These companies are using oceans and rivers to generate electricity (CNN Business)As the world looks to curb climate change and reduce fossil fuel emissions, some companies are focusing on a relatively untapped but vast and abundant source of energy — tidal waves.
On opposite sides of the Atlantic, two firms are working to harness ocean currents in different ways to try to generate reliable clean energy.
Off the coast of Scotland, Orbital Marine Power operates what it says is the "most powerful tidal turbine in the world." The turbine is approximately the size of a passenger airplane and even looks similar, with its central platform floating on the water and two wings extending downwards on either side. At the ends of each wing, about 60 feet below the surface, are large rotors whose movement is dictated by the waves.
"The energy itself of tidal streams is familiar to people, it's kinetic energy, so it's not too dissimilar to something like wind," Andrew Scott, Orbital's CEO, told CNN Business. "The bits of technology that generate power look not too different to a wind turbine."
But there are some key differences to wind energy, primarily that waves are far more predictable than winds. The ebb and flow of tides rarely differs significantly and can be timed far more precisely.
"You can predict those motions years and decades [in] advance," Scott said. "But also from a direction perspective, they only really come from two directions and they're almost 180 degrees," he added, unlike wind turbines that must account for wind from several different directions at once.
Tidal waves are also capable of generating more energy than wind, Scott says.
"Seawater is 800 times the density of wind," he said. "So the flow speeds are far slower, but they generate far more energy."
The Orbital turbine, which is connected to the electricity grid in Scotland's Orkney, can produce up to two megawatts — enough to power 2,000 homes a year — according to the company.
Scott acknowledges that the technology isn't fully mainstream yet and some challenges remain including the high cost of the technology, but the reliability and potential of tidal energy could make it a useful tool in the fight against climate change.
"It is becoming increasingly apparent that ... climate change is not going to be solved with one silver bullet," he said.
'Could be 24/7 power'
Around 3,000 miles away from Orbital's turbines, Verdant Power is using similar technology to generate power near Roosevelt Island in New York City's East River. Although not on the market yet, Verdant's turbines set up as part of a pilot project help supply electricity to New York's grid. But rather than float near the surface, they're mounted on a frame that's lowered to the bottom of the river.
"The best way to envision what Verdant Power's technology is, is to think of wind turbines underwater," the company's founder, Trey Taylor, told CNN Business. And river currents tend to provide the same advantages for energy generation as ocean currents, he explained (though the East River is also connected to the Atlantic).
"What's nice about our rivers and systems is that could be 24/7 power," he said. "Not to ding wind or solar, but the wind doesn't always blow and the sun doesn't always shine. But river currents, depending on the river, could be 24/7."
Over the course of eight months, Verdant has generated enough electricity to power roughly 60 homes — though Taylor says a full-fledged power plant built on its technology could generate enough for 6,000 homes. And by his estimate, the global capacity for tidal energy is enormous.
"The potential for energy is something like 250 gigawatts around the world," he said, which is enough to power 250 million homes for a year. "There's lots of room and we really hope our competitors succeed too, for the sake of the industry."
A costly technology
The biggest obstacle to reaching that goal at the moment is how expensive it is to set up and scale up tidal power systems.
"Generating electricity from ocean waves is not the challenge, the challenge is doing it in a cost-effective way that people are willing to pay for that competes with ... other sources of energy," said Jesse Roberts, Environmental Analysis Lead at the US government-affiliated Sandia National Laboratories. "The added cost of going out into the ocean and deploying in the ocean... that's very expensive to do," he added. According to 2019 figures from the US Department of Energy, the average commercial tidal energy project costs as much as $280 per megawatt hour. Wind energy, by comparison, currently costs roughly $20 per megawatt hour and is "one of the lowest-priced energy sources available today," according to the agency.
Roberts estimates that tidal energy is two or three decades behind wind energy in terms of adoption and scale.
The costs and challenges of operating underwater are something both Scott and Taylor acknowledge.
"Solar and wind are above ground. It's easy to work with stuff that you can see," Taylor said. "We're underwater, and it's probably easier to get a rocket to the moon than to get these to work underwater."
But the goal of tidal power is not so much to compete with those two energy sources as it is to grow the overall pie.
"The low hanging fruit of solar and wind were quite obvious," Scott said. "But do they have to be the only solution? Is there room for other solutions? I think when the energy source is there, and you can develop technologies that can harness it, then absolutely."
这些公司正在利用海洋和河流发电
随着世界希望遏制气候变化和减少化石燃料排放，一些公司正在关注一种相对未开发但巨大而丰富的能源——潮汐。
在大西洋的对岸，两家公司正致力于以不同的方式利用洋流，以尝试产生可靠的清洁能源。
在苏格兰海岸附近，Orbital Marine Power 运行着它所说的“世界上最强大的潮汐涡轮机”。涡轮机的大小与客机差不多，甚至看起来也差不多，中央平台漂浮在水面上，两侧有两个向下延伸的机翼。在每个机翼的末端，大约在地表以下 60 英尺处，是大型转子，其运动由波浪决定。
“潮汐流的能量本身对人们来说很熟悉，它是动能，所以它与风之类的东西并没有太大不同，”轨道公司首席执行官安德鲁斯科特告诉 CNN Business。 “发电的技术与风力涡轮机看起来并没有太大区别。”
但是风能有一些关键的区别，主要是波浪比风更容易预测。潮汐的涨落很少有显着差异，并且可以更精确地计时。
“你可以提前几年和几十年预测这些运动，”斯科特说。 “但从方向的角度来看，它们实际上只来自两个方向，而且几乎是 180 度，”他补充说，这与风力涡轮机必须同时考虑来自几个不同方向的风不同。
斯科特说，潮汐波还能够产生比风更多的能量。
“海水的密度是风的密度的 800 倍，”他说。 “所以流速要慢得多，但它们产生的能量要多得多。”
据该公司称，Orbital 涡轮机连接到苏格兰奥克尼的电网，可产生高达 2 兆瓦的电力——足以为 2,000 个家庭提供一年电力。
Scott 承认，该技术尚未完全成为主流，仍然存在一些挑战，包括该技术的高成本，但潮汐能的可靠性和潜力使其成为应对气候变化的有用工具。
“越来越明显的是……气候变化不会用一颗灵丹妙药来解决，”他说。
'可能是 24/7 电源'
在距离轨道涡轮机大约 3,000 英里的地方，Verdant Power 正在使用类似的技术在纽约市东河罗斯福岛附近发电。尽管尚未上市，但作为试点项目的一部分，Verdant 的涡轮机有助于为纽约电网供电。但它们不是漂浮在水面附近，而是安装在一个降低到河底的框架上。
“设想 Verdant Power 技术的最佳方式是考虑水下风力涡轮机，”该公司的创始人 Trey Taylor 告诉 CNN Business。他解释说，河流在发电方面往往具有与洋流相同的优势（尽管东河也与大西洋相连）。
“我们的河流和系统的好处在于，它可以是 24/7 全天候供电，”他说。 “不是风或太阳能，但风并不总是吹，太阳也不总是发光。但河流，取决于河流，可能是 24/7。”
在八个月的时间里，Verdant 已经产生了足够为大约 60 个家庭供电的电力——尽管 Taylor 说一个基于其技术建造的成熟的发电厂可以为 6,000 个家庭提供足够的电力。据他估计，全球潮汐能的容量是巨大的。
“全世界的能源潜力大约为 250 吉瓦，”他说，这足以为 2.5 亿个家庭供电一年。 “有很大的空间，我们真的希望我们的竞争对手也能成功，为了这个行业。”
昂贵的技术
目前实现这一目标的最大障碍是建立和扩大潮汐发电系统的成本。
“从海浪中发电不是挑战，挑战在于以一种人们愿意支付的具有成本效益的方式与……其他能源竞争，”环境分析负责人杰西·罗伯茨 (Jesse Roberts) 说。美国政府附属的桑迪亚国家实验室。 “进入海洋并在海洋中部署的额外成本......这样做非常昂贵，”他补充道。根据美国能源部 2019 年的数据，商业潮汐能项目的平均成本高达每兆瓦时 280 美元。据该机构称，相比之下，风能目前每兆瓦时的成本约为 20 美元，是“当今价格最低的能源之一”。
罗伯茨估计，潮汐能在采用和规模方面比风能落后两到三年。
Scott 和 Taylor 都承认在水下作业的成本和挑战。
“太阳能和风都在地面之上。处理你能看到的东西很容易，”泰勒说。 “我们在水下，将火箭送上月球可能比让它们在水下工作更容易。”
但潮汐能的目标与其说是与这两种能源竞争，不如说是扩大整体蛋糕。
“太阳能和风能的低垂果实非常明显，”斯科特说。 “但它们必须是唯一的解决方案吗？还有其他解决方案的空间吗？我认为当能源存在时，你可以开发可以利用它的技术，那么绝对。”
