Solar chimneys meet fuel cells for power generation

Solar chimneys meet fuel cells for power generation
The solar chimney by the Portage doors of Manitoba Hydro Place. Credit: Craig Bennett

Solar chimneys can be teamed with fuel cells to provide more electricity more economically and all year round, according to mathematical analysis.

Solar chimneys work best on hot, sunny days, relying on differences in air temperature to generate energy.

They use solar collectors at their base to heat the air inside the chimney, then this hot air rises, according to Curtin University engineer Omid Joneydi.

As flows up the chimney, cool air is sucked in at the base of the chimney, driving turbines that generate .

A challenge with solar chimneys, however, is supplying energy demands on cool days, or overnight.

"We wanted to analyse how solar chimneys could be used in combination with fuel cells to generate extra electricity, to supply electricity more economically," he says.

"Our primary aim was to minimise costs."

Solar by day, fuel cells by night, electrolysis in between

Fuel cells produce clean energy by combining hydrogen gas with oxygen from the air to produce electricity and water.

The fuel cells Mr Joneydi used in his mathematical iterations were solid oxide fuel cells, distinguished by their use of a solid rather than liquid electrolyte, and their need for high operating temperatures.

But how to operate a without hydrogen gas? Simple. Make some.

On those hot, sunny days when the solar chimney is supplying more than demand, any extra energy can be diverted to power electrolysis.

This process would split water into and oxygen gas, and generate a fuel that can be stored until needed.

Mr Joneydi's team considered the desert city of El Paso, in Texas, and determined how much of the city's power the hypothetical plant could provide, for every hour of a typical year.

"We used a genetic algorithm, trialling different calculation 'parents' to optimise outputs or 'children' over multiple cycles," Mr Joneydi says.

He found the plant could theoretically provide all of El Paso's electrical needs between 9am and 3pm during the winter month of January, stretching to 6am to 6pm over summer.

Calculating that the system can optimally produce 0.28kg of hydrogen fuel every second, Mr Joneydi determined the plant could supply nearly 80 per cent of El Paso's summer energy requirements, and 37 per cent of its winter demand.

Another bonus, he says, is that heat of the fuel cell reaction can be used to drive turbines or a steam generator.


Explore further

Research sets new record for generation of fuels from sunlight

More information: "Modeling and optimization of a novel solar chimney cogeneration power plant combined with solid oxide electrolysis/fuel cell," Energy Conversion and Management, Volume 105, 15 November 2015, Pages 423-432, ISSN 0196-8904, dx.doi.org/10.1016/j.enconman.2015.07.054
Provided by Science Network WA

This article first appeared on ScienceNetwork Western Australia a science news website based at Scitech.

Citation: Solar chimneys meet fuel cells for power generation (2015, September 4) retrieved 23 May 2019 from https://phys.org/news/2015-09-solar-chimneys-fuel-cells-power.html
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Sep 04, 2015
Energy harvesting can and will provide much power in a distributed power system, reducing the need for peaking plants. In fact, there will be no peaking plants, since alternative energy is available at the user level, and most available during peak periods.

Sep 04, 2015
Again with all solar technologies it only produces the most power when we need it the most.

What good is that?


Sep 04, 2015
When combined with new PV and other technologies, we can add this:

http://www.utilit.../405143/

Maybe we will not need Dirty Power for backup much longer.

Sep 04, 2015
This will kill Eikka:

http://www.fierce...internal

Sep 04, 2015
Just curious if this concept could be expanded. I envision a large solar collection field enclosed within a transparent structure to restrict and control airflow. Located on the floor of a desert valley with the chimney made of concrete conduit rising to the summit of the valley rim. Enclosed fans could be installed and would avoid the bird issues, scenery pollution by planting, or using gullies and the like... once started the siphon effect may continue through the night if elevation variance is sufficient. It seems to me if it would work, it would be quite efficient.

Sep 05, 2015
This will kill Eikka


Care to explain how?

First: GDP doesn't measure real productivity - it just measures how much money changes hands. You can do a whole bunch of pointless work and still increase GDP. Second: measuring GDP per dollar spent on electricity is a meaningless metric because it doesn't account for other fuels spent to make that GDP. Third: when you count all fuels, California is sixth at $35 per dollar spent instead of first at $59 counting only electricity.

The take-home, if any, is that Californian industries use proportionally less electricity and more cheap gas. A whole lot of noise for nothing.

" Californians, on average, spend less on total electricity bills than the rest of the nation due to the state's strong track record in energy efficiency."


Because it's a sunny state where people often don't even need to heat their homes. That has nothing to do with renewable power - except for the part where they get massive federal subsidies.


Sep 05, 2015
When combined with new PV and other technologies, we can add this:


A 2 kWh battery at $2000 is not a solution for anyone. That's an outright rip-off.

Sep 05, 2015
"GDP, or Gross Domestic Product is calculated either by measuring all income earned within a country, or by measuring all expenditures within the country, which should approximately be the same." - Investopedia.

The trick with spending tax money on renewables is that whatever you pay in tax, it doesn't count as an energy bill - even when you actually use the money to pay for solar panels and wind turbines. Instead, the money the government spends on energy subsidies shows up as industry income, which directly increases the industry GDP because they're selling something massively expensive to the govenrment. The industry GDP is also is the metric here that is used to argue that Californians are doing more with less.

Which is how you hide a massive energy bill from the public and argue everything upside down.


Sep 05, 2015
Yes, yes, . . we're all going to die from solar.

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