Fuel Cells in a Hydrocarbon Economy

Cleantech blog has got it right in Richard T. Stuebi's post on fuel cells on Nov. 13.

His main points are 1) (the hydrogen economy) to say the least, is not very likely, at least not anytime soon and 2)  in stationary application the fuel cell market continues to show improving vital signs.

A good short read.

Comments

[mds]

I agree that the transition to renewables will take time and we'll need relatively cleaner ways of extracting energy from fossil fuels in the interim. Solid oxide fuel cells may be one way to do this.

I think another important point is being missing relative to fuel cells: longer term energy storage. Solar, wind, wave, and maybe tidal power will all be dropping below peak electrical power rates. Wind and Conc. Thermal Solar are already there. With increased scales of production their costs should continue to drop. We are going to see an explosion in the use of renewables, particularly solar since it can reduce peak rates during summer days for much of the more populated southern USA. What happens when we start to see renewables become a very large percentage of our energy generation? You have more than a load leveling problem. You have a longer term storage problem. There is not much sun in December, in the northern half of the USA. The wind may not blow for several weeks. Hydrogen can be stored in pressurized tanks for months without much loss. Granted, hydrolysis is not very efficient to begin with. Is there a form of long term storage, for large amount of energy, that is more efficient or cost effective? Seems like hydrogen has a secure future here. Am I wrong?

[Engineer-Poet]

The advance of alternative energy sources like solar and wind is moving so fast that it seems to be creating a kind of tunnel vision on the part of its afficionados.  The conversion of energy from electricity to hydrogen and back is so inefficient, and storage so expensive, it probably makes more sense to generate some other form of energy and use that to cover gaps instead.

[Jim from The Energy Blog]

Energy storage in the form of eutectic salt thermal storage for thermal solar (on a utility scale) is already in use in Spain, in several projects and has been proposed for the US. It is fairly economical to extend the useful generation time for 4-6 hours each day--of course the solar facility has to be made that much larger. It is a rather low technology solution.

Vandium Redox flow batteries for storage of energy for small systems, up to 12 MWH, is in fairly wide useage and it is just a matter of time before it is scaled up for use with large wind power applications.

Hydrogen storage is not the answer!!

[Engineer-Poet]

Even flow batteries become unwieldy when you try to store energy across seasons instead of hours or days.  IMHO, the answer is carbonaceous solids or liquids.  They can be stored for months (heaps of charcoal will keep for years) and are both energy-dense and cheap to keep around.  You don't need to make enough to run the whole economy, just enough to fill the gaps when nothing else is available.  Last, the direct-carbon fuel cell is considerably more efficient than hydrogen fuel cells and has no electrolyzer losses on the front end.

[amazingdrx]

Using geothermal heat pumps for heating and cooling IS using seasonal energy storage. By cooling buildings with ground temperature and only using circulating pumps that summer cooling load would be a small blip on the grid radar, instead of the load that causes brown outs.

But as far as energy storage for the grid over seasons, that is why backup sources are needed when relying on reneweable energy.

And solid oxide fuel cell/turbines that run on natural gas,biogas, cellulose, pyroliozed cellulose (for longer term storage), and even coal; are the best alternative for grid backup. 75% efficiency and all emissions can be reprocessed through algae solar collector systems. That produce biodiesel and more dried cellulose (for use in the fuel cell) from the algae.

[George]

What about pumped water for energy storage?

[Engineer-Poet]

Most pumped-storage systems are cycled daily, their reservoirs filled overnight and emptied during the peak hours the next day.

Consider how much land you'd need if you wanted to store energy for months instead of hours (roughly 180 times as much, or 1/180 the power for the same size reservoir).  Consider the expense.  Pumped storage is a really poor fit for this sort of requirement.

[Harvey D.]

Water (pump) storage, in very large hydro reservoirs, has merits. It is their primary function and they can handle/store huge amount of power for very short or long periods.

Coupled with alternative energy sources such as wind and/or solar, hydro plants reservoirs become huge batteries that can be charged (refilled) or discharges (drained/used) at will.

Existing and new hydro plants could be made partially bidirectional with two reservoirs at different elevations. The main or high reservoir becomes the battery and the lower (smaller) one is the water source to be pumped up when you have a power surplus from alternate sources. Water turbines/generators are very efficient in both directions

In practice, you don't have to pump water up because you could select to use all the alternative power directly while shutting down the hydro source, partly or totally as required. This is equivalent to pumping water up because you stop using/draining water from the natural reservoir which in turn would refill naturally from the river feed.

Of course, some over-equipment would be required (if not already in place) to satisfy increased peak demands when alternative sources are not producing.

The beauty of such system is that it uses proven technologies and can be introduced quickly in many places across North America.