HPAC Magazine

Increasing The Appeal

More options are emerging for pairing hydronics and renewables.

September 2, 2013   By Mark Evans

The saying “What’s old is new again” is certainly valid when it comes to hydronics. That is because we have adapted old technology, improved it and found new applications for it. The efficiency of these evolved systems has improved. In fact our focus has been on efficiency, the buzzword in our industry. “Hydronic systems offer up to 30 per cent better efficiency than air systems.” Does this sound familiar? How has that increased efficiency manifested itself? 

Combustion efficiency was the focus when I entered the industry and since then we have progressed from single-pass atmospherically vented boilers being the norm to them now being the exception. Consumer demand and government regulation have both driven change here and compelled manufacturers to improve to the point where condensing boilers are reliable products that deliver good value. However, I also believe that we have reached the point of diminishing return. This is the concept that states “Once a commodity reaches a yield rate that after a certain point fails to increase proportionately to additional outlays, such as outlays of capital or investments of time and labour, it has reached its point of diminishing return.”

Why would a manufacturer invest millions of dollars to develop boiler technology that could increase combustion efficiency by one or two per cent and just as importantly, would anyone want to pay the price for this technology?

We later recognized the need to improve piping, control and overall distribution system efficiencies. We stopped piping wild loops in baseboard systems, near boiler piping methods evolved and we improved mixing methods. But we may be near the end of this cycle of improvements. The latest innovation, the introduction of ECM motor pumps, controlling Delta P, Delta T, and being able to achieve variable flow/pressure outputs as a result, are now common ways to reduce electrical consumption. 

Change in Focus

It is great that we have improved the combustion efficiency and distribution efficiency of systems, but has our focus been too narrow? As an example, the installation of solar thermal for domestic hot water pre-heat requires the integration of storage of off-peak period production for peak period use. How do we move beyond the paradigm of specific applications to more fully embrace renewable energy?

One answer lies in a concept I will call Intergration. The barriers to fully realizing the potential of renewable energy exist both at the point of production, as well as at the point of consumption. Much of this can be attributed to the fact that problems and solutions exist in exclusion of one another at the level of the producer and the consumer. Intergration brings together point-of-use and point of production issues such as: energy storage; peak use demand; threshold, stepped or tiered energy pricing models; and relative costs of various heating fuels per Therm. The solution lies in integrating the point of use and the point of production. Hydronics, and specifically low temperature radiant, presents a platform, which easily Intergrate the benefits of renewable energy sources.

Starting with energy storage, let’s look at some recent developments that offer potential solutions.

Electrolyzer devices — Two University of Calgary researchers have discovered a way to make affordable and efficient catalysts (called electrocatalysts) for converting electricity into chemical energy. Having cheap and efficient electrocatalysts would enable homeowners and energy companies to store and reuse, whenever needed, intermittently generated electricity such as solar and wind power. The research has been published in http://www.sciencemag.org/ and the researchers have formed a spin-off company, FireWater Fuel Corp., to commercialize the electrocatalysts for use in electrolyzers. The company expects to have a commercial product in the current large-scale electrolyzer market in 2014, and a prototype electrolyzer, using the new catalysts, ready by 2015 for testing in a home.

Electrolyzer devices use catalysts to drive a chemical reaction that converts electricity into chemical energy by splitting water into hydrogen and oxygen fuels. These fuels can then be stored and re-converted to electricity for use when it is needed. The only byproduct from the energy system is water, which can be recycled through the system. To store and provide renewable power to a typical house would require an electrolyzer about the size of a beer fridge, containing a few litres of water and converting hydrogen to electricity with virtually no emissions, the researchers say. 

According to UToday, the key to their discovery is that they deviated from conventional thinking about catalysts, which typically are made from rare, expensive and toxic metals in a crystalline structure. Instead, the researchers relied on simpler production methods using abundant metal compounds or oxides to create mixed metal oxide catalysts.

Solar cooling — In regard to peak use demand, air conditioning is responsible for six per cent of total energy consumption in the U.S., according to the U.S. Energy Information Administration’s (EIA) most recent Residential Energy Consumption Survey (RECS). It is coincidental that peak use hours for air conditioning correspond to the higher levels in the Stepped or Tiered energy pricing models of electric utilities. The Energy Resource Center in Downey, CA, is operated by Southern California Gas and serves as a showcase for new solar cooling technologies. According to the project brief: In early 2008, Southern California Gas Company (SoCalGas) launched a showcase pilot demonstration project for a solar thermal hot water system that could provide chilled water, hot water and electricity for SoCalGas Energy Resource Center (ERC) in Downey, CA. The system uses water heated by the sun to provide the energy needed. It can simultaneously provide chilled water for space cooling from a hot water-activated absorption chiller and hot water for either domestic use or space heating. It consists of two types of concentrated solar collectors that produce hot water. One is a parabolic trough and the other uses Fresnel lenses and incorporates concentrated photovoltaics to produce electricity in a cogeneration configuration. Both collector types track the sun on a single axis automatically. The electricity produced is delivered directly to the electrical distribution system of the building while the hot water produced is stored in a hot water storage tank. The storage tank is connected to a high-efficiency back-up hot water heater so that the system can be operated in the absence of sunlight. The storage tank also serves as a distribution point for the hot water to be used for DHW, space heating and/or cooling. When in cooling mode, hot water is pumped to an absorption chiller that generates 10 tons of chilled water as a base load for the building’s air conditioning system. 

Night sky radiant cooling — The Carnegie Institution for ScienceCenter for Global Ecology building is an example of a project that utilizes night sky radiant cooling. According to the project profile, “During summer nights, water sprayed over the roof loses heat to the cold night sky. The cooled water is collected and stored in an insulated 12,000-gallon tank and pumped through the building during the day. This system supplies chilled water at 55-60 degrees F for an energy cost of 0.04 kW/ton and a water usage one half of that of conventional water cooled systems.” The Western Cooling Efficiency Center at UC Davis has also done research on this technology as part of their study of thermal storage options. 

Fuel cells — At the June 2013 Hydrogen + Fuel Cells 2013 International Conference and Exhibition in Vancouver, BC, it was announced that  “As part of its beneficiation strategy and the drive to improve on the uses of platinum, the S
outh African Government, through its funding institutions, will partner with Ballard Power Systems and Anglo American Platinum with initial field trials of a new methanol-fuelled ‘home generator’ prototype product designed for use in off-grid residential applications. The product encompasses a complete fuel cell system, including fuel cell stack, methanol fuel processor and other components needed to meet the market requirements of rural electrification within a local mini-grid.” Panasonic continues as a market leader in Japan, recently having released a second generation of residential fuel cell products. According to the company, “The “Ene-Farm” fuel cell co-generation systems generate electricity through a chemical reaction between oxygen in the atmosphere and hydrogen extracted from city gas. The heat generated as a byproduct of this process is also used for hot water supply. This system is extremely eco-friendly. Since the electricity is generated and used at the same place, there are no losses in transmission. Also, all heat produced during electricity generation can be used without waste. Compared to conventional method of using electricity from thermal power plant and hot water supply using city gas, the fuel cell system allows primary energy consumption to be reduced by approximately 37% and CO2 emissions by approximately 49%.” 

The relative cost of energy as measured by cost per therm has long influenced system choices for heating and cooling. An interesting tool is available on the Penn State web site*, which allows you to compare what your own local costs would be based on the fuel options and costs in your market. I compared the cost of electricity versus natural gas for a consumer in BC and the result is shown in Figure 1.

Hence, it is understandable that most homes are heated by natural gas, but why are most cooled with electric heat pumps or air conditioning systems? According to gasairconditioning.org “Natural gas cooling helps reduce demand charges, frees consumers from higher summertime electric rates for cooling, and improves the reliability of the electric grid.”

As an industry we seem to have these fuel biases that are based on what our primary need is. If we look at the totality of the system would we make different choices? If our systems are designed to anticipate the problems of energy storage, peak use demand leveling, tiered energy pricing, and economy based on fuel costs could we apply the expertise that we have developed in our pursuit of the old efficiencies (combustion and distribution) to the integration of renewables and offer a new type of “system” efficiency? Food for thought and proof that “what is old is new again.” 

During the course of his career in the mechanical industry Mark Evans has worked in the wholesaler and manufacturer sectors in sales and marketing positions. Contact him at mark@markevans.net.

*http://extension.psu.edu/natural-resources/energy/energy-use/making-decisions/comparison-charts

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