ACEEE Publishes 2015 State Scorecards

ACEEE has released its annual “State Energy Scorecard” for 2015 that ranks states based on a variety of criteria such as: utility policies and programs, transportation policies, building energy codes, combined heat and power (CHP) policies, state government-led initiatives, and appliance standards.   A summary of key findings is detailed here, while the full scorecards for each state can be found here.

The top 10 states for energy efficiency are Massachusetts, California, Vermont, Rhode Island, Oregon, Connecticut, Maryland, Washington, and New York, with Minnesota and Illinois tied for 10th place.

It is noteworthy that renewable energy consumption is not included in the ranking criteria.  Although the installation or usage of renewable energy technology does not necessarily reduce energy consumption, it does reduce the consumption of energy generated using more conventional non-renewable methods such as coal and natural gas.  Since the terms “energy efficiency” and “renewable energy” seem to go hand-in-hand these days, perhaps ACEEE will include this criteria in future rankings as a measure of overall efficiency.

It will also be interesting to see how the rankings change within the next few years, as several states are in the process of changing their policies and programs.  In particular, New York State’s organization NYSERDA is revising their program to place a larger emphasis on the R&D of new clean energy technologies.  They are also in the process of phasing out incentives that they currently provide to energy-reduction projects.  Although the effect may be a short term reduction in the growth rate of the state’s energy savings, the plan is that it will spur greater long term energy savings and promote economic growth.

Installing Wind Turbines in Viaducts Have Potential to Produce Electricity

Researchers in Great Britain have determined that wind turbines installed between the pillars of viaducts have the potential to produce electricity.  See the full press release here.  Their analysis was based on the Juncal Viaduct, which is located on the island of Gran Canaria.  The results of the study showed that although a variety of turbine configurations are possible, the most viable configuration would be two 0.25 MW turbines placed next to each other.

This application may be beneficial in areas where traditional wind turbine configurations are not possible due to geographical constraints or existing development.

wind turbine in viaduct

Conceptual drawing of two turbines installed in a viaduct.

Thinking about installed a wind turbine?  We can help you!  Our staff includes professional engineers, project managers, and analysts who have supported the development of over 450 MW of operational utility-scale wind power, and includes many gigawatts of projects in various stages of early development.

Why you may want to consider installing a VSD

Why should I install a VSD?

Motors that are used to operate fans, pumps, and air compressors typically operate at a constant load.  To control air or fluid flow, you can either mechanically throttle the motor—for example, a valve or damper—or you can electronically reduce the speed or frequency of the motor using a variable speed drive (VSD) or a variable frequency drive (VFD).

When you mechanically limit the output of a motor in these applications, the motor is still operating at full load and consuming the same amount of electricity, even though the amount of work that you get from it is being reduced.

However, when you electronically limit a motor, the resulting power consumption of the motor can be drastically reduced, benefiting from favorable scaling offered by fan and pump affinity laws:

vsd 1

Which can be rearranged to make the calculations easier when you’re trying to calculate the new demand of your motor:

vsd 2

So, if your existing motor is operating at 90% loading and has an electric demand of 5 kW, reducing the load down to 50% will reduce the motor’s kW down to 0.86 kW:

vsd 3

This is an 82% savings on electric load over the existing case!  So yes, adding VSDs or VFDs to existing motors has the potential to save you a lot of energy at your facility.


vsd 4 vsd 5


VSDs on Pumps

Many facilities are interested in replacing their constant speed pumps with either a two-speed pump or a VSD controlled pump.  But which one fits best? To demonstrate the difference between a dual speed pump and a pump with a VSD, the graph below displays a demand curve over a 20 hour period.  Both are providing the same total flow of water (in gallons), but the two-speed pump is cycling between high/low and on/off as a way to control the overall flow, whereas the variable speed pump adjusts its flow automatically according to the system’s demand.

vsd 6

The Short Answer

Two speed pumps are appropriate if you have large amounts of storage available or your water demands are fairly constant or predictably at a ‘low’ or ‘high’ flow periods.  If you have a varied water demand or little to no buffer storage, a pump equipped with a VSD may be the best solution for you.

The Long Answer

The type of pump and controls that are most effective for your system depends on your water demand profile.  For example, conventional pump stations control their pumps by using high and low level tank controls.  When the tank water level reaches its low set point, the pumps initiate full speed operation to fill the holding tank until the water level reaches its maximum set point.  If there is enough water storage, the pumps may only operate for a few hours a day or intermittently throughout the day.  In this case, the best option may be a two speed pump.  The benefit of operating the pumps is found by working with pump suppliers to determine the make and model with best fit impellor size to find pump curves that maximize the efficiency of the two proposed flowrates with your system curve.  The idea is to operate at the best efficiency points (BEP) of the pump versus the best flowrate for your facility, which is possible if the required flowrates are predictable and there is enough storage room as a buffer.

A pump station that serves a receiving tank with a low amount of storage, or that has demands that range widely may benefit from a VSD-controlled pump.   With a small storage buffer, the pumps have to react quickly to meet demands or slow down to prevent overflow conditions.  The VSD would prevent excessive on/off cycling of the pump motor and decrease power demand (through the affinity fan laws) by automatically varying its flow to meet the requirements of the system.

VSDs on Air Compressors

A lot of the compressed air projects that we look at involve the replacement of a constant speed air compressor with a new comparable VSD unit.  But how do you know if your facility would benefit from a similar replacement project?

The Short Answer

Again, it depends on your compressed air demands.  If your existing air compressor is consistently loaded and your compressed air loads are fairly high and don’t vary much throughout the day/week, then you’re probably better off sticking with your constant speed unit.  If your existing air compressor is frequently switching between being loaded and unloaded, this could indicate that your compressed air loads have a lot of variation throughout the day/week, and switching to a VSD unit may be beneficial to you.  We usually put a data logger on the air compressor in question to see what it does when no one’s watching.

The Long Answer

VSD air compressors do save you energy—but only up to a certain point.  Below I’ve graphed the average electric demand for two air compressors: one 200 HP VSD compressor, and one 200 HP constant speed compressor.  They both have the same max flow rate (1,115 CFM), but the constant speed compressor must switch between operating at full load and then idling to meet any compressed air demands that are less than the maximum rated flow, whereas the VSD compressor is capable of easily modulating itself to meet lower compressed air demands.  As you can see, at very high loads, the VSD air compressor actually consumes a little bit more energy than the constant speed air compressor.  This is why if your compressed air loads are already near the peak flow capacity of the air compressor, you’re better off sticking with your constant speed unit.

Many facilities choose to have a constant speed air compressor as their base-loaded unit, with an additional VSD unit being used to meet their swing demand.  This arrangement capitalizes on the advantages that are offered by both the constant speed and VSD units and has the potential to save them a significant amount of energy.

vsd 7

Need Help?

Energy efficiency projects such as VSD installations are some of the easiest ways to reduce your facility’s overall energy consumption.  To date, ANTARES has performed over 100 energy audits for a wide range of commercial and industrial clients.  The results of our studies have helped clients to identify areas of their facility that could benefit from efficiency projects, and help them prioritize their project implementation.

PepsiCo Converts to Biomass Energy in Brazil Plant

A PepsiCo oat processing facility in Brazil has converted their natural gas and diesel-powered steam boilers over to biomass boilers that run on oat hull waste.  See their full press release here.


Prior to the switch, the facility was milling the oat hull waste and selling it for livestock feed.  Now they will use 1,440 tons of oat hull waste for the biomass boiler, and sell the remaining for feed.  The project will reduce the facility’s overall energy consumption by 41%.

Are you looking to install a biomass project?  Our feasibility studies provide all the information you need to confidently decide whether or not a biomass-fueled project is the best investment for your needs.  Contact us here!

Antares to speak at the 2015 CNYSHE Healthcare Conference

On June 1, 2015, Jim Olmsted from Antares will be a panelist on the Energy Sustainability Panel at the 2015 Healthcare Conference to be held at the Turning Stone Resort Casino in Verona, NY.  The panel discussion will discuss energy sustainability topics applicable to healthcare buildings including incentive opportunities for energy projects.  To attend the conference or for more information on the 1 day conference, please visit

Using Ice Storage to Offset Peak Demands

Last year Southern California Edison solicited a proposal for 2,221 MW of new energy generation systems and 264 MW energy storage systems.  The utility is looking for ways to offset the peak electric generation capacity that they’re going to be losing by retiring some of their older nuclear and gas-fired generation plants.

The winning energy storage bids included a mix of battery storage and ice storage systems.  Ice storage systems use chilled water to build up banks of ice at night when electricity prices and electric demand are low, and then discharge the ice during the day to reduce a facility’s peak electricity consumption.  The facility benefits from lower electricity and demand prices, and the utility benefits from lower peak electric demands during their busiest times, effectively offsetting the need to replace all of those generation plants that they’re retiring.

We’re in the middle of a study involving ice storage as a method of demand reduction, so this article seems especially timely.

Learning to Look Critically at Your Vendor Energy Savings

Whenever I talk to a vendor, I always learn something new because they truly are experts in their field.  With that being said, even though these guys are really good, you have to keep in mind that they don’t work for you, they aren’t your energy managers, and they aren’t the ones who answer to upper level management as to why a project isn’t performing adequately.  At the end of the day, only you can make the final call if a project is a good investment or not.

As part of their sales pitch, many vendors present a high-level energy savings estimate showing you just how much energy or money you could be saving by implementing their equipment.  It is important to keep in mind that these energy savings estimates are based on a series of assumptions that may or may not be totally inaccurate for your facility.  You’ll need to do a “sanity check” and then make the decision as to whether or not you can reasonably believe the provided estimates.

Things to Look For

The vendor analysis will usually outline a series of assumptions that were used to complete the calculations (and if they don’t outline their assumptions, you need to be extra careful!).  Check the following metrics to make sure that they line up with what you would expect for your facility:

  • Annual hours of operation – how long is your equipment really on?  How much product are you really using?  Check the assumptions against your historical data.
  • Equipment efficiencies – Check boiler efficiency (%) and cooling equipment efficiencies (kW/ton).  These can really vary depending on the age, type of equipment (ex: steam boiler vs. hot water boiler), and how often the equipment cycles on and off (more cycling = less energy efficient).  When in doubt, check out the ASHRAE rated efficiencies for your type of equipment and rated capacity for a good starting point, and then make adjustments as needed depending on your situation.  Want some more reading material?  I really like this write-up, which was done by a PE engineer out in California and talks about looking critically at boiler efficiency claims.
  • Utility rates – Your natural gas rates in $/therm and electricity rates in $/kWh.  Make sure you take into account your supply rates too, if you go through a third party provider.  And check out this article that Clair wrote on utility rates that may be just a little too optimistic for their own good.
  • Historical utility consumption – We frequently look at historical utility bills to make sure that the level of savings proposed makes sense.  Total up your annual consumption and compare it to the vendor energy savings.  Anything that’s really high is probably too good to be true.
  • Peak Loads – You may have three 100 ton chillers, but maybe only two of them operate at peak load.  The vendor won’t know this until you tell them.  Conversely, maybe you have separate winter and summer boilers.  When does each one operate throughout the year?

Real Life Examples

Facility #1 – This facility was installing a new tank-less hot water heater.  The vendor estimated that the facility was consuming 6,000,000 gallons of water each year, when in reality they were only consuming about 2,000,000 gallons (per their historical water bills).  This one assumption alone cut their energy cost savings down to 1/3 of the vendor’s initial estimate.  The vendor also estimated that the site was paying $1.00/therm of natural gas, when in reality the facility was paying close to $0.60/therm.  This cut their energy cost savings down even further.  The vendor estimated $30,000 in annual energy cost savings.  In reality, the energy cost savings were closer to $2,000.  Ouch…

Facility #2 – This manufacturing facility was upgrading their Building Automation System (BAS) that would automatically control their heating and ventilation units.  Initial vendor estimates projected that the facility would save a total of 80% of their existing natural gas consumption.  This magnitude of energy savings doesn’t seem realistic because the facility still needs to heat its large manufacturing area.  In reality, the projected energy savings are closer to 26% of the facility’s existing natural gas consumption.  Contributing factors to the over-estimation of the energy savings included over-estimating the facility’s annual run hours and under-estimating the new amount of outside air needed to keep the building pressurized.

However, not all of the projects that we evaluate are this far off.  Below is a bar chart summary of ten different vendor cost savings estimates versus the savings that were compiled by ANTARES for a random selection of past projects.  As you can see, some of the vendor estimates are close to, or even less than the energy cost savings that we evaluated for the project.  However, 2 of these 10 projects were disastrously different. It would be counterproductive to generalize from this sample, but in our experience, these are not isolated examples.

Vendor Savings Chart

What You Can Do

Make sure that your vendor has as much information as possible—utility rates, efficiencies, annual hours of operation etc.  The more information that you give them, the more accurate their calculations will be.  If you are spending lots of money on a new project – it may be a good idea to get a second opinion upfront, rather than pay for the forensic opinion after management asks you, “What went wrong?!”

New NREL Reports Discuss Best Options for Financing Solar Energy Projects

Looking to install a solar PV installation?  You’re probably facing the all-important question: “How am I going to finance my solar energy project?”  While you can certainly pay for the system upfront, not everyone has ample cash flow to fund a project right way, especially if it’s a larger-scale system.  In terms of paying for it over time, there are a variety of options available to you, including (but not limited to) a low-interest solar specific loan, and even leasing your solar PV system from a third party provider.

Two new reports that were funded by NREL look at the benefits, risks, and overall levelized cost of energy for the different options that are available for financing solar energy projects. One study evaluates solar specific loans versus PV system leasing for home scale applications through financial modeling while the second evaluates the business case for solar and various financing methods through a case study approach.  So whether you are a homeowner or a business,  take a look at the link and if you’re still having trouble deciding which option may be best for you, let us know—we have a lot of experience evaluating the economics of solar PV systems and helping clients make the best decisions moving forward.

Absorption Chillers – Answers to Common Questions

OK, so our first post on this topic — “How to Decide if an Absorption Chiller is Right for You” —was really popular. If you haven’t seen it yet, then you can check it out here. It looks like a lot of you are interested in seeing if absorption chillers will help you reduce your overall energy consumption. Congratulations on asking a very good question! Below is follow-up post that takes a closer look at some of the key things that people keep asking me about absorption chillers.
[Read more…]

Basics of Ground Source Heat Pump Technology (Part 2)

In last week’s post, I gave you some things to think about regarding ground source heat pump (GSHP) or geothermal heat pump (GHP) technology design. GSHP technology takes advantage of the fact that the ground temperature stays relatively consistent throughout the year, and uses electrically powered systems to transfer energy to and from the ground. During the winter GSHP systems use the ground as a heat source, and during the summer they use the ground as a heat sink.

In this post I’m covering some topics on economics and project implementation. GSHP technology can be quite the expense, but picking the right designers/contractors to be on your team can vastly simplify the process and help manage costs.
[Read more…]