What Happens When the Wind Stops Blowing?

Published to LA Confidential, Fall 2015

Rosie, the Jetsons’ robot maid, keeps the home clean and running like clockwork, all on renewable energy. But will she slow down if the wind stops blowing, or if clouds block the sun?

Many megawatts (MW) of wind and solar power are being added to grids across the U.S. While routinely intermittent, until recently they represented such a small part of the system that their variability was inconsequential. That has begun to change.

During the rapid deployment of solar and wind in the last five years, climate was relatively stable. About every 5-7 years, however, we see an El Niño weather pattern that heats and wets parts of the nation. As a result of major warming of the Pacific near the west coast, a strong El Niño is now emerging. During the last cycle, wind and solar energy generation was relatively small compared to the overall electricity generation. However, with the current El Niño cycle and greater wind output, the impact on a network’s reliability has changed. At present, we are seeing the variability of renewable power output.

According to numbers compiled by Bentek, a trade source of energy data, sustained cloudiness in California (home to 70% of all U.S. solar capacity) has, in the first quarter of this year, resulted in a net drop in solar kilowatt-hours (KWh) relative to the same period last year, even as solar capacity kW grew by more than 10%. Find charts detailing the drop at www.eia.gov/todayinenergy/detail.cfm?id=22452&src=email

Average wind speeds in the west have also dropped. Although wind turbine capacity grew by 197 MW, actual wind-based kWh dropped in California by 14%. It fell by 20% in the northwest and 7% in Texas, despite a 10% increase in that state’s wind power capacity. Wind turbine output has remained steady further east where wind wattage is much lower.

The daily variability of wind and solar is also impacting wholesale power market pricing. One myth of solar is that because its output is greatest when the sun is highest in the sky, it will automatically translate into a peak grid demand reduction comparable to its installed kW capacity. As some who have installed rooftop solar systems have learned the hard way, that is often not the case.

Due to air conditioning loads from rising temperatures and the hours of internal building loads, most buildings as well as the overall grid may instead peak in the mid or late afternoon. By then, the earth has rotated to a point where photovoltaics kW output may be noticeably lower than its installed capacity. Lots of solar energy kWh has indeed been supplied, but the coincident solar demand kW has not been proportional to it.

Power output from wind farms also varies, but it peaks at night. While fortuitous as a balance against solar, which is always off at night, wind-heavy grids have been experiencing a glut of wind output during such off-peak periods. Once again, peak output does not coincide with grid demand. As a result, off-peak wholesale power prices plunged into negative dollars, disappointing wind developers and advocates.

Similar weather woes have caused hydroelectric output, a big part of generation in the northwest, to also drop. Down over 11% for the first half of 2015, June and July output were (respectively) down 35% and 40%.

None of this means that renewables are on the ropes, its pricing is increasingly competitive to fossil-fueled power. Instead, it points to the need for careful integration of new power sources, and a realization that, until utility-scale power storage systems become feasible, the need for gas-driven power plants, and the infrastructure that supports them, will continue to grow.

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Will LEDs Light the Future?

Published to LA Confidential, Fall 2015

In George Jetson’s world, Light Emitting Diodes (LED) are nothing new. Earlier light sources are only found in his kids’ history e-books. Back here in the 21st century, however, not all LEDs are Jetson-ready. While we are rapidly replacing fluorescent and incandescent lamps, and even some high intensity discharge (HID) lamps, care is needed when specifying LEDs for existing fixtures.

Three federally-supported programs make choosing easier:

  • CALiPER provides comparison studies of LED units against each other, and against standard light sources. Download it at energy.gov/eere/ssl/caliper-testing
  • Lighting Facts Label www.lightingfacts.com tests LED systems, providing a standardized way to compare its various lighting and operating characteristics, and a list of LED lamps that meet them.
  • DesignLights Consortium (DLC) www.designlights.org builds off the Lighting Facts program by providing specs for many LED devices (e.g., fixtures, retrofit kits, and lamps).

In the past, customers used the Energy Star branding program to choose high-efficiency light sources. While still a valid source of information, Energy Star does not test devices, and its specs for LED devices may be looser than those of the other programs.

The best ways to ensure acceptable lighting from an existing fixture using an LED lamp is through multiple mockups installed in your facility and careful specification. Even when two LED brands claim the same color rendering index (CRI), color temperature (CCT), or beam angle, (i.e. the spread between angles at which output is 50% of maximum), the end results may differ. However, lumen output may be less than the old-style lamp being replaced.

While all screw-in LED lamps work in standard medium base sockets, not all will fit properly in a fixture. Even if the lamp designation (e.g., PAR 38,) is the same as the existing lamp, some may be shaped differently or be longer. Outdoor use requires close reading of specs as not all LED outdoor lamps are rated for wet locations. One customer’s $30 LEDs shorted out after they filled with rainwater, giving new meaning to the term “floodlight.”

When an LED unit replaces a plug-in compact fluorescent lamp (CFL), the existing ballast may need to be disconnected, or removed and the wiring altered to accommodate it. Doing so may impact a fixture’s Underwriters Laboratories (UL) rating. At least one brand of LED (Lunera’s Helen Lamp), we are told, works with existing CFL ballasts.

LED replacements for linear fluorescent lamps present several challenges. Depending on a room’s ceiling height; color scheme; and office layout, spaces may appear quite different under LED illumination. Some LED T8 tubes, for example, have relatively narrow beam spreads, providing light only from its undersides, while a typical fluorescent lamp shines equally around its circumference. When installed in a fluorescent fixture, the “cave effect” may occur in which walls and partitions appear much darker. This problem is diminished when fixtures are mounted in high ceilings. A few LED T8 tubes distribute light almost as widely as fluorescents.

Unlike fluorescent lamps that, regardless of manufacturer, use standardized phosphors producing similar color, room surfaces and products may look different under various brands of LED lamps. Where appearance is important such as in retail applications, test several brands to find which yield the best results.

At least five types of LED devices are designed to replace linear fluorescent lamps:

a) A strip of LEDs on a board screwed into the fixture’s reflector, powered by a driver that replaces the existing ballast; existing sockets are not used

b) A tube containing LEDs that fits into existing sockets; a new LED driver replaces the existing ballast

c) Same as b), but the lamp contains its own driver; the existing ballast wiring is bypassed

d) Same as c), but the lamp uses the existing ballast as long as it is electronic instant start

e) Same as d), but the lamp will work with several types of fluorescent ballasts.

When doing mockups, note the duration and difficulty of installation, and if it impacts a fixture’s UL rating. Loss of UL could mean that a resulting fire may not be covered by insurance.

The intensity of individual LEDs may create glare, either directly into occupants’ eyes or when bouncing off specular surfaces such as glass or plastic. This problem is reduced in fixtures that have lenses or diffusers which cover lamps. Fixtures that distribute light indirectly by bouncing most of it off a ceiling or wall do not have this problem.

Pay attention to an LED device’s warranty and ease of replacement. Unlike most fluorescent technology, much of LED equipment is not compatible across brands i.e., a lamp may only work with one manufacturer’s driver. The best technology becomes problematic if a failed unit cannot be quickly replaced because the manufacturer is gone. Except for screw-in units which are easily replaceable, hedge your bets by stocking extras (at least a few %) of each type of LED device. Even the best LED vendors have had failures. Cree recently recalled almost 750,000 of its LED T8 tubes (sold between August 2014 and April 2015) because of overheating that may, “cause the LED T8 lamp to melt thereby posing a burn hazard.”

The warranties provided by manufacturers will not generally cover lighting output and color rendition. The marketplace recognizes this and third parties have stepped in to offer insurance solutions that guarantee the ongoing performance of LEDs for color consistency and it provides lumen maintenance to meet the guaranteed levels for periods up to five years. Since most LED projects will provide a simple payback of less than five years, this will go a long way towards reducing performance risk. If the installed equipment does not provide these assurances, you can ask the developer to include this insurance policy in the project.

For additional guidance and background on switching from linear fluorescents to LEDs, check out www.designlights.org/content/QPL/ProductSubmit/LinearReplacementLamps

Is There a Fuel Cell in Your Facility’s Future?

Published to LA Confidential, Fall 2015

Orbit City, the Jetsons’ home town, gets all its power from renewable energy. When the wind blows and the sun shines, it makes the electricity that keeps the city humming. But what happens at night, or when the air is still?

When the sun and wind provide more power than needed, the excess is used to electrolyze water into hydrogen and oxygen, with no carbon emissions. When sun and wind power are insufficient, stored hydrogen feeds into fuel cells whose only output is power and water vapor. While this may sound like science fiction, all the components needed to make it happen have been around for decades.

So what are fuel cells?

Several types exist, using various electrochemical reactions to make power without combustion, fission, or turbines. Find a good comparison table at http://energy.gov/eere/fuelcells/comparison-fuel-cell-technologies. Initially used in spacecraft, the technology has gradually come down to earth to run cars, buildings, and remote sites off the grid. However, like many new energy technologies, the ride has often been bumpy. In the last decade, some fuel cell firms have gone under or performed poorly, disappointing both stockholders and advocates.

Adoption of the technology has also been much slower than renewables. According to FuelCells2000, a non-profit promoter of this technology, over 170 Megawatts (MW) of fuel cells are running in the U.S., many at customer sites (e.g., 35 Walmart stores have fuel cells). However, by comparison, California has over 2,000 MW of rooftop solar photovoltaic (PV).

At present, nearly all commercial fuel cells consume natural gas to make power by first “reforming” it into hydrogen and carbon dioxide. While still venting some carbon, other fuel cell emissions (e.g., the nitrous and sulfur oxides that cause acid rain and other problems), are extremely low. Unlike the combustion-based power plants that produce such emissions, fuel cells do not need the scrubbers, smoke stacks, sound attenuation, vibration isolation, and other support systems common to them.

Building operators and owners have asked if a fuel cell may be profitable for them. Depending on a variety of specific issues, the answer is a qualified “maybe”.

Cells are also more efficient (40-60% of gas’s energy is converted into kilowatt-hours) than other on-site power sources. Even higher overall efficiency is possible when a cell’s waste heat is utilized in a combined heat-and-power (CHP) system. But, as Jesse Hayes, the product manager for Doosan Fuel Cells points out, sometimes the extra installation cost to make that heat useful outweighs the extra dollar savings. See the comparison table mentioned earlier for the waste heat temperatures produced by each technology. Hayes also stated that, unlike many other types of CHP technologies, fuel cells have excellent turndown ratios, meaning they run quite efficiently across the variable loads common in buildings. He also touted cells’ fast startup during an outage, 10 seconds, which rivals the startup time of diesels.

Where power quality and reliability outweigh dollar savings, fuel cells may be ideal: banks, military and research facilities, and data centers have installed many of them. Where significant rebates or financial incentives are available (e.g., California, New York, New Jersey), other types of facilities have seen acceptable paybacks.

So why are fuel cells not taking off like solar PV, which takes up much more space and only works when the sun shines? Hayes attributes much of the difference to successful lobbying by the solar industry as it secured many financial perks like net metering, rebates, and renewable portfolio standards that are not presently available for fuel cells.

To make the case for fuel cells at your site, start by determining what financial benefits, aside from energy cost reduction, may be available. Federal tax credits are generous, some states and utilities offer rebates and tax abatements, and other vendors have offered novel financing methods including one company that offers a discount when also buying stock in the fuel cell vendor. In states such as New York, fuel cells are considered renewable resources and provide the same favorable public recognition as wind and solar.

Do not forget about a cell’s capability in an outage. Unlike solar PV systems which automatically shut off when utility power is unavailable, fuel cells can quickly “island” themselves to provide nearly instant backup power at any time of the day. All of this makes them excellent candidates for integration into microgrids. Hayes refers to this as “the point where sustainability and resiliency meet.”

A good source for unbiased fuel cell data and links is the home of FuelCells2000, www.fuelcells.org.