DC Microgrids are a proven means to optimize efficiency and performance.
While Alternating Current (AC) is still the most efficient means to move electricity over long distances “local” power inside of facilities wastes less electricity with DC Microgrids.
Independence LED Lighting developed its first Direct Current (DC) powered LED fixture series in 2015 for an industrial facility. Our DC LED fixtures are “driverless” with 24 volt DC wiring from a “Power hub Driver” (PhD), which is provided by our strategic partner Nextek Power Systems. Together, we are at the forefront of DC Microgrids, with the proven systems that leverage high efficiency power converters and smart controls to optimize energy usage while drawing power from renewables, batteries, and/or the grid. The technology reduces the payback time for lighting ROIs and improves control functionality, yielding the most practical solution for powering LEDs for facilities across the public and private sector.
|Energy Use:||Loss with AC||Loss with DC||Avg Net SAVINGS with DC|
|Lighting:||12%-20% (avg 16%)||3%-6% (avg 4.5%)||11.5%|
|Computers:||15% -20% (avg 17.5%)||3%-6% (avg 4.5%)||13.0%|
|Air Conditioning:||2%-10% (avg 6%)||0% (avg 0%)||6.0%|
|Elec. Vehicle Charge:||3%-10% (avg 6.5%)||1%-5% (avg 3%)||3.5%|
Lighting is typically the “low hanging fruit” of energy efficiency.
Lighting typically accounts for about 25% of commercial energy use.
11.5% savings with Direct Current lighting on 25% = 2.8% property savings.
LED lights cut consumption by 50%, making half of 25% = 12.5% property savings.
12.5% + 2.8% = 15.3% Total Savings for a property that retrofits with LED Direct Current lighting.
DC based power distribution, lighting, and controls technology offers the most efficient use of energy available. For the Independence LED Lighting / Nextek system, this is achieved by eliminating the traditional LED ‘driver’ in each fixture and replacing it with a centralized “Power hub Driver” that provides control and fixture power at a higher efficiency than any stand-alone driver. This approach also saves significant maintenance cost over time since drivers typically require replacement long before the LED chips are spent.
Results of DC Microgrids:
A significantly improved Total Cost of Ownership (TCO). Beyond the driverless approach, use of safe-to-the-touch Class 2 wiring allows for a much more simplified labor installation as compared to traditional AC methods. Use of simple 2 conductor wire can be installed with Low-Volt or General Trades labor resources.
Added labor advantage with DC Microgrids:
Facility owners and managers save both time and hourly rate costs, as compared to traditional electrical labor.
Added integration advantage with DC Microgrids:
By establishing a DC microgrid based backbone to power lighting, controls and other loads, it can be easier to connect additional power sources to the DC buss such as Photovoltaic (PV) solar, DC power from wind driven generators, fuel cell generators or all 3 renewable sources. By basic engineering of DC voltage performance, a DC bus can be very effectively managed. Accomplishing the same with AC technology would require use of less reliable inverters that then require phase management to work with other systems.
SUPPORT INFORMATION for DC Microgrids
Re-Inventing Microgrid Power Systems for Net Zero Buildings
Brian T. Patterson IEEE | EMerge Alliance
Douglas B. Hamborsky AIA | Nextek Power Systems
Presentation on DC Microgrids for GREENBUILD International Conference & Expo: https://www.emergealliance.org/portals/0/documents/events/greenbuild2015/151104_Greenbuild_2015_Final.pdf
DC Microgrids and the Virtues of Local Electricity
Report on DC Microgrids by: The Institute of Electrical and Electronics Engineers (IEEE), the world’s largest technical professional organization dedicated to advancing technology for the benefit of humanity.
Excerpt: It’s worth revisiting Edison’s vision of local electricity generation. We and other champions of this idea refer to a system of local power generation and distribution in the form of direct current as a DC microgrid. The modern conception is quite similar to what Edison had in mind, but with the added benefit that the local DC grid is able to operate either in parallel with the surrounding AC grid or in isolation from it.
DC microgrids, with their much smaller footprints, avoid most transmission and distribution losses. They also eliminate the waste of energy associated with the conversion of AC to DC, which is required for so many of the electrical loads found these days: LED lights, variable-speed motors, computers, televisions, and countless other forms of consumer electronics—loads that account for a steadily increasing fraction of the electricity consumed. (Some estimates suggest that most of the electricity used in commercial buildings already goes to serve such loads.) In a time of increased concern about energy efficiency and carbon-dioxide emissions, DC microgrids obviously have a great deal to offer. Yet traditional AC distribution systems are still all most people ever think about when you use the term “power grid.”
The only places you can count on finding local grids carrying DC now are within data and telecommunications centers or, on a much smaller scale, within automobiles, ships, and airplanes. But we expect to see more DC microgrids sprouting up soon, at least in certain settings.
For example, future army outposts in war zones will probably use them to reduce energy consumption and to deploy wind turbines and photovoltaic panels more easily. Replacing the usual diesel generators with renewable sources of power would be especially valuable in hostile territory, where fuel costs can be enormously high, both in dollars and in lives lost protecting supply lines.
DC microgrids may also prove irresistible for certain energy-intensive manufacturing operations. These include paper and pulp production and the smelting of aluminum, which now wastes more than 6 percent of the total energy consumed in the conversion of AC to DC current.
DC microgrids hold great promise, too, for ordinary residential and commercial buildings, where they could service the many electrical loads that use DC. These include LED lighting and, increasingly, charging stations for electric vehicles, whose hefty batteries demand (or produce) DC. Heating, ventilation, and air-conditioning (HVAC) equipment and various household appliances are also well suited to powering with DC. That’s because the most energy-efficient types of HVAC equipment and appliances incorporate variable-speed motor drives, for which AC power from the regional grid must be converted to DC internally. So it would be straightforward—and more efficient—to power such motors directly from a local DC source.
Developments on the generation side only strengthen the case for DC microgrids. Consider how often you see photovoltaic panels mounted on the roofs of houses or commercial buildings nowadays. These panels produce DC power. And even if all that power is used within the building where it is generated, the electricity flowing from those panels is typically converted to AC using an inverter, which wastes about 10 percent of the energy right off the bat. The AC is then sent to various loads, some of which convert the electricity back to DC, in the process squandering about a third of the energy fed to them. Being able to distribute and use DC within a building would prevent the substantial losses that result from having to make the round trip from DC to AC and back to DC again.
Events like 2012’s Hurricane Sandy also highlight the advantages of local power generation, storage, and distribution. That one storm caused more than US $50 billion in damages and left many residents of the U.S. Northeast without power for days, weeks, in some cases even months. DC microgrids fed by batteries, generators, fuel cells, photovoltaic panels, or small wind turbines would surely have proved much more resilient in the face of this natural disaster. They would have been less prone to the most common form of damage—the downing of power lines—and the DC electrical equipment itself would probably have exposed far fewer critical points of failure.
Other reasons to expect a proliferation of DC microgrids come from the developing world, where about 3 billion people still burn wood, charcoal, or animal dung to meet their day-to-day energy needs. These people are, of course, eager to see electrification reach their communities, but it’s far from clear what form that electrification should take.
Round Trip: Today, locally produced DC power (say, from photovoltaic panels) is typically converted to AC using inverters. Much of the time, though, the power supply in the end user’s equipment just converts the AC fed to it back to DC.
With the decreasing cost of electricity generated by photovoltaics and wind turbines, DC microgrids may be the most efficacious way to provide electrical energy to those who have none. Just as cellphone use in the developing world exploded without the prior installation of landlines, DC microgrids could leapfrog over the traditional system of centralized AC generation. The market for microgrids in the developing world could be huge, and the benefits they would bring to what are now grossly underserved regions are monumental.
Clearly, DC microgrids hold extraordinary promise for a wide variety of situations. Why then are they still so few and far between?
Some of the blame, at least in developed countries, can be placed on antiquated building codes that make it difficult to set up the infrastructure needed for generating and distributing DC power locally, perhaps within a single building. And even if property owners can overcome this hurdle, they will still struggle to find advice on how to construct such a system.
One of the few resources now available is the EMerge Alliance, an organization of more than 100 member companies interested in fostering the development of DC microgrids for commercial buildings. Alliance members are working to speed the adoption of this approach to improving energy efficiency, in part by setting relevant standards.