A California jail offers a glimpse of the economic and environmental benefits of locally generated energy.
Chevron Energy Solutions
A recently completed distributed energy project at the large, 4,000-inmate Santa Rita Jail in Alameda County, California, ties together power from fuel cells, solar panels, wind turbines, and diesel generators—all located at the jail—to form a microgrid that can operate independently of large, centralized power plants. The system keeps the power on when storms take down the grid, which is essential for safety at the maximum security facility, and it’s saving the jail about $100,000 a year.
The jail microgrid is one of the largest and most advanced in the United States. It’s the latest example of an emerging smart-grid technology that’s providing a cleaner, more reliable, and, in some parts of the country, significantly cheaper alternative to the conventional grid. “In many cases, it has a very nice payback, with or without subsidies,” says Michael Clark, president of Fort Collins, Colorado-based Encorp, which recently installed the software and equipment needed to manage the jail’s microgrid. Microgrids also provide new ways to use solar and wind power. Ordinarily, the intermittent nature of such power sources makes them a challenge for utilities. By integrating them with batteries and other sources of power, they can provide a reliable boost to conventional power supplies to help utilities meet peaks in demand.
Microgrids are a step beyond either emergency backup systems or stand-alone solar-panel arrays. They use special software and power electronics to integrate multiple sources of power and energy storage to provide electricity around the clock, even when the sun isn’t shining or regulations limit the use of diesel generators. In the case of the system at the jail, Encorp has installed networked controllers—the size of large computers—at each source of electricity, including a large array of thousands of batteries, as well as at the point where the jail connects to the grid. Coordinating power from diesel generators, solar panels, and other sources of power also requires equipment that can adjust the frequency and voltage of the power they produce.
Clark says Encorp has developed algorithms to help the system get the most out of each power source. At the jail, where the system is connected to the grid, this includes responding to the needs of a utility. If the utility experiences a large spike in demand, the microgrid can respond by selling excess power to the utility.
At certain times, it makes sense to use the system’s ability to temporarily decrease power consumption at the jail for things like the air-conditioning or lighting to create more excess power to sell to the grid.
The first customers for microgrids are businesses and organizations that can’t afford even short power outages—such as jails, hospitals, data centers, and military bases—or remote areas that don’t have access to the grid. They make economic sense in places such as California, where electricity costs are high and regulations on backup generators are strict. But they could soon make sense in more places as the cost of renewable energy and large-scale batteries decreases, and as advanced controls and power electronics make them more efficient.
by Bob Skinner
Kathy and I started our off grid living experience in 1993 after we found our 20-acre homestead in north central Oregon. It was bare land with good access, a great view and a mild climate that was perfect for our planned garden and orchard. Best of all it was at a price we could afford and still have enough cash left over to put in the road, a well, septic system and modest home.
That was when I was presented with a dilemma: Should we be slaves to the power company or make our own? An avid reader of country and off grid living magazines like Mother Earth News , Backwoods Magazine and Organic Gardening I’ll confess that I would enthusiastically sing along with John Denver “Thank God I’m a Country Boy” and envisioned country life to include an off grid power system (we had lots of sun and wind). I had also promised my fine wife that she wouldn’t have to “live like a refugee” and I definitely wanted those “cakes on the griddle” when the sun came up. What we needed was a good, reliable and affordable power system but we were going through our cash reserves rather quickly and we didn’t want to take on any debt.
Before I explain what we did let me share with you the 5 most common off grid mistakes folks make.
- Attempting a “do it yourself” off grid power system project beyond your skill level or willingness and available time to obtain the information and skills necessary. There are many design considerations and equipment choices to be made and a mistake here can be expensive and result in an under-performing power system with lots of frustration. Make sure that you do your homework first or consult with an off grid professional.
- Inaccurate assessment of available solar, wind or hydro-power resources. Some properties have great energy potential and others are much more limited and that often results in an under estimate of system power production and costs. Tall trees causing shade, nearby mountains or hills resulting in short sun days, limited wind resources and/or trees and other obstructions that would create wind turbulence and a lack of or inability to use hydro power are all problems that should be carefully considered before investing in an off grid power system. Once again, you can do your homework and get the tools you’ll need or hire a professional with off grid experience and the right tools to help you with an accurate site assessment.
- Underestimating the lifestyle changes, equipment operation and maintenance skills required to live off grid. “To everything there is a season” is often quoted and there are seasons of both energy abundance and brutal scarcity. Living in sync is the key to successful off grid living. With current battery technology, energy storage is limited so you learn to use power (sun, wind or hydro) when you have it and cut back when you don’t. In time this becomes second nature but thinking about energy use is a learned skill for most Americans. One family member may have to be the “Power Police” but over time efficient habits are formed and your power system may grow enabling you to not have to be as careful. You could, with a large budget, eliminate the need to live in natures cycle but for most of us that would be too expensive – at least initially. Plan for solar to meet most of your needs for 3 seasons (spring, summer and fall) and rely on a “good” back up generator to supplement your winter power and other peak demands. A professional off grid installer will offer a full system warranty, an owners manual, complete operations instruction manual as well as an initial hands on training with one or two free call backs for further training and system fine tuning. None of this however will eliminate your need to be personally familiar with your own system’s operation and maintenance.
- Failure to incorporate home efficiencies to reduce demand on their off grid power system. Your home’s biggest energy loads are typically for heating and cooling. Switch to a non-electric heat source (wood, gas or oil) and a very efficient cooling system that can run within the capacity of your off grid system (with solar you will often have more power than you need in the summer months). Switch to on-demand gas hot water system and consider adding a solar hot water system. Some have added a clever thermo cycle water-heating coil to their wood cook/heat stoves. Consider purchasing new high efficiency Energy Star electric refrigerators and freezers. A couple of extremely efficient refrigerators/freezers are Sun Frost and Sun Danzer . Efficient lighting is important especially during the winter low solar power season. CFL’s are very common and the new bright full spectrum LEDs are now commonly available. Choose high efficiency TV’s like edge lit LEDs over plasma. Choose a gas stove that doesn’t use a “glow bar” ignition system like the Unique Gas Ranges or Peerless Gas Stoves. An efficient dishwasher on sunny or windy days when you have a lot of power works great and that’s also a good time to use the vacuum cleaner and do the laundry.
- Going cheap on critical off grid components. There are places to save money on an off grid power system but don’t do it on your core components! Your core components are your 48-volt Power Distribution Panel or AC/DC enclosures and the inverter/charger(the inverters change the solar & battery DC to AC that regular appliances can use). Make sure you can add another inverter/charger and can easily add more solar or wind generators later without having to replace what you have already purchased. If you are on a budget you can start with a relatively small battery bank and small solar array to keep cost down initially. A good propane or diesel back up generator is an essential component for good battery maintenance and life. You could start with that inexpensive portable generator you already have and replace it when your budget allows. Its not recommended that you mix older batteries (over about 1 year old) with new batteries. Your initial battery bank size is something you will want to think carefully about but if you started small you won’t be sacrificing much to start over with a larger battery bank in two or three years should you decide you need it.
And we made all the mistakes.
Inverters: To keep our initial costs down we decided on a good 48-volt power distribution center with lots of room for future expansion, but we bought an inexpensive, modified sine wave inverter/charger . Trying to save money on the inverter was a mistake. We ended up swapping it out for a couple of stacked Trace SW 4048 true sine wave inverter/chargers a year later. Those inverters are still in service and working fine after 17 years but may be coming to the end of their expected service life.
Batteries – ‘nuf said: We installed a small bank of the inexpensive Trojan T-105 batteries that lasted us about 3 years. We learned to not cycle them as deeply and give them a regular equalizing charge to make our next set of Trojan L-16 batteries last about 7 years.
The solar we got pretty right. We installed 6 (expensive at the time) Siemens 75 watt solar modules on a 12 module top of pole Watt-Sun tracker (its still working well) which left us room to add 6 more modules in the future. A side note: The value of tracking solar has gone down with the dramatic drop in the price of solar modules in the last few years.
The rattling generator from hell: We bought an inexpensive diesel generator that we had to replace less than a year later. A “back up” duty generator isn’t made for those long hard charges. We installed a “commercial duty” diesel which is still running today.
Death by wind machine: After going through four screaming, crashing, flying, insane wind turbines we finally installed a Skystream 3.7. With only a couple minor problems it’s still running almost 3 years later. Skystream support through Southwest Windpower is really very good and they helped us work through those early problems. A quality wind generator is a great investment for off grid systems as it will often run at night, and offer that extra kick during the solar darkness of winter.
We still love our country off grid lifestyle and I still “Thank God I’m a Country Boy.” Off grid living is not for everyone but for those willing to do their homework and invest wisely it’s a great life and may just be the best preparation for an unstable world! Here are some web sites I’ve found interesting: Urban Danger Video Sustainable Preparedness the Book
Bob Skinner has lived off grid since 1993 and has been doing comprehensive energy system design for Hire Electric since 2007. firstname.lastname@example.org
Klickitat PUD sends out the Ruralite Magazine to all of its members. I was very excited to see this article by Debby Schoeningh in the February 2012 issue about a Haines, Oregon rancher who converted his 1986 Ford pickup truck into an electric hay hauling wonder. Check out the full article here: http://www.ruralite-digital.com/ruralite/201202_DEC?pg=10#pg10 The operator can control the truck remotely while unloading hay, it costs about 35 cents to run approximately 50 miles and you don’t have to work in the diesel fumes.
New post about the Henry Electric Feed Truck on YouTube: