For every watt you put in, you need to cool that watt, which requires a high percentage of a second watt. Some of that equipment is almost 20 years old, maybe more. One those old machines could warm an office back in 1994.
On top of the electricity for the servers and for cooling, there is also maintenance: replacing ancient drives and other system components when they fail (which may require paying out the arse for some gear on eBay), fixing cooling equipment (ever replaced a dead AC unit in your house?), network maintenance and upgrades, internet connection, etc., etc. The list goes on and on. $20K seems reasonable to me. He's not asking for $20MM or even $200K, guys. He's not mining bitcoins. Please be reasonable.
$20k is not inherently unreasonable, but I won't donate if I don't have a better idea of what is going on "behind the curtain", which is why I'm idly musing.
Quick back-of-the-envelope: At $0.12/kWh, the shortfall is about 20kW of continuous power.
Do they have significant HVAC requirements? I don't think I see 20kW of iron in the two racks that get pictured.