Wood, the world’s oldest source of fuel, is making a big comeback in the medieval Belgian city of Ghent. Belgian Eco Energy (BEE) has selected GE to build what will be the largest and most efficient supercritical wood-chip-biomass-fired power plant in the world.
Located at the city’s port on the Ghent-Terneuzen Canal, the plant will produce 215 megawatts of electricity and 110 megawatts of thermal energy. That’s enough to power large industrial clients and district heating in Ghent. When it begins operations in 2019, the plant’s total energy efficiency will be above record-breaking 60 percent in combined power and heat mode. The net electrical efficiency will reach 42.5 percent, also a new high for the industry.
Top: The medieval heart of Ghent. Image credit: Getty Images Above: BEE’s new wood-chip burning power plant. Image credit: GE Power
Biomass is a type of biological fuel derived from “living” material such as used wood. It’s becoming a popular option for generating electricity. In Ghent, GE will combine biomass fuel with its “supercritical technology,” which exposes water to high temperature and pressure until it becomes a supercritical fluid, a state in which it no longer has specific liquid and gas phases. This allows the turbine to operate more efficiently.
The high-pressure and high-temperature fluid expands in the turbine and produces mechanical energy, which drives an electric generator. The plant will then send the remaining thermal energy to a local heating system to keep neighboring homes and businesses warm. “This is groundbreaking and the first of its kind,” says Alain Remy, business sales manager at GE Power. “Most biomass plants are conversions of coal plants or still use some coal. In this case, we will have no additional fuel.”
A pile of wood chips. Image credit: Getty Images
In fact, compared with a coal-fired power plant, the technology at the Ghent power plant will allow the operator, Veolia, to avoid emissions equivalent to heating the homes of Ghent’s 240,000 residents.
BEE will store 100,000 tons of wood chips at the plant at all times to make sure it always has fuel. The rest will arrive by ship from the U.S. and South Africa, where BEE has signed 15-year contracts with suppliers.
Most of the wood coming from the U.S. will be coming from the paper and pulp industry. With the demand for paper shrinking, trees that were once tagged for the pulp mill will now go to Belgium to produce power and heat. South Africa will supply wood from bushes that need to be cut down in order to make room for agriculture. Remy says there are no worries about running out of wood for fuel. “The market for wood chips is that big,” he says.
When wood burns, it generates flue gas that contains both carbon dioxide and a low level of particulates. Since BEE was designed to stay carbon-neutral, the operator will run a massive reforestation campaign to ensure that new trees offset the wood waste the plant burns.
The plant will also inject limestone into the boiler, which binds to the sulfur in the ash and prevents it from going into the air. The plant will sell the spent limestone for reuse in the construction industry. Says Remy: “This technology is taking us back and into the future.”