the limited life span and high cost of battery technology points to other possibilities for storage. A house has far less constraints on size, capacity, and weight then a vehicle so other storage methods are more possible. For lighting and electronics, capacitors are a possible electric storage with a very long lifespan (really just the average fail rate rather then an actual lifespan). I will be experimenting with pneumatic motors for powering fans and pumps and utilizing thermal storage for thermal-based loads (cooking heating refrigeration). This can be as simple as adding glycol packs to a normal refrigerator and powering the refrigerator by a timer set for solar peak. (more complex solutions will involve solar thermal panels and thermal storage). These solutions do not require a change in the user habits but do require less-conventional equipment. Other then costs of research and development and lack of warranty and possible building code restrictions, these methods can provide a great ROI when their long (often indefinitely long) life span is factored in.
@ christina-nelson-45845 and Joel_Fairstein The PV people totally ignore the solar thermal industry. The addition of thermal storage to a solar thermal collection system is very low cost and provides all the 'solar load control' you will need... the solar peak can also be matched with the load peak too and eliminate a lot of the need for make-up energy that fuel and hydro dams provide allowing solar to contribute close to 90% of the electricity needs of a grid (10% being extreme rapid use fluctuations - flywheel storage would be good to fix that). This does not address the fluctuations of PV and Wind inputs though but adds extra economics to go with solar thermal over PV for large scale operations. Note that Spain has been leading the way with this form of storage for years and now most new solar thermal collection systems include some thermal storage. Regarding the "mag-lev weight system", most rocks are similar to aluminum in density but iron is much higher (about 2.5 times the densest common rocks as in 7.87 compared to 3.1 g/m^3). I had the idea of lifting the house with hydraulic rams for weight-elevation storage.
an idea I came up with but will never be able to capitalize on is to use street lamp poles to hold storage batteries and grid interconnections (smart charging and inverter systems controlled by the utilities). The poles are hollow, have grid wiring, good ventilation, secure, on public land, and located all over residential areas. Powering street lighting during an outage might also have significant value for public and traffic safety. Large spiral designed batteries are known to last longer and be relatively cheap to make but few applications like round batteries... but this use would love round batteries to fit in poles.
@ JHB : the biggest problem with low voltage is the amperage squared is used to calculate the energy loss in the wires. If you drop the voltage by 10 times (125v to 12.5v), you increase the energy loss in the wires by 100 times (10 x 10) or with a wire that is 100 times as thick in cross-sectional area will have the same loss as the original wire using the 125v. This can be solved by putting the battery close to or inside the appliance using the energy but you still have to connect the batteries to the source (solar? wind? fuel burning generator?) so you are still stuck with a high amperage, thick-expensive wire problem. I am hoping to design units for homes that provide light (LED), occupancy detection (turns on the lights and heat/cool only when needed), fire alarm, and a small sealed battery with charging circuitry. This unit would receive 125 v AC from a "micro grid" of the solar panels that only is powered when the sun is shining and the small battery would take care of the lighting in the rooms. Some inverters will detect electrical need so plugs can be hooked to such inverters and they will only operate when someone plugs stuff in (and powered by bigger batteries located in a protected box outside the house). More things can also be powered by rechargeable batteries (like power tools) and only charged up when an energy source is available. Like what has already been mentioned in this thread, thermal storage can keep your refrigerator cold over night and your hot water tank hot all night and only be using energy when the sun is shining. This local storage is great for customers of the grid but only if they pay different rates based on solar or wind energy availability. Otherwise, it is not part of the discussion of grid management but rather how to no longer need the grid (which power companies obviously do not like to hear).
@ JHB : The idea with these lighting units is to have one in each room (with the fire alarm optional for rooms like the bathroom) and to have the house heating/cooling/HRV(heat recovery ventilation) controlled separately for each room by this same unit. An infrared detector could be incorporated in it to measure the floor temperature (and internal ceiling temperature measured) to get an accurate temperature profile of the room. CO2 detection is part of CO detection so can also be used to detect air quality along with humidity detection to control the ventilation through the HRV. HRV units usually use brushless electronically controlled DC motors (many times as efficient) and last longer) so HRV fans can be located in each room instead of in HRV unit (a flow detector can be used to match the flow of the opposite flow) or an even more radical idea of an HRV for each room (they are a bit expensive so the increase in efficiency is likely not enough to justify the extra expense). This idea came to me on a quest to make houses without the need for utilities and using high insulation and high air-tightness to compensate for the lack of solar in city homes with a building 4 feet to the south of your house. In such a situation, there is a bit of solar but only for a short time in the day on the roof so electrical energy is at a premium and so is concentrating thermal solar for hot water and some heating. It can still be applicable to grid customers though for safety and security during power outages and of course building energy efficiency (no matter the source of the heat). An interim system I am planning to use incorporates a tankless condensing natural gas water heater as the source of thermal energy to be replaced later with concentrating thermal solar panels later. A stratified hot water storage tank will store the 'used' hot water in the HRV that replaces the furnace until I add the radiant floor heating in each room. check out PassivHaus and "1 watt house"
I was disappointed that the article did not concentrate on solutions. I see some solutions mentioned in the comments. One solution that seems to be overlooked is thermal storage. This is best implemented in thermal solar installations where the energy is already in the form of heat and only needs to be stored for a few hours to keep the plant producing peak power 24 hours of the day (and most just needs storage from solar peak of early afternoon to use peak in the early evening). Most big uses of energy (including natural gas) are creating heat or cool with that energy. You can store that heat or cool and with smart metering, can use the cheapest electricity (which would be based on what renewables are available and the capacity of the distribution). Actual stand-alone heat-based storage may compete with batteries in cost when done at a significant scale and incorporated with other thermal energy sources such as fuels. On the consumer level, Germany has embraced the PassivHaus standard of high efficiency buildings. With smart metering and incentives, houses can be heated and refrigerators cooled during cheaper power (which would match available renewables of course).
@ Bob_Wallace: Thanks for the heads-up on PHES. Spain has been adding thermal storage to it's thermal solar installations for years now and there are projects around the world doing this. The lower cost of PV (then PV's cost earlier) has taken away some of the financial advantage of solar thermal but when thermal storage is included and power delivered when needed most (and output can be fluctuated within seconds), thermal storage can continue to be more cost effective then PV. I plan to build a wind-powered high temperature kiln that does not use electricity but rather high temperature storage and heat created by fluid friction in pipes. The windmill would be pumping air to move liquid iron in chrome pipes to create the high temperatures underground. A simpler related concept would be to use wind power to pump hydraulic oil and use friction in pipes underground to make steam-producing temperatures to make steam on demand and thus steady electricity production no matter when the wind blows or how strong the wind is. Steam turbines are not as efficient as direct electric generation though so the advantage is only the storage side of things.
regarding Isentropic's Pumped Heat Electricity Storage: looks like they are storing 500 degrees C and -160 degrees C. Looking at the heat of fusion of various common materials, the three that stood out as highest were water, aluminum and ammonia. Water freezes at 0 degrees C but aluminum and ammonia at 660.32 °C and -77.73 °C respectively. With adjustments to their working fluid or pressures, they might be able to hit those temperatures for the storage and store aluminum and ammonia in partial solid and liquid states. Magnesium is also a good choice at 650 degrees C (and only slightly lower heat of fusion)
@ Bob_Wallace: yeah, they do a lot of mentioning the safety aspects of their system. Argon is a gas above -185.85 °C so works great for this range of temperature (and is safe and relatively cheap... extracted from air). Gravel is easy for lots of surface area achieving maximum heat transfer. On the other hand, the ammonia will be liquid and solid (not gas) and likely held inside thin metal containers in a bath of argon so the chance of a leak is nil when in operation. When it evaporates if warmed up to room temperature, the pressure would need a place to go (or strong containers). I will look for an alternative material that remains liquid at room temperature.
Another important thing often missed is indicating what part of the world you serve or are located in. live chat and web-direct email creation are also effective tools for those unwilling to give out their email address (or don't have one). You can provide answers in forum format if they choose.
OK, here is my basic rant about the internet for businesses. When you pick a plumber or electrician or even a building contractor, you usually head for the yellow pages. If they have a web site, you are there for information after you have them on your short-list for who you are going to spend your money on. I am an old-school web site builder and stick to HTML. I started using my cell phone for all my internet needs due to the low energy requirements. All my websites opened and displayed well on my cell phone browser but very few other websites did. My pages were under one K in size where most others were in the 200k to 400k size and ate up lots of my precious cell phone data and minutes. Leave the fancy graphics and flash animation to big time players selling millions of items. For the dozens of customers a year an alternate energy contractor or parts supplier has, you want to give them fast and clean information in text that can be highlighted and cut and pasted... even on a cell phone browser (mine would even dial phone numbers I highlighted).