从垃圾到天然气:填埋区能源项目持续上扬

自然灾害、恶劣天气、生存环境恶化,令人们对地球――这个我们所赖以生存的环境,给予了更多的关注。本期特别策划给大家提供不同视角的环保文章,供大家思考!

1Hundreds of trash trucks across California are rumbling down city streets using clean fuel made from a dirty source: garbage.

2The fuel is derived from rotting refuse that San Francisco and Oakland residents and businesses have been discarding in the Altamont landfill since 1980. Since Nov. 2009, the methane gas created from decaying detritus at the 240?鄄acre landfill has been sucked into tubes and sent into an innovative facility that purifies and transforms it into liquefied natural gas.

3Almost 500 Waste Management Inc. garbage and recycling trucks run on this new source of environmentally friendly fuel instead of dirty diesel.

4In a state that has passed the most stringent greenhouse gas reduction goals in the United States, the climate change benefits of this plant are twofold ― methane from the trash heap is captured before entering the environment and use of the fuel produces less carbon dioxide than conventional gasoline.

5“We’ve built the largest landfill?鄄to?鄄LNG plant in the world; this plant produces 13,000 gallons a day of LNG,” said Jessica Jones, a landfill manager for Houston?鄄based Waste Management. “It will take 30,000 tons a year of CO2 from the environment.”

6Altamont is one of two California landfills making LNG; the other is a smaller facility about 40 miles south of Los Angeles. Other natural gas facilities are being planned by Waste Management at some of the 270 active landfills nationwide, and the number could grow quickly as communities seek to reduce greenhouse gas pollution.

7In 2009, the U.S. Environmental Protection Agency counted 517 active landfill energy projects in the nation’s approximately 1,800 operational municipal landfills. That was up almost 50 percent from 2000, and 28 percent from 2004.

8Landfills have plenty of the ingredients to produce methane. Bacteria break down the food scraps, paper, lawn trimmings and other organic waste dumped there. Over time, the material ferments, releasing methane and other gases. About 50 percent of the gas emitted from landfills is methane. It is 21 times more effective than CO2 at trapping heat in the atmosphere, the EPA said.

9“Methane is the second most important greenhouse gas after carbon dioxide,” Tom Frankiewicz, program manager for EPA’s Landfill Methane Outreach Program in Washington, said in an e?鄄mail. “Methane is also the main component of natural gas, so by capturing and using methane as an energy source you get an even bigger bang for the buck.”

10At the Altamont landfill, seagulls hover over the sprawling complex, set among the rolling green hills and wind farms of the Altamont pass about 50 miles east of San Francisco. Dotted throughout the facility are more than 100 wells with black tubes that vacuum up methane from the heap.

11The LNG is then pumped into the garbage and recycling trucks at a company fueling station in Oakland, while vehicles elsewhere in California get their gas at specially equipped stations.

12The idea of turning garbage into clean energy is not a new one ― the Altamont site has had a methane?鄄fueled electric power plant since 1989 that can power 8,000 homes a day. Hundreds of other landfills in the U.S. also use methane captured from rotting garbage for electricity projects.

13In 2005, the last year data was available, landfill methane electricity projects made up 10.8 percent of the country’s renewable energy output, not including hydroelectric power, EPA said.

14Given its impact on greenhouse gases, four state environmental agencies contributed grants to help build the $15.5 million Altamont plant. Mike Beckman of Linde Group North America, the company that built and runs the natural gas plant, said the Altamont plant should continue producing fuel for 20 years or more.

15That makes the nascent Altamont plant potentially profitable, as the gas is sold to Waste Management and other customers.

16 But to many who may want to use the technology, the cost of purifying the methane into usable liquefied natural gas can be a daunting barrier. The $15.5 million it took to build Altamont’s LNG facility is far more than it costs to build a small electrical plant.

17“There is growing interest, but because removing impurities from the methane is currently quite expensive, right now it’s only profitable at larger landfills where you have enough landfill gas,” Frankiewicz said. “With today’s economics, these projects only happen at the biggest sites in the U.S.; the thought is that as the technology becomes cheaper, that will change.”

1 数以百计的垃圾车在美国加利福尼亚州这个使用清洁能源的城市的街道隆隆驶过,而这个城市的低污染燃料都来自于肮脏的垃圾。

2 这种燃料来自阿尔塔蒙特垃圾填埋场的腐烂垃圾,这些垃圾是自1980年以来被旧金山和奥克兰的居民和企业丢弃于此的。自2009年11月以来,这个240英亩的垃圾填埋场的腐烂碎屑所产生的甲烷气体已被吸入管道,并输进了一套新改良的设备,由其将甲烷净化并转换成液化天然气。

3 已经有近500辆废物管理公司的垃圾回收车使用了这种环保的燃料,而不是肮脏的柴油。

4 在已经通过了美国最严格的温室气体削减目标的状态下,这种工厂对气候变化具有双重好处:一方面,从垃圾堆里产生的甲烷在进入自然环境之前被捕获;另一方面,这种燃料和传统汽油相比产生的二氧化碳相对较少。

5 “我们已经建立起世界上最大的垃圾填埋场向液化天然气转化的工厂;这个工厂一天可以生产1.3万加仑的液化天然气,”负责休斯敦一家废物管理公司垃圾填埋场的经理杰西卡・琼斯说。“它一年将会带走环境中3万吨的二氧化碳。”

6 阿尔塔蒙特是加利福尼亚州两个制造液化天然气的堆填区之一,另一个较小的位于洛杉矶以南约40英里。其他天然气设施由废物管理公司正在全国范围内的270个活跃的填埋区进行筹划。随着各地区寻求减少温室气体污染的进行,这个数字将持续增长。

7 在2009年,美国环境保护局在全国大约1800个经营的城市垃圾填埋场中开展了517项活跃垃圾填埋厂能源项目。这个数字从2000年开始已经增长了50%,自2004年增长了28%。

8 垃圾填埋场有足够的成分产生甲烷。食物残渣、废纸、草坪辅料及其他倾倒的有机废弃物经细菌分解,随着时间的推移,发酵释放出甲烷和其他气体。从垃圾填埋场排放的气体大约有50%是甲烷。甲烷的吸热能力是二氧化碳的21倍,环保署如是说。

9 负责环保局在华盛顿填埋场甲烷拓展计划的项目经理汤姆・弗朗基维克兹在电子邮件中说:“甲烷是仅次于二氧化碳的第二个最重要的温室气体,”“甲烷也是天然气的主要成分,通过捕获并将其作为能源利用,可以一举两得。”

10 在阿尔塔蒙特填埋场,海鸥盘旋在这个庞大的建筑群之上,起伏的绿色丘陵和阿尔塔蒙特风力发电场经过旧金山以东约50英里。整个设施通过100多个带有黑色管道的井来吸收来自垃圾堆的甲烷。

11 然后液化天然气被注入奥克兰加油公司的垃圾回收车内,而加利福尼亚州其他地区的车辆则在有特殊设备的加气站补充液化气。

12 把垃圾转化为清洁能源的想法并不是一个新想法――阿尔塔蒙特自1989年以来就有以甲烷为燃料的电厂,可供8000户居民使用一天。在美国还有其他数以百计的垃圾填埋区也在使用来自腐烂垃圾的甲烷支援电力项目。

13 2005年垃圾填埋场沼气发电项目占全国可再生能源产量的10.8%,不包括水力发电,环保局说。

14 鉴于其对温室气体排放的影响,4个州的环保局共投资1550万美元来帮助建立了阿尔塔蒙特工厂。北美林德集团是一家建立和运行天然气发电厂的公司,公司的迈克・贝克曼说,阿尔塔蒙特厂应继续生产至少可供应20年的燃料。

15 这种新生的燃料使阿尔塔蒙特公司有利可图,因为天然气是出售给垃圾管理公司和其他客户。

16 但是,对那些可能要使用这种技术的人来说,净化甲烷成可用的液化天然气的成本可能是一个令人畏惧的障碍。花费1550万美元建立的阿尔塔蒙特液化天然气设施远远超过了建造一座小型发电厂的成本。

17 “虽然有越来越多的人感兴趣,但是从甲烷中去除杂质的费用目前还相当高,而且它只有在大型垃圾堆填区才有利可图,因为那有足够的垃圾填埋气,”弗朗基维克兹说。“在现有的经济条件下,这些项目只能在美国最大的公司进行;随着科技费用的下降,这种情形将会改变。”