SEEBECK - using the Seebeck effect to power sea-ice instrumentation

冰在融化！从1979年到2007年，北极夏季海冰面积减少了一半，从800多万平方公里减少到400多万平方公里。此外，潜艇的测量表明，其厚度已经下降了约40%。至于未来，政府间气候变化专门委员会（气专委）最新报告中使用的所有气候预测模型一致认为，这种减少将继续下去，到本世纪末，北极夏季可能没有冰。然而，观测表明，这些模型在空间和时间上都严重低估了这种减少，北极可能早在2040年就成为无冰区。这些模型是错误的，因为我们不完全了解海冰是如何生长、移动和衰变的。我们对此一无所知的一个原因是，海冰的性质是不断变化的，受当地环境条件（如气温、积雪深度、海洋温度等）变化的影响。我们根本没有足够的测量数据，分布在整个北极地区，一年四季，来完善我们的理解，建立和测试更好的模型。这部分是因为成本、后勤困难和缺乏人力的综合因素，部分是因为我们还没有廉价、简单和可靠的自动仪器，可以大量分散在北极周围，并且可以在漫长的极地冬季生存下来。我们计划在这项工作中解决的一个关键问题是，如何在极地冬季为我们所需的仪器提供动力，因为那时没有太阳能可供使用。传统的解决方案采用风力发电机和/或大型汽车电池，这两者在遇到的极端条件下都不可靠。电池也是一种污染危害，我们可以尽量减少。我们建议开发、测试和部署利用塞贝克效应的热电发电机。这种发电机将热储库和冷储库之间的热流转化为电能，已广泛用于航天工业，但迄今尚未在极地地区使用。一个问题是，当“热”水库（在我们的情况下，冰下的海水）和冷水库（海冰上方的空气）之间的温差只有几十度时，发电机的效率相当小。然而，现代极地仪器非常节能，我们的计算表明，在大多数情况下，中等尺寸的塞贝克效应发生器能够在冬季提供足够的能量。典型的仪器包括垂直传感器链（已经在NERC的赠款下开发），连接到小型卫星发射机，可以很容易地和机会主义地通过冰部署未经训练的操作员。这些链的测量结果正被用于改进现有的海冰及其与海洋和大气相互作用的模型：因此，它们将在阐明海冰与全球气候变化之间的相互作用方面发挥重要作用。

The ice is melting! Between 1979 and 2007 the summer sea ice extent in the Arctic has halved, from over 8 million square km to just over 4 million square km. Moreover, measurements from submarines suggest that its thickness has plummeted by some 40%. As to the future, there is unanimous agreement between all the climate prediction models used in the latest report of the Intergovernmental Panel on Climate Change (IPCC) that this reduction will continue, and that the Arctic could be ice free in summer by the end of this century. However, observations suggest that these models are significantly under-representing this reduction, in both space and time, and that the Arctic could become ice free as early as 2040. The models are wrong because we do not fully understand how sea ice grows, moves and decays. One reason for our ignorance is that the properties of sea ice are constantly evolving, driven by changes in local environmental conditions such as air temperature, snow depth, ocean temperature and so on. We simply do not have enough measurements, spread out over the Arctic and throughout the year, to refine our understanding and build and test better models. This is partly because of the combination of cost, difficult logistics and lack of man-power, and partly because we do not yet have cheap, simple and reliable automatic instruments that can be scattered round the Arctic in large numbers, and that can survive the long polar winter. A key problem, which we plan to address in this work, is how to power the instruments that we need during the polar winter, when there is no solar energy to call upon. Traditional solutions have employed wind generators and/or large car batteries, both of which are unreliable in the extreme conditions encountered. Batteries are also a pollution hazard which we could well do to minimise. We propose to develop, test and deploy thermo-electric generators that exploit the Seebeck Effect. Such generators, converting a flow of heat between a hot and a cold reservoir into electricity, have been widely used in the space industry, but have not been used so far in the polar regions. One problem is that the efficiency of the generator is quite small when the temperature difference between the 'hot' reservoir (the sea beneath the ice in our case) and the cold reservoir (the air above the sea ice) is only a few tens of degrees. However, modern polar instruments are very energy efficient and our calculations show that a Seebeck Effect generator of modest size will, in most cases, be able to supply sufficient energy during the winter months. Typical instruments consist of vertical chains of sensors (already being developed under NERC grants), connected to small satellite transmitters, that can be easily and opportunistically deployed through the ice by untrained operators. The measurements from these chains are being used to improve existing models of sea ice and its interaction with ocean and atmosphere: as such they will play an important role in elucidating the interaction between sea ice and global climate change.