L7 Heat Pumps & Geothermal

Air Source Heat Pumps

Extract heat from outside air, heating refrigerant, compressed, heated further and passed through heat exchanger. Less efficient esp in winter, easier to install

Ground Source Heat Pumps

Ground heats refrigerant, but if too small collector it will suck out heat, more efficient but hard to install

Coefficient of Performance

COP = Thot / (Thot-Tcool)

Pros of Heat Pumps

Low operating and maintenance costs, high lifetime, low noise, reduced emissions

Cons of Heat Pumps

Expensive installation, GSHP - disruption during installation and most effective in new buildings, ASHP - variable performance dependent on air temp

Geothermal

radioactive decay and gpe of space dust accretion

Dry Steam

Directly routing steam through turbine, condenser, re-condenser, and through cooling tower. Requires hot, dry steam, and can cause corrosion of generator

Flash Steam

Drops pressure so fluid can evaporate to steam driving turbine. Waste brine recombined with waste and pumped back into reservoir. Requires hot steam and sulphur smell if small leaks

Binary Cycle

Heat exchanger transfers heat from brine to isobutane to drive turbine. Condensed via cooling water so it keeps recondensing. Lower temp and pressure requires, not vaporised so sulphur smell less likely

Pros of Geothermal

Low emissions, free heat, not intermittent, easy to predict output

Cons of Geothermal

Location specific, gases may be released during digging, high capital expenses, risk of triggering earthquakes, needs to be pumped back into reservoir faster than its depleted