District heating isn’t a new concept. Using heat from one resource to meet demand among a centralized group of consumers has long been in use, primarily through combined heat and power from natural gas.
But communities are turning to sustainable sources for their heating demands with drastically smaller carbon footprints compared to fossil fuels – a trend being pioneered across The Netherlands with technology based on locally available renewable resources.
From biomass to aquifers or synthetic natural gas and even seawater, sustainable district heating is advancing by leaps and bounds across Holland. And while cutting emissions is important anywhere, it’s especially important in this corner of Northern Europe where heating represents 40% of all power demand.
Turning Wood Waste Into Clean Heat
In Purmerend, a city of 80,000 people located one hour north of Amsterdam, a 44-megawatt (MW) biomass-to-heat facility will go online in August, diverting 100,000 tons of forest waste from low-value manufacturing, replacing an existing 65MW combined cycle natural gas plant, and providing district heating for 25,000 homes.
The District Heating Company Purmerend (SVP) was created in 1980 to provide heat to the community via natural gas-fired boilers, but in 2007 SVP was privatized and its new owners decided to improve operations by cutting emissions and improving pipeline efficiency.
The first step was switching to biomass, using 10-inch wood chips from local forest maintenance operations to power four 11MW-capacity boilers at a price comparable to natural gas. These boilers generate nearly 100% efficiency values by reusing heated air from the burn chamber for additional combustion, water from flue gas condensation for the plant’s washing tower, and ashes for concrete manufacturing.
In 2008 the utility carried out SlimNet, a system-wide efficiency benchmarking and improvement effort. By spending €25 million on renovation and redesign, SVP eliminated “hotspots” leaking heat, reduced the system service area 32%, and lowered heat loss from 33.6% in 2008 to 22.1% in 2014, all without existing customer equipment retrofits.
In total, SVP estimates its efforts will reduce emissions 50,000 tons and cut natural gas demand 30 million cubic meters per year.
Groundwater + Biomass + Biogas = Hybrid Heat System
Just up the road, biomass is going one step further by combining with underground energy storage and biogas cogeneration to provide low-cost heating and cooling for the Nieuwveense Landen district of Meppel.
This planned community will eventually number 2,100 homes, and is being built in stages over the next 25 years with 65-150 homes completed annually. Each stage will use the most efficient energy systems available to create a series of modular heating districts, all linked together in one local grid.
In the first phase of 444 residences, planned for completion by 2020, carbon emissions will be cut by 45% with 10% lower energy costs. Effluent from a nearby sewage treatment plant and local farming waste will be converted into biogas for electricity and heating through a combined heat and power system. Geothermal pipes will store energy in aquifers 100 meters underground while providing hot water in the winter and comfort cooling in the summer, and local forest waste will be stockpiled to provide peak power from a biomass boiler.
Perhaps best of all, new homes will be affordable. The first 70 homes sold this year for €150,000-200,000 apiece, in range with other new construction, and residents will get free “comfort cooling” and stable energy prices comparable to natural gas. Project planners eventually hope to incorporate rooftop solar panels and electric vehicle charging en route to a 100% emissions-free energy system by 2034.
From Excess Renewables To Green Gas
Meanwhile, about two hours south of Meppel, Dutch utility Stedin is converting excess renewables into green gas for one apartment complex in Rozenburg.
Europe’s first residential power-to-gas facility won’t be fully online until September 2014, but it will eventually convert excess renewable electricity into synthetic gas to power the central heating system for 30 apartments, pushing gas onto the grid whenever supply exceeds residential demand.
Electricity and water first flow into an electrolyzer, separating water into hydrogen and oxygen. This step supplies one cubic meter of hydrogen per hour to a methanizer, which adds carbon dioxide to create 2,000 cubic meters of synthetic methane per year. This green gas not only burns 1% cleaner than natural gas, but it creates a closed carbon cycle by consuming equal parts carbon dioxide to produced methane.
Stedin sees the Rozenburg facility as a demonstration project for eventual installation at larger residential communities or industrial manufacturing facilities. By empowering consumers to take advantage of cheap off-demand power prices, excess renewable electricity converts to renewable heating – “ensuring we use the full potential of sustainable energy,” said Alfred van der Molen, Innovation Leader at Stedin.
Holland’s Most Renewable Resource: The Sea
Last but not least, a small community near The Hague is using Holland’s most abundant resource – the sea. While the Dutch are most famous for reclaiming land from the ocean, a power plant in Duindorp is busy reclaiming heat from under the waves for a low-income community of 800 homes.
The world’s first seawater district heating system went online here in 2008, drawing up to 190,000 gallons per hour from the harbor through a series of five intake filters and five miles of pipes. Consumers pay a fixed price of €70 per month for sustainable heat – comparable to heating costs before the system went online.
During the summer, seawater stays around 70 degrees, and in-home electric heat pumps boost temperatures to 110-150 degrees Fahrenheit for heating and warm water. In the winter, a 3MW heat exchanger at the intake building boosts water temperatures from as low as 37 degree Fahrenheit up to the minimum 50 degrees each home’s heat pump can handle.
The process generates 15 kilowatt-hours (kWh) of heat from just 1kWh of grid-connected electricity while reducing emissions 50% compared to conventional heating from natural gas. Duindorp’s facility has since been replicated at several sites across Northern Europe, and could technically become emission-free if low-cost solar or on-site wind turbines were added to the system.
Environmental And Economic Benefits
While each sustainable district heating system helps Holland move toward its national goal of 14% renewable energy supply by 2020, each project’s ability to shave domestic natural gas demand could also boost the country’s economic fortunes.
Between 15-20% of the natural gas consumed in Europe is produced in The Netherlands, and the country exported 25.3 billion cubic meters of gas in 2010, meaning every district heating innovation frees up additional volumes that can be exported and sold to other countries.