River heat pump: Heating homes with cold water
Heating our homes with cold water sounds crazy! But it's not. Heat pumps are revolutionizing the way we heat and cool our homes and cities. We went to the German city of Mannheim to find out how.
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00:00Being a reporter is fun, but not always.
00:05Okay, let's do it.
00:07I think that's beyond next level.
00:10Today we want to find out how entire residential areas can be heated with this icy cold water.
00:16With a heat pump. A fairly large one.
00:19I don't hear anything.
00:21It's minus one degree. It feels like a thousand needles in my leg.
00:26And I thought I'd just see how cold this water really is.
00:29Bad idea. It really hurt.
00:33Heat for homes and industry requires more energy than any other sector.
00:37The majority from fossil fuels.
00:41So, for the climate, emissions need to be reduced.
00:44To make the building sector more sustainable, there's no getting around heat pumps, large or small.
00:49They convert energy from the air, water or earth into heat.
00:54Around 300,000 people live in Mannheim directly on the Rhine, and the river plays a special role today.
01:04The magic is happening in this.
01:06The local energy provider is producing electricity and heating through a mix of fossil fuels and cold water.
01:15In this region, it still comes primarily from climate-damaging coal.
01:20I meet Felix Haack, an energy manager at the MVV Energy Group.
01:31The site where we are located is part of the Mannheim coal-fired power plant.
01:36It emits an estimated 1% of Germany's CO2 emissions per year.
01:41But that should change soon.
01:44Millions of liters of water flow through the Rhine,
01:47which is several times the amount of heat Mannheim needs, even at such cold temperatures.
01:54It's now 6 or 7 degrees Celsius, so physically, there's still enough heat in it.
02:02We're now in the anteroom, and we need to take our earplugs because it's really loud in there.
02:07This deafening giant machine is a flow heat pump.
02:10800 liters of river water are pumped through here every second.
02:15This generates heat for around 3,500 households.
02:22This is where the river water from the Rhine comes in and goes into the large heat exchanger, the evaporator,
02:28where it then transfers the heat to the refrigerant.
02:31Okay, let's take a step back.
02:33Here's what happens in the pipes.
02:35The water is cold, but it's warm enough to vaporize a refrigerant at very low temperatures.
02:41This gas then expands.
02:43An electric pump compresses the gas.
02:46That generates heat.
02:48It's like a bicycle pump.
02:50The more you pump, and the higher the pressure goes,
02:53the more heat is released.
02:56It's like a bicycle pump.
02:58The more you pump, and the higher the pressure goes,
03:01the hotter the pump becomes.
03:03The heat is then used to heat water or air.
03:06The coolant, therefore, releases the energy and becomes liquid again,
03:10and the whole process starts all over.
03:13This method is three times more efficient than heating with a gas boiler.
03:17It not only works with river water,
03:20but also with energy from the air or the ground on a large and small scale.
03:25Ideally, the electricity for the heat pump should come from green energy,
03:29but even if it comes from fossil fuels, it's still more sustainable.
03:34The principle of a heat pump isn't new at all.
03:37It's based on a concept which has existed for a very long time
03:41and on a technology which most of us have at home.
03:45A refrigerator.
03:47In the 19th century, there was a high demand to cool things.
03:51Ice blocks were even imported from far away.
03:54In 1859, Frenchman Ferdinand Carré developed one of the first commercial cooling systems.
04:01It works just like a heat pump, only the other way around.
04:05It transports the heat from inside to outside.
04:09Later, another machine made the headlines, the air conditioner.
04:13It was originally invented to solve moisture problems in the paper industry.
04:18It wasn't until later that the heat pump had its big moment.
04:22The pride and joy of the man of the house is the weather control center.
04:27A center that puts you in charge of the electric heating and air conditioning
04:32and the electronic air filtering of the entire house.
04:36After the Second World War came widespread electrification and new lifestyle expectations.
04:42Heat pumps fit into the picture well.
04:45But as many people still used cheap oil and gas for heating, they didn't really catch on.
04:50Today it's different.
04:52So now we're going to see the heat storage from where the heat is being distributed over the entire city.
04:59That's the thermos flask. 43,000 cubic meters of water.
05:05Okay, wow. How much is that in liters?
05:0843 million liters.
05:12That takes a while to fill.
05:16In Mannheim, most of the heat still comes from coal, only 3% from the river.
05:21However, that will soon change as the coal-fired power plant is expected to be shut down by 2033.
05:30We want to go even bigger.
05:32We want 50,000 households to be supplied with river water heat pumps.
05:37That means a tenfold increase in the next few years.
05:42From an environmental perspective, there is a theoretical problem with river heat pumps.
05:47If heat is extracted from the river, cooler water is returned later.
05:52However, the quantities here are so small that the temperature in the river only changes minimally, according to MVV.
05:59But now imagine all along the river Rhine, all the major cities there, wanting to cover their entire heat demand,
06:05including industrial plants such as the BASF or covestro plants along the river Rhine,
06:11that might use water for heat pumps for their processes.
06:16And suddenly you get an issue.
06:19In Mannheim, the heat is distributed above and below ground via a district heating network.
06:25In Germany, around 15% of all buildings are now heated in this way.
06:30And the largest part of this could be covered by large heat pumps that make coal and gas redundant.
06:36But it's still a niche market.
06:38The model is the Swedish capital Stockholm, where around 90,000 homes are heated with wastewater.
06:44In Mannheim, the city's climate targets and state subsidies for the construction of the plant were decisive factors for the changeover.
06:52Their goal is to produce almost completely clean heat by 2030.
06:57The heat pumps won't cover all of that, but will be one important component to eventually shut down the dirty coal power plant behind me in the near future.
07:06Whether large or small, heat pumps are sustainable and can make regions, cities and individual buildings less dependent on fossil fuels.
07:16And they even work in winter.
07:18All right, I made it.