Geothermal pluses and minuses

[c1ue]

Re: Geothermal pluses and minuses

"...The 30-megawatt (MW) PGV plant uses air-cooled condensers and noise reduction enclosures. It is a low-profile plant, 24 feet high, and has near zero emissions. One hundred percent of its geothermal fluid and gas is reinjected into the deep earth..."

Yes, but just how much "geothermal fluid and gas" is involved?

Note Hawaii is just a series of volcanoes - I'd just about guarantee it isn't necessary to drill down 2 miles to access high geothermal heat.

This isn't true for most of the rest of the world, including the entire lower 48 of the US.

30 megawatts also is completely puny. Hawaii only has 1 million or so people, so perhaps 30 MW is a significant chunk, but California alone used 258 Terawatt-hours in the year 2000.

Even assuming 100% load factor, this equates to 29.4 Gigawatts of capacity - or over 1000 of the example plants.

Throw in transmission losses, load factors in the 60% to 80% range (fossil fuels) and we're talking serious volumes.

[thriftyandboringinohio]

Re: Geothermal pluses and minuses

...30 megawatts also is completely puny. Hawaii only has 1 million or so people, so perhaps 30 MW is a significant chunk, but California alone used 258 Terawatt-hours in the year 2000.

Even assuming 100% load factor, this equates to 29.4 Gigawatts of capacity - or over 1000 of the example plants.
....

Yup. Smallish commercial synchronous generators are 120 MVA (i.e, 120 million watts) popular at co-generation plants and small peaking units moved by gas turbines. At the big end of the spectrum are base load steam turbine generators of 800 MVA or more, nearly a billion watts.

[lektrode]

Re: Geothermal pluses and minuses

....30 megawatts also is completely puny. Hawaii only has 1 million or so people, so perhaps 30 MW is a significant chunk,...

coulda/woulda/shoulda been an even bigger chunk, but for the protest committee, virtually every step of the way...

and wouldnt be surprised to find that hawn electric aided/abetted em, to boot = competition for the oil-fired boilers, ya know

[mooncliff]

Re: Geothermal pluses and minuses

http://www.livescience.com/9777-eart...-projects.html


My cousin uses a geothermal heatpump to heat/cool her house. It's very efficient.

Combined with something like the IceEnergy system it could significantly reduce base load demand.

http://www.ice-energy.com/

The geothermal systems are extremely efficient, but aren't they like 50 to 80 thousand dollars?

The most energy efficient Panasonic heat pump/air conditioner in Japan costs about $1,500 on sale and runs at about 2 cents per hour at the US average rate of 10 cents/kwh. There are models made for Hokkaido, which has a climate like New England.

It usually takes much less energy to move heat than it does to produce heat like by heating an electrical element or filament in a light bulb. Since the ground 10 feet down does not vary in temperature much during the course of the year, the temperature differential is low, and it is easy to extract heat from the ground during the winter and pump heat down into the ground during the summer. However, I think the compressors in the heat pump/air conditioners have become so good that even though the air is much colder than the ground in winter, and the air is much hotter than the ground in summer, it is now possible to use the atmosphere efficiently, and a geothermal system is unnecessary in most situations? I have no experience with geothermal systems so would like to hear comments.

[lektrode]

Re: Geothermal pluses and minuses

The geothermal systems are extremely efficient, but aren't they like 50 to 80 thousand dollars?

the numbers i have heard for the in-the-ground part = 15 to 30k + the cost of the mechanical install (the actual heatpump and assoc hardware) = several thou more.

and the correct terminology is 'ground source' heatpump

geothermal is the term for deep earth/volcanic source (but dont quote me here)

The most energy efficient Panasonic heat pump/air conditioner in Japan costs about $1,500 on sale and runs at about 2 cents per hour at the US average rate of 10 cents/kwh. There are models made for Hokkaido, which has a climate like New England.

the one i have, a 9000btu unit, with r-410a gas, would typically retail for appx 800, a low end appliance - a range on this size would be to appx double that - and uses 810w in cooling mode, 770w in heating, with a SEER rating of 13... the higher end/newer models are upto 19seer

It usually takes much less energy to move heat than it does to produce heat like by heating an electrical element or filament in a light bulb. Since the ground 10 feet down does not vary in temperature much during the course of the year, the temperature differential is low, and it is easy to extract heat from the ground during the winter and pump heat down into the ground during the summer. However, I think the compressors in the heat pump/air conditioners have become so good that even though the air is much colder than the ground in winter, and the air is much hotter than the ground in summer, it is now possible to use the atmosphere efficiently, and a geothermal system is unnecessary in most situations? I have no experience with geothermal systems so would like to hear comments.

the issue, for heating, gets to be the air temp... once down to appx 40degF, an air-to-air heatpump is perty much useless - altho i once upon a time had a 'solar heatpump' that utilized a flat-plate evaporator (vs a finned-tube/coil assy) that did a great job in lower temps as long as the sun was shining on the panels, and it could keep up with DHW (hot water) use down to appx 20degF, but was useless below that for anything (tho it used r-12 for gas in them daze, and with r-410 mightve done better) - so in colder climates, obviously a ground-source unit would work much better - but air-to-air is purrfect for the climate (and elevation) that i'm in, out here

[c1ue]

Re: Geothermal pluses and minuses

The most energy efficient Panasonic heat pump/air conditioner in Japan costs about $1,500 on sale and runs at about 2 cents per hour at the US average rate of 10 cents/kwh. There are models made for Hokkaido, which has a climate like New England.

The units you speak of make much more sense for a typical Japanese home than a typical American one.

In the US, a typical home has 6 or more rooms: 3 bedrooms, dining room, family room, kitchen, 2 large bathrooms

In Japan, a typical home has perhaps 4: 2 (much smaller) bedrooms, 1 room which combines kitchen/family/dining, 1 bathroom (also much smaller).

Putting 6 units in vs. the 2 in a typical Japanese home - you're not saving much vs. central air conditioning any more.

[lektrode]

Re: Geothermal pluses and minuses

The units you speak of make much more sense for a typical Japanese home than a typical American one.

In the US, a typical home has 6 or more rooms: 3 bedrooms, dining room, family room, kitchen, 2 large bathrooms

In Japan, a typical home has perhaps 4: 2 (much smaller) bedrooms, 1 room which combines kitchen/family/dining, 1 bathroom (also much smaller).

Putting 6 units in vs. the 2 in a typical Japanese home - you're not saving much vs. central air conditioning any more.

my shack is 1000sqft, with the 'main living area' (combo galley/bar/living rm) appx 360sqft of the total - the heatpump is a 'mini-split' with the comp/condensor assy outside and a wall mounted airhandler (blower) on the wall in the next room, a straight-line path thru the doorway into the main living area, so it effectively covers the entire space - with my office suite being the primary focus - but the main area getting plenty of cooling or heating - its interesting to note that heating the space seems to take much less effort than cooling it (altho the temps dont vary all that much here) this i attrib to me being more sensitive to hot than cold (a NH 'fish out of water' in HI perhaps? ;)

bottom line?
with electric at .45/kwh (this month) it costs me appx $us40-50/mo to keep the interior temps in _exactly_ the range i prefer it: no lower than 72 in the summer, 75 'winter' (hawaii) and no higher than 75-79 in the summer, with humidty appx 20pts lower inside than out = comfort that one can feel.. theres a lot of days (in winter mostly) when its actually warmer inside than out, but feels colder inside, due to 20-25 pts lower humid (which keeps the flora that would blow in thru the windaz from sprouting...)

[c1ue]

Re: Geothermal pluses and minuses

my shack is 1000sqft, with the 'main living area' (combo galley/bar/living rm) appx 360sqft of the total

http://www.census.gov/const/C25Ann/s...medavgsqft.pdf

Average square footage of residences in the United States in 2010: 2,169 square feet

http://en.wikipedia.org/wiki/Housing_in_Japan

The average number of rooms per unit of housing was 4.77, the average total floor area in was 94.85 square meters (28.69 tsubo; 1,021.0 sq ft)

I don't spout numbers out of thin air...