How Mirrors Could Solve our Energy Problem

Where does the hydrogen come from if you say you get it from water then you are in a for a big mistake , if you say it produces water as a by product your in for a big mistake  . How much water do we have on the planet and how long will it last if we turn it into a fuel source you cant burn something and get the same amount out as a by product . Water is not unlimited there is only so much on earth and if we turn it into fuel in any form it will create water shortages .Because pure hydrogen does not occur naturally on Earth in large quantities, it usually requires a primary energy input to produce on an industrial scale. Hydrogen fuel can be produced from methane or by electrolysis of water.  As of 2020, the majority of hydrogen (∼95%) is produced from fossil fuels by steam reforming or partial oxidation of methane and coal gasification with only a small quantity by other routes such as biomass gasification or electrolysis of water.

Steam-methane reforming, the current leading technology for producing hydrogen in large quantities, extracts hydrogen from methane. However, this reaction releases fossil carbon dioxide and carbon monoxide into the atmosphere which are greenhouse gases exogenous to the natural carbon cycle, and thus contribute to climate change. In electrolysis, electricity is run through water to separate the hydrogen and oxygen atoms. This method can use wind, solar, geothermal, hydro, fossil fuels, biomass, nuclear, and many other energy sources . Combustion engines using hydrogen are of interest since the technology offers a less substantial change to the automotive industry, and potentially a lower up-front cost of the vehicle compared to fully electric or fuel cell alternatives. However, the non -zero emission nature of the engine means it will not be able to operate in city zero emission zones, unless part of a hybrid powertrain. I have one question where is the electricity coming from to make the hydrogen in the first place , if you say wind farms or solar farms then how much carbon emissions did that process  make to produce the products to produce them . Some of this is quoted from Wikipedia.