• Question: how different are hydrogen from electrical engines and id diesel engines are so bad dont you need to burn to make electricty to charge the engines

    Asked by jayj on 23 Oct 2021.
    • Photo: Robert Astbury

      Robert Astbury answered on 5 Oct 2021:

      All Fossil fuel cars need to go, and when it comes to comparing Hydrogen and Electric Cars. there is no comparison in terms of energy efficiency.

      Hydrogen fuel is a very ineffiecent way to power a small vehicle. if you take 100Watts of power from a power station, only 38 watts makes it to the cars wheels (through all the infrastructure and conversion in-efficencies). Now compared to battery electric cars, 100 watts from the power station equates to 80 watts delivered to the wheels.

      So hydrogen would cost the UK twice as much power demand in electric than battery electric cars. Hydrogens main use case would be for much larger heavy vechicles / aircraft where batteries have more limited ranges.

    • Photo: Paul Adams

      Paul Adams answered on 5 Oct 2021:

      In comparison to EV battery recharging, hydrogen refueling has a distinct advantage. A hydrogen tank can typically be filled within five to ten minutes.

      Although technology for electric charging and batteries has advanced recently, recharging times have remained slow. There are now fast chargers that can restore a battery to 80% capacity in about 30 minutes. It takes four to eight hours for Nissan Leafs and BMW i3s to charge completely, however.

      The technology, supply, and infrastructure of hydrogen cars lag behind that of electric vehicles. By March 2020, there were roughly 78,500 charging outlets and nearly 25,000 charging stations available exclusively in the U.S.

      42% of the UK energy production now comes from renewable sources such as wind farms. Compare that to 2000 when it was approximately 75%, and 1980 when it was more than 90%.
      So the shift is definitely in progress. There is still a long way to go but it is moving in the right direction. If you pair that statistic with the increasing number of EVs on the road then the net movement is favourable.

    • Photo: Beatrice Browning

      Beatrice Browning answered on 5 Oct 2021:

      1) To answer the first part of your question, here is the difference between electric and hydrogen-powered vehicles:

      – Electric vehicles don’t actually have engines, they run on electric motors which are powered by rechargeable lithium-ion batteries. These batteries are recharged at electric vehicle charging points, where the battery is plugged into a power supply. The speed at which charging can be done is currently limited by the technology, and infrastructure needs to be improved.

      – Hydrogen-powered vehicles have hydrogen tanks which supply hydrogen to a fuel cell. In this fuel cell, hydrogen mixes with oxygen to create water (H2O). The energy from this reaction generates electricity is used to power motors within the vehicle. The way a hydrogen cell is recharged is similar to a petrol or diesel car – a pipe is connected to the hydrogen tank and filled up.

      2) To answer the second part of your question:

      Based on figures presented by the U.K. government (published by the Department for Business, Energy and Industrial Strategy):

      In 2020, the proportion of fossil fuels used to power the UK was only 37.7% which is a record for UK energy production. 43% of energy produced was by renewable energy resources, mainly from wind solar and biogas. As the years go by, the proportion of renewables powering the UK is increasing (in 2019 only 37% of power was from renewables). This increase means that the electricity supplied to EVs is far more likely to be from renewables in years to come, whereas for diesel engines, there will always be harmful waste emissions produces from the combustion of diesel.

    • Photo: Ferran Brosa Planella

      Ferran Brosa Planella answered on 5 Oct 2021:

      I don’t know much about hydrogen vehicles, so I suggest you check what my colleagues wrote. About the latter, the short answer is that an electric vehicle will be as clean as the electricity you use to charge it. If the electricity comes from charging coal, the car will be more contaminant than an internal combustion engine car.

    • Photo: Chris Muir

      Chris Muir answered on 6 Oct 2021:

      Hydrogen can be a combustion process – it burns (Oxidises) and releases heat energy, which is used to provide pressure much like petrol inside an internal combustion engine.

      A more efficient Hydrogen energy flow is to use a fuel cell, which mixes hydrogen and oxygen generating electricity. This wastes less energy in the form of heat, so is much more efficient – energy in – energy out.

      Both hydrogen methods have a byproduct of water – really easy to deal with at the electricity generation site, be it in a car, train, at a home etc.

      Fossil fuels (Gas, Coal, Petrol, Diesel, etc. etc.) byproducts are quite harmful particulates as well as the greenhouse gases (GHGs) which contribute to climate change. The particulates are really bad at the generation site – I think of cycling behind a diesel bus.

      So you can see that Hydrogen has a couple of benefits. 1. It removes particulates from the end use (normally in city centres). 2. It has the potential for higher energy efficiency – reducing total amount of particulates and GHG produced.

      Note that it doesn’t eliminate them – we still need to harness the energy in the first place. But with it, it’s easier to incorporate renewables (solar, wind, tidal, even nuclear) into that process, further reducing environmental impact.

    • Photo: Rohin Titmarsh

      Rohin Titmarsh answered on 12 Oct 2021:

      In very simple terms hydrogen powered vehicles use a fuel cell, which is a stack of layers of material and catalyst that when the hydrogen passes through, generates electricity. The output is water.
      In electric vehicles the electricity is stored in the battery (we call these battery electric vehicles or BEVs) and is sent to the motor to drive the car. There is no output.
      In diesel powered vehicles it’s a similar principle, diesel is stored and sent to the engine to drive the car, but the output is far worse for the environment. The emissions are harmful for humans too.

      On the point of burning fuel to generate electricity then yes this is a problem but when that electricity that charges BEVs is generated from sustainable means like wind, solar, tidal etc. then it’s much better than fossil fuel powered vehicles.

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