根據美國環境保護署的報告,在2013年,美國產生的城市固體廢物量達到了2.54億噸。其中有8700萬噸來自垃圾填埋場的物質被送去進行了垃圾回收和混合堆肥處理,如果這個國家能做的更好呢?如果垃圾填埋場能成為當地清潔能源的生產來源呢?更好的是,如果所有的廢物流,如來自農業、畜牧業和糧食生產方面的,能夠從實質上成為當地燃料精煉廠呢?
這些問題是美國國家實驗室研究人員在合作過程中提出的,他們希望創建能源轉換技術,這項技術旨在從廢物處理過程中獲取碳,從傳統意義上說,碳是我們這個星球上的環境負擔,也是令人類頭痛的廢品。
“利用垃圾作為能源確實不是什么新穎的想法,” 辛西婭 詹克斯說,她是艾姆斯實驗室科學規劃部副主任,也是化學和生物科學分部主任。“例如,一些城市和地區利用已經焚燒的垃圾廢物作為電力來源。但是我們認為,還應該有更好的、更清潔和更有效的方式來獲取碳,并利用它的潛在能量。
2015年,在美國能源部和能源部實驗室舉辦的大創意峰會上,產生了一個新的概念。這次努力,是由艾姆斯實驗室和太平洋西北國家實驗室共同領導下,聯合了美國12家國家實驗室的一項合作,目的是發明一種新的催化技術,可以有效地從廢物流中生產生物燃料。
目標很具體。使技術盡可能簡單,還要適用于不同的廢物流。技術定位就是廢物流,無論它是垃圾填埋場、畜牧場,或商業設施。通過模塊化制造方法,使其容易、經濟的生產和運輸。
“這項技術開發需要多學科共同努力:化學研究、應用工程、模塊化制造、廢物管理、工業、工業和能源部門投資者。這項復雜研究具有多重益處,但我們認為,其中一個好處是提高了我們從這些未充分利用的資源中獲取潛在能源的可能性,以及更加接近國家可持續能源生產目標,”詹克斯說。
為了完成這個目標,所有參與研究的國家實驗室都將竭盡所能,發揮他們在材料和化學科學、高性能計算、工程和應用技術方法的特長。艾姆斯實驗室將通過化學催化與生物科學分部發揮它們在催化研究方面的專長。Igor Slowing和亞倫 薩多兩位科學家已經在生成能夠轉化碳的催化劑方面做了大量工作,具體做法是將催化劑放置在高比表面積的納米材料上。他們想要開發一種工藝,可以將廢聚合物控制分解成有用的碳氫化合物,
“大量進入垃圾場的垃圾是聚合物,如塑料。這些垃圾都富含碳,是已加工材料,如果我們能夠將這些廢物轉化成新的、有利用價值的化合物或能源,就能更好地利用它們。現在,我們把這些碳都浪費了。它們就在垃圾堆里。”亞倫 薩多說。
薩多和Slowing也將采用類似技術來轉化濕污泥和農業廢棄物。
薩多說科學面臨的挑戰是復雜的,需要一種在低溫低壓下操作、高效的化學反應。這些化學反應也需要適應這樣一種情況,即發生反應的原材料是不斷變化的。
“任何廢物流都是高度混雜的,其組成成分隨時間而變化,”薩多說。“我們可以從物理特性上進行分類,然后轉化,有一個分離步驟。一般來說,我們并不知道如何從化學性質上轉化混合物。這是一個非常大、非常有趣也是最根本的一項挑戰,目前本研究還沒有解決這個問題,要去周密思考這個問題非常令人興奮。”
這個大的研究團隊估計,本地化的生物燃料精煉廠將生產少量的生物燃料,大約相當于每天125桶石油,但是這個集合效應可能是驚人的。將國家可利用的廢物流轉化成燃料和其它有用的化學產品,每年能夠轉化成相當于27億桶石油,或美國每年原油消耗量的40%。
“這確實是一個‘大創意’,”詹克斯說。“哪里有廢物,哪里就有能源。我們相信,集合美國各個國家實驗室的集體智慧,包括艾姆斯實驗室化學研究的優勢,這一偉大的創意觸手可及。”
英文原文:
What if America's next big fuel source is its trash?
According to the U.S. Environmental Protection Agency, the United States produced 254 million tons of municipal solid waste in 2013. And though 87 million tons of that material from the landfill was diverted through recycling and composting, what if the nation could do better? What if landfills could become local sources of clean energy production? Better yet, what if all waste streams, like those from agricultural, livestock, and food production, could essentially become fuel refineries at a local level?
It's a question being asked by a collaboration of National Laboratory researchers who want to create energy conversion technologies designed to mine the carbon out of waste processes that traditionally have been an environmental burden to the planet and a disposal headache for humans.
"The idea of using waste as energy source really isn't new," said Cynthia Jenks, Assistant Director of Scientific Planning and Division Director for Chemical and Biological Sciences for the Ames Laboratory. "For example, some municipal and regional utilities already burn landfill waste as a source for electrical power. But we think there are better, cleaner, and more efficient ways to get at that carbon and use the potential energy from it."
A new concept was born of the Big Ideas Summit, held by the Department of Energy and its National Laboratories in 2015. The effort, being co-led by Ames Laboratory and Pacific Northwest National Laboratory, is a collaboration of 12 national laboratories to find new catalytic technologies that can efficiently produce biofuel from waste streams.
The goals are specific. Make the technology as simple as possible, yet adaptable to diverse waste streams. Locate it right at the waste stream source, whether it's a landfill, livestock farm, or commercial facility. Make it easy and economical to produce and deliver through the use of modular manufacturing.
"The idea brings together a lot of overlapping interests: chemical research, applied engineering, modular manufacturing, waste management, agriculture, industry, and energy sector investors. It's a complex idea with a lot of moving parts, but one that we think will get us a lot closer to accessing the potential energy in these underused resources, and a lot closer to the nation's sustainable energy production goals," said Jenks.
To meet the goal, the participating National Laboratories will pool their skills in materials and chemical sciences, high performance computing, engineering, and applied technology. Ames Laboratory will lend the project its expertise in catalysis through its Chemical and Biological Sciences Division. Scientists Igor Slowing and Aaron Sadow have already done extensive work in creating catalysts that are able to convert carbons, by placing catalytic agents on high surface area nanomaterials. They want to develop processes that make possible the controlled decomposition of waste polymers into useful hydrocarbons.
"A large amount of the waste that goes into landfills is polymers…plastics. These are very carbon rich, very processed materials, and if we were to be able to convert that waste into new, useful compounds or energy, that would make much better use of them. Right now, we're wasting all that carbon. It's just sitting there in the trash." Aaron Sadow.
Sadow and Slowing will also be applying similar techniques to the conversion of wet sludge and agricultural wastes.
Sadow said the scientific challenges are complex, with a need for chemical reactions that can be highly efficient, operating at low temperature and low pressure. They will also need to be capable of adapting to changes in the raw material feeding them.
"Any waste stream is very mixed, and its composition varies over time," said Sadow. "We can physically sort and then convert, but then there's that separation step. We don't really know how to chemically convert mixtures in general. That is a really big, interesting, fundamental challenge that research hasn't yet tackled, and that's exciting to contemplate."
While the group estimates that these localized biofuel refineries would produce small quantities of biofuel, an average of the equivalent of 125 barrels of oil per day, the collective impact could be staggering. Transforming the available national waste streams into fuels and other useful chemical products could translate to the equivalent of 2.7 billion barrels of oil per year, or 40 percent of the nation's annual crude oil use.
"That's really the 'big idea,'" said Jenks. "wher there is waste, there is energy. We believe that the collective expertise of the national labs, including the chemical research strengths of Ames Laboratory, puts that big idea within reach."