A bucket-wheel excavator stands at the edge of an open-cast mining in eastern Germany. Photo by Eckehard Schulz: AP

Germany may have ambitious targets about cutting its carbon dioxide emissions, but those targets will likely remain just that, targets, as long as the country continues its heavy reliance on lignite.

Every year, Germany mines about 175 million metric tons (Mt) of lignite (brown coal) and that coal provides about 25 percent of the country’s electricity. Similar contributions are provided by hard coal (20 percent) and nuclear power (23 percent), with the remainder covered by renewable sources and natural gas.

In 2002, Germany passed legislation aimed at phasing out the country’s 19 nuclear reactors within two decades. The hope was that lignite and wind power would fill the ensuing gap. An estimated 40 billions of recoverable lignite reserves would be hypothetically adequate to provide half the country’s electricity (twice current lignite generation) for over a century. However, the EU Emission Trading System (ETS) introduced in 2005 has restricted the economic viability of this option.

Lignite currently covers about 12 percent of Germany’s primary energy requirements, but it makes up over 20 percent of its CO2 budget. The calorific value of the lignite is 7.8 to 10.5 MJ/kg, or about half that of firewood, necessitating three times the fuel tonnage of hard coal (27 - 33 MJ/kg) in power generation. Abundant lignite deposits lie only a few hundred feet below the ground and are readily extracted by imposing bucket wheel surface excavators, some heavier than the Eiffel Tower (10,000 tons).

The material handling challenges are enormous. On average, six times as much clay and sand must first be removed from lignite before it can be burned. Mining 175 million tons of lignite per year therefore becomes comparable to excavating the original Suez Canal (74 million cubic meters) every three weeks. That rate would be accelerated by energy intensive carbon capture and storage (CCS) technologies for circumventing the ETS. Superseding nuclear power by lignite generation would require even greater mining expansion, particularly if the inherent CO2 emissions were likewise to be captured and sequestered in distant saline aquifers.

Geological accessibility makes lignite Germany’s least expensive fuel at 1.1 euro/GJ, or about $1.70/MBtu, which is less than half the price of imported coal. The low energy content precludes it from being profitably exported, effectively stabilizing domestic prices.

Mined lignite consists of about one-third elemental carbon that is permeated with residual groundwater, mineral impurities, and sulphur deposited by prehistoric volcanoes. The bonding of two oxygen atoms at combustion results in carbon dioxide emissions weighing as much as the fuel itself. The energy lost in burning damp lignite and scrubbing sulphur from the flue gases limits power generating efficiency to between 35 percent for older plants and 43 percent in advanced designs. The resulting CO2 emissions per kWh are approximately three times those of clean-burning natural gas.

Geological carbon storage in Europe began with CO2 enhanced recovery of oil in the North Sea and natural gas in the Netherlands. The commercial viability of such ventures has been promoted by high carbon taxes in certain countries, beginning with Sweden in 1991 at $100 per ton of CO2. Research on carbon emission reductions was initiated at the Chalmers University of Technology in Gothenburg and intensified after the Swedish state-owned Vattenfall AB bought four major lignite power stations in eastern Germany in 2002. These installations collectively emit 57 million tons of CO2 per year. Lignite is employed from the company’s own mines and from the MIBRAG mining corporation near Leipzig.

Despite an enviable sales record at MIBRAG, the two American owners, NRG Energy and URS Corporation, sold the operations to a Czech-Slovak consortium in 2009 after CO2 allowance purchases of 28 million Euro the previous year had largely depleted operating profits. Superseding emissions trading by CCS technologies would nevertheless be too expensive unless current exchange prices (ranging from 7.98 to 15.41 euro/t CO2 in 2009) proved greatly undervalued.

Green Budget Germany, an organization of government-contracted economists, has issued a pessimistic appraisal of fossil-fuel generation. At present, 29 coal and lignite power plants are being constructed or planned without provisions for CO2 capture. With a service life of 40 years, these installations could prevent Germany from achieving the 80 percent to 95 percent greenhouse gas reductions recommended by the Intergovernmental Panel on Climate Change (IPCC) for industrial societies by 2050. Referred to the one billion tons of CO2 emitted in 1990, the atmospheric carbon released by 175 million tons of lignite would accordingly exclude all other fossil fuel usage in Germany, an untenable assumption.

Under the German Renewable Energy Sources Act, conventional power plants have been subordinated to alternative technologies that are granted priority access to the grid. If this policy is maintained, the federal environmental ministry estimates that the yearly full-load schedule of existing power plants will be declining to 3,900 hours by 2030 and diminish to 3,200 hours by mid-century. By contrast, many lignite base-load power stations currently operate over 7,500 hours per year. Since the additional capital expenses of CCS equipment cannot be compensated by increasing plant operating hours, CO2 allowance prices of 30 - 48 Euro per ton, or 100 Euro per ton for retrofits, would be required to insure investment returns, according to Green Budget findings.

CCS may ultimately prove viable only if pilot projects reveal significant cost reduction perspectives. The first 30 MW demonstration oxyfuel equipment installed by Vattenfall in Brandenburg and a RWE pilot CO2 scrubber in the Rhineland cannot verify scalability. Widespread public resistance, potentially on par with anti-nuclear movements, has now arisen in the potential sequestration regions of northern Germany due to growing anxiety over long-term geological integrity. With the timely realization of commercial CCS installations therefore in doubt, current lignite plant emissions continue to inhibit compliance with CO2 reduction obligations.

If carbon capture should be mandated or subsidized in the European Union, a possible result of 12 current pilot projects, then lignite could prevail in Germany as the mainstay of fossil fuel power generation. The added energy requirements of capture and storage translate to extracting a quarter billion tons a year. The commensurate excavation of two Suez Canals per month, however, would constitute disproportionate mining and reclamation efforts compared with diversified concepts of regional sustainability.

In Brandenburg, Germany’s second largest lignite mining state, the Advisory Council for Sustainable Development and Resource Protection has concluded that CCS would be far more expensive than an alternative strategy of energy efficiency, renewable energies, and new storage technologies. Complex subterranean zoning regulations will be required for any CO2 sequestration.

The decisive challenge for future lignite usage has therefore become the maintenance of investment credibility despite costly generating technologies relying on uncharted geological territory. In other words, the future of lignite in Germany, at least, in theory, depends on CCS. But if Germany wants to keep its lights on, it’s logical to assume that the country’s lignite will continue to be a major source of energy for electricity generation for decades to come regardless of whether CCS proves viable or not.

Jeffrey H. Michel is the Energy Coordinator of Heuersdorf, a German village threatened by lignite mining.