Would an ETS (Electric Thermal Storage) System work for you?

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  • DanS26
    Solar Fanatic
    • Dec 2011
    • 972

    Would an ETS (Electric Thermal Storage) System work for you?

    In March 2015 I installed an ETS (Electric Thermal Storage) system in a upstairs workshop that was hard to heat. In order to heat the workshop meant the entire second story of my house had to be brought up to the temperature desired. It seemed a waste to me to heat four rooms when only one needed the heat.

    I tried many area space heaters....but whatever the tech they all were limited to 1500 watts input. Not only under powered, but slow to heat or noisy. Stand alone or wall mounted they did not get the job done.

    Finally I found the ETS product. It was developed for the utility industry to store excess electrical energy at night when rates are low and release that energy as heat in the daytime when rates are high. They sold the systems to users in cold climates that were on TOU plans. The systems use high density ceramic bricks to store heat energy.

    In my particular case, I produces excess solar PV energy in the daytime, which I sell to my POCO at wholesale rates since I am on a "net billing" system. If you are on a "net metering" system then you can probably ignore this thread since you receive retail for your excess production and an ETS will not make much sense. So I turned the premise of this product around with my excess solar PV energy in the daytime. I charge the system in the day and release heat in the early morning when heat is needed and where there is no or low sunlight. The heat is distributed exactly where it is needed. Yes, it is a glorified space heater, but I have found out it is much more. The device has not only exceeded my expectations but impressed my wife...which is very hard to do.

    The device will keep an area at exactly the temperature you want without the wild fluctuations of a normal space heater. It is intelligent.....if you want setback at night it will do that. It has a vacation switch.....which means you can shut down the system for absences or when you anticipate long sunless days without adjusting your temperature controls. Really nice feature. It only charges itself when you want it to. My system charges 10am to 1pm only.

    Look, I know electric heat is inefficient when compared to other forms of heat energy, but if you have a specific area that needs a specific heat solution in a cold weather climate it may be cost effective solution. My advice is to look at your cost per BTU for each proposed solution. Here in Indiana I can buy propane for $.89 per gallon.....that is cheap heat. Wood is even less expensive. Fuel oil is starting to make sense.

    So look at an ETS, it may make sense, especially if you have excess PV energy and the POCO is paying you wholesale for it. The number of solar PV producers looking to soak up excess production is growing.......here's an option.

  • DanKegel
    Banned
    • Sep 2014
    • 2093

    #2
    I always figured resistance heaters were a bad idea, even when coupled with an ETS. Is yours resistance, or heat-pump based?

    Comment

    • inetdog
      Super Moderator
      • May 2012
      • 9909

      #3
      Originally posted by DanKegel
      I always figured resistance heaters were a bad idea, even when coupled with an ETS. Is yours resistance, or heat-pump based?
      Resistance heating is a bad economic/thermodynamic idea unless the cost of the electricity used is very very low (i.e. wholesale price instead of net metering.)
      And if you are looking specifically at a thermal storage system, I do not think that a heat pump can output heat at a high enough temperature to make storage of that heat energy practical.
      Say whatever else you want about electric resistance heat, but it sure is capable of delivering high temperatures. Right up there with propane, natural gas and wood.
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

      Comment

      • DanS26
        Solar Fanatic
        • Dec 2011
        • 972

        #4
        Originally posted by DanKegel
        I always figured resistance heaters were a bad idea, even when coupled with an ETS. Is yours resistance, or heat-pump based?
        I have both.

        On my water heater I have a Nyle heat pump that stores heat energy in the water tank. It is on a timer so that it only operates when the sun shines and in warm weather. I call it my "Too good to be true project". Heats my water, cools my house, dehumidifies my basement, and uses only my excess PV electrical energy to operate.

        My ETS system uses resistance heat. Yes inefficient when compared to conventional energy sources. But I produce electrical energy at $0.03 per kWh...in that context it's not so expensive compared to competitive energy sources.

        i have for a long time, encouraged everyone to calculate their proposed or actual cost of production for PV electrical energy. How do you do that.....easy. Take your PV Watts estimated annual kWh production for your array...multiply by 25 years...then divide by your net investment in your system....that's your cost of production per kWh. When people say that they produce "free" energy with their PV system...they have no clue. Now convert kWh into cost per BTU. Then compare cost per BTU for any energy source.

        For example:

        $0.03 kWh = $8.82 mBTU
        $2.00 per gal gasoline = $17.54 mBTU
        $0.89 per gal propane = $10.56 mBTU
        $65.00 per 1 rick of hardwood = $5.20 mBTU (but is pretty messy and annoying to your neighbors)

        Ask any economist......low cost producer prevails in the long run.
        Last edited by DanS26; 02-16-2016, 09:51 PM.

        Comment

        • J.P.M.
          Solar Fanatic
          • Aug 2013
          • 14926

          #5
          Originally posted by DanS26

          I have both.

          On my water heater I have a Nyle heat pump that stores heat energy in the water tank. It is on a timer so that it only operates when the sun shines and in warm weather. I call it my "Too good to be true project". Heats my water, cools my house, dehumidifies my basement, and uses only my excess PV electrical energy to operate.

          My ETS system uses resistance heat. Yes inefficient when compared to conventional energy sources. But I produce electrical energy at $0.03 per kWh...in that context it's not so expensive compared to competitive energy sources.

          i have for a long time, encouraged everyone to calculate their proposed or actual cost of production for PV electrical energy. How do you do that.....easy. Take your PV Watts estimated annual kWh production for your array...multiply by 25 years...then divide by your net investment in your system....that's your cost of production per kWh. When people say that they produce "free" energy with their PV system...they have no clue. Now convert kWh into cost per BTU. Then compare cost per BTU for any energy source.

          For example:

          $0.03 kWh = $8.82 mBTU
          $2.00 per gal gasoline = $17.54 mBTU
          $0.89 per gal propane = $10.56 mBTU
          $65.00 per 1 rick of hardwood = $5.20 mBTU (but is pretty messy and annoying to your neighbors)

          Ask any economist......low cost producer prevails in the long run.
          Dan: On the economic analysis part, ask any economist about the time value of money, and then ask any economist where it enters into your calc., or were a comparison of alternatives comes in - as in, where else could you put your money and get a better rate of return or be further ahead economically after the 25 years. You usually do better in analysis. Just sayin'.

          Comment

          • DanKegel
            Banned
            • Sep 2014
            • 2093

            #6
            It's probably because I'm looking at how to increase wind + solar penetration past 75%.
            Heating the ETS at night with coal-fired electricity don't do much for that scenario.
            (And even heating it during the day with your own solar panels doesn't seem like a good use of electricity unless your panels are massively oversized, and you've already bought them?)

            Comment

            • J.P.M.
              Solar Fanatic
              • Aug 2013
              • 14926

              #7
              Originally posted by DanKegel
              It's probably because I'm looking at how to increase wind + solar penetration past 75%.
              Heating the ETS at night with coal-fired electricity don't do much for that scenario.
              (And even heating it during the day with your own solar panels doesn't seem like a good use of electricity unless your panels are massively oversized, and you've already bought them?)
              The older way of looking at the situation of supplying heat to a dwelling when considering thermal mass methods of time shifting a load is to increase the thermal mass of the dwelling while decreasing the heat loss from conduction/infiltration with the idea of increasing the thermal time constant of what is very approximately a lumped mass system and roughly f(thermal mass/overall heat loss rate). Until the time constant gets very large - the order of months to seasonal - the methods of costing the various ways of supplying energy to the storage and thus the dwelling are pretty much the same as conventional methods with electric resistance usually being the most expensive of the conventional methods. In the time shifting to save considerations, the costs, both initial and incremental of the added mass are then often considered separately against the savings realized by the expected differential POCO costs as f(time of use).

              Still, the easiest, most practical (where available), and least expensive way to heat a dwelling is to use other means and fuels to avoid using electricity, particularly electric resistance. For most, that usually means CH4. In such cases, thermal energy storage scenarios are rarely cost effective at this time.

              Even when cost effective or necessary in spite of cost, T.E.S. systems are a bitch to get right, both in terms of size and distribution methods, not to mention practicality and comfort for the occupants.

              Comment

              • DanKegel
                Banned
                • Sep 2014
                • 2093

                #8
                Originally posted by J.P.M.
                T.E.S. systems are a bitch to get right, both in terms of size and distribution methods, not to mention practicality and comfort for the occupants.
                I bet you're right in general.

                But there are small self-contained electric TES heaters that look like plain old electric heaters and are probably just as easy to put in; Centrail Maine Power even recommends them: http://www.cmpco.com/ETS/
                If you're going to install a small electric heater anyway, it might make sense.

                Also - mostly for bigger buildings - air conditioning systems using ice storage appear to be cost effective ( already discussed at https://www.solarpaneltalk.com/forum...-ice-for-later ).

                (And given the urgency of reducing co2 emissions, there's a fair bit of R&D going on in this area, see e.g. http://nvlpubs.nist.gov/nistpubs/Tec...ST.TN.1844.pdf
                So perhaps TES will become more practical in the future.)

                Comment

                • DanS26
                  Solar Fanatic
                  • Dec 2011
                  • 972

                  #9
                  I agree getting these systems setup right takes time and effort. I purposely waited until now, thru the coldest months to see if my ETS experiment was worthwhile. I can say from experience that yes this ETS system is a success in my application but it's not for everyone. I heat one room instead of four and I use energy I create at a low cost even if I didn't use a 3% cost of capital in the analysis.

                  As net billing becomes more commonplace, especially in the Midwest, I see a new market developing for these systems.

                  Comment

                  • J.P.M.
                    Solar Fanatic
                    • Aug 2013
                    • 14926

                    #10
                    Originally posted by DanKegel

                    I bet you're right in general.

                    But there are small self-contained electric TES heaters that look like plain old electric heaters and are probably just as easy to put in; Centrail Maine Power even recommends them: http://www.cmpco.com/ETS/
                    If you're going to install a small electric heater anyway, it might make sense.

                    Also - mostly for bigger buildings - air conditioning systems using ice storage appear to be cost effective ( already discussed at https://www.solarpaneltalk.com/forum...-ice-for-later ).

                    (And given the urgency of reducing co2 emissions, there's a fair bit of R&D going on in this area, see e.g. http://nvlpubs.nist.gov/nistpubs/Tec...ST.TN.1844.pdf
                    So perhaps TES will become more practical in the future.)
                    If the load shifting can somehow get in line/sinc with the POCO demand/T.O.U. requirements, for med./large systems, chilled water plants are usually more cost effective and just as easy, if not easier to maintain than ice/phase change methods, in addition to usually/always providing greater comfort and/or less required accommodation by building occupants.

                    I wish it were otherwise.

                    A better method is to look at the situation from a thermal time constant perspective, lowering the HVAC load, including particularly the ventilation/air exchange/makeup air rates and using integral building mass as much as possible. Additionally, storing thermal energy in relatively large quantities in fluids or phase change materials for building applications often and usually causes unforseen problems for the inexperienced.

                    They do however, make good copy for the treehuggers/dreamer rag circuit. Check back issues of something called Solar Age magazine.

                    Ice/phase change materials have their place, but are on the tails of the distribution as far as practicality and acceptance are concerned. They've been around a long time and are still somewhat of an oddity. If they worked well and were as cost effective as claimed, I'd think they'd have gone a bit more mainstream by now.

                    Comment

                    • DanKegel
                      Banned
                      • Sep 2014
                      • 2093

                      #11
                      Originally posted by J.P.M.
                      Ice/phase change materials have their place, but are on the tails of the distribution as far as practicality and acceptance are concerned. They've been around a long time and are still somewhat of an oddity. If they worked well and were as cost effective as claimed, I'd think they'd have gone a bit more mainstream by now.
                      All it takes is the right rate structure / incentives for adoption to tamp up. And it looks like that's starting, see eg the NYC incentives mentioned in the article I linked to, or discussion in "Teaching the Duck to Fly", http://www.raponline.org/document/download/id/7956 .

                      If it'll boost the possible renewable coverage significantly and save money to boot, you can bet your bippy it'll happen.

                      Comment

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