TDU Delivery Charge: TDU stands for transmission and delivery utility — in other words, the utility company in your area that is actually piping the energy from the power generation companies into your home. (Remember, REPs in Texas are just the middleman.) The TDU delivery charge is set by the utility and is consistent from plan to plan and provider to provider within its service areas. For example, AEP , the TDU for Corpus Christi, charges the same delivery fee for all TXU, Direct Energy, and Reliant plans. You don't typically get a choice in utility company, and therefore, these fees are pretty much unavoidable, non-negotiable, and won't factor into choosing an electricity plan or provider.
Residential real-time pricing customers pay electric supply prices that vary by the hour. To make a meaningful comparison between variable RRTP rates and RES offers, customers should compare their past electric supply cost savings from the total Electric Supply section of the bill, provided by their RRTP provider, with an electric supply cost savings estimate provided by RESs. Alternatively, customers can compute their average real-time hourly price in cents per kWh (each month the average real-time price is equal to the total of the Electric Supply section of the bill divided by the monthly kWh) to compare with RES offers posted in cents per kWh. Customer should bear in mind, however, that because RRTP rates vary over time, past savings do not predict future savings, but only serve as a guide to compare past performance.
Then, in 2002, Texas deregulated the electricity market and everybody cheered!  Except that, sure, deregulation opened up the market to competition that may (or may not) have resulted in lower rates, but it introduced a whole host of other issues.  These issues may not have been factors before but now they’re critical when you’re on the look-out for cheap Houston electricity providers.
How does that work? Spark Energy buys electricity and competes in the market for the best price -- a competition that ultimately drives prices down and allows us to deliver more value for your money. In Texas, switching to a different electricity provider is kind of like changing to a different long distance company. When you switch to Spark Energy, the utility will continue to deliver electricity to your home but Spark Energy will handle all the billing, including the utility’s delivery fees and the electricity you actually use.

There are over 60 different energy suppliers competing for your business on any given day in Texas. Many of these electric companies have websites that are confusing and nearly impossible to navigate, their rates and fees hidden by dense industry jargon and misleading advertising. Who has the spare the time to sort through the choices spread out over all these different sites and companies?