A group of scientists has been slaving away largely in obscurity for two decades, with very few publishable results. Suddenly, one of them has an epiphany, which turns out to be instrumental to enabling them to succeed at what they are attempting to do. This happens around year 2020 or so, on Earth, inhabited by humans. We are talking about the scientific Holy Grail.

The scientists have figured out a way to make net-positive-energy cold fusion possible. The process can run on ordinary tap water, and provides enough energy to power itself as well as leave some energy for other uses.

What's more: in retrospect, the process turns out to be scientifically sound, is repeatable, and is scalable. (The exact workings of the process are not relevant to this question, and are left as an exercise for the reader.) A patent is quickly filed for and approved essentially world-wide, and the details of the process get published in the scientific community. It is a truly world-changing event.

After some 15-20 years of refinement and miniturization, the technology has been refined to the point where it can be delivered in a box approximately the size of a large refrigerator, can run on any kind of dihydrogen monoxide (with or without a reasonable amount of contaminants, so can run on both tap water and sea water), is no more dangerous than most household appliances, the technology has a proven track record, and a reasonably-sized unit (think the size of a pair of large refrigerator and freezer) can deliver a net of a few dozen kilowatts of electricity. An outside source of electricity is required when turning on the unit, which can be provided either from electricity mains or from a rechargeable battery; both types are manufactured and sold.

At this point, household units in 10 kW and 25 kW rated sizes are available for approximately the price of a brand new, nice utility car (think somewhere in the range US$ 50k-100k plus inflation), other sizes are available as well to individuals, and industrial units capable of substantially higher power outputs also become available but at a much larger cost and physical footprint; the cost of the unit rises slightly slower than linearly when plotted against the unit's rated power output, and the volume of the unit rises roughly linearly with rated output. One of these units can be expected to keep working with minimal maintenance for 15-20 years in a household setting, and can be connected directly to the water mains or refilled manually. (For comparison, this works out to a cost of about 3-4 cents plus inflation per kWh delivered for the household-type units around year 2040, plus the cost of water.)

In earthly settings, the amount of water consumed by the process is small enough to not really be significant, but the requirements are large enough that energy considerations are still important in non-ground-based operations (and spaceflight in particular). Hence, in practice, this technology reduces (and moves up front as mainly a capital cost rather than an ongoing cost) but does not eliminate the cost of electricity. Because a large fraction of the cost is an upfront capital cost, the effective cost per kWh rises if the unit is used below its rated maximum power output, but because the larger units are more expensive, there is an incentive to purchase a smaller unit if that is deemed sufficient (and then not have to replace it). In principle, multiple units can be connected in parallel to provide both additional power as well as redundancy, but for technical reasons this is rarely done in households.

Given that the capital cost up front of one of these units is fairly high but not insurmountable for a large fraction of (but not the entirety of) the world's population, that smaller units are more affordable up front, and that they can provide a reasonable amount of electrical power for a single household at little ongoing cost and with little maintenance:

  • What is the short-term and medium-term (up to a few decades, say 2040 through 2080) effect on private individuals and households?
  • What is the short-term and medium-term (up to a few decades, say 2040 through 2080) effect on industries and production?

Answers should focus on how electricity is used within the society. Well-reasoned, logically and scientifically sound answers please, but scientific citations not needed.

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    $\begingroup$ "The exact workings of the process are not relevant to this question, and are left as an exercise for the reader." Heh, so actually inventing cold fusion is left up to the reader? $\endgroup$
    – loneboat
    Commented Sep 28, 2015 at 15:51
  • 1
    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ Commented Sep 29, 2015 at 13:12
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    $\begingroup$ Others have already expounded the idea in great details but in short: We already have cheap and abundant (electrical) energy available. $\endgroup$
    – Relaxed
    Commented Sep 29, 2015 at 15:37
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    $\begingroup$ I think this question could have been better if the price was much lower and the power output was much larger :( $\endgroup$
    – justhalf
    Commented Sep 30, 2015 at 2:31
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    $\begingroup$ You might mention the mass of this device as well. Or clarify that it's the size and mass (or weight) of the refrigerator. And, speaking of mass, clarify just how much water can be converted to a given amount of energy, because that could greatly limit its use in mobile applications that need to store the water. $\endgroup$
    – MichaelS
    Commented Sep 30, 2015 at 3:11

11 Answers 11


It's not that big a deal

I'm not sure how you expect 'relatively cheap and abundant (but not free or limitless) electrical energy' generation to change current society... if the solution you propose is not substantially different from existing solutions.

At this point, household units in 10 kW and 25 kW rated sizes are available for approximately the price of a brand new, nice utility car (think somewhere in the range US$ 50k-100k plus inflation)

Wow! That massively better than the $25,990 it'd cost to install a 10kW solar installation!

Here is a snapshot of residential solar pricing as of March 2014. Recently, we quoted a homeowner $25,990 for a 9.12kW rooftop solar electric system. http://thirdsunsolar.com/knowing-solar/residential-system-costs/

Oh wait... it's not. And remember your technology isn't available today, it's available in 2020 + some 15-20 years of refinement and miniturization!!! For comparison, the above source claims:

3 years ago, we quoted a 7.2kW system installed on the same home rooftop at $49,263. Prices have fallen a lot!

Furthermore I suspect a cursory glance at existing solutions will remove many other competitive advantages for example 3~4cents/kWh is not particularly cheap for bulk generation. The lack of granularity or peak generation at small scale suggests that a grid will still be used to distribute power as it is today.

Maybe the fusion generator will be used as portable, low maintenance power source for certain applications - transport, space and military come to mind but even there how is it revolutionary? Nuclear power can and does already fill these needs... this might at best be an incremental improvement.

But Solar isn't fair, those numbers are for 'peak' power only!

Several comments suggest that comparison to Solar is misrepresentative because it does not always generate the stated capacity (e.g. cloudy day, night etc).

I agree, this is greatly simplified the maths. However, I suspect that the maths are still accurate (even if not precise) when considering all factors in balance.

The average for solar is nothing like half. I have recently installed solar (in a fairly sunny part of southern England), and my 3.8kW capacity should generate about 3800 kWh per year, which is 1000 hours of peak production, which is about 11.4% of the peak capacity. --Mike Scott

Correct, solar does not give continuous generation in residential situations. On the flip side residential situations do not use power in a continuous manner. Since the fusion option has no ability to provide 'peak' power, both systems would have to be heavily over-provisioned in a trivial deployment.

You clearly know exactly nothing about the energy industry. A solar panel only produces during the day when it's sunny... This would be an huge change to have 10kW available on demand. Storage costs are much much larger than generation costs for sources like wind and solar. -- Sam

The energy industry includes a range of existing and upcoming technologies like Tesla Powerwall, Molten Salt Batteries, other methods of Grid Energy Storage or simply balancing various inputs over a grid.

Take the Tesla power wall for example, according to this link the cost per kWh of usage is roughly 10~12cents when bought upfront. In contrast, as GiliusMaximus points out in the comments to the question, the fusion device would likely cost of 30 cents per kilowatt hour for standard residential needs!

In order to provide full-time power you'd need 8 times the peak capacity PLUS a major energy storage system which needs to be factored in. Since average US household consumption is a bit over 10kWh/day (2013), the solar portion alone will run (per the price given) more than $200k, 4 times the Mr. Fusion Sir system quoted. Plus storage cost, of course. -- WhatRoughBeast

Issues regarding peak vs continuous power has been addressed earlier, so it's trivial to see where this argument falls flat. In short, the maths here fails to recognise that if assuming solar receives 3 hours of peak production a day, and is combined with a battery system, it only needs to be 3~5kW in size to power a 10kWh/day household.

However, for arguments say here's an compare on a pure output measure - regardless of it's usage.

The fusion system produces non stop 25kWh for \$100k! This is clearly stated in OP. Over 20 years this is about 2~3cents a kWh!

However it's also clearly stated that it'll be closer to 2040 when this is achievable, and that the \$100k in today's dollars. It's incredibly important to note that many of the systems we've been talking about - solar and battery in particular - are reducing in cost!

This source (lots of pretty graphs) notes that solar has gone from "\$76.67/watt in 1977 to just \$0.613/watt today [2014]" that's a drop of about 12% of cost per year, even with inflation! Should this continue then in 2040 the cost of power will be... \$24.52/kW installed, or a reduction of 96% of cost!

Given 3 hours of 'peak production' a day, and a twenty year lifespan this would be 0.11cents/kWh or 20 times cheaper than fusion!

In case one is wondering, battery storage is also dropping in price, say 9% per year, for a total price reduction of 90% by 2040 - or from 11cents/kWh to 1.1cents/kWh - assuming no breakthroughs etc

But a compact, cheap, and powerful energy source could change the world!

Some criticism of this answer claims that it misses the real benefit:

This answer is pretty shortsighted where a highly compact, cheap, and powerful energy source could change the world. -- Aron

It's important to note that I completely agree with this statement. Such a power-source would be revolutionary! However this power source is none of those things:

It's not compact!

Being as large as "approximately the size of a large refrigerator," - which'd be around 1300liters in size (Remember to count the volume of the entire unit, not just usable volume).

For contrast a quick search trivially finds a 10kw generator that's less than 400liters in size and only costs $3k. Car engines are also quite small. Is a large fridge is going to replace your mobile phone battery to give you unlimited power?

A compact power source is a big deal, but this is not a compact power source.

It's not cheap!

As noted by this and several other answers, the proposed fusion power source is not cheap. Not only is it not especially competitive today, by the time it eventuates (2040) it might be an order of magnitude more expensive than alternatives. So any imaginations of revolutionary free power supercharging our economy or making accessing space trivial are stillborn.

It's not powerful!

Need a big powerful energy source? Take a look at the A4W reactor - there are two of these in the USS Abraham Lincoln - generating a combined power of over 1GW!

Based off of the OP, assume for every 1300liters of fusion volume it produces 10kW of power. It'd need 100,000 of these, costing say $2,500,000,000 and taking up 130ML of volume - that's 40% the volume of a very large crude carrier supertanker!

The volume of the reactors in the USS Abraham Lincoln is hard to find (for some reason the military aren't sharing that), but given the whole thing only cost $4.726 billion in 2010 dollars It's hard to imagine that in 2040 a fusion reactor at more than half that cost and a volume 1.2x greater than the ship's displacement would be considered a significant improvement by the military.

This is the problem, it's a solution nobody needs!

The sad fact of this reactor, as magical as it sounds, is that it's too big, too weak, too expensive and too late for anyone to care. It's a commercial dud.

Mobile phones and cars use small powerful batteries. Not cheap enough to compete with other energy sources, any usage in the grid will have minimal impact.

Big transport may be interested, as this may be a low-cost replacement for hydrocarbons. However I suspect that this device will be so bulky and heavy as to strictly limit its usefulness.

Geographically isolated locations would love a low maintenance, reliable power supply. But a solar + battery combination already achieves this and is looking like it will be cost effective. Whether you just want to be off the grid, camp in the wilderness or live in space or mars, it's a killer combination.

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    $\begingroup$ Note: Certain areas of the world have lower levels of light, making solar energy a less approachable means of generation. Also, could it serve well on expeditions due to its relative portability? $\endgroup$
    – nickson104
    Commented Sep 28, 2015 at 13:05
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    $\begingroup$ @nickson104 I use solar simply because it's the most obvious and similar option - for lower levels of light you have options like geothermal, hydro, nuclear, wind, wave and even the simple option of importing energy from cheaper sources to contend with. For portable use - solar, nuclear, combustion, battery etc. are all well established solutions (even in space, where weight and simplicity are at a huge premium!) For these reasons even in extreme circumstances I conclude: "this might at best be an incremental improvement." $\endgroup$
    – NPSF3000
    Commented Sep 28, 2015 at 13:13
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    $\begingroup$ I was placing as a note, rather than as a counter argument, but well expanded. $\endgroup$
    – nickson104
    Commented Sep 28, 2015 at 13:48
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    $\begingroup$ Hang on. You're using the peak possible output of the solar installation. Not average. $\endgroup$
    – Murphy
    Commented Sep 28, 2015 at 14:08
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    $\begingroup$ @DoubleDouble The average for solar is nothing like half. I have recently installed solar (in a fairly sunny part of southern England), and my 3.8kW capacity should generate about 3800 kWh per year, which is 1000 hours of peak production, which is about 11.4% of the peak capacity. $\endgroup$
    – Mike Scott
    Commented Sep 28, 2015 at 19:51

household units in 10 kW and 25 kW rated sizes are available for approximately the price of a brand new, nice utility car (think somewhere in the range US$ 50k-100k plus inflation)

This isn't economically viable.

My electric bill today is around \$80/mo. If I invest \$19k today, and I can get a 5% annual return on that investment, that will pay for my electrical expenses for 100 years. Why would I buy a \$50k device?

Or to to solve the annuity equation another way, if a \$50k investment today means I don't have to pay for electricity for 100 years, your device represents a 1.49% annual return. It's about as revolutionary as a savings account.

Or one more way, assuming a 5% annual return and a life of 100 years, your device will need to save me at least \$209 per month to be economically viable.

Of course, these are all assuming the device has a life of 100 years with no maintenance or fuel costs. And that I'll live 100 years. And that the government doesn't charge me personal property tax on the reactor.

Because a large fraction of the cost is an upfront capital cost, the effective cost per kWh rises if the unit is used below its rated maximum power output, but because the larger units are more expensive, there is an incentive to purchase a smaller unit if that is deemed sufficient (and then not have to replace it). In principle, multiple units can be connected in parallell to provide both additional power as well as redundancy, but for technical reasons this is rarely done in households.

Sounds precisely like our current electrical distribution system, no? We have the technology for diesel-powered household electrical generation today. Why doesn't everyone use them?

People don't like capital expenses. Neither do companies. That's why cloud computing like AWS is so popular. There's no reason you can't build your own datacenter, but that's a large capital expense. Solution: let Amazon make the capital expenses for you, then you just pay some operating expense.

It's also more efficient to pool the resource demand of many users. My last electric bill was 680 kHh for the month, which works out to a mean power of 931W. But I'd need a much larger generator unless I want to pop the circuit breaker every time my AC compressor kicks on. Low duty cycle loads like AC compressors mean a high peak load for which I must buy a lot of excess capacity. Sharing capacity with neighbors makes a lot of sense because it averages these peak loads out.

So I think in the end, you'll still have electrical utilities for the same reasons we have them today. The industry won't look very different: it will just be a little cheaper, assuming you can solve the problem of economic viability above.

And of course there are still economies of scale. The larger units are a little more efficient.

But you'll also have to consider distribution costs. Roughly speaking, half of my electric bill is distribution. The distribution system could be simpler if electricity were more locally generated, but for the reasons already mentioned I don't think that would happen with the parameters you've set.

So in all, I don't think you are looking at much of a revolution. In summary:

  • the device needs to be a lot cheaper
  • distribution is still hard: peak loads are problematic

I think you'll need to make some additions to your scenario to have something feasible. Ideas:

  • also introduce some revolution in electrical energy storage, making it inexpensive and efficient. This addresses the issue with peak loads (though it would also be a huge money saver for traditional electric utilities)
  • stipulate that fossil fuels have profoundly increased in cost (though you'll have to address why this cold fusion device is better than wind, solar, and today's nuclear power)
  • 1
    $\begingroup$ Well, this should more or less take care of your last bullet point, at least. $\endgroup$
    – user
    Commented Sep 28, 2015 at 20:28
  • $\begingroup$ Economy of scale, plus one. $\endgroup$
    – Mazura
    Commented Sep 28, 2015 at 23:24
  • $\begingroup$ Nuclear power is the most obvious contender here - it's also a source where the fuel is pretty much free, while most of the cost is in capital costs. The ballpark somewhere around $1 000 - $4 000 of capital per kW, depending mostly on scale (as less plants are being built, the per-plant costs are going up). That's still quite a bit cheaper than the OPs fusion source. There were proposals for "local" NPPs too, at similar capital costs, optimized for low maintenance. $\endgroup$
    – Luaan
    Commented Nov 7, 2016 at 14:45

Depends on the technology utilised

Firstly, you state it utilises water, of any type, of a refrigerator-esque size (how long is a piece of string? How big is a refrigerator?). The first concern that immediately changes it's viability is it's environmental impact, not it's cost.

Does it permanently consume water? IE would it deplete water reserves? Even in small amounts, this would make water progressively less and less available. Sure, without oil we'd lose the current economy, but humanity could survive. Without water? Erm... nope!

Also, as a cold fusion reactor, is it at any risk of producing anything harmful? IE, if it returns water, does it pollute the water returned? Could it, when damaged, emit radiation? People will not have technology in their home that will cause them harm, even if that's via a minor accident. Oil is cheap but how many people do you know store petrol in a house? Most don't: it's a possible fire hazard.

But, assuming it's almost the infinity power generator of it's day and turns trivial amounts of regenerable water into chemicals that can be safely dealt with by a non-expert individual and has zero risk of giving them radiation poisoning via alpha, beta, gamma radiation etc...

It's actually useful

I disagree strongly with my peers on it not being revolutionary for cost, because they are only thinking of houses and people with small incomes who aren't very entrepenurial. As a 'refrigerator sized unit', this would have a huge impact: think vehicles, large boats (which travel by sea), space tech, military and anything else that demands portability.

Maritime industry

Essentially, anything travelling by sea would use this technology. You would revoluntionise the maritime industry because there would be no risk of oil spillages from overturned boats, there would be no need for nuclear reactors (think submarines and aircraft carriers) which have a possible radiation hazard and waste.

Cruises would be able to greatly reduce costs: no more using oil, but endless sea water!

You'll revolutionise cooling systems that use water: because they draw in water to cool down systems. Think along the lines of backup systems.

Search and rescue

You'd change the face of rescue operations: sea operations could go on indefinitely (you can grow plants using special bulbs that demand lots of electricity), and countries with no natural resources or electrical outputs (think Africa) where cost of electricity is prohibitively high, would also benefit greatly. Sure, people say in the first world electricity is cheap, but what options do you have in a ghetto? As a charity you can't just build a nuclear plant - but a refrigeration unit that only takes water? Genius.

Think of those sea-craft that dump tons of water onto forest fires? They would become incredibly efficient because their water load is also their fuel - which means, so long as the pilot isn't fatigued, they can fly for as far as they can carry water!

Water supply

You'd change the face of desalination plants, which take water to be desalinated: not only could they draw power from the water, but they'd be part of the process (it can use sea water to convert sea water into drinking water). This would change agricultural demand overnight as deserts become irrigated by sea-water powered desalination plants.


One key issue, though, that it would change (assuming it's non-harmful) is environmental waste. Now, people will try to argue that because they pay less for 'normal' electricity, it's better, but that's a false economy: because the cost comes from the funding of dictatorships via oil purchases, through oil spills in the ocean, through the waste produced by radioactive materials that will take millions of years to become safe and viable.

Overnight, you'd remove the threat of nuclear terrorism (unless your water generator becomes a water bomb...?), but also chemical catastrophes - oil explosions, toxic spillages, overturning vehicles (which deliver the necessary chemicals to neutralise, convert, cool or stop [in the case of a reactor] a runaway system).

Environmental groups would support this. Governments would turn to this. Charities would use it. People who are rich enough to afford this would buy it because it means they aren't at risk from a blackout, or being cut off if the company doesn't get paid, or require a wireless meter along with it's wireless radiation.

Think underground bunkers, where being trapped with a leaking nuke plant is a bad idea or a system that requires oil in a limited supply.

Electric cars

Being able to refill a car with water as fuel is awesome, and anyone who thinks it'd have no use is shortsighted. No longer will your cost of petrol be at a premium! Think aircraft too... depending on water conversion efficiency (cars can get away with constantly refueling... but aircraft can't).


One way that would solve this is, given it's a 25kW system, assuming it's output is based on water input, if it was purchased as a community to be shared, it's cost would divide optimally. Assume every person uses only 5kW per whatever unit of time you're care for (your calculations are unclear if it's 25kW per hour, a year, etc), you'd immediately divide the cost by 5. \$10,000 per person. Assuming it lasts for ten years and you use electricity roughly \$3,000 per year on the 'normal' system, in 4 years it will have paid itself: for 5 people.

You'd see two things occur:


Oil dictatorships, oil corporations, the nuclear industry, energy providers... would actively seek to cover up or destroy this research (perhaps even going so far as to kill anyone involved), because it would move people out of their reach: if everyone can get water to power their systems, where do they get a profit? They don't. So they would have to crush it as an alternative - before it even got out.

People would detach themselves from the grid. As there would be fewer and fewer people on it, the cost for everyone else would rise (sorta like insurance). It might even be power companies install the units themselves in their own power plant, but retain the control: no-one becomes free, and the power companies make a massive profit margin.

You'll be supplying power to the military, who, having water as a fuel source, would be able to build much larger systems and generate more power. Think lasers. Think lasers like the ones attached to the US navy prototype ship. At the moment, it takes a lot of power: but having numerous of these onboard would mean they'd start arming other ships with lasers.

This is a bad thing because it merely advances the weapons, but doesn't end the war.

What happens, really, is down to humanity... life saving tool that stop pollution? Or an energy monopoly that increases profits and powers dangerous weaponry and vessels?

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    $\begingroup$ "think vehicles, large boats..." We already have portable energy sources for these things. My Honda Fit (with warranty, financing, tax, and the whole car, not just the power source) cost less than $20k and includes a 130 HP (97 kW) motor. Roughly speaking, my Honda Fit manages a cost:power ratio two orders of magnitude better than the cold fusion reactor. I can't see any economically viable market for the cold fusion reactor except for applications where refueling must be avoided at all cost. Like nuclear submarines. But we already have those. $\endgroup$
    – Phil Frost
    Commented Sep 29, 2015 at 1:39
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    $\begingroup$ While your ideas are nice, you are completely ignoring the output of the unit. That would have to be a lot higher (one or two orders of magnitude at least) to be feasible for cars, and more like three orders of magnitude for aircraft. $\endgroup$
    – Burki
    Commented Sep 29, 2015 at 6:54
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    $\begingroup$ A plane could potentially actually extract "fuel" from clouds. $\endgroup$
    – Aron
    Commented Sep 29, 2015 at 10:51
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    $\begingroup$ You're analasys is great, except for noncommercial vehicles and especially desalination for agricultural water. This would be dramatically too expensive. $\endgroup$
    – wedstrom
    Commented Sep 29, 2015 at 15:13
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    $\begingroup$ Like you, I immediately thought about the third-world issues. But the reality is that anyone who can't afford solar or similar now wouldn't be able to afford this device either. I also considered the environmental impact, as its only real possibility for improvement over existing stuff, but that depends on its nature. If it's made of sea sponges and daffodils and turns water into energy plus something fairly inert, the lack of pollution could be a game-changer in densely populated areas. But if you need to process three tons of titanium to make one, pollution is just moved to the factory. $\endgroup$
    – MichaelS
    Commented Sep 30, 2015 at 3:05

The portable energy box as described isn't spectacularly better for fixed installations in the developed world. 3c/kWh is not going to set the world on fire. However, what it does revolutionize is transport. Suddenly "range anxiety" of electric vehicles is a non-issue, especially for large vehicles. The truck, bus and rail fleets would rapidly go electric. Transition away from fossil fuels would be accelerated.

I think a lot would depend on what the fossil fuel state is in your 2040. Has oil gone over $100/barrel again? Way over? What about domestic natural gas, which Europe is currently dependent on? What your technology might allow is the prevention of poverty and conflict resulting from an economically forced transition away from fossil fuels.

Electricity "too cheap to meter" would be more revolutionary, but only up to a point. It might allow for energy-based "basic income" and some commodities to be made free by society.

  • $\begingroup$ If there are sufficient improvements in either electrical storage systems or fuel cells then it may still nor be economic to use a fusion device $\endgroup$
    – Alchymist
    Commented Sep 28, 2015 at 15:13
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    $\begingroup$ I'd argue that Tesla has already solved 'range anxiety'... and while their system needs improvement it's already leagues ahead of a $50,000 large refrigerator. $\endgroup$
    – NPSF3000
    Commented Sep 29, 2015 at 0:56
  • $\begingroup$ @NPSF3000 Insofar as I know, the problem Tesla (and some others) have solved with regards to "range anxiety" is having the ability to store a sufficient amount of electrical energy in a small enough form factor to be transportable in a personal vehicle that still has enough room to actually transport people and some cargo. Their solution does not address electricity generation, and so can never work on its own. Don't get me wrong here; the ability to transport a useful amount of electrical energy is highly useful. It's just that that ability is the solution to a completely different problem. $\endgroup$
    – user
    Commented Sep 29, 2015 at 13:17
  • $\begingroup$ @MichaelKjörling "It's just that that ability is the solution to a completely different problem." Err no it's not. Tesla has solved range anxiety by solving range anxiety. The ability to generate electricity is a completely different issue. A Hydro Dam can generate electricity, but it won't solve range anxiety. $\endgroup$
    – NPSF3000
    Commented Sep 29, 2015 at 22:16
  • $\begingroup$ @NPSF3000 "The ability to generate electricity is a completely different issue." Exactly. The device I proposed in the question would be useful for generating electricity. It could also be thought of as a way of storing electricity, because of the relatively small additional mass needed to run it for a significant amount of time (small amounts of water don't take that much room) but that isn't its primary function. $\endgroup$
    – user
    Commented Sep 30, 2015 at 7:29

It may not be cheap enough

Seconding the other answers, 3c/kWh is not that cheap, and to add to the misery, it has a large upfront cost for the consumer. Fusion would have to be in the <0.5 cents/kWh to be a revolutionary technology. Might need to play with those numbers in a spreadsheet a bit, and check this source

Moreover, your described setup:

household units in 10 kW and 25 kW rated sizes are available for approximately the price of a brand new, nice utility car (think somewhere in the range US$ 50k-100k plus inflation)

..does not seem to come around to costing 3c, unless you assume that households actually consume about 87000 kWh per year, about 7-8 times the average household consumption. You could get around this by having neighbors share a unit, or having apartment and condo buildings install a few. Is still seems like maintenance would be easier in a centralized location though. Additionally, almost all processes have benefits of scale, and if as you stated performance in terms of power output scales with volume, if you move from your average refrigerator size, say $0.6 \times 0.6 \times 2 = 0.7 m^3$ to a generating unit the size of $6 \times 6 \times 20 = 720 m^3$ you should be able to generate about 1000 times as much power for a mere 10-fold increase in size in each axis. It would likely cut on maintenance costs significantly.

We can't assume near-zero maintenance, anything that has unfiltered water running through it will have deposits and calcium buildup that will need to be fixed more than once every 20 years. Additionally, since we're talking fusion, there will issues of radiation shielding and such. Regardless, it's always cheaper to change one big filter once a year than 1000 small ones, nevermind dealing with lost keys, scheduling, etc.

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    $\begingroup$ We aren't assuming zero maintenance. We are assuming "minimal" maintenance. Something like changing a filter once a year certainly falls into the "minimal maintenance" bracket at least in my book. $\endgroup$
    – user
    Commented Sep 28, 2015 at 13:06
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    $\begingroup$ @MichaelKjörling, still cheaper to change 1 larger filter than 1000 small ones. $\endgroup$ Commented Sep 28, 2015 at 13:14
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    $\begingroup$ "You could get around this by having neighbors share a unit" Not as easy as one would think because of peak power. Turns out that the one, hot stinking day I need to use the full 10kW to cool my house is the exact same day that everyone else in by suburb needs their whole 10kW to cool their houses. Funny that! $\endgroup$
    – NPSF3000
    Commented Sep 28, 2015 at 13:21
  • $\begingroup$ @SerbanTanasa Certainly fair enough. $\endgroup$
    – user
    Commented Sep 28, 2015 at 14:48
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    $\begingroup$ @NPSF3000, indeed, you'd have to have a way of managing power demand peaks, which is not trivial even with massive plants. $\endgroup$ Commented Sep 29, 2015 at 12:24

As many others have pointed out, the system itself isn't going to change a lot outside of large vehicles that would be able to be converted to pure electric power as they could carry their own box.

However, there is something that does not seem to be touched on in the question and is very important when dealing with electrical power. How has battery technology advanced and/or been affected during the time leading up to this discovery? I consider this to be the real tipping point here because of the issue being raised about peak power. Unlike some sources of power, electrical energy can be stored to at least some extent. As such, if the battery technology has improved along the way to this cold fusion break through, then not every single person or household would require a box to themselves.

I'm not going to bother with the math, others can do that if desired, but assuming a decently capable battery, I would gather that the ability of the machines to be shared would increase greatly. Instead of using them as direct energy feeds to a grid system, they would act more like trickle chargers working constantly to keep a system of batteries charging. The batteries would function as the actual source of power as far as households and the like would see, and during peak times they would drop power, but would ideally have a capacity to deal with that for some time and then recharge during periods of lower usage demand.

Efficient batteries would mean that the magic boxes could be more of a shared purchase, while the batteries would be the majority of the personal costs. Each household/business would have to decide how much power they need and can afford to store and make their battery/box purchases accordingly.

Or power companies would be the ones buying the boxes/batteries and continuing to dole out power to each customer as needed, charging in a manner similar to cell phone companies where you would have a certain amount that you were entitled to based on your payment plan, then extra fees if you go over. They would just purchase more boxes and batteries as demand for services rises. I consider this to be the most likely outcome as it would require the least amount of change to implement.

  • $\begingroup$ Hello James, welcome to WorldBuilding! While your answer isn't technically wrong, it doesn't really answer the question posed. If you would be willing to change your answer to include speculation on the effects that cold-fusion will have on society in the next 80 years, you would be far more likely to get more upvotes. $\endgroup$
    – Green
    Commented Sep 28, 2015 at 20:26
  • $\begingroup$ Relatively cheap and abundant but not free or limitless energy is already being produced IMO (it would have to be DIRT cheap - just like my water bill in Chicago was in the '80s). The next step that will change society is better batteries. $\endgroup$
    – Mazura
    Commented Sep 28, 2015 at 23:22

Large Scale Household Feasibility

This is more like a one-time expense versus monthly electric bills type investment. The feasibility of the product depends on the prevailing cost of electricity in 1st, 2nd and 3rd world countries for the life of the product. As in, how much does a normal household totally pay in electric bills for 15-20 years. The product must be at least 15-20% cheaper than the net electric cost through power lines for 15-20 years to be considered seriously.

Another important factor in determining the feasibility is the price of competing power generation systems such as solar panels and petroleum based electric generators. Considering that bio-fuel research is making a steady progress, grass or algae based petroleum products extraction methods could prove a strong competitor to this product, although this product appears to be more environment friendly. Data in this context is not provided by OP.

Yet another thing missing from OP's provided information is the type of electricity generated by the product. As in, whether it is AC or DC current. Considering that most large products in household use (such as TVs, refrigerators etc) run on AC electricity, a DC generator would require an additional toolkit to convert the output to AC.

Feasibility In Specific Environments

The product would be welcomed in locations where electricity provided by power lines is unreliable (on geological fault lines, high frequency of power lines in limited are resulting in tripping etc). Larger units of this product would be used by the government (or other power production authorities) in locations where it is economically unfeasible to install grid stations due to low population density or terrain issues (mountainous and desert environments).

Secret military research labs would quickly adopt this product instead of having to install their own dedicated power plants. It would also be used as standby power source for scientific labs and healthcare facilities, specially in areas mentioned in above paragraph.

Impact On Current Prevailing Power Supply Systems

The overall impact (nationwide) on the prevailing power supply systems would depend on the feasibility of the product, as discussed in the first paragraph.

It is expected to replace the prevailing power supply systems in all first world countries within 20 years. The process would be a chain reaction. The more houses shift to this product, the higher would the cost of electricity get for the remaining houses (because the power plants' expenses are the same as before, but the customers have decreased) which would encourage them to move to this product as well.

The 2nd world countries are difficult to predict. Too many factors are involved, especially the annual earnings of an individual.

The product would mainly be a failure in 3rd world countries. The unit price is simply too high for it to succeed in these countries.

  • $\begingroup$ I actually haven't considered whether the output would be AC or DC, but two things to keep in mind: many household appliances (though far from all) actually run on DC (most electronics prefer DC over AC, for example, and one of the first things they do with incoming power is to rectify and filter from AC at mains line voltage to DC at suitable voltage(s) for internal use), and converting DC to AC is a well-known technology. If this unit natively produces DC and is viable, it stands to reason that there would be a vastly larger market for high-power inverter technology. $\endgroup$
    – user
    Commented Sep 28, 2015 at 9:22
  • $\begingroup$ As for cost of electricity, the 3-4 c/kWh can be compared to, at least in Sweden, a cost of around 10-12 c/kWh delivered, including grid subscription fees, taxes etc. So assuming that the electricity produced by this unit is not taxed, effectively halving the cost of electricity is not at all unreasonable at least in some locales. Assuming the full price is paid up front (no loans, etc.), it also shields the owner from raised electricity prises (including taxes etc.) during the lifetime of the unit. $\endgroup$
    – user
    Commented Sep 28, 2015 at 9:28
  • 1
    $\begingroup$ @MichaelKjörling "So assuming that the electricity produced by this unit is not taxed, effectively halving the cost of electricity is not at all unreasonable at least in some locales." How does your device change tax systems? $\endgroup$
    – NPSF3000
    Commented Sep 28, 2015 at 13:30
  • $\begingroup$ @NPSF3000 It doesn't, but it is under the owner's control, not the control of some other entity. A lot of the time, own efforts are not taxed. $\endgroup$
    – user
    Commented Sep 28, 2015 at 13:38
  • 1
    $\begingroup$ @MichaelKjörling "but it is under the owner's control, not the control of some other entity. A lot of the time, own efforts are not taxed" Even if I accepted this on principle (which I don't) how does your invention differ from solar? Or a small generator? $\endgroup$
    – NPSF3000
    Commented Sep 28, 2015 at 13:46

One interesting development is that it makes transportation cheap. Enabling people to travel more freely.

Another is that it makes currently uninhabitable or marginally habitable places on Earth very viable for large populations (think desert regions on the seacoast - Saudi Arabia & Los Angeles). Cheap electricity makes water distillation plants economical. Or imagine an isolated homestead alone in the Rockies and connected only by microwave relay stations to the outside world. With the excess electrical capacity you melt your water from snow pack. Or perhaps a small village decides to go live on Antarctica. With cheap electricity they could provide for most of their basic needs without outside intervention (a steady diet of seal and penguin might benefit from fresh produce raised in the aquaculture sheds).

Very cheap electricity makes certain space launch infrastructure (e.g. coilguns and launch lasers) a cost effective method of getting into space.

Very cheap electricity makes the production of certain materials much cheaper (think steel & aluminum).

Theoretically given energy and enough of the right chemicals, we could construct food (looks at closed cycle habitats that NASA is working on).

I know you're not so interested in space applications but something like this would be tremendously useful (essential?) to spacecraft, colonies, and stations.

  • $\begingroup$ +1 5+ years on - EV charging is the (or a) killer app. $\endgroup$ Commented Jan 31, 2021 at 10:19

"The cost of the unit rises slightly slower than linearly when plotted against the unit's rated power output" implies there will be HUGE power stations built along bodies of water...much like they are now connected to the same power grid there is now. Taking the quote to its extreme it is possible that a single generator would be built somewhere and wireless transmission would be used to get power to everyone for free, but that would be a political nightmare (whose going to pay the initial costs when anyone can tap the power for free) https://en.wikipedia.org/wiki/Wardenclyffe_Tower.

Desalination would become much cheaper, so more land could be made arable in poor areas so that would be a huge impact.

Electric cars would be instantly more popular.


I'm going to add to the complaint pile. For base load energy sources where most of the cost is capital (not fuel), such as hydroelectric and nuclear power plants, a goal is to get the cost to be around \$4000.00 per KW; on the other hand, $10,000 per KW is considered pretty high and would nearly make electricity non-competitive. For comparison, the massive James Bay hydroelectric complex built by Hydro Quebec (publicly owned) cost \$20 billion and produces 16,500,000 KW, or a bit over \$1000 a KW. Your device runs around \$5000 per KW, so really isn't that great compared to existing power sources. Another problem is you would have to be grid connected to make it worthwhile, because you'd either have to shut it off at night (making it hard to get a payback) or you'd have to sell your night-time energy on the grid to other users (plus 10 KW is a lot for a household to use).

I'd propose that you make the units sell for more like $20k for 10 KW. That would actually be a breakthrough.


What you're describing will have a profound impact, but not on the everyday life. Not directly.

Your fusion refrigerator is too expensive, bulky and weak to be adopted by a wide audience. Even for transportation you'll have to wait for return of investments for too long.

However, they will replace RTGs as a power source of choice for machinery designed to be as non-requiring maintenance as possible. Space probes flying further than Mars orbit, lighthouses in frozen hellholes (though they're using solar now), deep water unmanned installations, etc. Such a discovery will revolutionize how these things are designed and used. And, indirectly, it will affect the everyday life, slightly.


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