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绿色能源与燃煤发电:燃煤电厂该何去何从

更新时间:2019/2/24 10:11:45 来源:纽约时报中文网 作者:佚名

The giant coal plant converting to green energy
绿色能源与燃煤发电:燃煤电厂该何去何从

On the train to visit one of the last places in Britain that burns coal for electricity, I pass three solar farms soaking up sunshine. I also pass a coal plant called Eggborough that has all but ceased operations. No steam rises from its giant cooling towers. It will shut in September.

我乘火车去参观英国最后几个烧煤发电厂之一,经过了三个正在吸收阳光的太阳能发电站。我还路过了一个叫艾格伯勒(Eggborough)的燃煤电厂,它几乎已经停止了运行。巨大的冷却塔上没有蒸汽升起。它将于九月关闭。

But the coal plant I’m visiting is different. It’s named Drax, after a local village, and is the largest power plant in Western Europe. By 2023, its owners plan to stop burning coal entirely. They hope that instead their plant will consume only natural gas and biomass – wood pellets crushed into powder.

但我要参观的这家燃煤电厂不同。它以当地一个村庄的名字德拉克斯(Drax)命名,是西欧最大的发电厂。到2023年,电厂主人计划完全停止燃煤。他们希望自己的发电厂将只消耗天然气和生物燃料——碾成粉末的木屑颗粒。

The European Union has some key targets for reducing pollution in the coming decades and coal power plants have been earmarked for closure by many countries seeking to meet these objectives. In the UK, government plans mean coal-fired electricity generation will end by 2025.

未来几十年里欧盟有一些减少污染的重点目标,许多国家已指定关闭燃煤电厂,以实现这些目标。在英国,政府计划到2025年结束燃煤发电。

A similar story is unfolding elsewhere in the world. Many nations, including the US, are moving away from coal as other energies become cheaper and as environmental regulations cool the market for this fossil fuel.

类似的故事发生在世界其它地方。包括美国在内的许多国家正在远离煤炭,因为其它能源变得越来越便宜,而环境法规也让这种矿物燃料的市场遇冷。

But this leaves a big question: what do we do with all of those old power stations?

但这留下了一个大的问题:我们该如何处置那些旧的发电厂呢?

For the past century, these facilities have been huge players in the world’s energy market. The plants have expensive connections to national grids – meaning that simply knocking them down might not be so smart. Many, including Drax’s management, are insisting that there is another way.

过去一个世纪以来,这些电厂一直是全球能源市场的重要参与者。这些电厂接入国家电网花费昂贵,这意味着简单地拆除它们可能并不明智。许多人,包括德拉克斯电厂的管理层,都坚持认为还有另一种方式。

The scale of Drax is immediately apparent. On either side of the huge buildings that house its boilers and turbines stand six beige cooling towers. White steam drifts skyward. In the middle of the complex stands a 259m-tall chimney. And at the back of the facility there is a huge pile of coal – but staff members tell me it is much smaller now than it once was.

德拉克斯的规模是显而易见的。在容纳锅炉和涡轮机的巨大建筑两侧,矗立着六座米色冷却塔。白色的蒸汽飘向天空。在厂房的中央矗立着一个高达259米的烟囱。电厂背后有一大堆煤——但是工作人员告诉我,现在比以前少了很多。

Coal is left here until it is brought into the power station on conveyor belts, ground up and burnt at ferocious temperatures. The furnace heats up water, turning it into steam that rushes through a complex system of pipes and spins turbines at a steady 3,000 revolutions per minute. It’s an easy way of producing electricity. It’s also a dirty one.

煤炭被放在这里,直到它被传送带运到发电站,碾碎并在高温下燃烧。熔炉把水加热,使其变成蒸汽,通过复杂的管道系统,使涡轮机以每分钟3000转的速度稳定旋转。这种发电方式很简单,但污染严重。

Energy shift

能量转换

This is a large part of why coal’s days here really are numbered. In April, Britain went for more than three full days without any coal power at all – a decline that has happened far more quickly than many expected. This trend has meant that since the start of 2018, the country has managed a total of 1,000 hours without coal energy, already topping last year’s tally.

这在很大程度上解释了为什么这里用煤炭的日子真的屈指可数。今年4月,英国整整3天没有使用任何燃煤发电——下降的速度远远快于许多人的预期。这一趋势意味着,自2018年初以来,英国总共已经有1000小时不使用煤炭能源,已经超过了去年的记录。

“In 2012, coal-fired generation was 45% of the power mix,” says Matthew Gray at Carbon Tracker, a think tank. “Today it’s at a very low amount.”

“2012年,燃煤发电占了能源组合的45%,”智库机构“碳跟踪”(Carbon Tracker)的格雷(Matthew Gray)说。“如今这个比例非常低。”

From the perspective of a plant operator, though, replacing coal isn’t easy. That’s because biomass is a far less forgiving material than coal, says chief executive Andy Koss.

然而,从电厂运营商的角度来看,替换煤炭并不容易。该公司首席执行官科斯(Andy Koss)表示,这是因为生物燃料是一种比煤炭更难以处理的物质。

“It clogs things up,” says Koss, remembering how early experiments in moving the biomass on coal conveyors led to the pellets disintegrating and creating dust. The biomass also has to be kept dry at all times, unlike coal, lest it swell into a useless porridge-like mix. It’s even liable to burst into flames as it slowly oxidises so piles of it have to be constantly checked for temperature rises. Drax spent £700m on converting Drax and ensuring that the new biomass could be handled gently and along rain-safe pathways through the plant.

“它会堵塞设备,”科斯说,他还记得早期将生物燃料移动到煤炭传送带上的实验是如何导致颗粒分解并产生尘埃的。和煤炭不同,生物燃料必须一直保持干燥,以免膨胀成无用的粥状混合物。它甚至很容易起火,因为它会慢慢氧化,所以对于成堆的生物燃料必须经常检查其温度是否上升。德拉克斯花了7亿英镑进行能源转换,确保新的生物燃料可以得到小心处理,在发电厂内沿着防雨的通道进行运输。

And the power station also has invested in four bulbous domes, each one 50 metres high, to store biomass in on site. Every day, 16 covered trains arrive and deposit more of the wood pellets to keep the plant’s supplies topped up. The wagons pass through a shed and open automatically, triggered by magnets, as they roll over a grate in the ground. The wood pellets spill down through the grate, deep into a cavern below before being taken to the domes for temporary storage.

该发电厂还投资修建了4座球径圆顶,每座高50米,用于在现场储存生物燃料。每天都有16列有盖火车抵达,并存放更多的木屑颗粒,以保证发电厂的燃料供应充足。货车通过一个棚子,当车轮滚过地面的格栅时由磁铁触发,自动打开。木屑颗粒从格栅中流出,落入下面深处的一个洞穴,然后被带到圆顶中临时存放。

In terms of biomass operations, “I would say it’s the largest in the world,” says Koss. At the time of my visit, Drax had two gigawatts of coal capacity and the same for biomass. It has now completed its fourth generating unit for biomass. The remaining two will eventually burn gas.

就生物燃料处理而言,“我认为它是世界上规模最大的,”科斯说。在我访问的时候,德拉克斯的煤炭发电能力和生物燃料发电能力均为20亿瓦。它现在已经完成了第四个生物燃料发电机组。剩下的两个最终会烧天然气。

Drax has tried to rebrand itself as a poster boy for what can be done with an old coal plant – where there’s enough will and, indeed, money to pay for conversions. Many small coal facilities in the US have recently converted to burning gas – a cheaper kind of transition than biomass.

德拉克斯试图将自己重塑为一个标新立异的形象,告诉人们如何利用一个老旧的燃煤电厂。在那里,人们有足够的意愿,而且确实有足够的钱来支付这种转换。美国许多小型燃煤电厂最近已转为烧天然气——这比转为生物燃料更便宜。

And Drax wants to build large batteries on site to store electricity for when the grid needs it most. There are other, similar projects around the world. A Canadian firm, Hydrostor, has designed schemes for turning old coal plants into compressed air batteries. The air can be released to force the plant’s turbines back into action whenever electricity is needed.

德拉克斯希望在现场建造大型蓄电池,在备电网最需要时使用。世界各地还有其他类似的项目。加拿大一家名为海德罗斯特(Hydrostor)的公司已经设计出了将旧燃煤电厂改造成压缩空气存储装置的方案。当需要电力时,空气可以被释放出来,迫使电厂的涡轮机重新运转。

There are plenty of other ideas for reinventing former coal-burning facilities, too. In 2016, China announced it had plans to convert some of its coal plants to nuclear power stations – though there has not been much news about the proposals since. And Drax is far from the only coal-to-biomass project in the world, even if it is the largest. In Denmark, a coal plant in Copenhagen is set to be turned into a 100% biomass facility. A new incinerator nearby will feature an artificial ski slope on the roof.

还有很多其它的想法可以重新改造以前的燃煤电厂。2016年,中国宣布计划将部分燃煤电厂改造为核电站——尽管此后关于这一计划的新闻并不多。德拉克斯远不是世界上唯一的煤转生物燃料项目,尽管它是最大的。在丹麦,哥本哈根的一家燃煤电厂将被改造成100%的生物燃料电厂。附近新建的焚化炉大到可以在屋顶上修建一个人工滑雪坡道。

Not all coal plant conversions are energy-producing ventures. Google is turning one old facility in Alabama into a data centre.

并非所有的燃煤电厂转换项目都是由能源生产企业完成。谷歌(Google)正在把阿拉巴马州(Alabama)的一个旧电厂改造成数据中心。

King coal

煤炭为王

It’s also true that, in some places, coal is still hanging on. Although it has abandoned more than 100 coal plants, China still relies heavily on this dusty black fossil fuel for its energy needs. And Germany, which has decided to close all of its nuclear power stations, currently gets more than a fifth of its energy from coal, including lignite – an even more polluting form of the fuel.

一些地方仍在继续使用煤炭,这也是事实。尽管中国已经放弃了100多家燃煤电厂,但仍然严重依赖这种尘土飞扬的黑色化石燃料来满足其能源需求。德国已经决定关闭所有核电站,目前超过五分之一的能源来自煤炭,包括褐煤(lignite)——一种污染更严重的燃料。

An interactive map of the world’s coal-fired power stations from climate news site CarbonBrief reveals a swathe of plants closing in the US and Western Europe, but plenty of new ones under construction in Asia.

气候新闻网站“碳简报”(CarbonBrief)发布的一份全球燃煤发电站互动式地图显示,在美国和西欧,有很多燃煤发电站关闭,但在亚洲,还有很多新电厂在建。

Meanwhile, some markets have questioned coal and then returned to it. Back in 2015, the New South Wales government in Australia sold a major coal plant for A$1 million (£570,000), a tiny sum. At the time, politicians believed the facility would close within 10 years but then electricity prices in the region hit the roof. The plant is now valued at A$730 million (£415m) and its new owners have no plans to shut it any time soon.

与此同时,一些市场对煤炭提出了质疑,然后又重新开始使用。早在2015年,澳大利亚新南威尔士州(New South Wales)政府以57万英镑的低廉价格出售了一家主要的燃煤电厂。当时,政界人士认为,该电厂将在10年内关闭,但随后该地区的电价飙升至峰值。这座电厂现在价值4.15亿英镑,它的新主人近期内没有计划关闭它。

Faith in coal may not always be rewarded, though. In Poland, energy giant PGE has been investing heavily in old coal infrastructure, hoping to keep coal units burning for years to come. But this costs hundreds of millions of dollars at a time when the price of renewable energy, particularly wind and solar, is falling rapidly.

不过,对煤炭的信心也许并不总是能得到回报。在波兰,能源巨头PGE一直在对旧的煤炭基础设施进行大量投资,希望在未来几年继续燃烧煤炭能源。但这要花费数亿美元,与此同时,可再生能源,尤其是风能和太阳能价格正迅速下降。

It’s also fair to question exactly how green some of the coal plant conversion options really are.

同样可以质疑的是,一些燃煤电厂的转换方案到底有多环保。

Take biomass. Although the wood pellets release carbon when they burn, it is touted as ‘green’ because the trees cut down for them can be replaced over time, thus sequestering carbon again later. But not everyone agrees that this truly makes biomass carbon-neutral. Even page 33 of Drax’s annual report reveals that biomass belches out more CO2 per unit of electricity generated than coal does – a serious problem with the fuel.

以生物燃料为例。虽然木屑颗粒在燃烧时会释放碳,但它被吹捧为“绿色”是因为为它们所砍伐的树木可以随着时间的推移被种上新树苗,之后可以再次吸收碳。但并不是每个人都认同这确实使生物质发生碳中和(carbon-neutral)。甚至德拉克斯年报的第33页也显示,生物燃料每单位发电产生的二氧化碳比煤炭多——这是此种燃料的一个严重问题。

Echoing the main pro-biomass arguments, one boss at Drax tells me this is offset by replenishing the forests that supplied the biomass in the first place. Drax also says that, after accounting for replenished forests and supply chain emissions, using biomass means 80% less CO2 is ultimately emitted than it would be if coal had been used.

德拉克斯的一位老板回应了支持生物燃料的主要观点,他告诉我,这个问题可以通过立刻补偿提供生物燃料的森林来解决。德拉克斯还说,考虑到森林的补充和供应链排放,使用生物燃料意味着最终排放的二氧化碳比使用煤炭少80%。

But it takes new trees decades to grow. Plus, on a global scale, forests are shrinking in size overall. The capacity of the world’s forests for re-absorbing atmospheric CO2, then, is getting worse rather than better.

但是新的树木的生长需要几十年。此外,在全球范围内,森林的总体规模正在缩小。于是全球的森林重新吸收大气中二氧化碳的能力正在变得越来越差,而不是越来越好。

“I agree that’s a bad thing,” says Koss. But regarding deforestation, he insists, “it’s happening in areas outside of the areas that we source from… we are not connected to that at all.”

“我同意这是件坏事,”科斯说。但是关于森林砍伐,他坚称,“森林砍伐发生在我们的木材来源以外的地区……我们与此完全无关。”

True, but not enough to convince some environmentalists. And some experts point out that we need   rapid emissions cuts now, not in the decade or several it will take for new trees to grow.

没错,但这不足以说服一些环保人士。一些专家指出,我们现在需要快速减排,而不是等上十年或几年让新的树木生长。

Drax is hoping to mitigate its emissions in another way: with a pilot of bioenergy carbon capture storage (BECCS) technology. Gases from burning biomass at the plant will, if it all goes ahead, be passed through a solvent that reacts with emitted CO2, capturing it before it enters the atmosphere. This CO2 can then be retrieved so that the solvent can be used for capture again and again. It’s clever stuff and has been shown to work commercially before at one or two sites - but Drax is testing a new version.

德拉克斯希望通过另一种方式来减少碳排放:生物能源碳捕获储存技术(BECCS,bioenergy carbon capture storage)的试点。电厂燃烧生物燃料产生的气体,如果一切继续进行下去,将通过一种溶剂,这种溶剂与排放的二氧化碳发生反应,在二氧化碳进入大气之前将其捕获。然后这些二氧化碳就可以被回收,这样溶剂就可以一次又一次被用于捕获。这是一种很聪明的方法,而且已经在一两个地方上进行了商业应用。德拉克斯也正在测试一个新版本。

There clearly can be life after coal. But if we are to make the most of these lumbering old plants, we need to be savvy, green-minded and prepared to pay in advance for meaningful results.

很明显,煤炭停用之后发电厂还能继续生存。但是,如果我们要充分利用这些笨重的旧电厂,我们就需要智慧、有环保意识,并准备为有意义的结果提前付出代价。

Coal powered the world for many decades. It was a symbol of Victorian achievement. Instead of simply sweeping it away, we might well benefit from making novel use of the structures that the once great industry is leaving behind.

煤炭为世界提供了数十年的电力。它是维多利亚时代成就的象征。与其简单地将其一扫而空,我们还不如利用这个曾经伟大的产业所遗留下来的结构进行创新。

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