<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>SigmundA</author><text>Look at volume instead of weight. Hydrogen is only 8 MJ&amp;#x2F;L in liquid form vs 38MJ&amp;#x2F;L for Diesel. Think of the space needed in the vehicle.&lt;p&gt;Next creating liquid hydrogen is a very energy intensive process compared to refining diesel.&lt;p&gt;Next energy in lithium batteries is converted to mechanical energy with +90% efficiency in a modern electrical motor. Fuel cells just like combustion engines are only 40-60%.</text><parent_chain><item><author>kasperni</author><text>The main thing hydrogen has going for it is the stored energy by weight which is around 142 MJ&amp;#x2F;kg. Lithium batteries are less than 1 MJ&amp;#x2F;kg. So around a factory 200x difference. Ir you want to find something better than hydrogen energy&amp;#x2F;kg wise you have to go nuclear.</text></item></parent_chain></comment><story><title>Volvo and Daimler bet on hydrogen truck boom this decade</title><url>https://arstechnica.com/cars/2021/05/volvo-and-daimler-bet-on-hydrogen-truck-boom-this-decade/</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>davidrm</author><text>Yes, but that&amp;#x27;s not the e2e efficiency of the hydrogen powertrain, a 120kW hydrogen stack found in Hyundai Nexo is as big as an average petrol engine and its energy efficiency is somewhere around 45%, so it&amp;#x27;s not only the hydrogen tanks and the hydrogen inside it. If we&amp;#x27;re going to analyze the volumetric and mass efficiency and compare it to a BEV, then we need to take everything into the account.&lt;p&gt;Majority of hydrogen produced is made from processing oil, the energy efficiency of &amp;quot;green&amp;quot; hydrogen (electrolysis) is very poor and thus expensive.&lt;p&gt;I believe there&amp;#x27;s a strong chance of using hydrogen for long haul type of transportation, however, there are a lot of misconceptions about the technology and its general practicality.</text><parent_chain><item><author>kasperni</author><text>The main thing hydrogen has going for it is the stored energy by weight which is around 142 MJ&amp;#x2F;kg. Lithium batteries are less than 1 MJ&amp;#x2F;kg. So around a factory 200x difference. Ir you want to find something better than hydrogen energy&amp;#x2F;kg wise you have to go nuclear.</text></item></parent_chain></comment><story><title>Volvo and Daimler bet on hydrogen truck boom this decade</title><url>https://arstechnica.com/cars/2021/05/volvo-and-daimler-bet-on-hydrogen-truck-boom-this-decade/</url></story>