1 / 14

Energy use -- a personal assessment

Like most Quebecers, a very significant part of my energy use is involved in trying to stay warm through the long winter; in my case, heating accounts for about 35% of my direct personal energy use.

shaunna-kelleher
Download Presentation

Energy use -- a personal assessment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Like most Quebecers, a very significant part of my energy use is involved in trying to stay warm through the long winter; in my case, heating accounts for about 35% of my direct personal energy use. Winter heating and much of the rest of our energy use doesn't necessarily require low entropy sources of energy. Energy use --a personal assessment Olivia for 666 October 21, 2009

  2. Most sources of geothermal energy are not very “hot”; that is, they offer their energy in an already high entropy state relative to available heat sinks. Still there is a vast resource of such energy that we may be able to tap. I offer some realistic as well as some probably whimsical examples. Energy at high entropy

  3. The St. Lawrence river flows past Montreal at about 1.4 x 1010 lt/s. In mid-winter, its temperature is about 4oC. From the entire flow, we could extract 5.86x104 GW/KΔ. That is equivalent to about 2x the installed generating power of Hydro-Quebec -- simply by lowering the temperature by 1oC. Heat pumping the St. Lawrence River

  4. I heat my house during the autumn and spring with a 2.5 ton “thermo-pompe”. Outdoor air input temp: 6C Output temp: 2C Freon temperature from compressor: 49C Indoor air input temp: 21C Output temp: 31C Power consumption in process: 3.58 kW Equiv. heat provided: ~5 kW. A marginal benefit but still a real benefit even on a 6C day. Heat pumping -- Saturday's simple experiment

  5. What do we need to extract energy from a heat source? A temperature gradient. Where do we have some interesting natural gradients? Consider the ocean. Water in the deep ocean basins is “cold” ~ about 4C. If we could move heat from the 13C surface to the base, we could run a thermal engine along this unusual temperature gradient. Unexploited thermal sources

  6. Under gravity, g, a material of volumetric expansivity, αP, and heat capacity, CP, determines an adiabatic temperature, T(z), that increases with depth, z, and pressure: dT/dz = g αPT / CP If the actual material temperature T(z) locally exceeds this gradient, the material will want to rise upwards -- bouyancy. If it is cooler it will sink – negative bouyancy – we have internal convection. Adiabatic gradient

  7. While it is not clear to me how one might build one, the unusual temperature gradient in the oceans (cold, rather than warm at depth) might be exploitable by a convection engine. A working material with high αP and low CPmight fill the bill by providing a rapidly increasing temperature difference relative to the water with depth. A convection engine?

  8. In the upper ~10 metres of the Earth, soil and rock temperature is dominated by insolation and climate rather than by the geothermal gradient caused by the outflow of heat from the Earth's hot interior. Luckily, last summer's heat is stored for this winter's use. We can pump that heat from the soil to warm our homes. Last winter's cold can provide summer air conditioning. The soil saves solar heat

  9. S Canadian Climate Data Online for Mirabel

  10. ..in my back yard! 5 years ago I seriously explored options for heating my home... geothermal, heat-pumping from the lake reservoir, passive solar panels, photo-voltaic panels and conventional oil-fired furnace. I need at least 90GJ (equivalent) to heat my home to Canadian comfort throughout the 6-month winter. Heating my home – finding heat wherever I can...

  11. Electrical (direct joule heating): 25000kWh @ ~$0.07/kWh = $1750/winter. Geothermal (soil): removing 100GJ of heat from 1000m2 x 3m cumulatively lowers the soil temperature by 0.17oC each winter. Moreover, the heat pump energy cost ~8600kWh = $600/winter. Geo-hydrothermal (lake water): removing 100GJ freezes 300 tonnes of water – plus heat pumping cost ~8600kWh = $600/winter. Choices... Environmental costs in italics!

  12. While no one would expect solar heating via photo-voltatic panels to serve much purpose, what would I need for Nov-April heating? In St. Jerome, during this 6 month period, the accumulated insolation on a well-positioned PV panel is 2597 MJ/m2. At the 15% efficiency of current high performance PV cells: 231 m2. Photovoltaic potential and solar resource maps of Canada Dow Powerhouse Solar Shingles Choices, con'd...

  13. Passive solar thermal heating is perhaps a better choice... It requires no conversion to electrical energy and, if well conceived, is more efficient as a simple source of heat. Parabolic solar collectors such as those used at the Kramer Junction, CA generating station recover about 25% of the available insolation. Direct use of the heated working fluid with some storage scheme might offer the least costly source of energy. Choices, con'd... 2 Kramer Junction thermal farm

  14. At 85% efficiency, 100GJ ~ 3050lt heating oil @ $0.67/lt (current) = $2050/winter. The Hydro Quebec DT rates: $0.0433/kWh > -12C (~ 2/3 heating period) $0.1814/kWh < -12C (~ 1/3 heating period) Using oil below -12C: ~ $730/winter; using electric joule heating above -12C but below 2C and heat pumping above 2C: ~$800/winter. Choices, con'd... 3What I chose.

More Related