Most people don’t think about biomass as a direct replacement for natural gas, but then most people might not have visited Purmerend, a town located about an hour north of Amsterdam.
In this city of 80,000 people, an innovative approach to district heating uses wood chip biomass to provide clean and renewable heat for three-quarters of the population at grid parity prices.
CleanTechnica toured the de Purmer biomass-to-heat facility one month before it officially goes online to see how waste wood is being used to cut emissions and natural gas use – an important sustainability measure considering heating homes and offices represents 40% of all power demand in the Netherlands (Full disclosure – while my trip is being sponsored by the Dutch Government’s Ministry of Foreign Affairs, it had no involvement in the editorial process of this post).
Biomass Fixes A Good Idea’s “Bad Execution”
The District Heating Company Purmerend (SVP) was established in 1980 as a municipal service to provide heat via underground piping to the fast-growing community of Purmerend via natural gas-fired boilers.
Their initial approach turned out to be “a good idea but bad execution,” said Martijn van Lier, SVP Chief Technology Officer, never realizing full potential due to a combination of inefficient piping infrastructure and reliance on fossil fuels.
And efficiency counts for SVP – it uses 175 miles of piping to deliver heat to its customers, good for the fourth-largest managed grid in the Netherlands, behind only the three national power grid operators.
10-Inch Wood Chips Chop 50,000 Tons Of Emissions
In 2007 however, that all started to change when the utility was privatized. Its managers decided look toward biomass, and started planning a 44-megawatt capacity biomass heating plant. The new facility, scheduled to go online in August 2014, features four 11MW capacity boilers, replacing generation previously supplied by a 65MW combined cycle natural gas plant.
Wood chips from local forest maintenance by the Dutch National Forest Authority will be diverted away from low-value plywood manufacturing to feed the turbines under a 25-year supply deal, priced at the median gigajoule heating value of delivered wood.
And if you think 44MW of biomass boilers use a lot of wood chips, you’d be right. When fully operational, the facility will consume 100,000 tons of 10-inch wood chips per year – roughly one-sixth of all national annual output.
By switching from natural gas to biomass, SVP will reduce emissions 50,000 tons and cut natural gas demand 30 million cubic meters, compared to individual natural gas-fired boilers, at a cost comparable to natural gas prices. For context, this one biomass plant’s output will be equivalent to one-third of Holland’s combined 2.3 million installed solar panels, or the decarbonization equivalent of adding 800,000 new solar panels, according to van Lier.
Nearly 100% Plant Efficiency
But SVP didn’t get greener, it also got much more efficient. In 2008 the utility started an efficiency benchmarking and improvement effort named SlimNet. Analysis showed system production capacity was reaching critical limits, with above average heat losses. The answer was a Euro 25 million selective renovation and redesign of system “hotspots” to reduce heat loss, and it worked.
Reducing system service area 32%, system dimensions 25%, and grid length 7%, SVP lowered heat loss from 33.6% in 2008 to 22.1% in 2014 – all without retrofitting existing customer equipment, according to van Lier.
SVP also boasts more than a 99% efficiency value by reusing nearly all the heat and water produced by burning wood chips. Heated air from the burn chamber is fed back into the system to fuel additional combustion, and water from flue gas condensation is reused on the plant’s washing tower to remove particles from emissions. Ashes are also either returned to the forest as fertilizer, or sold to concrete manufacturers.
Now Let’s Watch Some Awesome Video
All these project details are great for sustainability, but the most impressive individual aspect of the SVP plant may be the massive chamber where wood chips are stored and fed into the boilers. Six docking doors receive wood chips from dump trucks, and three cranes scoop them up into the storage bunker into piles sufficient to supply the boilers for seven days – a process shown in the video below: