Green city
January 21, 2011
The city of Bottrop, population 69,000, has set itself an ambitious goal: Within 10 years, it wants to be the greenest city in Germany's former industrial heartland, the Ruhr Valley.
By 2020, the city aims to reduce the amount of CO2 it pumps into the air by 70 percent.
It's doing so as the winner of a competition among 15 localities to develop a strategy for a massive reduction in emissions. The city will get some 2.5 billion euros in investment.
A zone in Bottrop's southwest is the center of his urban greening project. Plans are to reduce the area's heat use by 50 percent and its electricity consumption by 70 percent.
To do this, the Bottrop will use renewable energy sources such as wind, solar and biomass, but also exploit the hidden potential of its own industrial past.
On the edge of the project area, called the Ruhr Innovation City, thick clouds of steam pump out of the Prosper coking plant. A by-product of this process that turns coal into coke is hydrogen, a gas that is also a promising energy source.
When used in fuel cells it oxidizes, and can power cars or even small factories. During this process, neither soot nor CO2 results – the only emission is water vapor.
One of these fuel cell-drive communal power stations has started operating near the coking plant and provides a local educational center with heat and electricity.
Using what's already there
The fact that these projects have not originated on the drawing board, but use existing structures and systems makes the challenge even greater, said Markus Palm, director of the group managing the Ruhr Innovation City.
"We think we can use what the city already has in better ways, which is faster and makes more economic sense," he said.
Another source of sustainably produced hydrogen is a local sewage plant, namely, in the fermentation gas that the region's wastewater contains.
Buses from the local transport network will soon be able to tank up at the sewage facility. Right now, two small buses travel between three local communities powered by fuel cells. Two full-sized buses are about to get underway.
Bottrop is one of the last localities in the Ruhr Valley to still have a working coal mine, although its days are numbered. In 2014 or 2018 at the latest, subsidies for coal mining will end. The mine's operators, Ruhrkohle, are now thinking about what a post-subsidy world will look like and what will happen with the inactive mines.
The company has suggested growing algae in the mineral-rich water found in the pits. The organisms consume CO2 and could be processed into bio-coal or bio-diesel. Another possibility is the installation of geothermal pumps which transport heat out of the depths of the earth.
The power of competition
Competition among 15 localities for the best ideas in creating a city of the future led to scores of new ideas from different sources, according to Christina Kleinheins, head of Bottrop's city planning department.
Bottrop's plan to use its existing infrastructure impressed the competition's judges.
Large portions of the project area are to be heated using the system connected to the coal-fired power plant. But the kilometers of pipe already laid could also transport heat from other sources, even from the sewer.
Since temperatures in the sewage canal networks remain at a fairly stead 15 degrees C (F), they contain an almost inexhaustible source of power. In the future, heat pumps will support traditional heating systems at the Ruhr West University of Applied Sciences, while helping keep things cool in the summer.
Another unusual energy source has been developed by the Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT) near the area's waste rock piles, heat-containing stone that was brought up from more than 1,000 meters below ground during the mining process.
"That warmth can be used by installing a heat exchange system near the piles, and then using the resulting hot water to heat nearby buildings," said the institute's Josef Robert.
The process works as long as the mine is still in operation and hot excavation residue is still being dumped onto the piles. If the man-made hills have already cooled off, a solar-energy system can heat them up again, according to Robert.
Thinking outside of the box
Everything doesn't have to be invented, through. The project aims to combine already tested approaches, such as insulation, smart electricity networks, renewable energies and environmentally friendly transport, said Palm. The only must is creative and innovative thinking.
For example, anything in the city that produces heat, be it be a large bakery or a factory, can be an energy source.
"Is there someone nearby that can use it to heat a swimming pool or maybe a residential area?" he said. "We can use the heat that we already have and move it somewhere else."
If necessary, on wheels.
LaTherm, a young company from Dortmund, stores waste heat from the coking plant in containers insulated with curing salt and brings them to the Ebel elementary school. The principle is the same as those small hand warmers you trigger with a snapping action.
"We'll know it's a success if we can get more schools to participate in the program, otherwise our investment won't pay off," said city planner Kleinheins. "But there are many more schools and Bottrop and we'll find others to heat."
The need for heat and power in Bottrop isn't going anywhere, and will likely grow. In the past, coal was the resource for that, but in the future, it'll be a combination of innovative technologies, energy efficiency and alternative energy sources that will keep the city's radiators warm and its lights on.
Author: Matilda Jordanova-Duda (jam)
Editor: Nathan Witkop