A freezer is possibly another such use case, if it keeps the temperature to within +/- X degrees of the set temperature, it can delay kicking in during periods of expensive electricity, and over-cool during periods of cheap electricity.
I could load the washer or dryer and program it to run it when it's cheapest if I'm not in a hurry.
Charging an electric car could work the same way.
Air conditioners are a huge deal, my single biggest electricity consumer. In a world where things were smarter they would chill coolant/water/ice during times of cheap electricity, and that would be used to cool during the hot evenings.
The problem is I have no way to take advantage of any of that. The electric grid isn't giving me feedback on the spot price of electricity (and in many places they don't even break it down on the bill, showing just one value for $/kwH for the entire month - that's what my bill looks like.)
Even if that problem is resolved, my appliances are too dumb to take advantage of that information to optimize my costs.
The grid needs to convey the realtime pricing information to customers, and then smarter appliances will be developed to take advantage of that information. The market may be able to do a surprisingly effective job of moderating demand itself if both the information and the means to apply it are available.
When I worked at Ørsted, we did this all the time. We had a huge electric kettle, which we used to produce district heating water.
But there are many more things you can do with surplus energy. You can make methane gas from pure CO2 and hydrogen when you apply electric power as a catalyst.
The methane can then be eaten by bacteria to provide protein powder to be used as supplements to feeding livestock.
Or, we can yank CO2 out of the atmosphere and store it as ethanol. I think this was discovered last year or so? Ethanol is a really good "battery", and it only discharges as much CO2 as was captured by the surplus energy used to make it, making it a clean fuel that only exhausts CO2 and sterile water.
https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroel...
This sounds good to me and it claims have 86% efficiency.
Since kinetic energy = 1/2 m * v ^ 2 , the a slight change in velocity on the trains that are already moving fast at any point in time, could store a lot of energy (i.e. for 2 identical weight trains, from 0km/s to 1km/s is a smaller change in stored kinetic energy than from 100km/s to 101km/s ! [in fact the latter increase of 1 km/s stores 201 times as much kinetic energy than the former: ((101 * 101) - (100 * 100)) / ((1 * 1) - (0 * 0))]
Now that I think of it, this could probably explain why our local trains are suffering more and more irregular arrival times :) but why would it be kept secret or hidden in plain sight? perhaps all the negative news about negative prices for renewable energy during energy flood is just manufacturing consent to keep price hikes for the plebs palatable, or a kind of white lie to offset their airplane travels...
The trains move on a track 5.5 miles long at an inclination of 8 degrees. thats a height difference of sin(8deg) * 5.5miles * 1.609344km/mile = 1.232 km, now it may be hard to find a steep cliff 1.2km high, but you could use a smaller cliff and heavier weights, think of the steep section at the start of an amusement ride (they will probably be better equipped with safety for such systems anyway since they are used to designing crazy rides for human consumption). no need for train and electrical tracks 5.5 miles long, since the motor can reside on the top part of the cliff/hill...
https://arstechnica.com/science/2017/03/german-institute-suc...
I'd assume the only thing they look at is not to go above the pressure differential that the dome/sphere can sustain.
Norway is having great success with this strategy on their hydro plants.
The Balkans region, along the Adriatic coast, offers an interesting prospect: using the sea as a lower basin with mountaintop reservoirs. This is a rare topology, particularly near large populations.
What the results of localised salinisation might be is a concern though.
Bath County Pumped Storage Station in the US. Huge place.
https://www.dominionenergy.com/about-us/making-energy/renewa...
Besides, district heating produced on power from the grid is taxed as if produced on coal, as the power has no traceability. This makes it really expensive, unless you are directly hooked up to a solar or windfarm.
That's the law in Denmark at least.
PS: I worked in the administrative building just next door to Skærbækværket! :)
Sounds like there is room for improvement. E.g. an agreement with an energy provider and tracking when it was used on demand as a sink for excess energy instead of base-rate heating.
You can make methane gas from pure CO2 and hydrogen period. The reaction is exothermic, it's just the Sabatier method. You could however use electricity to split water into hydrogen and oxygen.
...and you thought you were heating with renewable energy. You were not. Much of the "surplus" power on the grid comes from coal plants (especially in Denmark!) that can't throttle down, so someone burns coal, converts the heat to electricity at an efficiency of 40% or so, and you turn it back into heat.
No we didn't. As a mathematical modeller and software developer for their inhouse production optimization software, I was perfectly aware of what was happening.
> Much of the "surplus" power on the grid comes from coal plants (especially in Denmark!)
Most of the power plants owned by Ørsted are bio-converted and runs primarily on wood chips and pellets. Unless you are talking about surplus energy imported from Germany, what you say simply isn't true.
Besides, the huge amounts of surplus energy that often came from germany were caused by their massive open sea wind farms, making the energy pretty green.
Ørsed operated almost exclusively combined heat and power plants, meaning that they can produce heat and power concurrently. The utilization of energy was well above 90%, when we ran the plants this way, because we cooled the plant with the district heating water, instead of sea water. The theoretical maximum is ~98%.
We also never planned for pure power production, only to turn it into heat again. That would be monumentally stupid.
We had many, highly skilled engineers and power traders, and they absolutely knew what they were doing.
This will encourage market for devices that can utilize the lower spot prices dynamically and keep the things more efficient overall (in steady state).
http://www.oriongroup.co.nz/customers/load-management-and-ho...
So, it's important to note that the old system doesn't allow one to run the heat pump both whenever it's wanted, and also on the lower price ripple-controlled power. Similarly in the other direction, it doesn't make sense to use ripple control to decide when to feed back in to the grid if you have generating capacity from PV or whatever.
So it provides pricing info, not any home automation.
It's not "smart" or automated, but it's a baby step.
This frequently targets very high demand customers rather than residential for the simple fact that it's easier to ask a company to delay starting a single piece of machinery than to reduce the load on an equivalent but large number consumer appliances like refirgerators.
Doing this at a residential level will require significant costs to support at a residential scale. Technology is the key in solving this problem.
https://www.peco.com/WaysToSave/ForYourHome/Pages/SmartACSav...
Whenever I get a couple of bored minutes I go and update a little go library I have to work with it https://github.com/kklipsch/reagle
https://smartgrid.ieee.org/ http://www.whatissmartgrid.org/smart-grid-101
An interesting note from the video is how they said they could detect the grid frequency from the plug to detect times of over supply and (in theory) that would be the right time to absorb some of that excess.
Some other interesting benefits (mentioned in the comments) about how it can periodically cycle the heat better than traditional water tanks to kill off bacteria.
They already work on this principle, more or less: heat up overnight when electricity is metered cheaper, then discharge during the day.
There are several companies working on making "smarter" versions that can switch on and off in response to real time data.
Some metropolitan areas have residential level demand response programs that address the obverse issue: when there is too little power, participating opt-in residential electricity customers with a qualifying Internet-connected thermostat would see their HVAC systems reduce power consumption through adjustment of the temperature set point. I suspect most of them use OpenADR [1].
If my skim of the OpenADR specification (requires free registration) is off, and we can't use it to pass pricing signals through the EIEvent/Quote/Report/Avail/Opt services, then we can use the OASIS Energy Interoperation parent specification, though that seems much more heavyweight and baroque to work with, and likely a harder sell to utility organizations to adopt. The utilities would need to expose pricing history as well, so longer-term planning by consumers can be performed through predictive trend analysis.
The communications and protocol infrastructure is there to convey the information to your residence, but the back-end at the utility side is an open question, and likeliest hardest to hook up. If I had access to near-zero cost electricity when they're trying shed load, then I would use it for drying clothes, chilling a pool (thermal mass) during hot months, heating a pool (thermal mass) during cold months, baking and pressure cooking while running a kitchen A/C at full blast, etc. All of these activities either use capital equipment already paid for, or very cheap to acquire to add to my existing equipment stock (like heat exchanger to thermal mass and even a brine tank).
But desalination may be a poor example in general. It’s not actually very energy intensive, at least compared to the value of potable water in an urban location.
Just a big resistor in a big tank (or pond), a big fume hood and coil to another tank. Capital cost can probably be minimized a whole lot.
[1] http://workingwithmckinsey.blogspot.com/2013/11/Avoid-Boilin...
Also, you only want to run the desalination plant when the electricity price is too low ("below zero" with the transmission included), so you want generators for most of the time, when you actually sell the power.
I can even imagine a SETI-like application where people who over-generate power are able to donate it to causes of their preference...
Someone is having to build a lot of highly wasteful, redundant infrastructure.
Money > Energy > Money
> Someone is having to build a lot of highly wasteful, redundant infrastructure.
We're nowhere near having the energy infrastructure necessary to support everyone having an electric vehicle yet.
Energy storage is key to maximizing returns from renewables and minimizing irreversible environmental damage.
And then you have the plant sitting there for most of the year, able to help the power grid. So the example makes sense.
So in financial terms wouldn't this mean a rather weak profit margin? Plus the relatively high-risk that flood energy might not always result in free or negative energy prices gives it a bleak risk-to-profit ratio.
In other words, there would always be something more utilizable to be done with excess energy (e.g. mining bitcoins etc. and buy water with it when you need it).
PS: But I like the main point you make, to take in more aspects when calculating efficient renewable energy systems. Not a crypto-investor (or even believer).
In hindsight I should have ended with posing the following question: how do we make a simple guide for factory/etc operators/consultants to recognize such steps in their production line?
Desalination is a bad example, because you need a complete new plant, while it is conceivable that other products have one or more energy dense steps.
What should such instructions look like?
Follow the product through your production line, and at each step measure the energy consumed per part at the step, and the volume per part when efficiently stacked. Also note if the step is automated or needs a human, if it is human, check if it can be automated.
If it is automatable, and the energy density for the step is high enough, calculate the cost for changing the production line, allocating sufficient storage, and possibly automating a certain task, and parallellizing the step such that it can be run during energy flood. Then calculate through the price difference how fast it pays itself back.
Mention the importance of actually measuring the energy consumption, instead of just reading off a machine specification of wattage, and cycle time.
Etc.
Edit:
The banks that wish to invest in cheapening such a step could train consultants and send them to factories interested in good deals. I.e. any potential profit is shared between company and bank, and the bank takes the risk (hence has the motivation to do the calculation properly, and will have best knowledge through experience of suitable step energy densities)
Or at a higher level of abstraction, instead of us trying to figure out which "energy dense step" is the right one to target, instead the grid can provide a real-time price signal that flexible loads can use to get a cheaper overall rate by selectively turning on when the demand is lower.
This stuff is pretty well discussed under the umbrella of "smart grid" technologies: https://en.wikipedia.org/wiki/Smart_grid#Market-enabling
You're going to build a $100M desalination plant and run it for three hours a day? That's a ton of money sitting idle most of the day, far more than what is recovered with zero operating costs.
(This is called the utilization factor -- how long a piece of equipment is used vs. staying idle)
Ideally you want useful processes with low capital costs and expensive marginal/energy costs. Desalination is not one of those.