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Sustainable Power Generation and Battery Storage

Author: Kevin Grauer

Efficient, high-capacity storage is a major missing factor in cost effective, sustainable electricity generation. Massive amounts of heat and light from the sun bombard the earth all day long, raging winds sweep over the land and sea, and yet the full potential of this energy remains inaccessible to us. Although we can capture some of this awesome power, the amount depends to some extent on the whim of nature, but more on the ability of our technology to capture and store energy from these bountiful sources.

In order to make solar and wind energy reliable and competitive with traditional methods of electricity generation, we need to harness as much energy as possible when it is available and store it for later use. There are a few ways of doing this, batteries being the most viable.

Current Battery Technology and Applications

When a battery is connected to a device or circuit, electrons are allowed to flow from the negative to the positive terminal of the battery. Inside, two chemical reactions are taking place as the electrons are released from one material and absorbed by another. Feeding electricity into the battery reverses these reactions, recharging the battery.

As the materials inside the battery break down over time, it loses efficiency and power. A typical deep-cycle battery, one which is designed to be significantly depleted and recharged repeatedly, will last longest if it is rarely discharged beyond 50% capacity.

Lead-acid batteries are typical for many deep-cycle applications, including home electricity storage. Electrons travel between two lead plates which are submerged in acid. These batteries are relatively cheap, efficient, and have a good energy-to-weight ratio. However, they require a fair amount of maintenance-their fluid levels drop as they recharge, and need to be replenished. They might also leak from time to time.

Absorbent Glass Mat batteries-AGM for short-are a newer, slightly more expensive alternative. They last about the same amount of time, but are designed so that the liquid component of the battery is stored in a sort of glass sponge. Gas circulates within the battery as it is charged, and the battery is sealed shut. There is no need to replenish the fluid, and even if the battery is dropped and breaks, no acid will ever spill.

Typical home renewable energy setups will use a battery bank. Many individual batteries are wired together in a way that brings their storage and output capacity up to a level that is useful for home applications. Battery banks take up a lot of space, involve a lot of wiring, and suffer problems related to the way batteries work when tied together this way. A battery bank is only as good as its weakest cell, and works best if all the batteries in it are of the same type, manufacture, and age. In other words, if one battery goes bad, the whole set needs to be replaced. Also, the batteries will discharge differently depending on their location in the circuit; some will wear out more quickly, reducing the lifespan of the whole system.

New Battery Options Poised to Revolutionize Renewable Energy

Mankind’s need for energy is often at odds with how nature provides it; we consume electricity to light and heat our homes when the sun is gone from the sky. The use of renewable energy right now is limited by our capacity to store it. However, there are several new types of experimental battery rapidly approaching full-scale availability. These new batteries could potentially be used in a wider variety of applications, giving us several options for improving the efficiency of our electrical system and allowing a greater reliance on renewable energy sources.

Salt Lake City’s Ceramtek, the R&D division of leading ceramics and components manufacturer CoorsTek, has developed an astonishing new battery that they believe will revolutionize home electricity generation. Their battery operates below 100 degrees Celsius, has a ten year lifespan, and is only the size of refrigerator. It could provide enough energy to run every appliance and light every bulb in a very large house simultaneously for four hours, if you wanted to do that. And it will deliver this electricity at less than half the current price offered by power companies.

Ceramtek’s battery uses a new type of ceramic membrane which greatly reduces the battery’s internal resistance. This means much less potential energy is wasted as heat, and the battery can operate at a temperature where sodium remains in its solid state. Coupled with wind turbines and/or photovoltaic panels, they could increase a home’s energy storage capacity to the point where power from the grid is no longer necessary. And at the price predicted by Ceramtek-around $2000 per unit-putting a battery in every home could be much more cost effective than replacing or continuing to maintain our nation’s aging electrical grid.

Dr. Donald Sadoway at MIT recently demonstrated a battery where the electrodes-the electron producing and absorbing components-are liquid metals. This battery can absorb ten times the amount of charge as a conventional battery. However, the use of high temperature materials makes this type of battery less than ideal for household use. More likely, it would be used for grid augmentation. That is, utility companies would generate and store electricity on a massive scale, with solar or wind forms. Large batteries would store the energy and release it into the grid when demand spikes above availability.

This type of grid-level application is already underway at Luverne, Minnesota. Xcel Energy, the largest provider of wind-generated electricity in the United States, is testing a facility that uses a battery bank the size of two tractor-trailers to store electricity generated by a huge wind farm. The batteries use liquid sodium and sulfur, and came from a Japanese manufacturer. Xcel claims this is the first attempt to store renewable energy at such a large scale. Their facility could radically alter the way we use our electrical grid.

Two Models for Renewable Energy (R)evolution

It’s obvious to most of us by now that our nation’s approach to electricity generation needs a massive overhaul. In addition to our unsustainable dependence on poisonous fossil fuels and nuclear materials, we rely on an aging electrical grid, cobbled together ad hoc as our energy demands have increased throughout the 20th century and into the 21st. The technologies outlined above will allow us greater flexibility in the pursuit of our energy goals. Two approaches recommend themselves; we can continue to retrofit the grid to keep up with increased energy demands and new technology, as suggested by the current administration, or we can move toward small-scale, widely dispersed home generation.

The main advantage of the electrical grid is its ability to provide instantaneously for increased electrical demand (in most regions). At present, the batteries that are available can’t meet all the energy demands of a household. Sometimes a home can get by on the amount of energy provided by its systems, but it will still need to draw from the electrical grid when its reserves run low.

However, the grid itself is largely composed of outdated, arcane technology that will fail sooner or later. Although it is widely dispersed, it is a centralized system; even outfitted with “smart” technology that can better control the flow of electricity, any kind of failure, whether natural or due to external attack, can have widespread consequences.

Personally, I prefer the attitude of the battery developers at Ceramtek. Home energy storage takes the power out of the hands of utility companies, some of the most bloated monopolies still around, and puts it in the hands of ordinary people. It operates at a low temperature, so it is safe enough to have in any basement, and since it is one cell, and by replacing battery banks, it eliminates the need for specialized electrical knowledge. It is both consumer friendly and more true to the American value of self-reliance. It makes us independent and insulates us from grid failures.

Ultimately, the model that prevails will be determined by several factors. No regulatory framework yet exists for the type of energy storage applications discussed here, so the governments of individual countries may very well have a deciding role in how we store our renewable energy. Here in the U.S., it means all sorts of lobbies will have their fingers in the pie. What’s more, each product will have to compete in the marketplace. Once these batteries become available, those that are cheapest, most reliable, and safest may hope to dominate. And since this technology could shift our entire energy paradigm, unpredictable factors may come into play as well.

Please share your opinion in a comment. I’m a writer, not an electrician, and this is far from the final word. What sort of approach will better serve us and our environment? How will this technology impact our way of life? Tell us what you think!

Sources:

• General battery information – http://www.windsun.com/Batteries/Battery_FAQ.htm#Cycles%20vs%20Life
• Example solar system – http://www.wagonmaker.com/newbatt.html
• MIT liquid battery – http://www.ecogeek.org/content/view/2607/80/
• Ceramtek battery – http://www.heraldextra.com/news/article_b0372fd8-3f3c-11de-ac77-001cc4c002e0.html