據海上工程師網報道，在美國馬薩諸塞州和紐約州海岸，開發商正準備建造美國第一個政府批準規模的海上風力發電場——總共74個渦輪機，可為47萬戶家庭供電。美國 東海岸還有10多個其他海上風力發電項目正等待批準。  

美國政府的目標是到2030年前擁有30吉瓦的海上風電，足夠為1000萬戶家庭供電。 

用風電等清潔能源取代化石燃料為基礎的能源，對于阻止氣候變化導致的日益惡化的影響至關重要。 但這種轉變的速度還不足以阻止全球氣候變暖。 人類活動向大氣中排放了如此多的二氧化碳，我們也必須將二氧化碳從大氣中去除，并將其永久封存起來。

海上風力發電場具有這種獨特的優勢，既能做到這兩點，又能省錢。  

美國大西洋沿岸的可再生能源租賃區大多位于大西洋中部各州和馬薩諸塞州附近。 紐約灣大約48萬英畝的土地計劃在今年2月拍賣，用于建造風力發電場。

作為海洋地球物理學專家，研究者一直在探索將風力渦輪機與直接從大氣中捕獲二氧化碳并將其儲存在海底天然儲層中的技術相結合的可能性。 這些技術結合起來，可以降低碳捕獲的能源成本，最大限度地減少對陸上管道的需求以及減少對環境的影響。

從大氣中直接捕獲二氧化碳 

一些研究小組和科技初創公司正在測試直接從大氣中捕捉二氧化碳的設備，這種設備可以直接從大氣中吸收二氧化碳。 這項技術是可行的，但到目前為止，早期的項目都是代價昂貴且是能源密集性的項目。 

這個系統使用過濾器或液體溶液，從吹過的空氣中捕獲二氧化碳。 一旦過濾器滿了，就需要電力和熱量來釋放二氧化碳，并重新啟動捕獲循環。

為了實現凈負排放，電源必須是無碳的。

目前，世界上最大的主動直接空氣捕獲廠通過利用廢熱和可再生能源來實現這一目標。 然后，位于冰島的這種工廠將捕獲的二氧化碳泵入底層的玄武巖中，在那里，二氧化碳與玄武巖發生反應并鈣化，變成固體礦物。

類似的過程也可以用海上風力渦輪機實現。  

如果直接空氣捕獲系統與海上風力渦輪機一起建造，它們將從過剩的風力發電中獲得直接的清潔電力，并可以將捕獲的二氧化碳直接泵送到海底下儲存，從而減少對大規模管道系統的需求。

瑞士的Climeworks公司擁有15個空氣直捕工廠，將二氧化碳從大氣中去除。

研究人員目前正在研究這些系統在海上條件下是如何工作的。 空氣直接捕獲技術在陸地上的應用才剛剛開始，而且這項技術可能還需要進行改進，以適應惡劣的海上環境。 但現在就應該開始規劃，這樣風電項目就能充分利用碳儲存地點，并在設計上實現平臺、海底基礎設施和電纜網絡的共享。

合理利用過剩風電

從本質上講，風電是間歇性的。 對風電的需求也各不相同。 當風能產生的電力超過需求時，風電產量就會減少，本可以使用的電力就會損失。

這些未使用的電力可以用來去除大氣中的二氧化碳，并將其封存起來。

例如，美國紐約州的目標是到2035年前擁有9吉瓦的海上風力發電。 預計這9吉瓦發電能力每年將提供27.5太瓦時的電力。  

根據美國歷史上的風縮減率，隨著海上風力發電場的擴大，預計每年將有825兆瓦時的電力過剩。 假設空氣直接捕獲的效率繼續提高并達到商業目標，這些過剩的電力每年可用于捕獲和儲存50萬噸以上的二氧化碳。 

如果系統不利用剩余電力，那么這些剩余電力就會被浪費掉。 如果系統使用更多的風電，其碳捕獲和儲存潛力將會增加。

一些租借給海上風力發電場的大西洋中部地區也有在海底儲存二氧化碳的潛力。 這種能力是以每平方公里排放數百萬噸二氧化碳為單位來衡量的。 美國每年從能源中產生大約45億噸二氧化碳。

政府間氣候變化專門委員會預測，為了將全球氣候變暖控制在與工業化前水平相比的1.5攝氏度(2.7華氏度)以內，在本世紀內必須從大氣中去除1000至10000億噸二氧化碳。

據研究人員估計，在美國東海岸計劃進行的海上風力開發項目附近的海底地質構造具有儲存超過5000億噸二氧化碳的能力。 玄武巖有可能也存在于這一地區的一系列地下盆地中，這將增加更多的儲存能力，并使二氧化碳與玄武巖反應，隨著時間的推移而固化，盡管地質調查還沒有測試這些沉積物。

同時計劃捕獲和儲存可以節省時間和成本  

用空氣直接捕獲技術建造的新風電場可以向電網交付可再生電力，并為碳捕獲和儲存提供多余的電力，從而優化這一大規模投資，以獲得直接氣候效益。

但這需要在建設之前就做好規劃。 同時啟動風電和儲存的海上地球物理調查、環境監測要求和審批流程，可以節省時間，避免沖突，改善環境管理工作。  

李峻 編譯自 海上工程師網

原文如下：

Offshore Wind Farms Could Help Capture Carbon from Air and Store It Long-term

Off the Massachusetts and New York coasts, developers are preparing to build the United States’ first federally approvedutility-scale offshore wind farms – 74 turbines in all that could power 470,000 homes. More than a dozen other offshore wind projects are awaiting approval along the Eastern Seaboard.

By 2030, the Administration’s goal is to have 30 gigawatts of offshore wind energy flowing, enough to power more than 10 million homes.

Replacing fossil fuel-based energy with clean energy like wind power is essential to holding off the worsening effects of climate change. But that transition isn’t happening fast enough to stop global warming. Human activities have pumped so much carbon dioxide into the atmosphere that we will also have to remove carbon dioxide from the air and lock it away permanently.

Offshore wind farms are uniquely positioned to do both – and save money.

Most renewable energy lease areas off the Atlantic Coast are near the Mid-Atlantic states and Massachusetts. about 480,000 acres of the New York Bight is scheduled to be auctioned for wind farms in February 2022.  

As a marine geophysicist, I have been exploring the potential for pairing wind turbines with technology that captures carbon dioxide directly from the air and stores it in natural reservoirs under the ocean. Built together, these technologies could reduce the energy costs of carbon capture and minimize the need for onshore pipelines, reducing impacts on the environment.

Capturing CO2 from the air

Several research groups and tech startups are testing direct air capture devices that can pull carbon dioxide directly from the atmosphere. The technology works, but the early projects so far are expensive and energy intensive.

The systems use filters or liquid solutions that capture CO2 from air blown across them. once the filters are full, electricity and heat are needed to release the carbon dioxide and restart the capture cycle.

For the process to achieve net negative emissions, the energy source must be carbon-free.

The world’s largest active direct air capture plant operating today does this by using waste heat and renewable energy. The plant, in Iceland, then pumps its captured carbon dioxide into the underlying basalt rock, where the CO2 reacts with the basalt and calcifies, turning to solid mineral.

A similar process could be created with offshore wind turbines.

If direct air capture systems were built alongside offshore wind turbines, they would have an immediate source of clean energy from excess wind power and could pipe captured carbon dioxide directly to storage beneath the sea floor below, reducing the need for extensive pipeline systems.

Climeworks, a Swiss company, has 15 direct air capture plants removing carbon dioxide from the air. Climeworks

Researchers are currently studying how these systems function under marine conditions. Direct air capture is only beginning to be deployed on land, and the technology likely would have to be modified for the harsh ocean environment. But planning should start now so wind power projects are positioned to take advantage of carbon storage sites and designed so the platforms, sub-sea infrastructure and cabled networks can be shared.

Using excess wind power when it isn’t needed

By nature, wind energy is intermittent. Demand for energy also varies. When the wind can produce more power than is needed, production is curtailed and electricity that could be used is lost.

That unused power could instead be used to remove carbon from the air and lock it away.

For example, New York State’s goal is to have 9 gigawatts of offshore wind power by 2035. Those 9 gigawatts would be expected to deliver 27.5 terawatt-hours of electricity per year.

based on historical wind curtailment rates in the U.S., a surplus of 825 megawatt-hours of electrical energy per year may be expected as offshore wind farms expand to meet this goal. Assuming direct air capture’s efficiency continues to improve and reaches commercial targets, this surplus energy could be used to capture and store upwards of 0.5 million tons of CO2 per year.

That’s if the system only used surplus energy that would have gone to waste. If it used more wind power, its carbon capture and storage potential would increase.

Several Mid-Atlantic areas being leased for offshore wind farms also have potential for carbon storage beneath the seafloor. The capacity is measured in millions of metric tons of CO2 per square kilometer. The U.S. produces about 4.5 billion metric tons of CO2 from energy per year. U.S. Department of Energy and Battelle

The Intergovernmental Panel on Climate Change has projected that 100 to 1,000 gigatons of carbon dioxide will have to be removed from the atmosphere over the century to keep global warming under 1.5 degrees Celsius (2.7 Fahrenheit) compared to pre-industrial levels.

Researchers have estimated that sub-seafloor geological formations adjacent to the offshore wind developments planned on the U.S. East Coast have the capacity to store more than 500 gigatons of CO2. Basalt rocks are likely to exist in a string of buried basins across this area too, adding even more storage capacity and enabling CO2 to react with the basalt and solidify over time, though geotechnical surveys have not yet tested these deposits.

Planning both at once saves time and cost

New wind farms built with direct air capture could deliver renewable power to the grid and provide surplus power for carbon capture and storage, optimizing this massive investment for a direct climate benefit.

But it will require planning that starts well in advance of construction. Launching the marine geophysical surveys, environmental monitoring requirements and approval processes for both wind power and storage together can save time, avoid conflicts and improve environmental stewardship.