous fuel. In actual fact it is far safer than any of the liquid fuels or any of the gaseous fuels with a vapour heavier than air. This includes all of the alkanes except methane. Ethane has a vapour of almost equal density to that of air and all the higher alkanes such as propane, butane etc. have vapours heavier than air. If there is a hydrogen leak, the hydrogen dissipates upwards and removes itself from the hydrogen source. The rest of the gaseous and liquid fuels flow down and across the ground looking for a spark. If Hydrogen ignites, you have a fire ball which rapidly rises upwards and is gone. Gaseous fuels spread their fire on the ground as far as they have dispersed and liquid fuels stay on the ground, igniting everything flammable in their path.

Domestic regeneration
A further possibility for balancing power is re-generation by the domestic consumer. If there is a high demand, the consumer with an electric car or a home hydrogen system could be putting power back into the grid when yet another signal is sent down the line. A family on vacation, for instance, could leave their electric car and their hydrogen system plugged in with the switch set to "supply". The unit would be programed to receive power when it is at the lowest rate and send it back at times of highest demand. Over their vacation, their house and/or electric car would generate a small income for them.

A main criticism of renewable energy is that it is pulsating and unpredictable. There is certainly some truth in this although not as much as it appears at first glance. For instance, as solar panels become common all over the country, places in the sun will balance places with cloud cover. The same applies to wind power. As fronts move from South to North along New Zealand, a pulse of wind generated electricity moves with it to be distributed by our power grid. Hydro is the ideal power source to instantly balance any shortfalls and New Zealand is rich in Hydro resources. On top of this any system which store excess energy in times of high generation, as mentioned above, and makes it available in times of low generation is of value.

Here in New Zealand in our present (2008) la Nina climate an interesting fact has come to light. Our wind generation is somewhat lower than average while our sun hours are greater. At present, solar electric is insignificant as a power source but as more solar comes on line, it appears that solar will help to balance wind. This would not necessarily be the case in all countries.

In the end, as our fossil energy runs out, we may even have to take a look at our tendency to be control freaks and accept that we can not always have energy exactly when we want it. Where I live we have now being living with solar water heating for half a year and while we almost always have hot water, three completely cloudy days leaves the tank cold. We find we are now much more aware of the weather and we never leave the hot water running while we do the dishes. Perhaps living with renewable energy will make us all a little more aware of our environment and our impact on it.

Hugh Williams

Tuesday, March 4, 2008

Ultra-efficient LED

Ultra-efficient LED, Developed By Student, Will Vastly Improve LCD Screens, Conserve Energy

ScienceDaily (Mar. 3, 2008) — In recent years, light emitting diodes (LEDs) have begun to change the way we see the world. Now, a Rensselaer Polytechnic Institute student has developed a new type of LED that could allow for their widespread use as light sources for liquid crystal displays (LCDs) on everything from televisions and computers to cell phones and cameras.

Martin Schubert, a doctoral student in electrical, computer, and systems engineering, has developed the first polarized LED, an innovation that could vastly improve LCD screens, conserve energy, and usher in the next generation of ultra-efficient LEDs.

Next Generation of LEDs

Schubert’s polarized LED advances current LED technology in its ability to better control the direction and polarization of the light being emitted. With better control over the light, less energy is wasted producing scattered light, allowing more light to reach its desired location. This makes the polarized LED perfectly suited as a backlighting unit for any kind of LCD, according to Schubert. Its focused light will produce images on the display that are more colorful, vibrant, and lifelike, with no motion artifacts.

Schubert first discovered that traditional LEDs actually produce polarized light, but existing LEDs did not capitalize on the light’s polarization. Armed with this information, he devised an optics setup around the LED chip to enhance the polarization, creating the first polarized LED.

The invention could advance the effort to combine the power and environmental soundness of LEDs with the beauty and clarity of LCDs. Schubert expects that his polarized LED could quickly become commonplace in televisions and monitors around the world, replacing widely used fluorescent lights that are less efficient and laden with mercury. His innovation also could be used for street lighting, high-contrast imaging, sensing, and free-space optics, he said.

Schubert’s innovation has earned him the $30,000 Lemelson-Rensselaer Student Prize.

Adapted from materials provided by Rensselaer Polytechnic Institute.