Where do you get 150 000 kW? Even assuming all the miners are the best I could find (Achilles lab series) [1] that comes to 190000kW based on current hashrate [2].
Your transactions/second is also bit off. Right now based on blockchain.info the highest transaction day had 115787 transactions [3]. And that day the backlog of unconfirmed transactions got as high as almost 6000 unconfirmed transactions [4]. It doesn't matter at all if the network can "theoretically" support 7tps if it chokes at 1.3tps
That brings the actual kWh cost into 40kWh/transaction and up to the same ballback as what GP had.
Based on the arguments on forums right now it looks that increasing the block size is impossible. Because that would hard fork the blockchain.
When new coins are no longer being awarded to miners then people will have to start to pay the transaction fees themselves. Right now the mining is subsidized by what basically amounts to printing money and thus effectively is a small inflationary tax to everyone using bitcoin.
[1] https://en.bitcoin.it/wiki/Mining_hardware_comparison
[2] https://blockchain.info/charts/hash-rate
[3] https://blockchain.info/charts/n-transactions
[4] https://imgur.com/GAklIdZ The most delicious moment was not screencapped, but this is quite close. Even as this was happening the miners happily issued small blocks (500kB and less).