Geothermal energy makes Unterhaching independent: A village does not need a gas price cap

Created: 01/09/2023Updated: 01/09/2023 2:15 p.m

By: Matthew Schneider

Without the system, we would have to burn 100,000 liters of heating oil on a cold winter's day.

Wolfgang Geisinger, Geothermie Unterhaching © Marcus Schlaf

Cheap, green energy that is always available – a pipe dream?

Not at all.

The municipality of Unterhaching developed geothermal energy years ago.

Unterhaching/Germering – Geothermal energy is a niche phenomenon in Bavaria: Only half a percent of the thermal output is provided by hot thermal water.

The greater Munich area has one of the largest sources in Germany.

“We are sitting here on the so-called Bavarian Molasse.

This is a layer of limestone that contains around 30 percent water,” explains Wolfgang Geisinger, Managing Director of Geothermie Unterhaching.

"The limestone plate was pushed further and further down to the south by the unfolding process of the Alps.

What is on the surface in the Swabian Jura is here in Unterhaching at a depth of around 3,000 meters.”

Geothermal energy in Unterhaching supplies 13,000 households

The water there is 122 degrees.

It is promoted in an inconspicuous building on the edge of the commercial area, between a camping outfitter and a paint shop.

55 kilometers of line connect about half the community here.

You can't tell from the outside that the power plant could supply an entire small town: "We pump up to 140 liters per second through our production well and send it to our heat exchanger, where the energy is transferred to the district heating network," explains Geisinger .

It is then fed back into the earth via a second borehole around 3,000 meters away.

The thermal water never comes into direct contact with the district heating water.

The system has an efficiency of 90 percent, the heating water reaches the 13,000 customers at between 90 and 110 degrees.

“These relatively high temperatures are important because we have a lot of poorly insulated buildings here from the 1960s and 1970s.

You wouldn't get them warm with a heat pump close to the surface," explains Geisinger.

Because normal heat pumps often only manage 40 degrees economically.

The hot spring makes geothermal energy significantly more efficient: “A normal heat pump generates around three kWh of heat from one kilowatt hour of electricity.

We manage the factor 1:30.”

Geothermal energy as a substitute for hundreds of thousands of liters of heating oil

To operate the pump, a gas power plant generates electricity.

For emergencies and maintenance work, there are oil boilers as a backup power plant.

To compare what geothermal energy can achieve: "If we wanted to replace our system, we would currently have to burn 100,000 liters of heating oil on a cold winter day," says Geisinger.

The question arises: Why aren't more municipalities using the cheap and climate-friendly geothermal energy?

There is a lack – quite banal – of money.

Because the returns are too low for the private sector: “A liter of oil contains a hundred times more energy than a liter of hot thermal water.

That means you can drill for oil nine times without success, as long as you get it right the tenth time.

Nothing can go wrong with thermal water,” explains Geisinger.

“In addition, you can trade crude oil globally.

You can’t do that with hot thermal water.”

And municipalities that want to invest in the long term usually do not have the projects in mind: "Many municipalities are already overwhelmed with amounts in the low double-digit millions," explains Geisinger, head of geothermal energy.

In Unterhaching, the project was only feasible because of the dense population.

Geothermal energy: financing as a major problem

So far, the financing has suffered in two areas for the municipalities: Because of the cheap gas, gas-fired power plants, which generate heat as well as electricity, have been subsidized with 40 percent.

"The result is that the waste heat from the power plants can be marketed as district heating almost free of charge."

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Recently, however, equality of arms has prevailed here: “We are subsidized with 40 percent like combined heat and power.

This helps us to offer every Unterhachinger a district heating connection.

That wouldn't have been possible without the funding." But the remaining 60 percent of the financing is still a major hurdle: "Federal Minister of Economics Robert Habeck provided us with the basic economy.

Now it's Hubert Aiwanger's turn in Bavaria.

A liability-free investment pot is needed from which they can draw for geothermal energy.

You can do that in Berlin as well as in Bavaria.” Because no municipality can afford a failed drilling.

Alternative heating methods: "Need faster approval deadlines"

The processes also need to be speeded up: "We need faster approval periods: So far it's been seven to eight years." And that doesn't have to be the case, he is convinced: "Thermal water is treated like drinking water, although from the point of view of the authorities nobody will ever drink it.

But in Bavaria, this principle is firmly adhered to and that slows down the approval processes accordingly.”

With this course set, the heat transition could succeed in a few years: "The Munich, Pullach, Grünwald and Unterhaching municipal utilities have initiated a study at the TUM via the Bavarian Ministry of Economic Affairs, which states that the greater Munich area can be completely supplied with geothermal energy."

Wolfgang Geisinger's vision is a distribution network that is to be created between the various power plants: "It is realistic that in 2040 we will be able to do without fossil redundant power plants and only supply ourselves from the grid." The first step is already reality - in the form of a line to Grünwald: "When we are maintaining our systems or at peak load times, we can obtain heat from Grünwald - and vice versa.

So our oil boilers have to run much less frequently.”

Heating with spring water: even colder thermal water is sufficient

A concept that also works with colder water: “North of Munich, the thermal water is a bit colder, more like 80 degrees hot.

If you add a large electric heat pump, you can raise the district heating water to the necessary flow temperatures.

The city of Erding, which even gets by with thermal water at around 60 degrees, proves that this works.”

To the west of Munich, the community of Germering is hoping for a thermal spring that will feed the power plant in neighboring Freiham: "The system of the Munich public utility increases our hopes of a successful well," explains Roland Schmid, manager of the Germering public utility.

The project was put on hold for a few years, but has now been resumed in view of the changed conditions: "Previously, district heating could not offer a tariff that was competitive with natural gas," explains Schmid.

"Due to the rising CO2 price, the expensive natural gas and the question of whether we will still get some in the future, we have now dealt more intensively with the project again."

But the wheels of bureaucracy grind slowly: “We are currently in the application process for a feasibility study.

It will probably not be ready until 2024 at the earliest." The results should then be sufficiently concrete: "Then we will know whether we have enough thermal water and which distribution is economically viable," says Schmid.

Geothermal energy could cover 40 percent of Bavaria's heat requirements

Because despite the improved funding, it would be a lot of money: "We as a municipal utility would not be able to cope with it - and maybe the municipality of Germering too".

Because municipalities are only allowed to take out limited loans - and they are more expensive due to the interest rate turnaround.

One solution that Roland Schmid is aiming for is the involvement of private investors.

But finding them is difficult: "We used to be in talks, but so far everyone has jumped off when they heard that we can't produce electricity here."

A problem that makes deep geothermal energy unaffordable for many municipalities.

An absurdity: because according to the Geothermie-Allianz Bayern, the technology could cover 40 percent of Bavaria's heat requirements - not counting heat pumps close to the surface.