Thermal Energy Stored for Month in New Material

Global emissions must be reduced by 60% before 2050 to avoid 2 degrees of global warming. However, energy consumption is doubling in the next 40 years due to an increasing world population and economic growth. The amount of solar power in winter drops by 90%. Solar energy could provide a larger share of global power if there was a way to store all of the worlds energy usage for months. The development of solar energy can potentially meet the growing requirements for a global energy system beyond fossil fuels, but necessitates new scalable technologies for solar energy storage. Thermal energy can be used for a broad range of applications such as domestic heating, industrial process heating and in thermal power processes. One promising way to store solar thermal energy is so-called molecular solar thermal (MOST) energy storage systems, where a photoswitchable molecule absorbs sunlight and undergoes a chemical isomerization to a metastable high energy species. Here we present an optimized MOST system (providing a high energy density of up to 0.4 MJ kg−1), which can store solar energy for a month at room temperature and release the thermochemical energy “on demand” in a closed energy storage cycle. In addition to a full photophysical characterization, solar energy capture of the present system is experimentally demonstrated by flowing the MOST system through an outdoor solar collector (≈900 cm2 irradiated area). Moreover, catalyst systems were identified and integrated into an energy extraction device leading to high temperature gradients of up to 63 °C (83 °C measured temperature) with a short temperature ramp time of only a few minutes. The underlying step-by-step mechanism of the catalytic reaction is modelled in detail using quantum chemistry calculations, successfully rationalizing the experimental observations. Energy Environmental Science – Macroscopic heat release in a molecular solar thermal energy storage system

66 thoughts on “Thermal Energy Stored for Month in New Material”

  1. “The amount of solar power in winter drops by 90%” Huh? What kind of BS is this? Depending on your climate, the average drop is about 5% – 15%. Panels are also more efficient in colder weather.

  2. It’s a good thing that global warming is all a hoax or we might be having extreme weather events like flooding.

  3. If the utility is getting power from the home owner then they should discount the connection fee since they are also benefiting. Some would say they are buying the power at retail price but that retail price is the average cost of power which might be less that the price they are paying at peak periods during the day.

  4. There is this problem: unlike the “Laffer Curve”… before failing spectacularly every time it has been tried

    no, it did not fail. Income tax revenue doubled under Reagan’s supply side tax cuts.

    Nor did Laffer EVER claim that supply side tax cuts would ‘pay for themselves’, either.

    The debt increased because Congress spent like a drunken sailor, like it is doing now. But Laffer Curve supply side economics was all about the revenue side of things and spending is completely a different animal.

    Furthermore, I have not heard of any of the Democratic candidates for 2020 urging adoption of MMT.

    Yes, many of them did. It is integral to the New Green Bullshit Deal of AOCs, and several Dem candidates signed on to it. The fact that they were completely ignorant of what they were signing on to doesn’t somehow change the fact that they did and now it sticks to them.

    Otherwise, I’d advise not getting you panties in a knot

    Uh…didn’t you mean to direct that comment to GoatGuy, not me?

  5. Forbes Magazine is a GOPe rag that is more and more clueless. In effect, a lot of what they print is totally Democrat BS.

    “President Obama’s debt actually grew at a slower annual rate than any of the Republican presidents even though there were events that negatively impacted the deficit that started before he became President.”

    Right. It just more than magically doubled all by itself then.

  6. This might work if I lived in the Arctic where there is minimal winter insolation. In that case, though, it’d probably still be cheaper to simply pump summer hot water through a earthen thermal store and reuse it in winter.

    So basically, this stuff has to be cheaper than dirt or water to gain any traction… If they can increase storage capacity 5-10x per L, then I think there is a chance, even at higher costs; especially for retrofitting existing homes. For new construction, geosource thermal and/or solar hot water storage + ground reserve seems like it would be cheaper; especially if hot air instead of water is used.

  7. Geez, the equivalent amount of water using solar thermal would store about the same amount of energy in hot water. Decently insulated that’s probably going to give you a similar real-world capability to balance heating loads, and I’ll bet you that it’s cheaper +and+ the panels are more efficient at gathering solar thermal energy.

    One caveat, I probably screwed up the BTU aggregate consumption, confusing HVAC capacity with ongoing energy consumption.

  8. Hmm, that might actually provide the baseline required. If this uses a ‘reservoir’ of heat, combined with a heat pump, it would actually be in competition with geosource thermal. The advantage being you just need a large tank without the need for expensive boreholes or digging up the yard. The disadvantage is that you need direct sunlight and panels somewhere.

    Also, if this uses sunlight, does it need to store a full season’s worth of heat? No!

    There’s plenty of solar insolation during the winter if you have a decently insulated house and room for panels. The challenge is simply storing enough heat for a cold spell or cloud spell. I think 30 days storage would be adequate.

    Just did the math. I think the latter option of providing balanced heat during winter, with panels sized appropriately, is the way to go. Why? Each liter if this stuff is only good for ~110Wh thermal! That’s a lot of stuff to maintain your heat reservoir. Here in the Northeast, oil is used for heating a lot, and a 250 gallon tank is pretty common. That’s 1000L, which is good for 110KWh, or 400k BTU. Assume ~35BTU/sq ft for a 2000sq ft home, and that’s enough for ~6 hours of heating! Add another outside tank, and you’re good for just one or two nights!

  9. I like the direct solar->chemical energy conversion over solar->electrical->chemical pathways. Just seems more elegant, and simpler.

    However, the fact that actual efficiencies were not noted makes me suspect actually efficiency is <1%, and more than just scaling is needed to make it work.

    I think direct-to-storage cells like this need a minimum of 10% efficiency, and that’s not taking into consideration the inherent losses downstream. OTOH, focusing only on thermal storage reduces the barriers, but cost becomes even more important. AS noted in the article, this needs to scale millions/billions of tons, and do so safely.

    This also seems like a technology that is inherently residential. With the low temperatures and large volumes required, it doesn’t make sense to try to use for grid-scale power plants, which need high-temperature, high-effiency thermal stores. If the medium is ‘pumpable’ (e.g., always a liquid, or suspended in liquid), it could be used in a neighborhood thermal micro-grid, similar to centralized steam/water heating.

    Looking at the diagrams, the temperature gradient suggested is pretty low. At 70F, assuming that’s the output of a passive heat exchanger, forced air will feel cold, and radiant heating just won’t work (except maybe in a Passivhaus?). Ideally it would, with a passive heat exchanger, produce 120-140F water or air, which would be amenable to forced air or radiant heating.

    Otherwise, the additional cost of a heat pump will need to be included.

  10. There is this problem: unlike the “Laffer Curve”, which was incorporated into Republican economic orthodoxy by Reagan, before failing spectacularly every time it has been tried, I don’t think MMT has much of a following within the left. Liberal economists such as Paul Krugman and Larry Summers, are less than impressed. Krugman comparing it to “Calvinball” and Summers referring to it as the “new voodoo economics” (the Laffer Curve mentioned above, of course, is the original voodoo economics).

    Furthermore, I have not heard of any of the Democratic candidates for 2020 urging adoption of MMT, which is why I had to look it up when you mentioned it, I hadn’t remembered reading about it. If you have references from reliable sources actually connecting MMT to political figures, I’d be interested to hear about it. Otherwise, I’d advise not getting you panties in a knot, even the worst economic theory is harmless until someone actually tries to act on it.

  11. Forbes Magazine (not usually considered partisan towards Democrats in general or Obama specifically), in effect, calls bullshit.

    “President Obama’s debt actually grew at a slower annual rate than any of the Republican presidents even though there were events that negatively impacted the deficit that started before he became President.”

  12. Dunno… there is (to me) an acceptable fairness of the Municipal Utilities’ desire to have their grid maintenance and management funded, independent of go-it-nearly-alone homeowners who invest in solar panels and want net metering. 

    In California, AKA “Taxistan”, our municipal utility districts are larger than counties, and smaller too. Odd hodge-lodge of dominions. 

    In any case, we definitely have a grid-use fee now; the PUC, ostensibly watching over the monopolistic nature of utilities and regulating them, rolled over and let the PG&E utility have its grid access fee structure; it is rolling out even more of this, without significantly discounting the actual per-kilowatt-hour-used fees. We’re already at 18¢/kWh average, and it is only going higher. 

    But again, I don’t find fault with the grid-access fee. It is a reasonable cost, since the thing is pervasive, extraordinarily reliable, and needs constant investment in ordinary maintenance, emergency repairs and partial system upgrades as population and power use patterns change. 

    We’re hoping our funded-but-not-yet-installed-due-to-bad-weather 7.5 kW system will have us running less than $25/mo average (PG&E side), once in place. The ongoing mortgage of it is $185/mo. Which is ⅔ of what our electric bill is. So… an improvement. And a long term one.

    Just saying,
    GoatGuy ✓

  13. I am not sure how long “grid connection” will be an option. As the number of customers with solar panels in increasing the utilities has started fighting against net metering or the utilities want a monthly connection charge.

  14. As for a global grid of thermal storage of solar energy… Duh. A global anything is doomed to fail given the humans on a global scale. We cannot behave ourselves, never have.

  15. Yes, but there is an inverse logarithmic ratio of CO2 emitted and temp increases. In other words, in order to double the temps it takes way more than just doubling the CO2 from the last round that raised the temps you are to double.

  16. Speaking of neat refrigeration…

    Using shape memory alloys in a thermal wheel as a raw mechanical cooling solution.

    Also running with the shape memory alloy temperature reaction thing, there’s a startup using shape memory alloy based actuators to drive a linear alternator, by washing waste heat hot water and cold water over the actuator coils.

    Apparently they have achieved a nitinol variant that can achieve 10 million cycles before fatigue failure (10x regular nitinol alloys) for their actuator coils, which makes the linear alternator driver viable.

  17. I must have read something wrong in the morning. I had thought the groundwater sweetening was treating the water in the ground in-situ. Which naturally elicits the reaction, why does the water in the the ground need to be sweetened?

    I completely forgot that well water filtering and treatment after pumping it up was a thing.

  18. MMT is basically an academic cloak to give politicians cover to engage in Zimbabwe/Venezuelan-style hyperinflation policies.

    Consider just this ONE aspect of MMT: Under MMT, the monetary authorities just print the money but don’t control the supply, while the political authorities control the supply by raising taxes, the revenues of which go to the monetary authorities to withdraw from circulation.

    Ok, re-read that last part.

    So basically, these MMT academic morons believe that Congress will a) raise taxes because of some theory and b) take the political heat of raising said taxes and c) do all this but not get any revenue to spend from it?

    Yes, yes they get to spend the magically printed money by the Fed instead…but the political risk they face from being the guys and gals ‘taking away the punchbowl’ is still very real AND in order for all this to work, they HAVE to raise taxes at a certain time and for a certain amount — no political discretion on Congress’ part can change that. So if they miss just one of those times and/or it does not raise the right amounts, INFLATION WILL HIT.


  19. Obama had this thing called a huge recession to deal with

    So? Doesn’t change the fact that the debt doubled and you are full of it if you claim his published deficits didn’t do that.

    And he dealt with the recession POORLY. We didn’t even really recover until Trump got into office, took a weedwhacker to all Obama’s economy-killing EOs and boom! Ain’t that thing called ’empirical evidence’ just a royal b–ch, eh?

    Can you explain why the debt was caused by Obama, who only raised spending by 13%?

    Because most of his spending in his first two years were off the books. And Bush didn’t double the debt. AND Obama and the Dems could have easily cut all that Bush increases but didn’t. When you get called out on that, you scream ‘recession!’ yet still harp on Bush.

    You must be the ONLY Derangement Syndrome sufferer on here who is doing so because of Bush instead of Trump these days, btw. Time to ‘Move On’, don’t you think?

  20. When the screaming is about a half-degree, I point out that humans have spread across the planet from above the Arctic Circle to the equator, and tend to thrive better where it’s warmer.

    And that plants need CO2 to thrive.

    And that animals are mobile, and will not simply go “OMG, too hot, I die” but will move until they’re comfortable.

    And that the ‘normal’ daytime temperature swing can go from 10 to 40 degrees F, without mass extinctions or die-offs.

    You’d THINK that normal people might look at the possibility there is NOT going to be a climate catastrophe and go “Well, let’s weigh the evidence for and against and see which holds up.”

    But the AGW believers start acting like religious fanatics who are told that their beliefs may not be true. They start screaming “HERESY!” and do their best to burn the Deniers…

  21. Nice. I did the numbers a somewhat different way, but produced similar results … at least in the same order-of-magnitude:

    1000 W/m² — Noon insolation, equator
    35° — latitude
    +11° — mean seasonal inclination
    20% — cell-in-panel efficiency
    95% — panel fill
    92% — dusts, glass surface reflections, etc.
    70% — clear sky days/year (desert, Nevada)
    6.5 hr/day — full-sun equivalent, over year

    This gins up to 0.55 kWh/day per m² of dirt, with reasonably-optimally tilted panels. So…

    4 PWh → 4,000 TWh → 4,000,000 GWh → 4,000,000,000 MWh → 4×10¹² kWh
    ÷ 365 days a year
    ÷ 0.55 kWh/day⋅m² (dirt)
    = 19.8×10⁹ m² → 1,980,000 hectares → 4,900,000 acres → 7,660 mi² → 88 miles/side

    See? similar. 
    Nevada here we come.

    I’m pretty sure however that the EPA would frown.  

    And the greenies would want 3× more land used for glass-plastic corner reflectors to reflect sunlight back out at much higher albedo than the desert surface. To counteract all those black panels. You know, global warming.

    Just saying,
    GoatGuy ✓

  22. Those numbers are a factual indictment of the whole German solar-energy rollout dalliance. For whatever reason(s), culturally the Germans seem predisposed to not just “go All In”, but to do so in the face of All-In’s farce. I need not remind of their WW2 “issues”. However, the same attitude makes them the № 1 producer of fine tools, machines, robotics, tool-made products. All-In perfectionism has its rewards. Even if tilting-at-windmills is also an unfortunate but predictable outcome. 

    Just saying,
    GoatGuy ✓

  23. Mmmm… cloud-cover is never included in the “solar radiation” (i.e. inSOLation) figures, esteemed friend. Hence why the real power generation in Germany (“African” quote, herein) has a 10.7 : 1 difference ‘atwixt January and June.

    They’re real. 
    Solar peeps HATE clouds.
    If you get them talking, at bars. 

    Just saying,
    GoatGuy ✓

  24. Ah, yes. 
    Ohmic water heating. 
    Maintenance free? 

    The claim is rather bogus in the end: to heat water by ohmic heating, electricity needs to pass thru it. To do that, without increasing tap water’s conductivity (adding ions), a LARGE amount of metal plate area needs to be in contact with the bulk of the water. And in the end, it takes a LOT of electrical power.

    from their website:

    Voltage — 208–240 V
    Frequency — ⁵⁰⁄₆₀ Hz
    Power: — 6.2–24 kW
    Working Pressure — 30–80 psi / 2.06–5.52 bar / 206–552 kPa
    Conductivity — 80–2000 µS
    Current — User selectable 30–100 A

    So… 24,000 watts (240 volts, 100 amps) to heat 2 gallons per minute (a trickle, if showering) by +45° C. At our California rate of electricity (over 18¢/kWh) that is 7¢ per minute. Not overly expensive. But what about “the whole picture”? You know, warm water for laundry, for dishwasher, for showering, for hand-washing dishes, for the bathrooms’ washbasins? A lot of warm water needed. I know, I pay our utility bills.  

    It is not a miracle machine, what you referenced. 

    Their marketing spoof-of-metal-element-heating is factually irrelevant: the ohmic water heating concept does NOT in fact improve on the heating efficiency of conventional electric element heaters at all. They too are over 99% efficient, having NO OTHER OUTLET for the heat they generate than the water intended to be heated. LOL.

    Just saying,
    GoatGuy ✓

  25. MMT = Modern Monetary Theory? … or …
    MMT = Methadone Maintenance Treatment (kind of applies?)
    MMT = Magical Mystery Tour (really applies!)

    Probably none of the above.
    What say you?

  26. For our readers, COTS = Commercial, Off-The-Shelf.

    Well, where I am fixin’ to retire, the natural-gas supply is limited to only the newest suburban gated communities, not “the sticks” surrounding them. The “sticks” tho’ has the advantage of 100 acre sections at less than $1,500 an acre. And wild hogs, hills, deer, endless hardwood trees, outstanding grazing opportunities for our goats. (Yep, behind the Handle are real space-alien eyed capricious billies.)  

    I’ve been doing my homework, and it looks like the self-built kit log cabin, 2000 ft² is about right.

    The 500 gallon hot-water reservoir might as well have potable water, so having the whole house on reverse-osmosis water harms nothing, and decreases long term maintenance. No endless battles with hard-water soap scum, pot-and-pan scale, faucet fixture seal failure, toilet flapper breakdown. And the excess power from the solar panels, if not charging the e-car, can go into pumping groundwater into the RO system.  

    The use of “instant on-demand hot water” heating is also a good idea to take fairly tepid winter stored water and bring it up to 60° C as needed. Plenty of those run fine on propane. If they “only” get 30° C water in (compared to 5° C ground water), well, it takes less fuel to deliver the hot water stream.

    Just saying,
    GoatGuy ✓

  27. Having been around for some time, and having heard doomsday prophets proclaiming “the end is nigh” over quite a number of issues, and none of them ever came to be real, one tends to get a bit blase’. So while I personally think the places I have lived in are getting warmer, I am sure, that on 01. 01. 2051 none of them will turn into a fiery hellhole. People will still live and thrive there.
    But about this new material, it sounds promising, but it would be nice if we knew a bit more about it.

  28. Unsupported proclamations of “leading environmental groups and scientists” are irrelevant. Unsupported assertions are irrelevant.

    Most people have a tendency to view their own beliefs as reality.
    Belief is NOT evidence.

  29. I think those factors are already included in the numbers NewtonPulsifier has quoted.

    Another source is weather. If your local area is sunny in summer and thick clouds in winter that isn’t going to help.

  30. How COTS are dual fuel furnace/water heaters that can take propane or natural gas? Or were you expecting to be rural enough that you can’t expect town gas connections?

    Also, the ground water sweetening thing, what are trying to achieve there, systems wise?

  31. For the thermal ranges involved, you are looking at home water heating/HVAC applications, which is an interesting class of thermal storage, since most people are looking at bigger systems in support of electrical generation (neighborhood/grid level storage). The reasonable temps means the system engineering details are in theory easier, but the materials cost of the thermal medium itself will probably be the greatest driver of cost, followed by the nature of the heat source and the integration costs from that.

    If you are putting in cooled solar panels (flat panels with cooling loops would be cheap-ish, especially if the panel is using flat concentrating optics? Maybe one of those split rigs where you have a IR mirror plate in front of a CSP PV panel on a parabolic heliostat feeding a fixed IR target receiver via fiber?)

    Now, turning low level heat into electricity is pain, but recent work on thermoacoustic systems with bidirectional turbines looks promising, and appear to provide a cold sink so might allow hot/cold thermal storage. This company in the Netherlands, under EU research grants, has made progress (including finding that linear free piston backed thermoacoustic power generators have scaling issues due to frequency, thus the switch to and evaluation of rectifying bidirectional turbines).

  32. I think the evidence in this case is

    • In the 1970s leading environmental groups and scientists proclaimed that unless emissions were slashed by 1980 the world would suffer global environmental collapse. Emissions were not slashed, no collapse occurred.
    • In the 1980s leading environmental groups and scientists proclaimed that unless emissions were slashed by 1990 the world would suffer global environmental collapse. Emissions were not slashed, no collapse occurred.
    • In the 1990s leading environmental groups and scientists proclaimed that unless emissions were slashed by 2000 the world would suffer global environmental collapse. Emissions were not slashed, no collapse occurred.
    • In the 2000s leading environmental groups and scientists proclaimed that unless emissions were slashed by 2010 the world would suffer global environmental collapse. Emissions were not slashed, no collapse occurred.
    • In the 2010s leading environmental groups and scientists proclaimed that unless emissions were slashed by 2020 the world would suffer global environmental collapse. What will happen? How can we know? How can we possibly ignore leading environmental groups and scientists?
  33. Deficits don’t matter! Not when you have MMT!

    Deficits are about tax cuts too, or maybe you forgot.

    No. Deficits is about spending. Always has been.

    Spending increased 13% under Obama.

    Spending didn’t increase just 13% under Obama. That is flat out mathematically impossible as the debt DOUBLED under him. How did it do that? Magic?

    Your Prez just asked for $4.75 Trillion

    And your Democrat pals in the House are giving it to him, too.

    Read the Constitution. Presidents can propose a budget. But it is only Congress that has the power of the purse to enact it.

  34. What does deficits have to do with MMT? Answer: Nothing

    And what does criticism about conservatives and deficits have any validity whatsoever when the Democrat controlled House just approved the biggest budget ever, more or less?

  35. And that’s why I always have people check my math. the fact that it was my first cup of coffee had nothing to do with the errant decimal point. Many thanks for responding.

  36. “Global emissions must be reduced by 60% before 2050 to avoid 2 degrees of global warming. ”

    Clear red flag that this is probably a scam.

  37. Couldn’t fit it in the 1,500 characters, but the “hi-eff refrigerator” is a tinker-engineering hack: in summer, if cool ground water is providing interior air conditioning, then the same water loop should cool the refrigerator radiator coils. Likewise, in winter, the radiator coils should be cooled by bitter Winter air. Because it really makes refrigerators efficient. One good friend cut his refrigerator power (yearly) over 75% this way.

  38. Yes. Tho’ you and I would engineer different systems, for sure. 

    • Solar panel, BACKED by thermal water loop
    • Large well-insulate thermal tank (200 to 500 gallon)
    • Grid connection “virtual battery” with bidirectional power flow
    • Micro-geothermal summer cooling sink
    • Reverse osmosis groundwater sweetening
    • Dual aerobic and anaerobic septic leach field sewerage treatment
    • Double-thick wall insulation, including styrofoam outer-facing panels
    • Triple-thick ceiling insulation, etc.
    • Insulation-bulked up cellar ‘bucket type’ deep freezer.
    • 1 e-car, 1 p-truck (light duty), 1 10 foot trailer or mini-camper. 
    • LED lighting everywhere. Hi-eff. refrigerator. (see below)
    • Laptop-or-lighter-demand computing, no big can computers
    • OLED TVs and monitors. Running “black background”, not white. 
    • Propane backup for hot-water, central heating. 500 gallon tank.
    • Root cellar redundant sump pumps, dehumidifier, arms vault, ammo lockers

    That’d be my near-optimal country close-to-city habitation. 
    The propane doubles as fuel for a Honda generator in a pinch.  

    “Nearly off grid”, yet benefitting from grid-as-a-battery-and-backup-power-source for 99.5% of one’s needs. Right balance. Yet self-sufficient. Contrary to what one might imagine, the arms vault is mostly hunting pieces. Self defense if needed, but really mostly hunting. 
    ✓ ✓ ✓

  39. Perhaps they’re adding in a ‘shorter days in winter’ factor, and ‘sun’s a LOT lower in the sky’.

  40. A marvelous example of what sounds great in a lab doesn’t scale out to real-world usability…

  41. Solar radiation at Minneapolis MN is 6.22 in June vs 2.32 in December in kWh / m2 / day. 37.3%

    I’m not sure where “The amount of solar power in winter drops by 90%” comes from. That isn’t true in most places people live.

    Cherry picking a latitude where almost nobody lives – 5.78 vs. 0.86 for northern Quebec. 14.9%

  42. Depends entirely on the COST of the stuff. And its longevity. And its support system reliability. And the actual heat-in-heat-out thermodynamic efficiency (i.e. what happens as its entrained heat gradually decays? Is it exponential? 1/t hyperbolic? A “half-life” kind of curve?)

    For instance, the article claims “energy is stored for a month”. 

    I, wearing my marketing hat, would make such a claim were the material to hold even 10% of its heat-of-isomerization potential at the end of a month. It stores. For a month. Eat more bacon. 

    I, wearing an engineer’s mitre, would say that the same claim is ridiculous. 10% of the stored heat is nearly useless. However, if it follows a half-life type energy-loss curve (which wouldn’t surprise me in the least), then …

    10% raised to (¹⁄₃₀) = 93% retention, in a day.

    See? much more useful.  
    Nearly 70% in 5 days.  
    Still useful. 

    The point is that the stuff feels like a short-term photo-energy thermal storage system. That may in turn actually have a fairly good utility over much shorter time scales than a month. The question then gets back to the one at the top of this comment. 

    What does a 20 kW (25 m²) peaker system cost to install? ALL IN.
    And how long is it either maintenance-free, or what expected mean yearly maintenance cost?
    What is the system lifetime?
    And the cost of BTUs from either your natural gas, fuel oil or anthracite (LOL) provider?

    Then numerical comparison can be done. 
    ✓ ✓ ✓

  43. You know… your comment has had me thinking all morning. About “heating degree days”.

    The factor 404 BTU/HDD is the empirical side… which is not in and of itself necessarily related to your own factor in anything but a “proportionate scale” sort of way. The R-value of your house’s insulation, the amount of inSOLation it receives, the kinds of trees shading it, whether it is in an open windy location or more secluded, and of course the big one, just exactly what is the roof area, and exterior wall area of the thing must need come into the calculation. 

    But, be that as it is, it isn’t a useless number. Again, its purpose is for proportionality. 

    If you have 6,000 HDDs as your rating, and having an average house, with average-for-the-region R-value insulation and an average insulated roof, and so on, if 400 BTU/HDD is your factor, the your calcs are right. Except you “slipped a zero in”.

    404 × 7579
    = 3,062,000 BTU × 1056 J/BTU
    = 3,233,000,000 J ÷ 1,000,000
    = 3,233 MJ ÷ 0.4 MJ/kg
    = 8,000 kg

    not 80 metric tons. 
    Oh well.

    Problem is, you really would rather have the storage underground, I believe. I do wonder how much it costs per kilogram of the magic unicorn heat-storing stuff. And all the equipment needed to flow it, to catalyze its heat release, and all that. 

    The ship was sunk for want of a screw.

    ✓ ✓ ✓

  44. The environmentalists won’t even permit the current planned solar power plants.

    Also, the unions are extorting the solar power companies into making their plants closed shop which will drive up the cost of solar, which is already high to begin with.

    You’re being lucky to get 15 miles on the side let alone 150 miles.

  45. “Global emissions must be reduced by 60% before 2050 to avoid 2 degrees of global warming.”

    These type of proclamations remind me of Al Gore, who incidentally has a track record of being correct 0%.

  46. It is silly to think solar energy car replace fossil fuels for any developed country’s energy needs. A household, yes, as long as that household is willing to do without or be linked to the grid. Concentrate on the footprint needed for solar to replace fossil fuels, it becomes quite clear it’s a boondoggle.

  47. They are a lot of different technologies. What is needed is cost optimization. I think a system that has the following would be a good start: Solar panel, battery storage, heat pump, tankless water heater.

    Based on price and climate you could add a phase change heat storage unit.

  48. They don’t say how long it takes the solar collector to transfer the energy to the MOST system. Doing a basic sanity check of how big does it need to be to heat my home for a winter (I’ll assume that they can find means to store the energy for up to six months before going into production). There were 7579 Heating Degree Days in Minneapolis last year * 404 BTU/Degree day * 1055.56 J/BTU = 3,232 MJ just to heat my house last winter. At 0.4 megajoule per kilogram (about the energy density of a Li-ion battery); that means I need 80,800 kg (about 90 tons) of the MOST system to store the heat for my house for one season.
    If someone smarter than me wants to check my math, feel free. But 90 tons of material per household probably doesn’t scale – just on the question of where do we put these systems? They’re a bit heavy for roof top installations (even without my current snow load).

  49. Would be nice if adapted to a fossil-fueled centralized heating grid; could drastically reduce transport losses if that chemical is pumped around the town instead of steam / hot water. One caveat being that households need to change current radiators, I suppose.

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