Hacker News Reader

Using batteries for grid storage is terrible compared to pumped hydro and on demand hydro.

We agree on the chemistry. The point of my ps is the C becomes CO2 the H becomes H2O, but we don't care about H2O. Which is why hydrocarbons produce less CO2 per watt than coal.

View on HN

The downside of PSH of course is the massive reservoirs you have to create, but they have astonishingly good efficiency (I was skeptical when I first heard of the concept, but real-world examples can hit an 80% efficiency target which more than makes up for the constant replacement of batteries and the potential impact of sourcing lithium or other materials depending on who is mining them).

I agree pumped hydro is good, but there are only so many places you can site it.

> Which is why hydrocarbons produce less CO2 per watt than coal.

No. It has nothing to do with water. Coal is a hydrocarbon as well. It has to do with the type of hydrocarbon chains.

Anthracite coal is up to 85.7% carbon by weight the rest is not pure hydrogen but a mix of sulfur, oxygen, nitrogen, and hydrogen. (And yes, that Oxygen lowers the energy density while increasing CO2 release.)

Natural gas is 25% hydrogen 75% carbon.

Burning hydrogen produces water not CO2.

So, while the specific bonds play a role the actual carbon vs. hydrogen content is a major issue.

Reply on news.ycombinator.com