The energy and financial payback time and the maintenance costs are terrible on Solar PV, IOW the EROEI is unsuitable. The only places I have seen reports of Solar PV cells generating enough energy to replace themselves and create a large surplus is in high altitude locations where the sunlight is less attenuated by the atmosphere. So if you live in Quito or Nepal they might be suitable.cephalotus wrote:why?Tanada wrote:Solar towers are great, solar PV not so much.
Can you provide some numbers.I also would not go with hydrogen fuel cells, though you could get the precious metals needed by recycling catalytic converters off of the automobile fleet as it retires.
An average Catalytic Converter in the USA contains 1.5 grams of Pt, most of the Hydrogen fuel cells I was able to find figures for average 15g Pt. There are somewhere around 100,000,000 catalytic converters in scrap yards or on old cars used as a third vehicle for younger less experienced drivers plus twice that many on the primary and secondary vehicles because many of them have 2 converters each. So for every 10 scrapped you get enough Pt for a new hydrogen fuel cell auto and if you are doing a full conversion of the fleet the Pt that would go into new cars will go in as fuel cells instead of as cat converters. It wouldn't be an over nite switch, I was thinking in terms of all new cars being fuel cell and old cars being scrapped to provide some of the Pt.
I would instead store the hydrogen as Ammonia liquid in tanks and burn the ammonia in combined cycle gas turbine power plants when needed.
Do you want to burn ammonia (NH3) or do you want to burn methane (CH4)? Methane = natural gas = fuel for power plants. Ammonia is used for producing fertilizers for example.
It's "quite easy" to make methane out of CO2 and H2 (Sabatier process) and there is already a huge methane infrastructure for energy usage. You can mix natural gas and synthetic methane at any rate without the need to change anything in the infrastructure (as long as hydrogen content remains below 0,5%)
You can also use methane for heating, cooking and you can run your cars on it. All of this is already in existence and sold in the thousands, if not millions.
We are now building the first plants in the MW range in Germany. Our biggest problem so far is the electrolyseurs that make use of fluctuating energy inputs.
The problem for synthetic methane in the USA is, that natural gas is ultra cheap. There is no chance that it can compete EVER at that extremely low price level, even if you get the electricity at zero costs.
Nope, I meant Ammonia NH3. In the USA there is already an extensive Ammonia infrastructure, if you so desire you could convert any standard gasoline burning engine to run on it the same way you can with Methane. Where methane is orderless and a very potent greenhouse gas that has to be stored under high pressure to get a reasonable vehicle range Ammonia liquifies at moderately low pressure and has a very potent odor letting you know instantly if there is a leak. I don't know of anyone using it for heating or cooking but when you burn it in a gas turbine you produce electricity with very low CO2 emissions, none of it from the fuel itself. The two common methods of producing Ammonia are a Haber-Bosh alternative process consuming Methane and air and the electrolytic process where Nitrogen and Hydrogen gas (from electrolysis ) are run over the same kind of catalysts to produce Ammonia. If you are working on an electricity storage system like the author proposes to have grid power at night from storing Hydrogen Ammonia is a much simpler storage medium than Methane and requires only air, water and electricity as inputs instead of air, water, CO2, electricity. We do not yet have the technology to cheaply provide CO2 on an industrial scale unless we do it by heating Limestone or feed directly off a fossil fuel source.
