Every one of us who is trying to “go green” has at one time or another probably wondered, “How can I ensure that the energy that I am buying comes from clean, renewable sources?”

We all know that we’re going to use electricity at home and we’ve probably all thought, “If I could pay a little extra money to ensure that the energy I use is ‘green’, I would.”

So, how can you buy “green energy”?

It turns out that there are a number of different choices that we have. The choices provide a wide variety of costs and benefits.

Choice #1: Install Renewable Energy Sources Yourself

I am listing this option first, not because it is the easiest or cheapest solution or even necessarily the recommended solution, but because it is probably the easiest to understand.

I think we all can understand that if you install photovoltaic panels (”solar panels”) or a solar hot water heater on your roof, a wind turbine in your backyard, or a ground-source heating system (aka, a “geothermal heat pump”), how these directly benefit you. The energy from the solar panels or the wind turbine go directly to your house to power your electrical needs. The water from the hot water heater supplies your hot water needs. The heat from the geothermal system goes directly to your house to provide heat.

The obvious impediment to any of these solutions is cost; each requires a reasonably large up-front investment to buy and install. Now, there are federal tax credits, state tax credits, and even potentially grants to help offset these costs. But, even putting all of this together, we are talking real money.

In addition, the applicability of each of these may vary based on where you live (how many hours of direct sunlight do you get per day), the orientation of your house, the average wind speeds near your house, etc.

So, even if you had the inclination and the money, it isn’t necessarily true that you could take advantage of these choices.

Choice #2: Buy “Green Energy” from Your Electricity Provider

Every one of us is probably paying some company to provide electricity to our house. Depending on where you live, that could be NSTAR, National Grid (formerly known as Mass Electric), or another regional energy provider.

Each of those companies buys its energy from someone. And that energy can come from a variety of sources.

Some electric companies offer you a choice of how you want your electricity generated.

For example, Mass Electric has a GreenUp program that allows its consumers to choose to have some or all of their energy to come from renewable sources.

For consumers who have this option, this is a simple way to switch to green energy. There is no upfront cost. The ongoing costs are modest — approximately $10 - $20 / month of extra cost to switch to purely green energy sources.

Unfortunately, not all electricity providers offer clean energy options. For example, NSTAR does not offer any green energy choices to its consumers. Booooo NSTAR!

Choice #3: “Green Up” Your Existing Energy

This choice is probably the most complex to understand, but also an inexpensive choice that is available to everyone, independent of who their energy provider is.

There are many organizations out there that sell renewable energy credits (RECs) — these are also known as “green tags” or Tradable Renewable Certificates (TRCs).

I’m not going to get into the full details of how RECs work here — we’ll save that for another blog entry — but the basic idea is that you spend a little extra money to take your existing “dirty” energy supply and spend some extra money to buy the “green qualities” of clean energy.

Organizations that help you “green up” your energy supply include:

• The New England Wind Fund
• Native Energy

You can find a list of companies that sell RECs from the Green-e website. You can even choose what type of energy (wind, solar, biomass, etc.) that you want to support and what geographic region you want to support.

The costs of “greening up” your energy are relatively modest. Through Native Energy a $8 - $16 / month contribution can green up all of the energy for your house.