I love a good solar panel. I have them on my house and on my calculator. And, I’m enthusiastic about what is happening to costs of renewable energy. The future for renewables is bright and it cannot come soon enough. I am massively in favor of large, utility-scale solar and wind installations and look forward to my engineering friends figuring out grid–scale, economically-competitive storage solutions.

I also love truffles – yes I am a food snob. On pasta, they are amazing. But there are other places, where they are not the best use of this expensive resource. The same is true for solar panels.

What am I talking about? Like so many people, I take BART to work. I almost dropped my Kindle when I saw that my local BART station replaced its massive parking lot with car ports covered by solar panels. Twitter is full of group hug messages about how warm and fuzzy it makes us feel that our Teslas are now covered by shade providing solar panels. Big banner ads push this even further by stating that the solar panels generate enough electricity to power 200 homes.

So what is my gripe? We live in carmageddon. Traffic in the Bay Area is at an all-time high, and 40% of California’s greenhouse gas emissions are generated by vehicles. If we are going to tackle this problem we should incentivize people to take public transport. Parking at my station in Lafayette, a wealthy little California town, fills up by 7 a.m. at the latest, so many people drive.

What could one have done? One could have built a four- or six-story parking structure on the existing footprint. This would have at least quadrupled the parking capacity without changing the footprint. How much energy would that save, assuming people would opt to BART to work instead of drive if they could find a parking spot? If we assume people are commuting to San Francisco and back in an average car, that makes 9,774 gallons saved per day. That is 30 times the amount of energy the solar panels on the parking structures generate each day. Mic Drop.

For comparison, the Walnut Creek Station, one stop up, just put in a multistory parking garage and ample locked bike parking. It’s full at all times as are the bike lockers. Go Walnut Creek! Also, Walnut Creek has encouraged the development of multistory apartment buildings in walking distance to the BART station. This would enable the Kombucha-sipping, CBD-vaping generation to walk to BART and get to work without ever worrying about owning a car they don’t really want anyway.

My simple calculation does not even take into consideration the congestion externalities these parked cars no longer cause, the local pollution that does not end up in kids’ lungs and the safety consequences of having more cars. Of course I understand that dispatching more trains is a hard problem and increasing the capacity of local rail systems is not straightforward. BART is working hard on a better future. But failing to increase parking capacity and putting Band-Aid solar panels on top of single-story lots is just silly. Put those panels on top of a six-floor parking garage and then advertise savings if you have to.

Of course, there is always the NIMBY issue of land-use restrictions. The rich people of Lafayette probably don’t like the increase in local road traffic driving to BART, and multistory structures might be visually offensive. If we are going to make real environmental progress, we’ll need to get beyond warm glow to hard numbers.