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peristaltorMy last LJ tilted the joust at the simplest involvement one can have with one's electrical consumption and still be considered aware: Real-time monitoring. After all, how can one cut down on one's consumption if one has really no idea how much power the gadgetry scattered about the house is drawing from the power lines? Once that task is accomplished, the question arises about what to do next. That depends upon what options the utility makes available, unfortunately. For that reason, the following two stages of distributed generation, while promising in the extreme for managing power in a resource-poor future, may not be options for all.
Here's a couple of little secrets about the power company's meter spinning away on the side of the house. First, it doesn't care what time it is. This becomes a big deal when we consider that the time of day is of the utmost importance to the utility.
Why? Simply, most of us sleep at night and do things when it's Not Night. Those things often involve electricity. Therefore, much more electricity is used when it's Not Night, and much of that electricity is much more expensive . . . to the utility.
Utilities typically use at least two kinds of power: Base load plants and peaker plants. The base loads include big hydroelectric dams, coal-fired plants and nuclear plants. These facilities are so large they cannot be shut on and off like small lights; just reducing their output can take hours of planning. Once they get running, they usually stay running. So, when the electrical demand is higher, utilities call on so-called peaker plants to take up the slack. These are smaller power plants (like natural-gas-fired turbines directly coupled to generators) that can be activated a moment's notice. The per-watt cost from these peakers is far higher than that from the base plants, so they are only used when needed.
For that reason, some utilities have offered Time of Use metering, where the cost to the consumer changes based on the time of day "to better reflect the costs of generation and transmission." Though pretty darned popular in places where electricity is expensive and with high volume consumers like smelter plants, it hasn't caught on much with homes and small businesses, especially in our cheap hydro-power land. Many who switched around here, in fact, switched back because of skyrocketing bills; they had difficulty coordinating their lives around the now time-dependent cost of the power they used. Still, the concept has potential.
Let's take one example from the Wiki, hot water heating. "Historically, [time of use switches] have often been used in conjunction with electrical storage heaters or hot water storage systems." It makes sense to heat the hot water when power is cheap, provided it can stay hot enough to use later. Putting a simple switch on the tank to activate it only during cheap power times will easily pay for the switch in its lifetime, and reduce the amount of power the utility has to provide from more expensive sources.
Ah, but this entry concerns DG, so let's go there, shall we? What could an individual home owner do to not only consume from but perhaps contribute to the grid supply? In the first DG entry years ago, I noted solar, wind power and co-generation options that people buy for their homes, so I won't repeat those here. Let's get more basic: What about charging a bank of batteries during the off-peak hours when plenty of base load plant power is available and returning that power into the grid during peak times?
More than a few considerations must be made. First of all, most commonly available batteries are terrible choices for this. Typical automotive starter batteries, for example, would likely die after only a few months of service. Heavier-duty lead-acid golf cart or truck batteries would fare better, but only just, lasting a few years at most. Though it is almost ubiquitous today, the lead-acid battery sucks for such uses. The problem is simple. The chemistry is simply not very robust.
Other chemistries are better at storing and releasing power, but most suffer from a common problem of being frickin' expensive. Forget Lithium-Ion or Lithium-Polymer or Nickle-Metal Hydride. If people have trouble affording them for their electric car conversions, putting them in a household situation is just begging for bankruptcy.
Ah, but what of the past? Thomas Edison developed the Nickle-Iron battery over a hundred years ago. It was the de facto home storage battery for farm home radios and appliances. These are much more robust. Electric vehicle restorationists have gotten 80- year-old Detroit Electric batteries to take and hold a charge! They also have a chemistry much more conducive to home storage than L-A acid suggests. And they are still made today in China.
One would also have to purchase a pretty important bit of kit to achieve this charge-and-discharge, a grid inter-tie-capable power inverter. This bit of electronics transforms the direct current power from the battery bank to the alternating current used by the grid. Though not cheap, they are falling in price and more and more built to facilitate grid inter-tie installations.
So, let's say you get a three-tier time-of-use schedule, with a peak rate, an off-peak rate and a middle shoulder rate. During the off-peak, the charger and battery would power up, filling the batteries with a full charge; wait through the shoulder periods; then discharge during peak. There would be some losses (mostly heat given off by the charger, inverter, and battery internal resistance) so over all more energy would be consumed; but given a great enough difference between the peak and off-peak rates the system would not only pay for itself over time, but also would reduce the utility's reliance on peaker plant power for its customers.
Which brings me to the second little secret about utility meters: Not all of them measure power accurately. Specifically, they are designed to measure the power that flows through them, but not necessarily which direction that electricity flows. Meaning if you are in a house where all the appliances are unplugged and you activate your battery-inverter system to deliver power up to the grid, the meter on your house will bill you for power you deliver. For that reason, people who would employ this storage method had better darned make sure they have a modern meter that at least has the ability to spin backwards. In lieu of that, one would have to design a more complex system that coordinates information from the home energy meter and at peak times produces only as much power as the home is consuming. This would necessarily limit how much profit such a system can produce, but such a limitation would be inevitable until the meter can be upgraded. It would be silly to pay the utility for a product you deliver to them.
Before you scoff at this idea of simply storing energy for later use as feasible, keep in mind that it is already happening. Above is a drawing of the Grand Coulee Dam pump-generator facility. During times of low electricity demand, water continues to flow down the penstocks (the large pipes connecting the lake to the turbines), but some of the generated power is diverted to the pump-generator turbines shown above. This forces water from Lake Roosevelt to the higher elevation reservoir called Banks Lake. When demand starts to increase, this pumping stops; when demand exceeds the capacity for the main turbines, the flow from Banks Lake is reversed and the, er, banked energy produces power for peak consumption times.
Let's remember that this scheme is far less energy efficient than my home battery bank idea. At best, I doubt the pump generator turbines could produce more than a watt of energy for the every ten watts it takes to pump that water uphill to the reservoir. That, though, is not really the point. This configuration allows the Grand Coulee system to generate more power during peak demand times than it otherwise could using the same water flow by using that water twice. Per watt, the system is also quite a bit more cost effective than installing a corresponding amount of storage Ni-Fe batteries, either spread out in individual homes or concentrated in warehouse-like excess capacity factories. Given the low cost of power generated by the Grand Coulee, I doubt such warehouses would be in any way cost effective.
But again, "not cost effective" is only a metric applicable when one compares the pump-generator system to the battery system. There are precious few rivers flowing through geographic masses on this planet that would allow for a Roosevelt-Banks-Coulee construction; for this reason, the Grand Coulee Dam remains the largest hydroelectric facility in the country. If we are to dream up new grid supply systems, we need to consider that we have already plucked at the low-hanging fruit like the Grand Coulee.
We should also remember that Grand Coulee's construction came at a horrible price; no fish ladders were installed on the dam itself. Within five years, the historically mighty salmon runs up the Columbia River upstream of the dam ceased to return, denied thousands of miles of tributary spawning beds feeding the river system.
Take a look at the satellite image of the dam. Note the expansive swelling of Lake Roosevelt, and remember that at one time it was a large but simple river comparable in size to the "modern channel" of the Columbia marked on the map to the north and west of the dam. Consider the tributaries you can see on this image, branching into the hills as visible fingers of green reaching in amongst the brown land. Just about all of these streams proved perfect spawning grounds for salmon, some in the fifty-pound range, now completely absent from the landscape.
Dams are usually far more expensive to build than they actually cost. Just ask any fisherman from the Grand Coulee to Astoria.
With simple coordination, we can bank energy and use it later. No, it won't be as cost-effective as historic methods like the one shown above, but it proves almost infinitely scalable. As long as existing hydroelectric dams and coal, natural gas and nuclear base load plants have excess capacity during off-peak hours, that capacity can be shifted to peak times to reduce the need for supplemental generation plants. All we need is a rate structure conducive to investment.
The situation gets more complicated, though, when we consider the new breed of generation, the so-called renewables like solar photovoltaic, solar thermal and wind turbines. Simply put, while we humans are pretty dependably consistent creatures, we are not timed to be active only when the sun shines and the wind blows. This creates an energy management predicament that can be better addressed by the next level of Distributed Generation, which will be the topic of my next entry.
Simple Coordination
Here's a couple of little secrets about the power company's meter spinning away on the side of the house. First, it doesn't care what time it is. This becomes a big deal when we consider that the time of day is of the utmost importance to the utility.Why? Simply, most of us sleep at night and do things when it's Not Night. Those things often involve electricity. Therefore, much more electricity is used when it's Not Night, and much of that electricity is much more expensive . . . to the utility.
Utilities typically use at least two kinds of power: Base load plants and peaker plants. The base loads include big hydroelectric dams, coal-fired plants and nuclear plants. These facilities are so large they cannot be shut on and off like small lights; just reducing their output can take hours of planning. Once they get running, they usually stay running. So, when the electrical demand is higher, utilities call on so-called peaker plants to take up the slack. These are smaller power plants (like natural-gas-fired turbines directly coupled to generators) that can be activated a moment's notice. The per-watt cost from these peakers is far higher than that from the base plants, so they are only used when needed.
For that reason, some utilities have offered Time of Use metering, where the cost to the consumer changes based on the time of day "to better reflect the costs of generation and transmission." Though pretty darned popular in places where electricity is expensive and with high volume consumers like smelter plants, it hasn't caught on much with homes and small businesses, especially in our cheap hydro-power land. Many who switched around here, in fact, switched back because of skyrocketing bills; they had difficulty coordinating their lives around the now time-dependent cost of the power they used. Still, the concept has potential.
Let's take one example from the Wiki, hot water heating. "Historically, [time of use switches] have often been used in conjunction with electrical storage heaters or hot water storage systems." It makes sense to heat the hot water when power is cheap, provided it can stay hot enough to use later. Putting a simple switch on the tank to activate it only during cheap power times will easily pay for the switch in its lifetime, and reduce the amount of power the utility has to provide from more expensive sources.
Ah, but this entry concerns DG, so let's go there, shall we? What could an individual home owner do to not only consume from but perhaps contribute to the grid supply? In the first DG entry years ago, I noted solar, wind power and co-generation options that people buy for their homes, so I won't repeat those here. Let's get more basic: What about charging a bank of batteries during the off-peak hours when plenty of base load plant power is available and returning that power into the grid during peak times?
More than a few considerations must be made. First of all, most commonly available batteries are terrible choices for this. Typical automotive starter batteries, for example, would likely die after only a few months of service. Heavier-duty lead-acid golf cart or truck batteries would fare better, but only just, lasting a few years at most. Though it is almost ubiquitous today, the lead-acid battery sucks for such uses. The problem is simple. The chemistry is simply not very robust.
Other chemistries are better at storing and releasing power, but most suffer from a common problem of being frickin' expensive. Forget Lithium-Ion or Lithium-Polymer or Nickle-Metal Hydride. If people have trouble affording them for their electric car conversions, putting them in a household situation is just begging for bankruptcy.
Ah, but what of the past? Thomas Edison developed the Nickle-Iron battery over a hundred years ago. It was the de facto home storage battery for farm home radios and appliances. These are much more robust. Electric vehicle restorationists have gotten 80- year-old Detroit Electric batteries to take and hold a charge! They also have a chemistry much more conducive to home storage than L-A acid suggests. And they are still made today in China.
One would also have to purchase a pretty important bit of kit to achieve this charge-and-discharge, a grid inter-tie-capable power inverter. This bit of electronics transforms the direct current power from the battery bank to the alternating current used by the grid. Though not cheap, they are falling in price and more and more built to facilitate grid inter-tie installations.
So, let's say you get a three-tier time-of-use schedule, with a peak rate, an off-peak rate and a middle shoulder rate. During the off-peak, the charger and battery would power up, filling the batteries with a full charge; wait through the shoulder periods; then discharge during peak. There would be some losses (mostly heat given off by the charger, inverter, and battery internal resistance) so over all more energy would be consumed; but given a great enough difference between the peak and off-peak rates the system would not only pay for itself over time, but also would reduce the utility's reliance on peaker plant power for its customers.
Which brings me to the second little secret about utility meters: Not all of them measure power accurately. Specifically, they are designed to measure the power that flows through them, but not necessarily which direction that electricity flows. Meaning if you are in a house where all the appliances are unplugged and you activate your battery-inverter system to deliver power up to the grid, the meter on your house will bill you for power you deliver. For that reason, people who would employ this storage method had better darned make sure they have a modern meter that at least has the ability to spin backwards. In lieu of that, one would have to design a more complex system that coordinates information from the home energy meter and at peak times produces only as much power as the home is consuming. This would necessarily limit how much profit such a system can produce, but such a limitation would be inevitable until the meter can be upgraded. It would be silly to pay the utility for a product you deliver to them.
Before you scoff at this idea of simply storing energy for later use as feasible, keep in mind that it is already happening. Above is a drawing of the Grand Coulee Dam pump-generator facility. During times of low electricity demand, water continues to flow down the penstocks (the large pipes connecting the lake to the turbines), but some of the generated power is diverted to the pump-generator turbines shown above. This forces water from Lake Roosevelt to the higher elevation reservoir called Banks Lake. When demand starts to increase, this pumping stops; when demand exceeds the capacity for the main turbines, the flow from Banks Lake is reversed and the, er, banked energy produces power for peak consumption times.
Let's remember that this scheme is far less energy efficient than my home battery bank idea. At best, I doubt the pump generator turbines could produce more than a watt of energy for the every ten watts it takes to pump that water uphill to the reservoir. That, though, is not really the point. This configuration allows the Grand Coulee system to generate more power during peak demand times than it otherwise could using the same water flow by using that water twice. Per watt, the system is also quite a bit more cost effective than installing a corresponding amount of storage Ni-Fe batteries, either spread out in individual homes or concentrated in warehouse-like excess capacity factories. Given the low cost of power generated by the Grand Coulee, I doubt such warehouses would be in any way cost effective.
But again, "not cost effective" is only a metric applicable when one compares the pump-generator system to the battery system. There are precious few rivers flowing through geographic masses on this planet that would allow for a Roosevelt-Banks-Coulee construction; for this reason, the Grand Coulee Dam remains the largest hydroelectric facility in the country. If we are to dream up new grid supply systems, we need to consider that we have already plucked at the low-hanging fruit like the Grand Coulee.
We should also remember that Grand Coulee's construction came at a horrible price; no fish ladders were installed on the dam itself. Within five years, the historically mighty salmon runs up the Columbia River upstream of the dam ceased to return, denied thousands of miles of tributary spawning beds feeding the river system.
Take a look at the satellite image of the dam. Note the expansive swelling of Lake Roosevelt, and remember that at one time it was a large but simple river comparable in size to the "modern channel" of the Columbia marked on the map to the north and west of the dam. Consider the tributaries you can see on this image, branching into the hills as visible fingers of green reaching in amongst the brown land. Just about all of these streams proved perfect spawning grounds for salmon, some in the fifty-pound range, now completely absent from the landscape.
Dams are usually far more expensive to build than they actually cost. Just ask any fisherman from the Grand Coulee to Astoria.
With simple coordination, we can bank energy and use it later. No, it won't be as cost-effective as historic methods like the one shown above, but it proves almost infinitely scalable. As long as existing hydroelectric dams and coal, natural gas and nuclear base load plants have excess capacity during off-peak hours, that capacity can be shifted to peak times to reduce the need for supplemental generation plants. All we need is a rate structure conducive to investment.
The situation gets more complicated, though, when we consider the new breed of generation, the so-called renewables like solar photovoltaic, solar thermal and wind turbines. Simply put, while we humans are pretty dependably consistent creatures, we are not timed to be active only when the sun shines and the wind blows. This creates an energy management predicament that can be better addressed by the next level of Distributed Generation, which will be the topic of my next entry.