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Mermaid and Jellyfish

We never have to worry about the troubles of snowfalls in Hong Kong, not on the road, not on the roof, not on your solar panels.

However, heavy snowfall has been a headache to many people living in cold areas around the globe who are taking care of solar panels. They worry about the stress placed on the PV system structure from the weight of snow.  Also, being blocked by the snow, less sunlight could reach the panels, thus reducing electricity generation. Fortunately, engineers have solved these problems with a well-designed frame that allows the snow to slide down the solar panels. When the snow slides down the panels, it simultaneously clean the dirt on the panels, raising the solar system’s efficiency.

Not bad, right? Snowfall seems not to be a trouble anymore for the solar panels. Instead, snow could actually act as a helper to the PV system. Recently, scientists from the University of California discovered that snow could be a power source.

In order to know how snow generates power with solar panels, we need to learn about triboelectricity.

When we take off a nylon jumper, our hair would stand on end. Or when you shake somebody’s hand, you may sometimes feel a sudden and noticeable electrical discharge. It is the static electricity generated by the triboelectric effect. It happens when a material transfers the electrons to another. And this is the physical phenomenon the scientists harness to generate electricity from snowfall.

Since the snow has a positive charge, all we need is a material with a negative charge.  Silicone is a good choice because it could form an electrical current with snow. The American scientists have finished a technology prototype of a 3D-printed silicone layer with an electrode to capture the charge. Thanks to the low production cost of silicone, this design allows mass industrial production.

By covering the solar panels with this translucent silicone layer, snow will no longer block sunlight from reaching the PV cells, but it delivers triboelectricity in addition to solar power.

This technology could also be applied to wearable devices which detect physical activities such as boots and skis.

Now we know that snow is unique not only because of the crystalline structure of snowflakes, but its power could also be obtained from these tiny, fluffy and chilling particles.

(To read the article at SolarCare Programme’s website HERE)

雪中送「電」︰以冬雪提升太陽能板的效能

在香港，我們從來不用擔心冬天下雪所帶來的麻煩。我們不用為道路或屋頂鏟雪，更不用擔心太陽能板上會有積雪。

可是，在世界各地的寒冷地區，每年冬天的大雪都讓太陽能板管理者煩惱不已——積雪會否太重壓壞太陽能板？積雪又會否阻擋陽光，令太陽能系統的產電效能降低？幸好，工程師已經找到好辦法，設計出能卸去積雪的太陽能板，雪被滑走的同時還能清洗太陽能板上的灰塵，從以提升產電效能，可謂一石二鳥。

這很不錯，對吧？積雪從此不再是太陽能板的剋星。其實，積雪還能是太陽能板的福星。沒錯，加利福尼亞大學的科學家最近發現，雪竟然是一種能源！

要明白雪究竟怎樣讓太陽能板產生電力，我們首先要知道「靜電作用」的原理。

當我們在把頭穿過尼龍質料造的針織套衫時，頭髮很容易會豎起；有時當我們與別人握手時，會感到一下短促而明顯的電擊；這些就是由靜電產生的電流。當一件物件的電子轉移到另一物件上時，就會產生此種電流。科學家們就是利用這物理現象從雪中製造出電力。

雪本身帶有正電荷，只要找到一件帶負電荷的物件，我們就能製造電流。而其中，矽氧樹脂就是能與雪之間產生電流的好拍檔。美國的科學家利用3D打印技術製作科技原型，打印出一塊帶有電極並能鎖住電流的矽氧樹脂薄膜。而矽氧樹脂的生產成本低，有助讓這技術投入量產。

把這層透明的矽氧樹脂薄膜覆蓋在太陽能板上，積雪就再不是太陽能晶片吸收陽光的障礙，而是成為了傳遞摩擦電從而產生額外太陽能的助力。

這技術還能應用在可穿戴裝置如靴子或滑雪板上，用來偵測物理活動。

Electricity and water usually don’t get along well with each other. However, there is a growing number of floating solar farms developed worldwide. Why is that?

One of the reasons is because solar panel installations take up land space. While land space is limited, water surface is a good choice for building the systems.

Floating solar farms have the advantage of cooling down water temperature and reserve water resources. The Earth only possesses 1% of freshwater bodies on its surface, providing drinking water and crop irrigation for billions of people. Yet, the water surface temperature has been increasing by an average of 0.34°C per decade since 1985 due to climate change. Rising water surface temperature not only lowers the oxygen level of the waters, affecting the ecology underneath, it also causes toxic algal blooms that lead to water pollution. Water also evaporates under high temperature, in turn affecting the supply of fresh water.

Fortunately, in addition to mitigating global warming, floating solar farms could also bring down the water temperature and reduce water evaporation, thus reserving precious freshwater.

How does the system work to achieve all these?

By customizing the floating solar panel layout for different lakes or reservoirs, wind speed and solar radiation across the entire lake or reservoir could be reduced by 10%. This is the most efficient cooling effect that helps to change many of the ecological processes that happen within, capable of offsetting around a decade of warming from climate change. Acting as shelters, floating solar panels could also reduce water evaporation.

Recent studies also show that floating solar systems could generate more electricity than rooftops or ground-mounted solar systems do, thanks to their cooling effect. By cooling down the water temperature, they could boost the electricity generation by 12.5%!

If we cover just 1% of the surface of all human-made water bodies across 35 countries with floating solar panels, we can generate 400 gigawatts of electricity, which could power up 44 billion LED light bulbs for a year!

So far in Hong Kong, we have implemented two small-scale pilot projects of floating solar farms at Shek Pik Reservoir and Plover Cover Reservoir. The amount of electricity generated is equivalent to the annual electricity consumption of 36 average households with a reduction of 84 tonnes of CO2 emission.

CarbonCare InnoLab, under the Jockey Club SolarCare Programme, organises SolarVisits to the floating solar farms in Hong Kong. We hope that the Hong Kong Government could build more floating farms in the city in order to meet the target of achieving carbon neutrality in Hong Kong by 2050.

If you are interested in the SolarVisits, please keep an eye on our Facebook page for future event releases.

(To read the article at SolarCare Programme's website HERE)

保護水資源的浮動太陽能系統

電與水從來都不是好朋友，但全世界卻紛紛建設浮動太陽能發電系統。為什麼？

原因之一是太陽能板需要佔用一定的土地空間。在土地有限的情況下，水上空間就成為了另一個建設太陽能系統的好選擇。

浮動太陽能發電系統有一個好處，就是可以為湖水降溫，保護水資源。淡水只佔地球表面的1%，卻要供以億計的人口飲用和灌溉水利之用。因為氣候變化，自1985年以來，水表面溫度每十年就會平均上升約攝氏0.34度，這不單使水中的氧含量下降，影響水中自然生態；更同時導致有毒的藻類增生，污染水體。高溫亦令湖水蒸發，減低了淡水的供應量。

幸好，浮動太陽能發電系統除了能減緩氣候變化外，還能有效為湖水降溫及減少湖水蒸發，保護水資源。

究竟這系統是如何達到這效果呢？

只要為湖面度身設計合適的浮動太陽能發電板排列方式，就能減低整個湖或水庫的風速和太陽輻射，高達10%。這無疑是將降溫效果發揮到最大，從而幫助改變水底下的生態，抵消約十年因全球暖化造成的破壞。浮動太陽能板的遮擋還可以減少湖水蒸發。

近期的研究更顯示，拜降溫效果所賜，浮動太陽能發電板比安裝在屋頂或地上的太陽能發電系統能生產出更多電力。透過降低水面的溫度，產電量增加了12.5%！

若果在遍佈35個國家的人造水體中， 揀選其中的1%，並在之上建設浮動太陽能發電板，我們就能生產400吉瓦電力，足夠讓44萬億個LED燈泡全年無休地發亮。

目前，香港已在石壁水塘和船灣淡水湖安裝浮動太陽能發電系統，以作為先導計劃。兩套系統能生產出相當於36戶普通家庭每年的用電量， 也為地球每年減少84公噸的二氧化碳排放量。

低碳想創坊「賽馬會太陽能關懷計劃」舉行的太陽能導賞團，會帶公眾參觀香港的兩個浮動太陽能發電系統。期望政府能在香港建設更多浮動太陽能發電系統，為香港於2050年達致碳中和的目標努力。