Startup taps underwater volcano as energy source in "proof point" test

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The world’s first demonstration of a subsea geothermal power plant has taken place near an active underwater volcano almost a mile below the ocean surface. It generated less than 10 seconds of net-positive electricity but showed the technical feasibility of tapping another form of renewable energy underwater.

全球首个海底地热发电站演示已在海面下近一英里处的一座活跃海底火山附近完成。尽管其净正电力的产生时间不足10秒，但该实验证明了在水下开发另一种可再生能源的技术可行性。

The three-week test deployment of the 3-ton prototype power plant took place at the Axial Seamount in the northeast Pacific Ocean in September. Endurance Energy, the Seattle-based startup behind the effort, aims to eventually commercialize subsea geothermal power for Pacific island nations and other customers looking for alternatives to importing expensive fossil fuels.

这项为期三周的3吨重原型发电站测试部署于9月在东北太平洋的轴海山（Axial Seamount）进行。该项目的幕后推手是总部位于西雅图的初创公司Endurance Energy，其目标是最终将海底地热能商业化，为太平洋岛国及其他寻求替代昂贵化石燃料进口的客户提供服务。

“The deep ocean gives us unlimited cold seawater for cooling, and its weight keeps the system and the well pressurized, so our plants can be compact,” said Andrew Redd, founder and CEO of Endurance Energy, in an email to Ars. But efforts to tap geothermal power on the seafloor face many different challenges from land-based geothermal projects, which can also add up to higher installation and operational costs.

Endurance Energy创始人兼首席执行官安德鲁·雷德（Andrew Redd）在给Ars的一封电子邮件中表示：“深海为我们提供了无限的冷海水用于冷却，其压力能保持系统和油井的加压状态，因此我们的电站可以做得非常紧凑。”然而，在海底开发地热能所面临的挑战与陆地地热项目截然不同，这也可能导致更高的安装和运营成本。

So Endurance Energy must demonstrate consistent underwater operations as well as prove the approach can be cost-effective. “It’s probably technically feasible, but it would undoubtedly be more expensive than to do it on land,” said Roland Horne, professor of energy science & engineering at Stanford University, in an emailed response to Ars.

因此，Endurance Energy必须证明其水下作业的稳定性，并证明该方案具有成本效益。斯坦福大学能源科学与工程教授罗兰·霍恩（Roland Horne）在回复Ars的邮件中表示：“这在技术上可能是可行的，但毫无疑问，它比在陆地上进行要昂贵得多。”

Endurance Energy’s deployment required a subsea lander drill to deploy from the ship Ocean Guardian—operated by Stabbert Maritime—and drill two holes in the seafloor at a depth of about 5,000 feet (1,524 meters). That means the test took place at a depth exceeding 2.5 times the height of the One World Trade Center building in New York City, which is the tallest building in the United States.

Endurance Energy的部署工作需要从Stabbert Maritime运营的“海洋卫士号”（Ocean Guardian）船上投放一台海底着陆钻机，并在约5000英尺（1524米）深的海底钻两个孔。这意味着测试深度超过了美国最高建筑——纽约世界贸易中心一号大楼高度的2.5倍。

Both the drilled holes started venting hot hydrothermal fluid measured at a temperature of about 500° F (260° C). The Endurance Energy team proceeded to case and cement the second hole before installing a valve to create a well. Next up, the company deployed its 100-kilowatt power plant, named Adélie, that is designed to vaporize incoming hydrothermal fluid to spin a turbine and drive an electric generator.

两个钻孔都开始喷出温度约为500°F（260°C）的热液。Endurance Energy团队对第二个孔进行了套管和固井作业，随后安装了阀门以形成油井。接下来，该公司部署了名为“阿德利”（Adélie）的100千瓦发电站，该电站旨在通过汽化流入的热液来驱动涡轮机并带动发电机发电。

It used the assistance of Canada’s remotely operated submersible ROPOS to help connect the power plant to the newly drilled well. Adélie also connected to Endurance Energy’s Seattle command center by plugging into the Regional Cabled Array, a 559-mile (900-kilometer) network of undersea fiber-optic and electric cables that provides both power and connectivity to scientific sensors on the seafloor.

该项目利用加拿大的遥控潜水器ROPOS协助将发电站与新钻的油井连接起来。Adélie还通过接入“区域电缆阵列”（Regional Cabled Array）与Endurance Energy的西雅图指挥中心相连；该阵列是一个长达559英里（900公里）的海底光纤和电缆网络，为海底科学传感器提供电力和连接。

That all set the stage for the Adélie power test. But a major hitch soon arose—the drilled well extending 52 feet (16 meters) down into the seafloor was not delivering enough of the hydrothermal fluid to run the power plant. “For our first well, the goal was to show we could drill, case, cement, and cap a well on the seafloor, so we kept it small and shallow,” Redd explained.

这一切为Adélie的电力测试奠定了基础。但一个重大障碍很快出现——深入海底52英尺（16米）的钻井无法提供足够的运行发电站所需的热液。雷德解释说：“对于我们的第一口井，目标是证明我们能够在海底进行钻探、套管、固井和封盖，所以我们将其做得又小又浅。”

The test well was also just 2 inches (5 centimeters) wide, compared to oil, gas, and onshore geothermal wells that typically have casings 20 to 36 inches (51 to 91 centimeters) across. Endurance Energy plans to avoid this issue in the future by drilling deeper wells to access more fluid. The company’s current lander drill can reach about 260 feet (80 meters), which would be five times deeper than the initial test well.

测试井的宽度仅为2英寸（5厘米），而石油、天然气和陆上地热井的套管通常为20至36英寸（51至91厘米）。Endurance Energy计划在未来通过钻探更深的井来获取更多流体，从而避免这一问题。该公司目前的着陆钻机可达到约260英尺（80米）的深度，这将是最初测试井深度的五倍。

To try running the Adélie power plant anyway, the team redeployed it to a nearby natural vent where hydrothermal fluid was already flowing out at about 538° F (281° C). On September 27, they gave it a try. Over nearly half a minute, the power plant turbine reached about 26,000 rpm and enabled the generator to produce 60 watt-hours of electricity.

为了尝试运行Adélie发电站，团队将其重新部署到附近的一个天然喷口，那里流出的热液温度约为538°F（281°C）。9月27日，他们进行了尝试。在近半分钟的时间里，发电站涡轮机达到了约26,000转/分，使发电机产生了60瓦时的电力。

The power plant also became net-positive by producing more electricity than it consumed for about 8.7 seconds. It produced a median of about 2 kilowatts of net power and peaked at 16.5 kilowatts of net power. “It’s the proof point,” Redd told Ars. “Net-positive is the threshold that matters: the plant made more power than it took to run itself on the seafloor, which no one had done before.”

该发电站在约8.7秒的时间内产生的电力超过了其消耗的电力，实现了净正输出。其净功率中位数约为2千瓦，峰值达到16.5千瓦。雷德告诉Ars：“这是一个证明点。净正输出是关键的阈值：该电站在海底产生的电力超过了其自身运行所需的电力，这是前人从未做到的。”

But then a software issue brought the power run to a halt. Before the generator takes over, Adélie first relies on a battery to run its pumps, thrusters, and controls, along with spinning the turbine to get it up to speed, Redd explained. A battery module recorded a brief spike in current during the spin-up process and then stopped reporting.

然而，一个软件问题导致电力运行中断。雷德解释说，在发电机接管之前，Adélie首先依靠电池来运行泵、推进器和控制器，并旋转涡轮机以使其达到额定速度。一个电池模块在加速过程中记录到电流短暂激增，随后停止了报告。

That prompted Adélie’s software to automatically stop the power plant as a safety precaution, because it kept relying on the old reading from the battery module. When the team was restarting the power plant, a power cable feeding the refrigerant pump also failed when an imperfection in the cable casing allowed seawater to seep in and short two of the electrical conductors.

这促使Adélie的软件出于安全预防措施自动停止了发电站，因为它一直依赖电池模块的旧读数。当团队重启发电站时，为制冷剂泵供电的电缆也发生了故障，原因是电缆外壳的缺陷导致海水渗入，使两根导线短路。

That ended the trial run, although Endurance Energy already plans to use the experience to improve how it builds and tests subsea cables. Future deployments: Placing the geothermal plant on top of a natural hydrothermal vent was a one-time test for purely research and demonstration purposes, Redd said. His company still plans to rely on drilled wells in future deployments. Endurance Energy also described taking steps to reduce potential environmental impacts on.

这次试验运行至此结束，尽管Endurance Energy已计划利用此次经验改进其海底电缆的制造和测试方式。关于未来部署，雷德表示，将地热电站放置在天然热液喷口上是一次纯粹出于研究和演示目的的一次性测试。他的公司在未来的部署中仍计划依赖钻井。Endurance Energy还描述了为减少潜在环境影响所采取的措施。