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Domain: helsinginenergia.fi
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Comments · 7
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Re:Power stations can reach nearly 90% efficiency.
Unless you're talking about using the waste heat to heat homes and businesses, as some places in the north do, but that doesn't exactly apply everywhere.
e.g.
http://www.helsinginenergia.fi/en/tuotanto/chp.html
You might want to look up "District Heating" and "District Cooling", possibly adsorption chillers.
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Some people sell their "waste" heat
To heat domestic water, space heating and even to power adsorption chillers which can reduce AC requirements. Even coal power stations can hit 88% efficient.
http://www.helsinginenergia.fi/en/tuotanto/benefit s.html
US power stations are still only 40% efficient because -
Re:Just point out
The discharge temperature of our steam turbines is around 100 deg F (into a vaccuum), and the water we use to cool that final stage is put back in the ocean at around 80 deg F.
Um, yes... You know the whole idea is to replace the condenser with a heat distribution network... So instead of condensing the exhausted steam with seawater and thereby wasting the heat, you heat up a hot water distribution network and sell the heat. You lose a little efficiency from the steam turbine and gain a huge efficiency boost overall in harnessing the "waste" heat.It's highly ironic that power stations produce more energy as heat than they do as electricity.
No, it's not ironic, it's just the limitations of the physics involved. Basic thermodynamics.
No, it is ironic, and since you missed the point, the irony is the use the electricity is put to, the largest single use of electricity is either to create low grade heat or to create cold (move low grade heat).Taxation doesn't change the thermodynamics involved with the low discharge temperatures, heat losses from even insulated piping to move it around, energy costs of the pumps to move said heat, and the population densities involved.
It doesn't change the thermodynamics. It does change the type and location of the power generation. It's an economic tool which would substantially increase the overall efficiency of the power generators by making the inefficient ones uneconomic.
As to heat losses. You're deliberately throwing the product away at the moment... anything is an improvement. And since you disbelieve, Denmark has a truly huge district heating network (http://www.dbdh.dk/) and Finland also has a well developed district heating sector (e.g. http://www.helsinginenergia.fi/en/). The reason Denmark and Finland have well developed district heating sectors is that they are energy poor, they have no great stocks of oil, coal, gas which makes energy expensive and therefore district heating becomes economically viable. -
Re:Just point out
I don't believe that's correct. Power plants can achieve 40% because they vent heat to the environment. If that heat instead goes into industrial processes, then there will be a reduction of the initial 40% efficiency. Overall efficiency will be better, but heat is generally a lower value product than electricity because it is even more difficult to transport and store.
Instead of venting, it can be distributed through a heat distribution network. District heating is an old technology, insulated pipes can transport the heat for miles. It's been working on the continent in various places for decades, in fact the first district heating systems were created in the 19th century.
e.g.
http://www.helsinginenergia.fi/en/heat/heating.htm l
You're correct that the closer you are to the consumer the better, but then you were venting the "waste" heat to the environment anyway. Nuclear facilities in particular are likely to be difficult to use in this way. -
Re:being an Helsinki citizen
Actually, heated sidewalks can be found in Helsinki.
What's far more disturbing is the ongoing tearing up of streets all over the city to install a central cooling grid!!!
Then again, it makes sense. Ground is slowly rising in Helsinki at a 40 cm per 100 years rate (the ice age glaciers were pretty heavy) which compensates nicely for rising sea levels. The cooling thing must be for rising temperatures. ; )
J -
Where do you think all our waste heat goes?It ends up in the oceans. 60% of the heat from all of our power stations, including nuclear is pumped directly into the environment right now. Our power stations are only about 40% efficient. Rivers and seas are already used to cool power stations. Some of the heat goes into the water, some to the air. It all ends up increasing the baseline temperature, including the ocean.
In Finland and Denmark they use what is called District Heating and District Cooling , which improve the efficiency of power stations to 80%->90%. Instead of just dumping this "waste" heat they've created they pump it round homes and businesses or use it to power district cooling systems where cold water is pumped round houses and businesses in summer. It does still end up in the environment but it's at least useful first.
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Where do you think all our waste heat goes?It ends up in the oceans. 60% of the heat from all of our power stations, including nuclear is pumped directly into the environment right now. Our power stations are only about 40% efficient. Rivers and seas are already used to cool power stations. Some of the heat goes into the water, some to the air. It all ends up increasing the baseline temperature, including the ocean.
In Finland and Denmark they use what is called District Heating and District Cooling , which improve the efficiency of power stations to 80%->90%. Instead of just dumping this "waste" heat they've created they pump it round homes and businesses or use it to power district cooling systems where cold water is pumped round houses and businesses in summer. It does still end up in the environment but it's at least useful first.