Need some help with Heating shop

[vrocket]

I have a 30x30 shop, which Installed some in floor tubing before slab was poured. I need to finish the hookup now and I am not sure which way to go or what I need. I have ONLY electricity in this shop. Sounds like I could use a electric instant on, water heater or a electric water heater with tank? No water, no gas, no propane. I have included some picture of the tubing under my stair case. I can run water out to shop from house to fill system. Long story why no water and gas... any ideas or suggestions would be appreciated.