太陽能跟風能無法成為基載，而我一點都不在乎 Of course solar and wind can’t become base load. And I don’t really care
能源轉型ABC系列文之一 Energiewende Basics for Taiwan#1
慶祝本龜終於錄取研究所，這個暑期系列會介紹許多台灣當前能源轉型討論中欠缺的觀念和趨勢，以期讓眾人更能知道再生能源占發電比例20%的2025年可能是怎麼樣的光景。
To celebrate my acceptance into the master program of REM, this summer I shall be sharing concepts and trends of which the discussion of Energiewende lacks in Taiwan, in the hope of shedding some light on what might happen when renewables cover 20% of our island’s electricity by 2025.
「太陽能跟風能無法成為基載，所以能源轉型一定沒有辦法成功。」
So let us begin with the most famous claim of all when discussing the feasibility of an Energiewende in Taiwan:
“Solar and wind cannot become base load, thus Energiewende can never work.”
舉世皆然，如果有甚麼概念是對於能源轉型最大的危害，基載這個觀念可以算是名列前茅的禍害之一。看看這篇文章是怎麼形容的： goo.gl/Rm3vVB
If there is any ratings on what myth harms a global Energiewende the most, the myth of baseload might be just that. Check and see just how the following article puts it: goo.gl/Rm3vVB
在台灣，人們似乎更容易相信「基載電力」的必要性。於是我們便有了底下這個常常在網路論戰中看到的三段論：
一、只有能夠穩定供給、不受天候影響的發電方式（所謂的「基載電力」），才能夠有效減少電力系統的碳排。
二、太陽能和風能無法穩定供給，且受天候影響。
三、所以太陽能和風能無法取代核能的角色；核能的除役就等同必須增加同為「基載」的燃煤發電。
In Taiwan, people seem to be more likely to believe the necessity of a “base load”. Therefore we have the following common deduction on internet discussions:
1. Only sources which give stable supply and are not subject to meteorology (the so-called base load) can effectively reduce carbon emission of a power system.
2. Solar and wind power cannot be supplied stably, and are subject heavily to meteorology.
3. Therefore solar and wind cannot replace the role of nuclear; decommissioning nuclear power plants is equivalent to an increase of coal power, which is the only “base load” alternative to nuclear in Taiwan.
你或許注意到我剛剛的用字遣詞；不管是加上引號、或者是說「基載這個觀念」。因為就我來看，並沒有一種發電方式本質上可以被定義成「基載」的；「基載」這個觀念之所以存在且有效地描述目前台灣的電力系統，是因為過去我們一直都是以核煤為主要的發電方式。
For me, there does not exist a kind of power source which can be inherently defined as “base load”. The reason why the concept of base load exists and can effectively describe the power system in Taiwan is simply because we have been addicted to nuclear and coal in the past.
太陽能和風能永遠不可能落入舊有的「基載電力」框架中，這是不爭的事實。然而，執著於這一點而因此認為能源轉型無法成功的人們，對於能源轉型有本質性的認知錯誤。
There is no doubt that solar and wind can never fall into the existing category of “base load”. However, those who emphasize this point and thereby conclude that Energiewende can never work has a fundamental cognitive misunderstanding of Energiewende itself.
太陽能和風能的歷史任務是甚麼？除了促進能源民主、帶動廣泛的產業轉型（再蓋十座核電廠，台灣也不可能有核工業）、整合各領域專長齊心解決社會問題（還有甚麼發電方式會需要這麼多氣象專家、地質學家、社區溝通嗎）等等明顯的正面效益之外，它們對於電力系統還有一項重要的角色，就是要淘汰「基載」這個過時觀念。
What is the historical mission of solar and wind power? Besides all the obvious advantages, such as promotion of energy democracy, leading a widespread transition of the industry (obviously Taiwan will never be able to develop nuclear industry, even we somehow manage to build ten more nuclear power plants), integration of experts in every aspect into solving a major social issue (what other kind of power source requires so much meteorologists, geologists and social interaction), from the view of power system, they also serve another important purpose: to eliminate the outdated concept of “base load”.
要了解上面這句話，我們必須先知道一個觀念：鴨子曲線（duck curve）。你可以自己維基一下，這個曲線描述了傳統能源發電在陽光旺盛時的一日逐時負載變化：中午時日照充足，傳統能源發電量降低，但是早晨跟黃昏時日照較小，反而使傳統電力的發電量出現峰值。
To understand the words above, let me introduce the duck curve to you. Google it and you shall see that it is a curve which describes the diurnal trend of conventional loading during a very sunny day. At noon, sunlight is strong so conventional load drops, but in the early morning and at dusk sunlight is smaller, so conventional load has two peaks in these two period of time.
這個鴨子曲線似乎被許多台灣人認為是再生能源發展的瓶頸。不過在德國國內的，能源轉型專家則用不太一樣的角度看待鴨子曲線。德國人認為，鴨子曲線確是問題，然而問題從來不是再生能源發太多電，而是傳統能源彈性不足。
For many in Taiwan, this duck curve seems to be the bottleneck of developing renewables. But energy experts view the duck curve with a very different perspective in Germany. The Germans recognize this curve as an issue; the problem, they say, is not that renewables produce too much electricity, but the inflexibility of conventional power sources.
但是，如果一種發電方式被當成「基載」，怎麼可能也被要求同時有所彈性呢？所以德國人已經開始不叫核能和燃煤基載電力了；所有傳統發電方式逐漸被區分成技術限制造成的必載（must run capacity）以及理論上要隨再生能源供電情況和即時電價反映的殘載（residue capacity）。對德國人來說，不夠彈性的殘載才是未來需要日益降低的。
However, if a kind of power source is already being regarded as “base” load, how can you demand it to be flexible at the same time? So the Germans are starting to not call nuclear and coal as “base load”; for them all conventional power sources are now to be split into must run capacity, which is the real technical limit of operating these plants; and residue capacity, which should theoretically response to supply of renewables and real time price signals.
那麼目前德國的情況是如何呢？以上週的傳統能源和殘載的變化為例（圖一），6小時之內要增減10GW已經是家常便飯，有的時候甚至要反映15GW的殘載變化。由於目前主要的殘載彈性只反映在硬煤電廠上（圖二），大部分的情況下，德國還是必須（在尖峰用電時！）將多餘的電出口給其他國家來解決彈性不足的問題。傳統能源對電價訊號反應不足的情況也可以在圖三中看出。
So what is the current situation in Germany? Take the trend of conventional power sources and residue load in the previous week(12. Jun — 19. Jun) for example (graph 1). It is normal that conventional power varies 10GW regularly within 6 hours, sometimes even 15GW. Because the flexibility of conventional response to residue load variation is now mainly achieved from hard coal power plants (graph 2), in most cases, Germany still has to (during a period with maximum load!) export excess electricity to other nations to solve the problem of inflexibility.
以調度彈性來看，地熱、生質能、水力最佳，天然氣次之，燃煤再次之，核能則是最差的一種能源。然而我們不能只看技術層面；經濟層面來說，再生能源進入電網後造成的低收購電價和低功率因子對傳統發電形式也會造成傷害。大型設備的開銷更大，所以低收購電價和低功率因子皆會打擊他們的營運；再生能源邊際發電成本等於零、又有躉購費率支持，相較之下發電就較無顧忌。這也是為甚麼有些人認為只要天然氣用碳稅或最低碳價支持，德國的燃煤發電能夠在市場機制下逐步除役；雖然我個人對論述保有存疑（就規模和時效而言是否足夠？）。
From the viewpoint of dispatch flexibility, geothermal, bioenergy and hydroelectric are among the best, gas ranks the second, coal behind it and nuclear the last. Of course we should not only focus on the technical issues; economically speaking, the penetration of renewables into the grid will cause low wholesale prices and low capacity factors for conventional sources, which both damage it greatly since the operational and installment cost is greater for larger plants; on the other hand, renewables, with zero marginal cost and support of FIT, do not have similar constraints. This is why some claim that with carbon taxes or minimum carbon price supporting gas, Germany’s coal power plants can gradually decommission under market mechanism; although I cast doubt on the scale and efficiency of decommissioning the coal plants that way.
那麼，回到台灣。如果你仔細看一下台灣最近的傳統能源一日變化（圖四），大概界於24到31GW左右。如果政府的用電零成長政策成功，則等到2025年太陽能真的裝了20GW，再加上風能的4GW，按照德國的尖峰發電量和裝置容量的比率，抓個尖峰太陽能到14GW、風能2GW好了，那大概也快碰到淺橘色的頂端（燃煤）。不過，假設2025年底下的粉紅色區域（核能）消失，那麼單純照目前的電力調度邏輯，只讓天然氣做彈性反映是不夠的；甚至可以說，如果要同時達成非核減碳的目標，一定要做類似目前德國的調度方式－必須主要由燃煤電廠反映殘載的變化，而非主要由天然氣反映。
OK, let’s get back to Taiwan. If you take a closer look of Taiwan’s recent diurnal trend of conventional load (graph four), it should be between 24 to 31 GW. If electricity demand remains the same in 2025, and that installed solar capacity reaches 20 GW and wind 4 GW, let’s take peak solar supply 14GW and wind 2GW to do the math. We see that will make the residue load lie somewhere near the top of the light orange line (coal). However, should the pink area(nuclear) disappear in 2025, then it would be insufficient to continue the existing dispatch rules and let mainly the gas take flexible responses, if we are to achieve carbon reduction simultaneously with a nuclear phase out. We must, similar to what the Germans are doing right now, let the coal power plants do the main flexible response to residue load.
有足夠的證據使我們相信，以上的調度邏輯是接下來台灣能源轉型中期的做法。工研院綠研所在一次簡報中這麼說明政府為甚麼燃煤電廠裝置容量增加，但發電量依然可以降低。如果你執著於把燃煤當成「基載電力」，這樣的說法自然是荒謬至極（當然，是否所有計畫中的燃煤裝置容量真的都是必要的，可以再討論與盤點，重點是根據甚麼樣的供需模型，估計出燃煤發電的裝置容量有需要那麼多）。
There is evidence that the dispatch rule mentioned above might be how Taiwan manages its mid-term Energiewende. Some government agents mention it in their presentation to explain why the installed capacity of coal power plants might increase, but total power production by coal can still decrease. If you regarded coal as “base load”, such claims would be ridiculous. (Of course, whether or not all the planned installed capacity are necessary can be questioned and verified.)
所以，我們替本文作結。風和太陽能無法取代核煤成為「基載電力」，但當它們發展到一定的程度時，使用基載這個觀念的意義也不大。
Let us conclude this article. No, wind and solar can never replace coal and nuclear as “base load”, but when they do grow to a significant scale, it gradually becomes meaningless to use the concept anyway.
不過，德國人的傳統電廠彈性不足時，還有鄰國可以支援；做為獨立電網的台灣，2025以後的供需調度會如何處理呢？我下次再跟各位分享可能的情況。
But wait! The Germans has an entire continent to digest their inflexible conventional surplus, but how should we, as a more isolated power grid, manage our supply and demand balancing? Perhaps that’s another subject I can write about next time.
2018年4月11日後記：
稍早發現自己一年前的文章被大量流傳，《風光無法成為基載》是我剛申請上研究所的為文，行筆之間自然有股豪情，不到一年過去再看，早已覺得過於氣盛。但這當然是我內心小劇場而已，不應做為判讀文本的太大依據。
這一年下來，我對於殘載的問題看法並沒有太大的改變（雖然我最近想開始朝博弈理論來論述儲能或傳統電廠彈性兩者的先後緩急），但對於「破除迷思」這件事情，甚至是我在能源轉型過程中戰略上的角色，看法已經大不相同。
簡單來說，我認為「破除迷思」最有效的方式，是告訴別人自己提供的可能性是更健全、更完善、也可以被實踐。恆闢謠者，則永遠處在被動的位置，無法主導論述方向。
更進一步來說，「行文以證明對手是錯誤的」這種思維，對於當前整個戰略，意義不大。我們要做甚麼已經十分確定，重點是我們要怎麼做到。
面對迷思，需要提出已有和發展中的可行方案，如果這些方案開始被攻擊，「被闢謠」，某方面來說就是一種邁進。
所以，請把我接下來的專欄（《那些》文中有提）當成一場學習之旅的紀錄（某方面也是事實，畢竟算是在順便找論文主題）。至於學到的東西別人會覺得是黃金還是黃金（另一種意義的），只能說，事在人為。
再補記：
另外有留言區的人提到一篇德文的系列文章之二， Das “Energiewende-Paradox”: dreckig schlägt teuer。這個系列文有討論到再生能源對批售電力市場的劇烈變動，其實也算是印證基中尖載的概念在德國已經很難適用。
德國過去因為沒有適當政策，讓燃氣發電的低碳優勢無法顯現，所以和燃煤相比較難在市場上競爭，以至於綠能替代燃煤的成效不彰，這就是文章標題「dreckig schlägt teuer」的原意，並非是在說褐煤等非彈性機組在電力系統有必要存在(「基載」的思維)。
年初被凍結成「緊急備用機組」的褐煤機組，占了德國現役褐煤裝置容量的13%，凍結至今根本沒有被動用過，也是對非彈性機組必要性的直接反例。
也可以再深入討論該文寫成後3年的發展：煤氣相爭的狀況已有改善(燃煤發電目前正逐年下降)，不過燃氣發電佔比依然遠低於燃煤，因此批售電力市場仍應改進。
過去我即曾提過，解決煤氣相爭的問題在於更好的碳價格或政策上制定除煤時程；德國地底下的褐煤太多，要做到這件事情，政治魄力要夠。不過，如果真的提高燃氣佔比而降低燃煤佔比，對於電力系統的彈性也會大有助益，因此德國在未來應該還是會朝這個方向發展。
