Demand response without bothering the public

Warren Causey | Feb 12, 2010

 

I am not the only one who has been writing fairly extensively of late about the likelihood -- or lack of it -- of getting the general public involved in reducing their energy consumption during peak periods. The public just hasn't bought into the global warming driver for remaking the industry, as indicated by a recent PEW Research poll in which they listed global warming as last on their concern list and down from last year. And, they are showing increasing reluctance to let others tell them how much electricity they can use when.

However, with the environmental movement contesting every major power line, every major generation project, other than wind or solar, it is obvious that something is going to have to give. When and if the economy picks up, electrical demand will as well. Not enough generation is being built to meet that demand, so something will have to be done.

There are a number of fascinating technological approaches currently in development that could ease the pressure on utilities and the distribution system, without requiring the general public to significantly change their lifestyles in ways they've already shown a decided disinclination to embrace.

Since there is adequate baseload generation for most of the day -- you get a lot of figures for efficiency levels, but 50 percent for off-peak generation excess is quoted quite widely, the lack of electricity really isn't the problem, just when it is available. If load can be shifted from peak periods and wind power continues to grow, but is most productive at night in most locales, what obviously is needed is effective storage systems to shift the load.

There are at least three storage systems that I am familiar with that show promise of being able to store excess generation and then feed it back into the system when it is needed. And there are others I just haven't looked at closely. One I have examined, Ice Energy, shifts excess generation into ice during the night, and then releases it as cooling for large buildings during the day. Another thermal-based system is the Comfort Link district cooling system developed at Baltimore Gas and Electric, and sold to another company last week.

A new battery-powered system also is under development in the Northwest that has promise because it does not involve customers, but potentially can store intermittent renewable energy down to the transformer level. Called Demand Energy Network, the company already has some prototypes at Avista Utilities and a co-operative served by Bonneville Power. What is different about this system is that it doesn't try to store renewable electricity at the windmill or the large solar farm, but on a distributed network.

"We're in the early stages of putting the company together and we have a couple of prototype systems," said Doug Staker, vice president of product development. "Our goal is peak shaving. A lot of storage systems are doing frequency regulation, they ramp up and down to absorb excess generation. Our key differentiator is that we operate on a distributed network architecture -- the storage is distributed out to the end of the grid.

"Most energy storage discussions revolve around storing electricity near the generation site," he continued. "It seems to us you would locate the storage as close to the load as possible. Storage is a form of passive demand response. You keep the customer immune and they don't see the event. But from the utility side, it looks like demand response. It can be located in neighborhoods, at commercial facilities or at a substation."

"Solar generation peaks from 10 a.m. until 4 p.m., two hours early or two hours too late for summer/winter usage," Staker continued. "Storage can help with intermittency and with shifting the peak. We can store directly from solar, or from wind, which typically generates mostly at night."

The system described by Staker uses lead/carbon batteries that seem, so far, to provide longer life and more charge/discharge cycles than conventional lead/acid batteries. "What we have found is that with lead/acid batteries, you get about 500 deep discharges," he said. "What kills those batteries is the sulfation buildup in each cycle. Working with lead/carbon, we think we can get about 4,000 discharge cycles, which would give us roughly a 10-year life per battery."

If the company can achieve that kind of life span with batteries, what they plan to do with them is what is most interesting. The batteries could be distributed throughout a service territory to store excess generation. Then, during peak periods when generation is inadequate, the batteries would provide electricity to end-use customers. Thus a battery bank could be added to a transformer and serve as few as five or six homes.

While the system would be provide the utility with the needed peak-load shaving, individual residential customers wouldn't know anything about it. Their lights would stay on, they wouldn't have to shift their laundry, dishwashing and a host of other things to the night, and they wouldn't have to worry about complex variable rates, setting thermostats and appliances for different times of the day, tracking usage through smart meters, etc., etc. 

If it worked, utilities and policymakers wouldn't have to worry about a customer backlash which already seems to be building in some parts of the country. Technological answers to thorny problems always are better than trying to alter lifestyles through political means. 

I don't know if Demand Energy Network will be in business a year or more from now. But they are demonstrating the kind of thinking that needs to take place. Pushing the public can have negative consequences: they can push back.