電気カロリック材料を活用したHVACソリューションの進化

HVACからの膨大なエネルギー需要

Modern industrial society uses a lot of energy. One application we tend to underestimate when it comes to energy usage is cooling and heating. これは世界全体のエネルギー消費の半分以上を占めており、電力（20％）や輸送（30％）を上回ります。.

したがって、電気自動車（EV）以上に、HVAC（暖房、換気、空調）の電化と効率化が、エネルギー消費と炭素排出量の削減に不可欠です。特に、インドやインドネシアのような人口が多く温暖な国々の経済発展に伴い、冷房需要は2050年までに3倍になると予測されています。

出典： Daikin

これまで、高効率なHVACを実現する主流技術は、圧縮冷却を利用したヒートポンプでした。

A new technology is now coming to challenge the status quo, based on a physical principle called “electrocaloric cooling”.

ヒートポンプの仕組み

All heat pumps, from compression heat pumps to future electrocaloric heat pumps, function on a basic principle: moving heat instead of generating it.

これは、化石燃料や他の電気暖房システムが電気やガス・石炭・石油を消費して熱を生成するのとは大きく異なる原理です。

A heat pump, instead, takes heat from one side of a wall and transfers it to the other side. In winter, it absorbs heat from the outside and sends it into the building. In summer, it reverses this process to cool down the building and works like air conditioning.

熱を移動させる方が生成するよりはるかに効率的です。そのため、圧縮式ヒートポンプは消費電力1Wあたり2〜4Wの熱／冷気を生成できます。

出典： RMI

熱は環境内外を移動し、主に外気または地下配管を通した周囲の土壌を利用します。

ヒートポンプは主にオフィスや商業施設、住宅などの建物の暖房・冷房に使用されますが、産業現場でも利用でき、あるプロセスのエネルギー源を別のプロセスに再利用することで大幅なエネルギー節約が可能です。

出典： Sintef

圧縮方式を超える電気カロリックヒートポンプ

電気カロリック技術の進展

Traditional heat pumps use the thermal effect of compression & decompression to move the heat from one point to another. This requires refrigerant agents like hydrofluorocarbons or ammonia which have either direct or indirect greenhouse effects on the climate.

The electrocaloric principle is different. An electrocaloric system heats when exposed to electric fields, as it causes atoms to align in a single direction, reducing entropy. The reverse happens, causing cooling when the electric fields stop.

出典： Fraunhofer IPM

電気カロリック効果は1960年代から知られていますが、当時達成できた最大温度差はわずか2.5°Cでした。

Some progress was made 2006年に、鉛チタン酸素ジルコニウムの薄膜が12°Cの冷却能力を実現したとき.

しかし、ルクセンブルク・インスティテュート・オブ・サイエンス・アンド・テクノロジー（Belvaux）の研究者が達成した約21°Cの温度変化という最近のブレークスルーは、商業応用に十分なパワーを持つことを示しています。

電気カロリックプロトタイプ

The team used a polymer and lead-scandium-tantalum-oxygen (PST) multi-layer capacitors (MLC).

出典： UPCommons

The Luxembourg researchers have created a prototype that achieved maximum cooling when under 10V per micrometer of power, creating a maximum cooling of 4.2W.

出典： Techspot

This is a radical improvement from all previously developed methods, with temperature span and cooling power, respectively, 50 % and 15 times larger than the previous best electrocaloric devices.

This puts the prototype leagues ahead of all previously tested electrocaloric concepts.

出典： UPCommons

出典： UPCommons

The material was also tested for repeated heating and cooling cycles and has shown no sign of degradation.

Among the many advantages of electrocaloric systems is that the direct use of electricity makes EC coolers compact in volume and suitable for miniaturization. So, besides future heat pumps, it could also be used in small electronics and batteries.

It also has very high efficiency, potentially much higher than the compression heat pump system can hope to achieve.

さらなる改善

Science誌に掲載された研究 describes a prototype. Some further improvements are discussed as well.

For example, the current prototype uses dielectric fluid rather than water to prevent short circuits. However, this dielectric fluid has poor thermal properties compared to water.

So, developing waterproof multi-layer capacitors (MLC) could significantly improve the speed and cooling capacity of the system.

Increasing the number and density of MLCs could also result in more cooling potential.

Finally, thinner and flatter electrocaloric modules would help, and it is not clear if applying higher electric fields is possible and safe.

先進的なヒートポンプ企業

There is currently no company commercializing electrocaloric heat pumps or cooling systems. It is still very much an academic and applied physics field.

However, it is likely that now that the technology is evolving at a level of efficiency, making commercialization viable, these research institutes will look to monetize their patents.

So, it could be interesting to look at the leaders in the heat pump industry who could benefit from licensing the IP for electrocaloric devices.

It is also likely that the creation of commercial-grade electrocaloric systems and their distribution to end users will be a very capital-intensive process, favoring the largest actors in the industry.

1. Carrier Global

CarrierはHVAC（商業・住宅）、コールドチェーン、および防火・セキュリティのリーダーで、従業員は58,000人以上です。ヒートポンプだけを販売しているわけではありませんが、同社はこの製品カテゴリを業界の将来と位置付けています。

主にアメリカ大陸に焦点を当てており、HVACが売上の半分以上を占めています。

出典： Carrier Global

商業用HVACが330,000台以上、住宅用HVACが3,300万台以上、冷蔵設備が180万台以上、消防・セキュリティシステムが9,000万台以上という導入実績があります。

The company is determined to drastically reduce its greenhouse gas (GHG) emissions by 2030.

Considering that a lot of these emissions come from ammonia coolants, the possibility of switching to an electrocaloric system in the future offers the industry a path forward where its only emissions are related to energy consumption and metal mining, which will be powered by renewables.

出典： Carrier Global

2. Daikin Industry

The Japanese company founded in 1924 can claim to be the world’s number 1 air conditioning company.

The company has been active in the heat pump space since 2006 and has established as early as 2008 a business alliance with Gree Electric Appliance, China’s top air-conditioning manufacturer.

It is mostly selling in the Americas, Europe, and East Asia, but has experienced explosive growth in markets like India as well, with a 23x increase in sales between 2009 and 2022.

出典： Daikin

One of Daikin’s competitive strengths is its R32 coolant, with a much lower effect on global warming than its competitors.

This means that the emergence of electrocaloric systems might be in the short-term a threat to the company’s competitive position.

出典： Daikin

But at the same time, it reflects the company’s preexisting focus on the environmental effect of cooling systems and innovation capacities (it invested $300M in a new R&D center in 2015) and would make it a good candidate for developing these systems at commercial scale.

A strong indication of Daikin’s dedication to eco-friendly innovation is the worldwide free access to basic patents for R32 since 2015 and free access in 2019 to all the group patents since 2011.

3. NIBE Group

Investors interested in the prospect of heat pumps and electrocaloric systems might want a company fully dedicated to the sector, without the distractions and risks associated with other technologies.

In this case, they might be interested in Nibe, a European manufacturer of heat pumps, as well as wood stoves (another carbon-neutral heat source).

The company is originally from Sweden and still conducts a large part of its sales in Nordic countries, as well as Europe. It had 21,333 employees in 2022.

出典： Nibe

The company’s heat pumps have avoided the emissions of 360,000 tons of CO2 in just one year.

As a more focused company, Nibe is as big as Daikin or Carrier when it comes to heat pumps alone.

With research about electrocaloric materials ahead in countries like Luxembourg and Germany, this could open the way for European companies like Nibe to establish privileged relations with researchers and be among the first to expand their offer beyond compression-based heat pumps.