[enlyth]

Is gas expensive though? It's like 6p per kWh at the moment with electricity about 25p per kWh for consumers.

I think gas is dirt cheap, heating your home and hot water with electricity is 4x more expensive and costs hundreds a month.

[simonsquiff]

It’s only x4 more expensive to use electricity with old methods like immersion / resistance heaters

Heat pumps are 400% efficient or more, so have parity or better with gas prices

[leonidasrup]

Heat pump have problems to reach high enough temperatures for most industrial heat applications.

https://www.irena.org/Innovation-landscape-for-smart-electri...

With electric resistance heating you can gen very high temperatures, but with less than 100% efficiency. With electric arc heating you can melt steel, but again less than 100% efficient.

[pfdietz]

> Heat pump have problems to reach high enough temperatures for most industrial heat applications.

They do if you start from ambient temperature, but they can be more effective if they are pumping heat out of the waste heat stream of a process. This requires different working fluids than lower temperature systems, though.

Most industrial heat energy is not consumed at very high temperature. IIRC, 2/3rds is at less than 300 C.

Electric resistance heating might also allow PV to dispense with auxiliary equipment, like inverters, so even if inefficient that might not matter as much. Heat also allows easy long duration storage at scale, even at rather high temperature, so resistive heating can be used with intermittently available cheap surplus power.

[leonidasrup]

For example Haber process used for ammonia production, requires a temperature of at least 400 °C to be efficient. This process is accounting for 1–2% of global energy consumption, 3% of global carbon emissions, and 3% to 5% of natural gas consumption.

https://en.wikipedia.org/wiki/Haber_process

Electric resistance heating generated from PV will supply energy only for few hours each day.

Heating storage (also cold storage) in industrial applications is possible and is done, but in many cases you are limited by allowed temperature range of chemical/physical processes. For example you are limited on the lower side by melting temperature of material and on higher side by high temperature corrosion.

Cold storage for electric demand response https://www.enersponse.com/cold-storage

In cement industries models have been developed to flatten the grid's hourly demand curve by minimizing the industrial customer's hourly peak loads and maximizing the shifting of demand to off-peak periods.

https://www.sciencedirect.com/science/article/pii/S030626192...

[pfdietz]

> For example Haber process used for ammonia production, requires a temperature of at least 400 °C to be efficient.

I should note that this process doesn't require external heat input (except at startup). The reaction is exothermic and the excess heat is used to make steam that either is used to make power or to provide steam to other processes. It does require pressurization, but that's an input of work, not heat.

It would be nice if the process could be run at lower temperature, but we just don't have the catalysts for that.

> Electric resistance heating generated from PV will supply energy only for few hours each day.

Electric resistance heat is very storable and can provide heat 24/7, possibly even 24/7/365 at high latitude with PV.

[enlyth]

That's cool but who is going to pay the upfront cost for the heat pumps? The sources I could find say we currently have 412 heat pumps per 100k people in the UK.

Ordinary people can't just afford to drop 10k for a heat pump + installation for it to pay for itself 20 years down the line.

[leonidasrup]

You have to include the costs of conversion - gas power plant. Also you have some some losses during conversion from heat to electricity, a modern gas power plant can be up to 60% efficient.

https://en.wikipedia.org/wiki/Gas-fired_power_plant

Then you have electric distribution costs (costs for building and maintenance of electric grid, transformers, power lines).

In many industrial process heat applications direct burning of gas is preferred, because it lowers the costs.