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Comment by Certhas | Hacker News Reader

The author is absolutely wrong on power grids. The power grid is over-provisioned in the sense that it has a lot of power on stand by. The physical electrical grid is really balanced more or less instantaneously. Inertia in generators together with droop control take care of this balancing process. But you really do burn less fuel when there is less demand.

The energy is not wasted, it is ordered, not demanded and thus never produced. If it were produced it would actually be extremely difficult to get rid of this much energy. You can't just easily dump energy.

As the author is waving their credentials around, I am an active researcher on renewable power grids. It's a bit scary to think that someone with such a basic misunderstanding of the power grid was asked to referee a paper on this, but then a lot of marginal research is published everyday and referees have to come from somewhere...

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I want to add two things:

- The visualization used by the author shows US energy consumption while ~65% of mining takes place in China[0] where burning coal remains the dominant energy source.[1]

- Miners run 24/7/365, they add to the baseload!

[0] - https://www.statista.com/statistics/1200477/bitcoin-mining-b...

[1] - https://www.eia.gov/international/analysis/country/CHN

Can't china dump solar panel on its own market so miners run off grid and clean ?

I guess you have made a wrong conclusion: coal dominance in total does not conclude to coal dominance for mining. Because mining factories are very sensitive about the energy price, they are mostly built near locations where energy is cheap enough and will be wasted if not consumed locally by the mining or transmitted to other places in time.

People keep saying this yet https://www.aljazeera.com/economy/2021/1/22/iran-crypto-mine...

98 % of the electricity in Iran is generated from burning either gas or oil. https://www.eia.gov/international/analysis/country/IRN

Additionally assuming this power is rejected through shunts (effectively resistor banks) this power is from peaking plants shutting down or over provisioned baseload thermal plants.

The only way Bitcoin would use this energy is if they had a contract with the power company to be an on-demand load, switching on and off to help smooth the peaks.

If they aren’t they’re just driving up power use and forcing more operation of less efficient reserve generation on peak.

I understand that a lot of the servers are close to large hydro plants. Under-utilised hydro plants can simply spill water - they spin up and down rapidly compared to thermal plants.

> The only way Bitcoin would use this energy is if they had a contract with the power company to be an on-demand load, switching on and off to help smooth the peaks.

But that is exactly how power plants are using Bitcoin. That's the idea behind Seetee.

Isn't that a waste of the capital used for the Bitcoin mining hardware itself? Why would a miner shut down their profitable operation simply because a coal plant turned on?

The miner and the power plant operator are often the same entity. They turn the mining equipment on when they want to dump energy, and off when they have more productive places to sell it. Seetee is a good example.

If you own the mining hardware, why would you do that? You are better off running that hardware 100% of the time (using batteries or similar when necessary). Mining hardware is expensive.

Only when you are actually better off. isn’t there a crossover point between the outside market needing/paying for electricity and mining? Or is mining the most effective return in all cases?

Animats explained the meaning of rejected energy in the diagram below. It's efficiency losses in the entire system (I wasn't aware of this terminology). The actual size of load balancing energy used is quite small.

I didn't know about Seetee but potentially there are some minor opportunities to mine bitcoins (effectively as an on-demand load) to help balance the grid at short time scales. It also makes sense for a Norwegian Energy company to do this. However this is a tiny amount, especially compared to the efficiency losses the author is presenting in the graphic. I looked up some data I had handy right now and I think we are looking at a few percent of the overall energy consumed at most.

Do you know if the graph in the article is accurate, and what is meant by "rejected" exactly?

What surprised me is that "Transportation" in that graph is supposed to "reject" over 22% of its energy, which seems odd to me. For electricity I get it, it's hard to store so if you have excess production there's not much you can do. If your wind turbine can't dump its energy anywhere it's just lost, usually. But for petroleum can't you just... not use it?

As such I wonder if "rejected" means all losses? In which case it's unclear how bitcoin would fit into that.

In general I think the author doesn't make a good enough case. He'd have to show not only that there's enough loss to power the bitcoin network, but also that bitcoin actually slots into these losses instead of adding to the demand.

They mean rejected heat. That's basic thermodynamics. See "Carnot efficiency". Maximum possible efficiency of a heat engine is

    (Tin - Tout) / Tin.

Temperatures are from absolute zero. This applies to all forms of heat engines. Large power plants run steam around 840°K. Typical outside temperatures are around 280°K. So maximum possible efficiency for steam plants at achievable temperatures is around 66%.

Actual numbers for coal, oil, and nuclear plants run lower, maybe 40%. The most efficient natural gas plants come close, around 60%, by running at higher temperatures and avoiding conversion to steam.[1]

[1] https://www.brighthubengineering.com/power-plants/72369-comp...

Ok, but if that's the article's argument it really makes no sense, no? How would the author propose harvesting these various losses to mine cryptocoins?

It's a really weird take if that's what the author is saying.

That's what the diagram copied from Lawrence Livermore National Labs says about rejected heat. What the article author is trying to say is something else entirely.

It's mostly these sentences (in relation to that diagram) that I really fail to understand:

>If Bitcoin used only wasted energy it would consume >2/3rds of the energy of the planet.

>This is why hand-wringing about Bitcoin’s energy use is so frustrating. Bitcoin is pointing at the moon and people are yelling at its finger. The self-congratulatory ignorance I see in this debate is unreal.

I don't get what it means or what point the author tries to make here.

The best I can guess is that the author is mixing up load balancing through reserve energy and efficiency losses. The amount that is reserved for load balancing is also not anywhere near the size they are talking about.

How would you characterize rejected energy, if not wasted? What is your take on Seetee?

What is Seetee and why is it relevant to this discussion (genuine question, I don't know)?

A new Bitcoin mining company founded by a Norwegian energy company, focused on Bitcoin and renewables.

That doesn’t explain how it’s relevant.

> The energy is not wasted, it is ordered, not demanded and thus never produced.

There is no rejected energy. If there is an overproduction of energy, the price goes down (it may even go negative), and industries will consume the energy.

According to Lawrence Livermore Labs 2/3rds of all energy produced is rejected. There is a graphic in the article.

"Rejected" does not mean that the energy gets sent back to the producer like a parcel.

"For a coal fired power station, for instance, about 2/3 of the energy released when the coal is burnt is discarded as heat in the environment. This reject energy sometimes appears as clouds of vapour coming off a power-station’s cooling towers, such as the well-known ones at Didcot in England."

-- https://energycultures.org/2014/07/rejected-energy-much-ener...

This is a complete misinterpretation of the graphic. The "Rejected Energy" are the losses that occur when converting primary energy on the left into useful energy on the right. In a car, for example, this would be the difference between the chemical energy contained in the gasoline and the mechanical energy used to accelerate the car and overcome the drag during driving. In a thermal power plant it would be the difference between the heat released when burning the fuel and the electricity produced.

As others have pointed out, the power grid does not even have the capability to "burn off" excess power. It is simply nerver produced in the first place.

The graph is absolutely meaningless to me without further contex. So, the electric grid generates 12.7 "units". If we subtract solar, wind and hydro then we get down to 6.42 "units". I have chosen these because they are not thermal power sources. These power sources generate an almost equivalent amount of primary energy and electricity. So we are left with 6.42. 6.42/31 is 20%. Where are these 20% efficient power plants? Nuclear alone would be 30% efficient. Combined cycle gas is 50%. The numbers make no sense to me.

Edit: Ok I read the note at the bottom and the graph literally adjusts the rejected energy of renewables to match thermal power plants. Assuming 33% efficiency that means 12.56 phantom units of energy that never even existed in the first place are being rejected.

Thermodynamics is why. It’s not because of running big resistor banks.

Every time I play Tomb Raider I'm rejecting 300 watts per hour. How do you propose turning that into Bitcoin?

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