Technologies

Technologies#

This page describes each technology group modelled in GreenBubble: how it is represented in PyPSA, which parameters control its behaviour, and any modelling assumptions worth knowing. Each group corresponds to one or more entries in config/n_config.default.yaml and is activated by a flag in n_flags.

Note

This page documents the current technology set. New technologies follow the pattern described in Guide for Adding New Technologies.

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Renewable electricity (n_flags.renewables)#

Onshore wind and solar PV are modelled as Generator components with capacity-factor time series retrieved from Renewables.ninja for the configured site coordinates. Both are extendable by default (greenfield) with costs from the technology-data database.

Up to max_RE_to_grid fraction of total renewable output can be exported to the electricity grid; the remainder must be consumed internally.

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Electrolysis (n_flags.electrolysis)#

Alkaline electrolysis is a Link (electricity → hydrogen) with:

  • Ramp limits (up/down) to reflect the electrolyser’s response speed

  • Minimum load to avoid operating at inefficient part-load

  • Committable mode available for brownfield dispatch runs

The electrolyser cost is sourced from the IEA via the technology-data database. Efficiency is fixed (no part-load curve); an improved part-load model is planned.

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Biogas and biomass chain (n_flags.biogas)#

Biogas plant — modelled as a Generator producing raw biogas (CH₄ equivalent) from digestible biomass inputs (manure, co-substrate). Feedstock cost and availability are set in the options.Dig biomass block of n_config.default.yaml.

Biogas upgrading — pressure-swing adsorption (PSA) or equivalent, strips CO₂ from raw biogas to yield pipeline-quality biomethane. Modelled as a Link (raw biogas → biomethane + CO₂).

Biogas compressor — compresses raw biogas upstream of methanation; modelled as a Link with electricity input.

Biogas engine — combined heat-and-power unit; a multi-output Link (biogas → electricity + heat) with minimum load and optional committable mode for dispatch-only runs.

Belt dryer — hot-air dryer for biomass pellet production. Semi-empirical sizing based on moisture content. expansion: false by default — treated as a fixed brownfield asset.

Dewatering — screw press for digestate solid/liquid separation. Fixed capacity, no expansion.

Pelletization — biomass pellets production from dried fibres.

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Methanation routes (n_flags.methanation)#

Two technology pathways are available. Both convert H₂ + CO₂ (or H₂ + biogas) into synthetic methane:

Catalytic methanation (methanation CO2, methanation biogas)

— Sabatier reaction. Strict ramp limits (8 %/h) and minimum load (40 %) reflect the thermal inertia of the catalyst bed.

Biomethanation (biomethanation CO2, biomethanation biogas)

— Biological hydrogenotrophic process (trickle-bed reactor). Faster ramp response than catalytic (ramp limit 100 %/h); no minimum load constraint in the default configuration.

Both are modelled as Link components. The feed can be CO₂ (from the CO₂ distribution bus) or raw biogas (from the biogas bus).

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Methanol synthesis (n_flags.meoh)#

CO₂ hydrogenation to methanol (methanolisation): CO₂ + H₂ → MeOH + H₂O. Modelled as a multi-input Link with ramp limits (8 %/h) and minimum load (15 %). Waste heat is recovered to the medium-temperature heat bus.

An eSMR + methanol synthesis route is planned but not yet implemented.

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Storage (n_flags.storage)#

All storage components are activated together by the storage flag. Individual technologies can be disabled by setting expansion: false and initial capacity: 0 in n_config.default.yaml.

Component

Type

Notes

Battery (Li-ion)

StorageUnit

Includes inverter losses; default 2-hour duration

H₂ HP storage

Store

High-pressure steel vessel; extendable

CO₂ HP storage

Store

Pressurised cylinders; extendable

CO₂ Liq storage

Store

Liquefaction + insulated tank; e_nom and liquefaction capacity optimised separately

TES concrete

StorageUnit

Concrete thermal store; 10-hour duration; standing losses

TES district heating

StorageUnit

Hot-water buffer for DH; 50-hour duration

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Heat system (n_flags.central_heat)#

Three heat buses represent temperature levels in the cluster:

  • Heat MT (medium temperature) — process waste heat, biomass boilers, biogas engine CHP output

  • Heat DH (district heating) — optional connection to an external DH network (price and load set in options.DH)

  • Heat LT (low temperature) — low-grade cooling and heat pump source

A heat pump link can upgrade LT to DH heat (extendable, disabled by default). El boiler and NG boiler provide backup heat.

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Industrial symbiosis (n_flags.symbiosis)#

The symbiosis flag adds all internal distribution links between plants: electricity, H₂, CO₂, and heat exchange connections across plant boundaries. Disabling it isolates each plant to its own buses, useful for benchmarking individual plant economics.

The symbiosis El transformer (configured under options in n_config.default.yaml) controls whether the internal electrical transformer between plants is extendable.

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Grid connection#

A Link representing the point of common coupling (PCC) with the electricity grid. Capacity is extendable by default. Grid import carries the full Danish tariff stack (TSO, DSO, state levies) defined in tariffs_dict; grid export earns the sell tariff.

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External markets#

Configured under the options: section of n_config.default.yaml:

  • Pellets market — biomass pellet purchase at a fixed price; optional capacity cap

  • Moist biomass market — co-substrate purchase for biogas plant

  • Biochar credits — revenue credit for biochar sequestration from pyrolysis

  • CO₂ Liq credits — revenue credit for liquefied CO₂ export

  • District heating — heat sale to external DH grid (options.DH)