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Bitcoin挖矿是浪费的电力

作者:fjbit 来源:未知 日期:2011-9-23 9:57:38 人气: 标签:Bitcoin挖矿 【打印】

 

在本系列的最后 一部分,我谈到为什么Bitcoin网络所使用的电力,是不是像一些人认为,造成不必要的浪费。现在,让我们来看看到底有多少电力被利用起来。据挖掘硬件对照表,最好的采矿电脑可以执行2.5%焦耳megahashes 。整个网络 每秒3.5 terahashes,因此,假设在现实中挖掘的是,平均而言,作为最大休闲CPU矿工和使用不理想的GPU人(0.5 Mhash / J)高效的第五,我们得到了一个700万的数字焦耳每秒,或7000千瓦。随着发电成本每千瓦时11美分,我们发现,保持每天约18480美元的网络成本。这是昂贵的:在目前的8.3美元/ BTC汇率,250000 BTC在过去24小时内发送,或$ 2.08亿美元,我们得到了一个1%的平均交易成本。

即使这是一个误导的数字:正如我前面提到的,大多数bitcoin交易,不这样做,事实上,完全代表一个人到另一个发送 bitcoin。做进一步研究,因为写这篇文章时,我发现交易超过背后的原因:每一笔交易都必须与前一个交易,所以当你收到200000 BTC一次,花1000,系统将创建1个输入交易200000 BTC你收到了,和两个输出,1000到收件人199000回另一个你自己的地址 。因此,如果那些200000 BTC慢慢花,一次一个万,201万BTC的交易量将会看到 。这是一个极端的例子,这是很难分辨平均情况下是什么,因为它取决于精确分布上的交易规模和人们如何花自己的钱,但总的原则适用于。真正的交易成本可能会高达10% 。

这是极端的,但我相信问题将在短期内大幅减少,甚至更长远 。Bitcoin是在短期内,将成为一个更专业的企业:0.3.22 Bitcoin 版本将删除“生成硬币”从客户端的GUI选项(虽然产生硬币的能力仍然是在命令行 ), 从公式中删除休闲CPU矿工 。在经济上,CPU的开采已经没有意义,而且大多数的CPU矿工这样做,因为他们没有意识到挖掘是无利可图,因此消除了CPU的矿工,让市场来执行的能源效率标准,因为没有他们,人人参与,将是一个专业的矿工计算开采与否将是有利可图的。市场将继续被越来越多的优化:由于GPU开采变得越来越多的营利性企业更矿业公司,上市的GLBSE,更高端的采矿电脑将成为越来越多的必要,和低端矿工将被迫关闭采矿收入接近成本。FPGA采矿承诺的20%焦耳megahashes的价值,但我将在我的分析中忽略这些到目前为止,他们的患病率将增加难度,抵消了能源效率的提高,影响这将需要数周时间,自己解决问题 。如果平均开采效率提高到2%焦耳megahashes,交易成本将降低至0.25%,或与我们的保守估计,2.5% 。

不过,也有从那里,可以提出两个进一步改进:第一,是用于矿山电力最终以热量的释放。因此,它可能会成为标准的做法,为了这个目的预先设定的下载包,在寒冷的气候家园开启GPU的采矿(低优先级,使网页浏览和其他计算会优先考虑,而不是被它阻碍 ) 其供热系统的一部分,使电力基本上是免费的,因为它本来用于主要的采暖系统。其次,存在的超级计算机在运行超过每瓦500 megaflops -率12.7%哈希触发器用在这里,40%焦耳megahashes。这似乎是它会使Bitcoin采矿占用少得多电力,但是,就像FPGA矿工,这是不是这样的:如果的开采bitcoin成本的降低,采矿将更加有利可图,因此会有更多的矿工,直到盈利回报这是什么之前,(我将在下面详细解释)。重要的是再次提醒自己的CPU矿工的损失不遵循这一原则,因为CPU矿工休闲用户和不经济的盈利计算。

但是,一旦市场稳定,可以增加或减少对电网的电费开支?让我们考虑的经济计算,矿工从第一的原则,:

1)收益>成本
2)集体创作奖励*块创造机会>电力开支瓦* 600(1块),每10分钟每焦耳*美元
3)BTC价格*(货币创造+交易费)*矿工Mhash / S /网络Mhash / S>瓦* 6 *美分,每
焦耳4)BTC价格*(货币创造+交易费)*矿工Mhash / J>平均Mhash / S * *美分每千瓦时/ 60万矿工人数

让我们的简化假设,即所有的矿工有平等Mhash / S和Mhash / J 后者应自然发生的矿工转移到可能的最好的装备,前者可以有理由说,一个强大的矿工是相当于一百正常矿工。

5)BTC价格*(货币创造+交易费)*矿工Mhash / S /瓦>矿工Mhash / S *矿工的数量* / 600000每
千瓦时6 美分)BTC价格*(货币创造+交易费)>瓦*数量矿工*美分每千瓦时/ 60万
7)网络功耗<BTC价格*(货币创造+交易费)/每千瓦时* 600000美分

随着市场接近充分的效率,网络功耗的限制将等于右边的表达式。这是什么告诉我们什么?从本质上讲,网络成本功耗是不影响在所有的技术水平,它是通过创造新的块收入不仅影响。

眼下,采矿业的需求,是人为的,因为50创建一个新的块的 BTC的奖励高。然而,这个值是下降到2013年25 BTC,指数继续减少 。当货币创造达到零,会发生什么 ?从长远来看,一旦这种奖励消失,什么样的水平,市场交易成本安顿下来呢?不提供的交易费用自然水平的市场,我们已经推导出的方程 。从逻辑上讲,答案是包括在一个块中的事务,反对不包括它的概率划分,矿工会是一个解决块,或简化,电力成本散列乘以交易的电力成本矿工的数量 。此值将永远不会达到,因为这将导致在所有矿工的损失,但交易成本将接近它,也许会在一个量级 。交易不需要散列每次试图解决块,幸运的时间-如果是这样的话,那么将是一个强有力的激励矿工不包括任何交易 。以随机抽样在这里,平均成交7500字节长相当于60哈希(80字节,四舍五入到128 SHA256算法)或30块的解决尝试。眼下,解决由网络完成的哈希块数目是每秒3.2 万亿美元 ,而交易的数量,包括哈希:

0.06秒* 60%的交易相当于哈希交易的矿工人数

我们会估计后面的数字,扣除休闲CPU的矿工,被作为:

3,000,000 Mhash / s的每台计算机的Mhash / S(估计数字)* 0.4(池)/ 100 = 12000

这给我们带来了每秒43200交易哈希,解决块的3.2万亿美元相比微不足道。因此,理论的平均交易费用非常低,比我们现在看到的采矿收入。因此,在很长时期内可能出现有三种情形:

  1. 交易费用介于接近这个最低,和网络的功耗非常低 - 比我们现在还要小。
  2. bitcoin客户端执行任意高的值(如0.0005 BTC现在可能更低)最低交易费,并希望近即时接受的交易,相互竞争,使得许多交易费用最低的倍数。
  3. 人们提供了交易费用,仁慈,了解,有相当数量的矿工是必要的网络安全(我会稍后)和交易的收入是可观的,也许只要50 BTC总高。

平均总交易收入现在从一个随机块探险样本,每块0.038 BTC。因此,没有货币创造的收入,现在网络的力量会下降1315倍,为2.73 Ghash / S,或每天14元。因此,我们似乎是在目前的第二个场景,所以第一次似乎不太可能占据上风。

重要的是要保持头脑多大的权力,我们应该有blockchain工作:比任何单一的攻击者可以鼓起 。重要的是要注意的是,在采矿的经济无处是这个值的计算,所以,提供安全保障,我们将不得不依靠竞争和仁。然而,网络的安全性会增加不仅与采矿量,但也与采矿类型-一个更加专业的矿业经济,GPU和超级计算机,更强劲。专门的超级计算机矿工和图形用户界面矿工的作用其实是非常相似,菲亚特货币薄荷-只是作为法定货币的薄荷生产与全息技术和其他技术,传统的打印机不具备的法案,专门矿工会安全的网络与计算效率,攻击者没有。

有两个可能的威胁Bitcoin块链:僵尸网络和政府。僵尸平均电脑上运行,他们需要远远低于100%的CPU运行仍未被发现的,所以作为网络变得更加专业,他们会变得越来越弱。另一方面,各国政府,是一个潜在的问题 - 如果挖掘到属于大型机构的控制,各国政府已迫使大机构暗中操纵网络,为他们服务,电力,他们没有权力,在实践中,按住对个人的。但如果Bitcoin变得如此重要,那么它很可能,一些政府将提供网络计算能力,仁慈,以防止攻击其他国家的政府。眼下,这是所有的猜测,我们将不得不重新审视这个问题在几年,当我们看到什么Bitcoin矿工的人口统计数据,实际上最终被。

可以说,有必要为Bitcoin开始保护块链强大的矿业界,而它仍然是新生,但最终的长期趋势是Bitcoin挖掘网络,相对于作为一个整体的Bitcoin系统,将减少在规模和重要性。这是事实,在采矿业的兴趣是目前增长非常迅速,但由于突然增加Bitcoin价格,其中,正如我们推断,矿工的数量的增长,成为成正比,这是一个短期趋势。从长远来看,Bitcoin价格的增长将趋于稳定,Bitcoin经济将增长,我在本文开头谈到的1-10%的交易成本不会持续。

以上GOOGLE翻译,英文原文如下:

In the last part of this series, I talked about why the electricity used by the Bitcoin network is not, as some believe, as unnecessary waste. Now, let us see just how much electricity is being used up. According to the mining hardware comparison table, the best mining computers can perform 2.5 megahashes per joule. The entire networkdoes 3.5 terahashes per second, so assuming that in reality mining is, on average, a fifth as efficient as the maximum (0.5 Mhash/J) with casual CPU miners and people using suboptimal GPUs, we get a figure of 7 million joules per second, or 7000 kW. With an electricity cost of 11 cents per kWh, we find that maintaining the network costs about $18480 per day. This is expensive: at the current 8.3 USD/BTC exchange rate, 250000 BTC sent in the past 24 hours, or $2.08 million USD, we get an average transaction cost of 1%.

Even this is a misleading figure: as I have previously mentioned, the majority of bitcoin transactions do not, in fact, entirely represent one person sending bitcoin to another. Doing further research since writing that article, I have found the cause behind the excess in transactions: every transaction must be linked to a previous transaction, so when you receive 200000 BTC all at once and spend 1000, the system creates a transaction with 1 input, the 200000 BTC you received, and two outputs, 1000 to your recipient and 199000 back to another one of your own addresses. Thus, if those 200000 BTC get slowly spent, one thousand at a time, a transaction volume of 201 million BTC will be seen. This is an extreme case, and it is difficult to tell what the average case is since it depends on the precise distribution of the transaction sizes and how people spend their money, but the general principle applies. The true transaction cost may be as high as 10%.

This is extreme, but I believe the problem will decrease considerably in the short term, and even more in the long term. In the short term, Bitcoin is set to become a much more specialized enterprise: version 0.3.22 of Bitcoin will remove the "generate coins" GUI option from the client (although the ability to generate coins is still there in the command line), removing the casual CPU miners from the equation. Economically, CPU mining already does not make sense, and most CPU miners do so because they do not realize how unprofitable mining is, so removing CPU miners allows the market to enforce a standard of energy efficiency since without them everyone involved will be a professional miner, calculating whether or not mining for them will be profitable. The market will continue to be more and more optimized: as GPU mining becomes more and more of a for-profit enterprise, with mining companieslisted on the GLBSE, the higher end mining computers will become more and more necessary, and the lower end miners will be forced to shut down as mining revenue approaches cost. FPGA mining promises a value of 20 megahashes per joule, but I will ignore these in my analysis so far; their prevalence will increase difficulty, counteracting the energy efficiency gains, and the effects of this will take weeks to sort themselves out. If the average mining efficiency increases to 2 megahashes per joule, the transaction cost will reduce to 0.25%, or, with our conservative estimate, 2.5%.

From there, however, there are two further improvements that can be made: first, the electricity used to mine is ultimately released as heat. Therefore, it may become standard practice, with downloadable packages preconfigured for that very purpose, for homes in cold climates to turn on GPU mining (on a low priority, so web browsing and other computations would take precedence and not be impeded by it) as part of their heating system, making the electricity essentially free since it would otherwise be used by the main heating system. Secondly, there exist supercomputers that run atover 500 megaflops per watt - with the rate of 12.7 flops per hash used here, 40 megahashes per joule. This seems like it will make Bitcoin mining take up far less electricity, but, just like FPGA miners, this is not the case: if the cost of mining bitcoin decreases, mining will be more profitable, so there will be more miners until profitability returns to what it was before (I will explain this in more detail below). It is important to remind ourselves once again that the loss of CPU miners does not follow this principle because CPU miners are casual users and do not make economic calculations of profitability.

But, once the market stabilizes, what can increase or reduce the electricity expenditure of the grid? Let us consider the economic calculations that miners make, from first principles:

1) Revenue > Cost
2) Block creation reward * block creation chance > power expenditure in watts * 600 (1 block per 10 min) * dollars per joule
3) BTC price * (money creation + transaction fees) * miner Mhash/s / network Mhash/s > watts * 6 * cents per joule
4) BTC price * (money creation + transaction fees) * miner Mhash/J > average Mhash/s * number of miners * cents per kWh / 600000

Let us make the simplifying assumption that all miners have equal Mhash/s and Mhash/J. The latter should occur naturally as miners shift to the best gear possible, and the former can be justified by saying that a powerful miner is equivalent to a hundred normal miners.

5) BTC price * (money creation + transaction fees) * miner Mhash/s / watts > miner Mhash/s * number of miners * cents per kWh / 600000
6) BTC price * (money creation + transaction fees) > watts * number of miners * cents per kWh / 600000
7) network power consumption < BTC price * (money creation + transaction fees) / cents per kWh * 600000

As the market approaches full efficiency, the limit of network power consumption will be equal to the expression on the right. What does this tell us? Essentially, the cost network power consumption is not influenced at all by the level of technology, and it is only influenced by the revenue of generating new blocks.

Right now, demand for mining is artificially high because of the 50 BTC reward for creating a new block. However, this value is set to decrease to 25 BTC in 2013, and continue decreasing exponentially. What happens when money creation reaches zero? In the long term, once this reward disappears, what level would the market make the transaction cost settle down to? The equation of the market that we have deduced does not provide for a natural level of transaction fees. Logically, the answer is the electricity cost of including a transaction in a block as opposed to not including it divided by the probability that that miner will be the one that solves the block, or, simplifying, the electricity cost hashing a transaction multiplied by the number of miners. This value will never be reached, since it would result in a loss for all miners, but transaction costs would approach it, perhaps going within one order of magnitude. Transactions do not need to be hashed every time an attempt at solving the block is made, fortunately - if that were the case, then there would be a strong incentive for a miner not to include any transactions. Taking a random sample from here, the average transaction is 7500 bytes long equivalent to 60 hashes (80 bytes, rounded up to 128 by the SHA256 algorithm) or 30 block-solving attempts. Right now, the number of block solving hashes done by the network is 3.2 trillion per second, while the number of transaction including hashes is:

0.06 transactions per second * 60 equivalent hashes per transaction * number of miners

We will estimate the latter figure, discounting casual CPU miners, as being:

3,000,000 Mhash/s * 0.4 (not in pools) / 100 Mhash/s per computer (estimate) = 12000

This brings us to 43200 transaction hashes per second, an insignificant amount compared to the 3.2 trillion done to solve the block. Thus, the theoretical average transaction fee is extremely low compared to the mining revenue we see right now. Thus, there are three scenarios that could arise in the very long term:

  1. Transaction fees are somewhere close to this minimum, and the network power consumption is very low - even smaller than what we have now.
  2. The bitcoin client enforces a minimum transaction fee at an arbitrarily high value (eg. the 0.0005 BTC it is now; probably lower then), and transactions hoping for near-instant acceptance compete with each other, making many transaction fees multiples of the minimum.
  3. People offer transaction fees benevolently, understanding that having a substantial number of miners is necessary for network security (I will get to this later) and transaction revenue is substantial, perhaps as high as 50 BTC total.

The average total transaction revenue right now, from a random block explorer sample, is 0.038 BTC per block. Thus, without the money creation revenue, the network power right now would fall by a factor of 1315, to 2.73 Ghash/s, or $14 per day. Thus, we seem to be at the second scenario at the moment, so the first seems unlikely to take hold.

It is important to keep in mind just how much power we should have working on the blockchain: more than any single attacker could muster. It is important to note that nowhere in the economics of mining is this value calculated, so we will have to rely on competition and benevolence to provide security. However, the security of the network will increase not only with the amount of mining done, but also with the type of mining done - a more specialized mining economy, with GPUs and supercomputers, is more robust. The role of specialized supercomputer miners and GUI miners is in fact very similar to that of a fiat currency mint - just as a fiat currency mint produces bills with holographic and other techniques that conventional printers do not have, specialized miners will secure the network with computing efficiency that attackers do not have.

There are two possible threats to the Bitcoin block chain: botnets and governments. Botnets run on average computers, and they need to run far below 100% CPU to remain undetected, so as the network becomes more specialized they will become weaker and weaker. Governments, on the other hand, are a potential problem - if mining falls into the control of large institutions, governments have the power to compel large institutions to secretly manipulate the network to serve them, a power which they do not, in practice, hold over individuals. But if Bitcoin becomes that important, then it is likely that some governments will provide computing power to the network benevolently, in order to prevent other governments from attacking it. Right now, this is all speculation; we will have to revisit this question in several years when we see what the demographics of Bitcoin miners actually end up being.

Arguably, it is necessary for Bitcoin to have a strong mining community at the start to protect the block chain while it is still nascent, but ultimately the long-term trend is that the Bitcoin mining network, relative to the Bitcoin system as a whole, will decrease in size and importance. It is true that interest in mining is growing very rapidly at the moment, but this is a short-term trend due to the sudden increase in Bitcoin prices, which, as we have deduced, the number of miners grows to become proportional to. In the long term, Bitcoin price growth will stabilize, the Bitcoin economy will grow and the 1-10% transaction cost that I talked about at the start of this article will not last.

 

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