Outcast_Searcher wrote:This kind of unscientific "gee, this science stuff seems counter-intuitive, so I'll just throw some random idea that seems more comforting out there" thinking just doesn't cut it in the 21st century.
How about some math or geology to back up your idea, to show that it "seems just as plausible"? Otherwise, you might as well propose unicorns or imaginary religious figures in the sky as a "plausible" solution. (And sorry, but math and science take education and hard work).
OK, since you ask, though a little more civility would have been in order. I used the terms huge and massive since most people nowadays seem to respond better to adjectival terms like awesome, extreme, etc - that's so 21st. century - and skim over the boring details. Plausible also seemed to me to be a good shorthand description of the status of geothermal engineering at this time. Trying to create an ideal length for a post to get a message across is no easy matter, while giving credit to the readers for understanding the context. Obviously in your case I failed.
The most common storage need seems to be in the area of offsetting peak or downtime loading on the electrical power grid. There's nothing wrong with positing the concept. The logic and desirability are strong, but that does not mean it can be accomplished to any degree of satisfaction.
http://www.youtube.com/watch?v=2C2W_O9BX4gAccording to the latest nos I could find, the US only electrical power generation for 2012 amounted to 4054 TWh. Of this, nuclear was 19.1%, coal was 41.9% and hydro was 7.7%. The remainder was nat gas , oil and renewables. The first three represent the best base loading potential. The others can be used as peak smoothing as well as base loading. Of the renewables, wind represents 2.9% and solar is 0.04%. By this proportion, wind produced 120 TWh of power during the year. Wind is probably the least reliable of all and is in most need of downtime backup. So lets look at this.
Taking an arbitrary average downtime of just 10%, which I suspect is low, the amount of reserve back up should be around 12TWh. (I could find no reported numbers)
The major areas of back up I have seen discussed are battery, hydro and capacitive/electrostatic.
Lead acid batteries typically have a capacity of around 1.2 kW. Heavy duty Li batteries have a capacity of around 0.6kW. Thus, to provide backup across the grid for the downtime of just the wind component, would require 10 million lead acids or 20 million Li batteries. Remember also, that these are in units of 12v dc. At approx. $1,000 each for Li batteries, the purchase cost alone is around $20b. That's not encouraging, although a billion today is not what it used to be.
Pumping water into a reservoir is often suggested as a desirable means of energy storage. It is a net energy loser overall of course because of the inefficiencies in pumping and energy restoration. Nevertheless, a cubic meter of water flowing at a rate of one cubic metre per sec over a one meter drop has 10kW potential energy, rounded out to avoid inconvenient decimal places. So, collecting this water in a 30m high tower for future use is a possible solution, for example. One of the largest such tank/towers in the USA has a capacity of 7,600 cubic metres, so it's possible to build this size, 30m above ground. This capacity gives an equivalent energy storage value of 600kWh. It's not a great solution, unless the idea of powering 6,000 traditional incandescent light bulbs for an hour is acceptable, all inefficiencies excluded. While it's better than nothing and possibly the best method available, it's a lot of investment for a relatively puny result. Using this technique requires the building of some 20,000 water towers to satisfy the assumed average downtime. It's a large, though not an impossible task and of course, the storage infrastructure can be built anywhere on the grid, so it is not restrained to the generating area. Using natural water basins rather than constructing towers would be a far better solution. However, there are many situations where local back ups are preferred. Estimating an installed cost of $0.5m per tower, the gross capital to realise this idea would be of the order of $10b.
In either of the above, it begins to make more economic sense to develop more generating capacity, except that has the knock on effect of increasing demand again and so on and so on.
So far, attempts at large scale electrostatic/capacitive storage have led nowhere, except perhaps to bankruptcy, although it remains a tantalizing and speculative area with possible positive outcomes.
There are other possibilities, such as compressing various gases, but all generally suffer from a low energy density and process inefficiencies, which is reflected in low storage capacity relative to needs. Flywheels are being re-examined.
Remember, this is only attempting to address the back up needs expressed as 0.29% of energy generation and only of the wind generation sector.
Whilst energy can be released easily enough, it is extremely difficult to store it. Electrical power is essentially transient and ephemeral. In fact, all energy use is transient. All of the storage techniques are feasible at a low level, but with the possible exception of hydro, fail to satisfy the needs of grid scale applications. The auto industry is having a tough time creating/finding a battery of even 40kWh - equivalent to one gallon of gasoline. The relentless laws of physics, mechanics, thermodynamics and economics work against the realisation of large scale storage solutions for electrical power, which is essentially the transformation of one form of energy to another and back again.
As far as suggesting that drilling to find hot areas underground is concerned, it is not a facetious comment. If plans are underway to drill to find rock 'reservoirs' that could store heat, why not also go deeper and find temperatures that could support steam turbine activity? Many such installations world wide are already functioning. It's actually much more energy effective that way. This is what geothermal engineering is all about. It is an established science, with much exploration already done. It too has its problems, but since we are now in the mode of scratching around for energy solutions why not put effort into this area?
http://en.wikipedia.org/wiki/Geothermal_electricityhttp://en.wikipedia.org/wiki/Electricity_sector_of_the_United_States
