# Solving the flaws with wind and solar, i.e. energy storage systems. Why not hydrogen? **URL:** \ **Category:** Great Debates\ **Created:** [June 5, 2019, 3:24pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076 "2019-06-05T15:24:57Z")\ **Posts on this page:** 18\ **Page:** 3
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [June 6, 2019, 12:12pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/41 "2019-06-06T12:12:39Z")
> [@TriPolar](#): > > Hydroelectric power is pretty well established so there’s nothing that has to be done to start using it. However it may require some big ass reservoir that can have it’s own issues. It can’t be big enough to cause flooding from a breach, or get destroyed if it gets flooded. You can gain the drop with a hole in the ground though, geology isn’t very limiting in that regard. You’ll want it to operate with the least drop practical because it’s costing you energy the higher you pump it. I suggest you, at a minimum, read the Wikipedia article on this topic prior to commenting further. Least drop practical? :smack: ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 6, 2019, 12:17pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/42 "2019-06-06T12:17:00Z")
> [@Ruken](#): > > I suggest you, at a minimum, read the Wikipedia article on this topic prior to commenting further. Least drop practical? :smack: Maybe I’m off base here, I should brush up on this instead of relying on a poor memory. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 6, 2019, 12:35pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/43 "2019-06-06T12:35:13Z")
> [@Ruken](#): > > I suggest you, at a minimum, read the Wikipedia article on this topic prior to commenting further. Least drop practical? :smack: Well right off the bat the [Pumped-storage Hydroelectricity page](https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity) says: > [@](#): > > The relatively low energy density of pumped storage systems requires either large flows and/or large differences in height between reservoirs. So I misinterpreted something sometime in the past. There is a cost to pumping water to higher elevations but overall it must be outweighed by the greater efficiency of the difference in height. But I am surprised to see the efficiency is so great: > [@](#): > > Taking into account evaporation losses from the exposed water surface and conversion losses, energy recovery of 70-80% or more can be achieved. In addition it’s use is already greater than I expected: > [@](#): > > Pumped storage is the largest-capacity form of grid energy storage available, and, as of 2017, the United States Department of Energy Global Energy Storage Database reports that PSH accounts for over 95% of all active tracked storage installations worldwide, with a total installed nameplate capacity of over 184 GW, of which about 25 GW are in the United States. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 6, 2019, 2:32pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/44 "2019-06-06T14:32:04Z")
> [@XT](#): > > We have a lot larger natural gas storage facilities than 190 million liters. … That 129 MWh of energy from the Tesla plant is impressive…for a battery system. It’s nothing to a natural gas plant. … That’s exactly my point. To match even that small Tesla battery farm, you need to store 190 million liters of hydrogen. Because hydrogen has so little energy density - only 1/3 that of natural gas. And actually I did the math wrong there. At 3.3 WH/liter, you need 600 million liters, not 190 million. ---
**Author:** ![zimaane](https://avatars.discourse-cdn.com/v4/letter/z/a3d4f5/32.png) [@zimaane](https://boards.straightdope.com/u/zimaane)\ **Post date:** [June 6, 2019, 5:54pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/45 "2019-06-06T17:54:35Z")
Would it be practical to store excess energy as thermal energy? Say, during the day, the electricity could be used to heat up something inert (salt?) then at night the hot material could be used to boil water to drive a turbine? ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [June 6, 2019, 6:31pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/46 "2019-06-06T18:31:21Z")
> [@zimaane](#): > > Would it be practical to store excess energy as thermal energy? Say, during the day, the electricity could be used to heat up something inert (salt?) then at night the hot material could be used to boil water to drive a turbine? Absolutely. Many, many forms of this are being tried. Here are two I like. From Wiki: [Heat storage in hot rocks, concrete, pebbles etc](https://en.wikipedia.org/wiki/Thermal_energy_storage#Heat_storage_in_hot_rocks,_concrete,_pebbles_etc) > [@](#): > > This could, in principle, be used to store surplus wind or PV heat due to the ability of electrical heating to reach high temperatures. At the neighborhood level, the Wiggenhausen-Süd solar development at Friedrichshafen has received international attention. This features a 12,000 m3 (420,000 cu ft) reinforced concrete thermal store linked to 4,300 m² (46,000 sq ft) of solar collectors, which will supply the 570 houses with around 50% of their heating and hot water. Siemens builds a 36 MWh thermal storage near Hamburg with 600 °C basalt and 1.5 MW electric output.[23] A similar system is scheduled for Sorø, Denmark, with 41-58% of the stored 18 MWh heat returned for the town’s district heating, and 30-41% returned as electricity.[24] Many more methods described on that page. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [June 6, 2019, 7:30pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/47 "2019-06-06T19:30:10Z")
> [@Chronos](#): > > And a car using a gaseous fuel needs a high-pressure tank, because the volume of the tank needs to fit into the car. But a power plant built where land is cheap (which is where most of them are) could just use a really big tank, at more manageable pressures. Nor need the energy used to pressurize the gas be entirely wasted: … 1. Nuclear Energy is not Carbon free : [False solution: Nuclear power is not 'low carbon'](https://theecologist.org/2015/feb/05/false-solution-nuclear-power-not-low-carbon) “…,the Climate Change Committee believes, the true figure is probably well above 50 grams - breaching the CCC’s recommended limit for new sources of power generation beyond 2030.” 2. Hydrogen is the worst gas to compress : Whether you use an adiabatic process (reciprocating compressors) or a polytropic process (centrifugal compressor), much of the energy used for the compressor ends up heating the hydrogen than compressing it. This is from basic thermodynamics (gamma). Also Hydrogen compressors are hard to make and operate because Hydrogen is nature’s Houdini and escapes from everywhere. 3. Hydrogen is the worst gas for gas turbines or boilers : Hydrogen burns at a high temperature (so you need excess air) and the combustion products are low molecular weight. Since gas turbines convert momentum to energy, hydrogen gives the least efficiency in a gas turbine. Combustion of hydrogen almost always produces NOx since it burns at such high temperatures - so that in itself is a problem. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 6, 2019, 7:39pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/48 "2019-06-06T19:39:24Z")
Was that first point meant to be a reply to me? The post you quoted didn’t say anything about nuclear. And yeah, you’ll have losses in compressing and then releasing a gas. I said that the compression energy wouldn’t be _completely_ wasted, and that you could get back _some_ of that energy. **TriPolar** , I think you still don’t get it. The energy cost of pumping to greater heights is balanced out by… the energy cost of pumping to greater heights. ---
**Author:** ![Delayed\_Reflex](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/delayed_reflex/32/3172_2.png) [@Delayed\_Reflex](https://boards.straightdope.com/u/Delayed_Reflex)\ **Post date:** [June 6, 2019, 9:16pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/49 "2019-06-06T21:16:09Z")
> [@TriPolar](#): > > Hydroelectric power is pretty well established so there’s nothing that has to be done to start using it. However it may require some big ass reservoir that can have it’s own issues. It can’t be big enough to cause flooding from a breach, or get destroyed if it gets flooded. **You can gain the drop with a hole in the ground though, geology isn’t very limiting in that regard.** You’ll want it to operate with the least drop practical because it’s costing you energy the higher you pump it. And how exactly is water going to leave this hole in the ground? The rate of power that you can generate from this system depends on how quickly you can drain your reservoir. Having a system that drains at the rate that you need is absolutely a function of geology. You can’t just dig a hole and expect water to drain out of it fast enough to be able to generate any meaningful power from your system - it would have to connect to a lower elevation open area or reservoir. The reality is that hydro is really only realistically feasible when the geology enables formation of natural above-grade reservoirs - or if you want to frame it differently, the only thing holding you back from building pumped-hydro storage anywhere is cost. You could theoretically build an entirely above-grade dam structure in Kansas to do your hydro storage (assuming there is enough construction material available to build such a dam), but it would be astronomically expensive. There’s a reason that hydro facilities are generally built in river or mountain valleys. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [June 7, 2019, 2:51pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/50 "2019-06-07T14:51:34Z")
In undergraduate school, a guy who worked at North Little Rock Electric told me they used the water that collected behind the dam overnight to generate power for morning toast, coffee and shaving water. It was all gone by the end of the morning. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 7, 2019, 4:11pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/51 "2019-06-07T16:11:54Z")
XT, you absolutely have the right idea, though you are 1 step back from the full answer. First, the majority of the electric load/energy load (since most of the cars and trucks will be electric), you have to handle with either immediate renewable production or short-term batteries. That is, very large distributed wind grids are optimal when the batteries are expensive, when they are a bit cheaper then solar works. But you realize that you still need a substantial backup reserve for that 3% edge case where the solar + wind just isn’t cutting it, even with overcapacity and lots of batteries. It’s a “3%” case in that this form of backup power is a small fraction of the _energy_ you need but you do need a long term, stable storage of the energy. And the simplest answer to this is either you just keep using fossil fuels, or you electrolyze water to hydrogen…and reform it to methane. Why methane? It’s much more stable and energy dense than hydrogen, storing far more energy (orders of magnitude more) in the same volume. It also doesn’t leak out of tanks and connections nearly as readily. You then store the methane underground, in, ironically, depleted natural gas wells. You get the CO2 either by atmospheric carbon capture, or the easiest thing to do is to recycle the output of your power plant, like so : [Allam power cycle - Wikipedia](https://en.wikipedia.org/wiki/Allam_power_cycle) So you store CO2 in underground formations or large surface tanks. When renewable energy is plentiful, you electrolyze water, in large efficient plants, and combine it with the CO2, storing it up over months as methane. During those rare 3% cases when the weather is against you or grid interconnects have failed or many other causes, you burn the methane, keeping the CO2. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 7, 2019, 4:19pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/52 "2019-06-07T16:19:24Z")
Note: efficiency doesn’t really matter for this form of long-term energy storage. (short term would be efficient batteries). That’s because, since it’s handling an edge case that will be less than 10% of the time, it’s just fine if you need to produce 2-3 times the renewable energy that you get back after the storage. During a sunny day in California, there is excess energy on the grid during today’s buildouts, with the market price dropping to fractions of a cent. Note that while my idea above of using Allam cycle plants is technologically interesting, the actual backup solution for the 10% case will have to be whatever is actually cheapest. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 7, 2019, 5:05pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/53 "2019-06-07T17:05:48Z")
> [@zimaane](#): > > Would it be practical to store excess energy as thermal energy? Say, during the day, the electricity could be used to heat up something inert (salt?) then at night the hot material could be used to boil water to drive a turbine? Sure, but it’s best if we can store it as heat (or cold) and use it as heat/cold later, rather than converting it back to electricity (which is very inefficient). And there are already many systems that take advantage of off-peak electricity to heat water or make ice for later use. And it’s nothing new - 40 years ago my grandmother in Japan had a tank water heater that ran off night-time electricity. I know someone in Phoenix AZ whose condo building has an [ice storage air conditioning](https://en.wikipedia.org/wiki/Ice_storage_air_conditioning). I really think this is the ultimate solution to renewable energy storage. Don’t store it as electricity, but instead use energy when it’s available. Do you really care if your freezer goes down to -30F at night (when electricity is available/cheap) and drift up to 0F during the day? Do you care if your car starts charging immediately when you get home, or wait till 3am? (Assuming you can override it if you really do need it charged now.) Would’t you switch to a slightly larger capacity water heater if it saved you money (by refilling only when electricity is cheap)? Obviously we need a smart power grid with smart meters to incentivize people to make these changes. But that’s probably easier than building massive energy storage plants. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [June 7, 2019, 5:41pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/54 "2019-06-07T17:41:09Z")
If you want to work with hydrogen and store it for reserve energy, consider adding a bit of N. 3 parts H to one part N produces a substance that is far easier to handle than raw hydrogen, can be catalyzed fairly easily to extract the H (probably for fuel cells), offers a tad more than 3x the storage density and can be manufactured from renewable electricity sources. And, well, we have no shortage of N. Note that fuel cells produce a large amount of waste heat: during polar vortex type events, that waste heat could actually be useful. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 7, 2019, 7:45pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/55 "2019-06-07T19:45:43Z")
> [@eschereal](#): > > If you want to work with hydrogen and store it for reserve energy, consider adding a bit of N. 3 parts H to one part N produces a substance that is far easier to handle than raw hydrogen, can be catalyzed fairly easily to extract the H (probably for fuel cells), offers a tad more than 3x the storage density and can be manufactured from renewable electricity sources. And, well, we have no shortage of N. Absolutely. Anhydrous ammonia is also a deadly poison gas, so you need to produce it/store it/burn it in large facilities far from places where people live. But yes, I was thinking of methane because it’s safer and you can fuel vehicles, including rockets and airliners, with it. But for large storage of backup energy for electric power, NH3 might be a good choice. Note you have to store it at -33C for it to remain liquid - it expands 850 times in the gas phase, so that’s a negative. You’d have to store it in very large refrigerated tanks. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [June 7, 2019, 8:51pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/56 "2019-06-07T20:51:12Z")
> [@SamuelA](#): > > Note you have to store it at -33C for it to remain liquid - it expands 850 times in the gas phase, so that’s a negative. You’d have to store it in very large refrigerated tanks. Why are you storing it at standard pressure? Do you have it in big open vats? ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 7, 2019, 10:43pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/57 "2019-06-07T22:43:33Z")
> [@eschereal](#): > > Why are you storing it at standard pressure? Do you have it in big open vats? Shrug. Maybe pressure vessels are cheaper. They are for natural gas - lng is only used when the volume matters, such as for moving it by ship. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [June 10, 2019, 7:27pm UTC](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076/58 "2019-06-10T19:27:35Z")
A hydrogen filling station in Sandvika, just outside of Oslo, Norway, just had a massive explosion and is still on fire. It will be interesting to see what went wrong, if it should have been preventable and what it will do to the progress of hydrogen vehicles in Norway. The station was producing hydrogen by electrolysis with solar power from a nearby building and serviced a rather small number of fuel cell cars. [Previous page](https://boards.straightdope.com/t/solving-the-flaws-with-wind-and-solar-i-e-energy-storage-systems-why-not-hydrogen/835076.md?page=2)