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Questions tagged [renewables]

a resource that can be created or used over and over again without depleting the materials from which it is made.

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1answer
59 views

Which measure of solar irradiance is needed to calculate the energy output of PV systems?

According to "E = A * r * H * PR" global formula to estimate energy generated, the solar irradiance value is needed. I have Horizontal irradiance, Tilted irradiance, and Normal irradiance values but ...
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0answers
48 views

What are some office writing materials made from renewable resources?

My understanding is that many disposable pens use non-renewables like tungsten and polystyrene. Pencils use graphite which is carbon but can be depleted faster than it is used. What are the good and ...
4
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2answers
39 views

Is there a simple on-line tool for estimating wind turbine power output?

The back-and-forth in the comments on this answer sent me searching for a simple tool that would enable a user to put in a location, wind turbine size, and a few other parameters, in order to estimate ...
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4answers
172 views

Are trees more productive than wind turbines?

Tree farm assumptions: 250,000 square meters (m2) tree farm A 1 ton tree contains 1 MWh of energy Each tree takes 10 m2 of space Total energy for this farm is thus 25 GWh Wind farm assumptions: 5 ...
4
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1answer
68 views

Will natural gas or propane generators also run off of methane?

I'm looking at building a sustainable energy project that will convert biogas (methane) into electricity. I haven't found any biogas or methane electric generators for sale. It seems that there are ...
5
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3answers
61 views

Cost benefit analysis of a PV array with racking to set optimal angle, vs a larger array

I'm thinking of installing some panels on the roof. It's unshaded but only pitched at 5 degrees on long run roofing iron. Would I be better off racking at an angle to optimize for winter sun, or just ...
3
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0answers
28 views

Are there any articles that describe to correlation between the forecast errors for renewable energy resources, depending on the distance?

In an article by Zhang et al., the authors describe how the (normalized) forecast errors of different renewable energy sources (like solar panels and wind mills) are correlated. To that end, they ...
0
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1answer
107 views

Is it possible to reverse the air flow of a roof turbine/whirlybird?

I am currently working on a device that requires omnidirectional air currents (e.g. breezes/winds) to be directed downwards through a vertical tube. I think it would be a very similar design to a ...
8
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3answers
477 views

Is solar energy the best renewable source of energy?

Here is my thinking on renewable resources. Biomass is the absolute worst way to go because it releases CO2 and damages habitats. Geothermal is not far behind but is for a different reason. ...
6
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0answers
58 views

Calculating wheel and motor size for run-of-river hydroelectric generator [closed]

I am a student designing a hydro electric generator used on rivers to collect kinetic energy from horizontal water flow, rather than potential energy from vertical water drops. My idea is to turn a ...
6
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2answers
163 views

Are RECs (Renewable Energy Certificates) an effective method to “green” industry?

Chris Goldie's answer to a question on sustainable web infrastructure brought this question up. From the US Environmental Protection Agency: A renewable energy certificate, or REC (pronounced: rěk)...
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3answers
85 views

Is “renewable” a proper term for both solar and hydro power?

The common definition for renewable energy sources includes at least: Wind Solar Biofuels Hydro Geo-thermal However, the common definition of renewable makes this grouping a bit awkward. Webster ...
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1answer
84 views

Should we leave all fossil fuels in the ground and not use them?

I get the feeling that there is such a strong backlash against fossil fuels that there is an irrational movement to purge them completely. Maybe because people are transferring their worries about ...
4
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1answer
96 views

What is a good database containing wind speed and direction?

I am pursuing a science project involving wind power, and am looking for some data on wind speeds, directions, and ideally turbulence and shear. Do you know where I could find this? I would need to ...
3
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1answer
95 views

Is a master's degree in computer science relevant for working in sustainable living?

I'm currently at the end of computer science bachelor and not quite sure what to do after. In a way I'd like to continue with a Master's degree and at the same time help somehow for a more eco-...
6
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1answer
86 views

What metrics are usually used to quantify forecasted power error for weather-dependent renewables?

What metrics are usually used to quantify forecasted power error for weather-dependent renewables such as wind or PV? I guess that there are at least two kinds of errors: where the magnitude of the ...
9
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3answers
113 views

How the grid is managed in markets with high renewable energy penetration

As many people know, many of the renewable energy technologies generate fluctuating power dependent on availability of the power generating source e.g. wind and solar et al. Balancing power must be ...
6
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1answer
32 views

How accurate are consultant pre-construction energy assessments?

For power plants where the energy that could be generated is driven by exogenously variable factors, such as wind farms, PV power plants, and run-of-river hydro, which are all driven by weather, how ...
8
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1answer
55 views

How are readings from the wind sensors mounted on wind turbines influenced by the blades' wakes?

Utility-scale wind turbines have various sensors mounted on the nacelle, to ensure the power generation is optimised. How are readings from the wind sensors mounted on wind turbines influenced by the ...
4
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1answer
217 views

What does the P90 of a wind resource mean?

I've heard that investors use the P90 of a wind resource when considering an investment. What kind of measure is it, what does it actually mean, and how is it calculated?
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0answers
19 views

Which part of the process of estimating wind resource has the potential greatest benefit from further research?

Estimations of the potential generation resource of wind power happens at all scales from very coarse global estimates, to detailed estimates at individual sites based on specific locations and ...
4
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0answers
44 views

Is there a recent study that shows how accurate wind turbine wake models are?

Wind-turbine wake models are used in the design of wind farms, to optimise the choice of turbine model, and the layout of the turbines. They're also sometimes used in the operation of wind farms, to ...
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3answers
2k views

What's the average efficiency of pumped hydroelectric energy storage facilities?

Pumped hydroelectric storage has, to date, been the most scalable way to store electricity (in this case, in the form of gravitational potential energy), allowing us to spread the time between when ...
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0answers
81 views

What are the advantages and disadvantages of using lidars over sodars for wind resource assessment?

The process of wind resource assessment has used a variety of methods over the years; more recently, lidar - radar-style sensing using lasers; and sodar (similar, but using sound) have come to ...
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1answer
96 views

How close are renewables prices to scrap value?

I suspect that it's less than a factor of two. Is this right? A 1 kw panel has 10kg of silicon at $20/kg. That's $200 for a panel that costs less than $400, at 34 cents/watt. A 1.5mw turbine has ...
2
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1answer
48 views

Are Eco-Schools more effective teaching children about sustainability?

Is there any evidence that Eco-Schools are better at building sustainability awareness for school kids and teaching them about renewable energy technologies? Or is there a better approach that might ...
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1answer
202 views

Does a PV panel take more energy to build than it generates in its lifetime? [duplicate]

Industrial energy costs are $1 per million BTU (MMBTU) or 300kWh, or $3*10^-6 per watt hour (Wh). http://www.eia.gov/consumption/manufacturing/ Solar has 1 kg of 9n silicon per 100W, at $20/kg. ...
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3answers
144 views

Is pellet fuel a sustainable energy source in the way it's used now?

Pellet fuel is considered a sustainable energy source. But the way it's used now seems to produce air pollution which I think should not happen in case of sustainable energy source. So is pellet ...
5
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1answer
97 views

Hydro-electric generation from roof-collected rainwater

Can electricity be produced from running water by the use of dc motors? For example rainwater collected from from the roof of a very tall house say 15m high is directed through a pipe and at it's exit,...
6
votes
1answer
92 views

Are there different types of water-source heat pump?

I have heard multiple names for water-source heat pumps. What's the difference between something called a water-to-water heat pump, and a seawater heat pump? Are they just different names for the same ...
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1answer
62 views

What is the difference between Geothermal HVAC and Heat pump?

What is the difference between these two renewable energy air conditioning systems?
4
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1answer
72 views

Solar Panel short section of string due to obstacle

Recently I have installed a set of 10 panels connected in series with 1 single Inverter. I have realised that for the first 2 hours 2 PVs have a cast shadow on them from a neighbourhood tank (that ...
2
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0answers
63 views

How effective are “GreenUp” (opt-in utility company green energy) programs? [duplicate]

My local Seattle utility offers a "Green Up!" program where customers can pay extra on each bill to buy energy from more renewable sources. I'm signed up to contribute at the highest level ($12/month),...
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1answer
199 views

What software should I use to design and simulate a solar-assisted cooling system? [closed]

I will be developing a solar-assisted absorption cooling system similar to the one described in the image attached. What software could I use to design and simulate a thermal system like the one ...
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3answers
2k views

Why the world is using non renewable resources?

According to Wiki, A renewable resource is an organic natural resource which can replenish to overcome usage and consumption, either through biological reproduction or other naturally recurring ...
5
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1answer
67 views

Is there an “energy returned on materials invested” index for energy sources?

We already try to measure how much energy is invested (EROEI) in the production of energy, but I have a hard time finding numbers on the materials invested. For example: What is the total energy a ...
7
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1answer
251 views

Transmit solar over multiple time-zones?

I heard that at big voltages (10 000+V) the energy loss along a wire is very small. Unfortunately I've got little electrical knowledge, but this sparked up a question: Considering that peak ...
5
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2answers
207 views

Can The UK Be Powered Practically By 100% Renewables?

Taking into consideration the landmass of the whole of the United Kingdom, areas of open country where windfarms could be placed, areas of country designated as wildlife havens and also areas of ...
5
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1answer
65 views

What's the applicability of biochar?

Could the cost of biochar production ever be less than that of coal extraction? Is the thermal potential good enough? I have seen certain articles (sorry, no links) that point to its applicability ...
6
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1answer
147 views

Where are the world's wave resources, beyond the UK and Portugal?

Are there maps of the global resource for near-coast (<200km or so) wave power? I know that the UK has a particularly good resource - the kinetic energy in the waves in UK waters amounts to an ...
7
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1answer
92 views

What scope is there for price reductions in photovoltaic inverter costs?

In almost all of the world (except the USA, which has specific local cost challenges), system photovoltaic (PV) costs have come down a lot, to about €2 per installed watt. A large part of the ...
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2answers
553 views

What are the physical limits on wind turbine size?

Wind turbines just seem to keep growing. Predictions a few years ago that a 120-metre diameter rotor was going to be the maximum, have turned out to be wrong, and 154-metre rotors are being installed ...
6
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1answer
200 views

What is the number 1 country by global installed wind capacity: the United States or China?

In the following graph: We see that China surpassed every single country in wind energy production, except the United States. But these statistics are up to 2009 only. So my question is: what about ...
4
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5answers
16k views

What is the difference between “hydro” and “tidal/wave”? And what is the difference between “solar (heat)” and “solar panels”?

In the following graph: What is the difference between "hydro" and "tidal/wave"? And what is the difference between "solar (heat)" and "solar panels"?
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1answer
51 views

What is the % of energy produced per year which is renewable energy (including hydropower, biomass, …) in the U.S. and in the whole world?

I would like to know what is the % of energy produced per year which is renewable energy (including hydropower, biomass, wind, geothermal, solar) : in the United States in the entire world . And ...
9
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2answers
153 views

How worthwhile is it to use energy during daylight to take advantage of grid-based solar power?

Common sense is telling me to try to do things like vacuuming, laundry and cooking at times of maximal sunlight during the day so that more of the electricity I use comes from solar power generators ...
9
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2answers
2k views

How renewable is diatomaceous earth? (How much is left on earth?)

I've read a lot about diatomaceous earth being useful for organic gardening, animal raising, pest control, intestinal parasite treatment, etc. However I am somewhat conflicted about the material ...
6
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1answer
68 views

How quickly can the offshore-turbine supply chain expand?

To date, there were until recently just a few players in the manufacture of multi-megawatt scale offshore-wind turbines, though with the entrance of new Chinese manufacturers, that's been expanding ...
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1answer
173 views

How many vessels does it take to build an offshore wind farm?

How many vessel-days does it take to build an offshore wind farm, per turbine or per megawatt? I notice that when an offshore wind farm is being built, there are quite a few vessels milling around: ...
6
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1answer
498 views

How long does it take to construct a new port suitable for offshore wind construction?

How long does it take to construct a new port suitable for offshore wind construction? I'm thinking about the whole period: the design and planning, construction, and commissioning? I'd value real-...